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视频解码同步

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[原]零基础学习视频解码之同步视频

2014-08-06 00:20 by 雪夜&流星, 525 阅读, 0 评论, 收藏, 编辑

在前面几章，我们了解了视频解码的原理，了解了音频解码的原理，也将视频和音频分别放在了相应的解码线程中去了。所以这整个过程中，我们有一个基本无用的电影播放器。它可以播放视频，它也可以播放音频，但是这个并不完整，因为音频和视频并不同步，我们接下来要做的就是将音频和视频同步起来。

音频流有一个采样率，并且视频流具有每秒值的帧。但是，如果我们只是靠只是计算帧和帧速率乘以同步视频，有的情况下，它会声画不同步的。

当我们从av_read_frame()的数据包，它包含了这个包里面的信息的PTS和DTS值。但我们真正想要的是我们的新解码原始帧的PTS，所以我们知道什么时候来显示它。但是，我们从avcodec_decode_video得到的给了我们一个AVFrame，不包含有用的PTS值。然而，ffmpeg的重新排序，使数据包的DTS由avcodec_decode_video（处理的数据包）将永远是相同的因为它返回的帧的PTS。

有另一种方式来找出一帧的PTS，我们可以重新排列数据包。我们保存一帧的第一个包的PTS：这将是最终的帧的PTS。因此，当该流不给我们一个DTS，我们只是用这个保存的。我们可以通过avcodec_decode_video()找出哪些数据包是一个帧的第一个数据包。

虽然这一切都很好，好到什么时候我们应该表现出特定的视频帧。但是我们如何真正做到同步? 这里的想法：我们利用这个框架，计算出下一个应该显示的时候。然后，我们只需设置一个新的超时时间量后，再次刷新视频。正如你所预料的，我们核对系统时钟的下一帧的PTS值，看看我们的超时时间是多久。这种方法有效，但也有需要被处理的两个问题。

第一是知道何时下一个时刻将成为问题。现在，你可能会认为，我们可以在视频速率仅添加到当前PTS - 你会是基本上是正确的。然而，要重复某些种类的视频的帧。这意味着我们应该重复当前帧中的特定的次数。这可能会导致程序太早显示下一帧。因此，我们需要考虑到这一点。

第二个问题是，大量的视频文件都没有我们需要的视频速率。因此，我们有三种选择：同步音频到视频，同步视频到音频，或者两者同步至一个外部时钟（如计算机）。现在，我们将同步视频到音频。

一、添加数据结构，VideoState新增了audio_clock、video_clock，分别用来做相应的音频同步和视频同步

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/* ============================================================================ Name        : VideoDecodeTutorial5_1.c Author      : clarck Version     : Copyright   : Your copyright notice Description : Hello World in C, Ansi-style ============================================================================ */#include <stdio.h>#include <stdlib.h>#include <math.h>#include <libavcodec/avcodec.h>#include <libavformat/avformat.h>#include <libavformat/avio.h>#include <libswscale/swscale.h>#include <libavutil/avstring.h>#include <SDL/SDL.h>#include <SDL/SDL_thread.h>#ifdef __MINGW32__#undef main /* Prevents SDL from overriding main() */#endif#define SDL_AUDIO_BUFFER_SIZE 1024#define MAX_AUDIOQ_SIZE (5 * 16 * 1024)#define MAX_VIDEOQ_SIZE (5 * 256 * 1024)#define AV_SYNC_THRESHOLD 0.01#define AV_NOSYNC_THRESHOLD 10.0#define FF_ALLOC_EVENT   (SDL_USEREVENT)#define FF_REFRESH_EVENT (SDL_USEREVENT + 1)#define FF_QUIT_EVENT (SDL_USEREVENT + 2)#define VIDEO_PICTURE_QUEUE_SIZE 1#define AVCODEC_MAX_AUDIO_FRAME_SIZE 192000 // 1 second of 48khz 32bit audiotypedef struct PacketQueue {    AVPacketList *first_pkt, *last_pkt;    int nb_packets;    int size;    SDL_mutex *mutex;    SDL_cond *cond;} PacketQueue;typedef struct VideoPicture {    SDL_Overlay *bmp;    int width, height; /* source height & width */    int allocated;    double pts;} VideoPicture;typedef struct VideoState {    AVFormatContext *pFormatCtx;    int videoStream, audioStream;    double audio_clock;    AVStream *audio_st;    PacketQueue audioq;    uint8_t audio_buf[(AVCODEC_MAX_AUDIO_FRAME_SIZE * 3) / 2];    unsigned int audio_buf_size;    unsigned int audio_buf_index;    AVPacket audio_pkt;    uint8_t *audio_pkt_data;    int audio_pkt_size;    AVFrame audio_frame;    AVStream *video_st;    PacketQueue videoq;    int audio_hw_buf_size;    double frame_timer;    double frame_last_pts;    double frame_last_delay;    double video_clock; ///<pts of last decoded frame / predicted pts of next decoded frame    VideoPicture pictq[VIDEO_PICTURE_QUEUE_SIZE];    int pictq_size, pictq_rindex, pictq_windex;    SDL_mutex *pictq_mutex;    SDL_cond *pictq_cond;    SDL_Thread *parse_tid;    SDL_Thread *video_tid;    AVIOContext *io_ctx;    struct SwsContext *sws_ctx;    char filename[1024];    int quit;} VideoState;int main(int argc, char *argv[]) {    return EXIT_SUCCESS;}
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二、添加AVPacket排队的操作

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/* ============================================================================ Name        : VideoDecodeTutorial5_1.c Author      : clarck Version     : Copyright   : Your copyright notice Description : Hello World in C, Ansi-style ============================================================================ */#include <stdio.h>#include <stdlib.h>#include <math.h>#include <libavcodec/avcodec.h>#include <libavformat/avformat.h>#include <libavformat/avio.h>#include <libswscale/swscale.h>#include <libavutil/avstring.h>#include <SDL/SDL.h>#include <SDL/SDL_thread.h>#ifdef __MINGW32__#undef main /* Prevents SDL from overriding main() */#endif#define SDL_AUDIO_BUFFER_SIZE 1024#define MAX_AUDIOQ_SIZE (5 * 16 * 1024)#define MAX_VIDEOQ_SIZE (5 * 256 * 1024)#define AV_SYNC_THRESHOLD 0.01#define AV_NOSYNC_THRESHOLD 10.0#define FF_ALLOC_EVENT   (SDL_USEREVENT)#define FF_REFRESH_EVENT (SDL_USEREVENT + 1)#define FF_QUIT_EVENT (SDL_USEREVENT + 2)#define VIDEO_PICTURE_QUEUE_SIZE 1#define AVCODEC_MAX_AUDIO_FRAME_SIZE 192000 // 1 second of 48khz 32bit audiotypedef struct PacketQueue {    AVPacketList *first_pkt, *last_pkt;    int nb_packets;    int size;    SDL_mutex *mutex;    SDL_cond *cond;} PacketQueue;typedef struct VideoPicture {    SDL_Overlay *bmp;    int width, height; /* source height & width */    int allocated;    double pts;} VideoPicture;typedef struct VideoState {    AVFormatContext *pFormatCtx;    int videoStream, audioStream;    double audio_clock;    AVStream *audio_st;    PacketQueue audioq;    uint8_t audio_buf[(AVCODEC_MAX_AUDIO_FRAME_SIZE * 3) / 2];    unsigned int audio_buf_size;    unsigned int audio_buf_index;    AVPacket audio_pkt;    uint8_t *audio_pkt_data;    int audio_pkt_size;    AVFrame audio_frame;    AVStream *video_st;    PacketQueue videoq;    int audio_hw_buf_size;    double frame_timer;    double frame_last_pts;    double frame_last_delay;    double video_clock; ///<pts of last decoded frame / predicted pts of next decoded frame    VideoPicture pictq[VIDEO_PICTURE_QUEUE_SIZE];    int pictq_size, pictq_rindex, pictq_windex;    SDL_mutex *pictq_mutex;    SDL_cond *pictq_cond;    SDL_Thread *parse_tid;    SDL_Thread *video_tid;    AVIOContext *io_ctx;    struct SwsContext *sws_ctx;    char filename[1024];    int quit;} VideoState;/* Since we only have one decoding thread, the Big Struct can be global in case we need it. */VideoState *global_video_state;void packet_queue_init(PacketQueue *q) {    memset(q, 0, sizeof(PacketQueue));    q->mutex = SDL_CreateMutex();    q->cond = SDL_CreateCond();}int packet_queue_put(PacketQueue *q, AVPacket *pkt) {    AVPacketList *pkt1;    if (av_dup_packet(pkt) < 0) {        return -1;    }    pkt1 = av_malloc(sizeof(AVPacketList));    if (!pkt1)        return -1;    pkt1->pkt = *pkt;    pkt1->next = NULL;    SDL_LockMutex(q->mutex);    if (!q->last_pkt)        q->first_pkt = pkt1;    else        q->last_pkt->next = pkt1;    q->last_pkt = pkt1;    q->nb_packets++;    q->size += pkt1->pkt.size;    SDL_CondSignal(q->cond);    SDL_UnlockMutex(q->mutex);    return 0;}static int packet_queue_get(PacketQueue *q, AVPacket *pkt, int block) {    AVPacketList *pkt1;    int ret;    SDL_LockMutex(q->mutex);    for (;;) {        if (global_video_state->quit) {            ret = -1;            break;        }        pkt1 = q->first_pkt;        if (pkt1) {            q->first_pkt = pkt1->next;            if (!q->first_pkt)                q->last_pkt = NULL;            q->nb_packets--;            q->size -= pkt1->pkt.size;            *pkt = pkt1->pkt;            av_free(pkt1);            ret = 1;            break;        } else if (!block) {            ret = 0;            break;        } else {            SDL_CondWait(q->cond, q->mutex);        }    }    SDL_UnlockMutex(q->mutex);    return ret;}int main(int argc, char *argv[]) {    return EXIT_SUCCESS;}
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三、得到音频时钟

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/* ============================================================================ Name        : VideoDecodeTutorial5_1.c Author      : clarck Version     : Copyright   : Your copyright notice Description : Hello World in C, Ansi-style ============================================================================ */#include <stdio.h>#include <stdlib.h>#include <math.h>#include <libavcodec/avcodec.h>#include <libavformat/avformat.h>#include <libavformat/avio.h>#include <libswscale/swscale.h>#include <libavutil/avstring.h>#include <SDL/SDL.h>#include <SDL/SDL_thread.h>#ifdef __MINGW32__#undef main /* Prevents SDL from overriding main() */#endif#define SDL_AUDIO_BUFFER_SIZE 1024#define MAX_AUDIOQ_SIZE (5 * 16 * 1024)#define MAX_VIDEOQ_SIZE (5 * 256 * 1024)#define AV_SYNC_THRESHOLD 0.01#define AV_NOSYNC_THRESHOLD 10.0#define FF_ALLOC_EVENT   (SDL_USEREVENT)#define FF_REFRESH_EVENT (SDL_USEREVENT + 1)#define FF_QUIT_EVENT (SDL_USEREVENT + 2)#define VIDEO_PICTURE_QUEUE_SIZE 1#define AVCODEC_MAX_AUDIO_FRAME_SIZE 192000 // 1 second of 48khz 32bit audiotypedef struct PacketQueue {    AVPacketList *first_pkt, *last_pkt;    int nb_packets;    int size;    SDL_mutex *mutex;    SDL_cond *cond;} PacketQueue;typedef struct VideoPicture {    SDL_Overlay *bmp;    int width, height; /* source height & width */    int allocated;    double pts;} VideoPicture;typedef struct VideoState {    AVFormatContext *pFormatCtx;    int videoStream, audioStream;    double audio_clock;    AVStream *audio_st;    PacketQueue audioq;    uint8_t audio_buf[(AVCODEC_MAX_AUDIO_FRAME_SIZE * 3) / 2];    unsigned int audio_buf_size;    unsigned int audio_buf_index;    AVPacket audio_pkt;    uint8_t *audio_pkt_data;    int audio_pkt_size;    AVFrame audio_frame;    AVStream *video_st;    PacketQueue videoq;    int audio_hw_buf_size;    double frame_timer;    double frame_last_pts;    double frame_last_delay;    double video_clock; ///<pts of last decoded frame / predicted pts of next decoded frame    VideoPicture pictq[VIDEO_PICTURE_QUEUE_SIZE];    int pictq_size, pictq_rindex, pictq_windex;    SDL_mutex *pictq_mutex;    SDL_cond *pictq_cond;    SDL_Thread *parse_tid;    SDL_Thread *video_tid;    AVIOContext *io_ctx;    struct SwsContext *sws_ctx;    char filename[1024];    int quit;} VideoState;/* Since we only have one decoding thread, the Big Struct can be global in case we need it. */VideoState *global_video_state;void packet_queue_init(PacketQueue *q) {    memset(q, 0, sizeof(PacketQueue));    q->mutex = SDL_CreateMutex();    q->cond = SDL_CreateCond();}int packet_queue_put(PacketQueue *q, AVPacket *pkt) {    AVPacketList *pkt1;    if (av_dup_packet(pkt) < 0) {        return -1;    }    pkt1 = av_malloc(sizeof(AVPacketList));    if (!pkt1)        return -1;    pkt1->pkt = *pkt;    pkt1->next = NULL;    SDL_LockMutex(q->mutex);    if (!q->last_pkt)        q->first_pkt = pkt1;    else        q->last_pkt->next = pkt1;    q->last_pkt = pkt1;    q->nb_packets++;    q->size += pkt1->pkt.size;    SDL_CondSignal(q->cond);    SDL_UnlockMutex(q->mutex);    return 0;}static int packet_queue_get(PacketQueue *q, AVPacket *pkt, int block) {    AVPacketList *pkt1;    int ret;    SDL_LockMutex(q->mutex);    for (;;) {        if (global_video_state->quit) {            ret = -1;            break;        }        pkt1 = q->first_pkt;        if (pkt1) {            q->first_pkt = pkt1->next;            if (!q->first_pkt)                q->last_pkt = NULL;            q->nb_packets--;            q->size -= pkt1->pkt.size;            *pkt = pkt1->pkt;            av_free(pkt1);            ret = 1;            break;        } else if (!block) {            ret = 0;            break;        } else {            SDL_CondWait(q->cond, q->mutex);        }    }    SDL_UnlockMutex(q->mutex);    return ret;}double get_audio_clock(VideoState *is) {    double pts;    int hw_buf_size, bytes_per_sec, n;    pts = is->audio_clock; /* maintained in the audio thread */    hw_buf_size = is->audio_buf_size - is->audio_buf_index;    bytes_per_sec = 0;    n = is->audio_st->codec->channels * 2;    if (is->audio_st) {        bytes_per_sec = is->audio_st->codec->sample_rate * n;    }    if (bytes_per_sec) {        pts -= (double) hw_buf_size / bytes_per_sec;    }    return pts;}int main(int argc, char *argv[]) {    return EXIT_SUCCESS;}
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四、解码音频包的同时更新音频时钟

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/* ============================================================================ Name        : VideoDecodeTutorial5_1.c Author      : clarck Version     : Copyright   : Your copyright notice Description : Hello World in C, Ansi-style ============================================================================ */#include <stdio.h>#include <stdlib.h>#include <math.h>#include <libavcodec/avcodec.h>#include <libavformat/avformat.h>#include <libavformat/avio.h>#include <libswscale/swscale.h>#include <libavutil/avstring.h>#include <SDL/SDL.h>#include <SDL/SDL_thread.h>#ifdef __MINGW32__#undef main /* Prevents SDL from overriding main() */#endif#define SDL_AUDIO_BUFFER_SIZE 1024#define MAX_AUDIOQ_SIZE (5 * 16 * 1024)#define MAX_VIDEOQ_SIZE (5 * 256 * 1024)#define AV_SYNC_THRESHOLD 0.01#define AV_NOSYNC_THRESHOLD 10.0#define FF_ALLOC_EVENT   (SDL_USEREVENT)#define FF_REFRESH_EVENT (SDL_USEREVENT + 1)#define FF_QUIT_EVENT (SDL_USEREVENT + 2)#define VIDEO_PICTURE_QUEUE_SIZE 1#define AVCODEC_MAX_AUDIO_FRAME_SIZE 192000 // 1 second of 48khz 32bit audiotypedef struct PacketQueue {    AVPacketList *first_pkt, *last_pkt;    int nb_packets;    int size;    SDL_mutex *mutex;    SDL_cond *cond;} PacketQueue;typedef struct VideoPicture {    SDL_Overlay *bmp;    int width, height; /* source height & width */    int allocated;    double pts;} VideoPicture;typedef struct VideoState {    AVFormatContext *pFormatCtx;    int videoStream, audioStream;    double audio_clock;    AVStream *audio_st;    PacketQueue audioq;    uint8_t audio_buf[(AVCODEC_MAX_AUDIO_FRAME_SIZE * 3) / 2];    unsigned int audio_buf_size;    unsigned int audio_buf_index;    AVPacket audio_pkt;    uint8_t *audio_pkt_data;    int audio_pkt_size;    AVFrame audio_frame;    AVStream *video_st;    PacketQueue videoq;    int audio_hw_buf_size;    double frame_timer;    double frame_last_pts;    double frame_last_delay;    double video_clock; ///<pts of last decoded frame / predicted pts of next decoded frame    VideoPicture pictq[VIDEO_PICTURE_QUEUE_SIZE];    int pictq_size, pictq_rindex, pictq_windex;    SDL_mutex *pictq_mutex;    SDL_cond *pictq_cond;    SDL_Thread *parse_tid;    SDL_Thread *video_tid;    AVIOContext *io_ctx;    struct SwsContext *sws_ctx;    char filename[1024];    int quit;} VideoState;/* Since we only have one decoding thread, the Big Struct can be global in case we need it. */VideoState *global_video_state;void packet_queue_init(PacketQueue *q) {    memset(q, 0, sizeof(PacketQueue));    q->mutex = SDL_CreateMutex();    q->cond = SDL_CreateCond();}int packet_queue_put(PacketQueue *q, AVPacket *pkt) {    AVPacketList *pkt1;    if (av_dup_packet(pkt) < 0) {        return -1;    }    pkt1 = av_malloc(sizeof(AVPacketList));    if (!pkt1)        return -1;    pkt1->pkt = *pkt;    pkt1->next = NULL;    SDL_LockMutex(q->mutex);    if (!q->last_pkt)        q->first_pkt = pkt1;    else        q->last_pkt->next = pkt1;    q->last_pkt = pkt1;    q->nb_packets++;    q->size += pkt1->pkt.size;    SDL_CondSignal(q->cond);    SDL_UnlockMutex(q->mutex);    return 0;}static int packet_queue_get(PacketQueue *q, AVPacket *pkt, int block) {    AVPacketList *pkt1;    int ret;    SDL_LockMutex(q->mutex);    for (;;) {        if (global_video_state->quit) {            ret = -1;            break;        }        pkt1 = q->first_pkt;        if (pkt1) {            q->first_pkt = pkt1->next;            if (!q->first_pkt)                q->last_pkt = NULL;            q->nb_packets--;            q->size -= pkt1->pkt.size;            *pkt = pkt1->pkt;            av_free(pkt1);            ret = 1;            break;        } else if (!block) {            ret = 0;            break;        } else {            SDL_CondWait(q->cond, q->mutex);        }    }    SDL_UnlockMutex(q->mutex);    return ret;}double get_audio_clock(VideoState *is) {    double pts;    int hw_buf_size, bytes_per_sec, n;    pts = is->audio_clock; /* maintained in the audio thread */    hw_buf_size = is->audio_buf_size - is->audio_buf_index;    bytes_per_sec = 0;    n = is->audio_st->codec->channels * 2;    if (is->audio_st) {        bytes_per_sec = is->audio_st->codec->sample_rate * n;    }    if (bytes_per_sec) {        pts -= (double) hw_buf_size / bytes_per_sec;    }    return pts;}int audio_decode_frame(VideoState *is, double *pts_ptr) {    int len1, data_size = 0, n;    AVPacket *pkt = &is->audio_pkt;    double pts;    for (;;) {        while (is->audio_pkt_size > 0) {            int got_frame = 0;            len1 = avcodec_decode_audio4(is->audio_st->codec, &is->audio_frame,                    &got_frame, pkt);            if (len1 < 0) {                /* if error, skip frame */                is->audio_pkt_size = 0;                break;            }            if (got_frame) {                data_size = is->audio_frame.linesize[0];                /*av_samples_get_buffer_size(NULL,                 is->audio_st->codec->channels,                 is->audio_frame.nb_samples,                 is->audio_st->codec->sample_fmt, 1);*/                memcpy(is->audio_buf, is->audio_frame.data[0], data_size);            }            is->audio_pkt_data += len1;            is->audio_pkt_size -= len1;            if (data_size <= 0) {                /* No data yet, get more frames */                continue;            }            pts = is->audio_clock;            *pts_ptr = pts;            n = 2 * is->audio_st->codec->channels;            is->audio_clock += (double) data_size                    / (double) (n * is->audio_st->codec->sample_rate);            /* We have data, return it and come back for more later */            return data_size;        }        if (pkt->data)            av_free_packet(pkt);        if (is->quit) {            return -1;        }        /* next packet */        if (packet_queue_get(&is->audioq, pkt, 1) < 0) {            return -1;        }        is->audio_pkt_data = pkt->data;        is->audio_pkt_size = pkt->size;        /* if update, update the audio clock w/pts */        if (pkt->pts != AV_NOPTS_VALUE) {            is->audio_clock = av_q2d(is->audio_st->time_base) * pkt->pts;        }    }    return 0;}int main(int argc, char *argv[]) {    return EXIT_SUCCESS;}
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五、同步视频，根据音频时钟计算下显示需要的延时时间，并利用上一篇文章所使用的schedule_refresh来刷新显示的帧。

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/* ============================================================================ Name        : VideoDecodeTutorial5_1.c Author      : clarck Version     : Copyright   : Your copyright notice Description : Hello World in C, Ansi-style ============================================================================ */#include <stdio.h>#include <stdlib.h>#include <math.h>#include <libavcodec/avcodec.h>#include <libavformat/avformat.h>#include <libavformat/avio.h>#include <libswscale/swscale.h>#include <libavutil/avstring.h>#include <SDL/SDL.h>#include <SDL/SDL_thread.h>#ifdef __MINGW32__#undef main /* Prevents SDL from overriding main() */#endif#define SDL_AUDIO_BUFFER_SIZE 1024#define MAX_AUDIOQ_SIZE (5 * 16 * 1024)#define MAX_VIDEOQ_SIZE (5 * 256 * 1024)#define AV_SYNC_THRESHOLD 0.01#define AV_NOSYNC_THRESHOLD 10.0#define FF_ALLOC_EVENT   (SDL_USEREVENT)#define FF_REFRESH_EVENT (SDL_USEREVENT + 1)#define FF_QUIT_EVENT (SDL_USEREVENT + 2)#define VIDEO_PICTURE_QUEUE_SIZE 1#define AVCODEC_MAX_AUDIO_FRAME_SIZE 192000 // 1 second of 48khz 32bit audiotypedef struct PacketQueue {    AVPacketList *first_pkt, *last_pkt;    int nb_packets;    int size;    SDL_mutex *mutex;    SDL_cond *cond;} PacketQueue;typedef struct VideoPicture {    SDL_Overlay *bmp;    int width, height; /* source height & width */    int allocated;    double pts;} VideoPicture;typedef struct VideoState {    AVFormatContext *pFormatCtx;    int videoStream, audioStream;    double audio_clock;    AVStream *audio_st;    PacketQueue audioq;    uint8_t audio_buf[(AVCODEC_MAX_AUDIO_FRAME_SIZE * 3) / 2];    unsigned int audio_buf_size;    unsigned int audio_buf_index;    AVPacket audio_pkt;    uint8_t *audio_pkt_data;    int audio_pkt_size;    AVFrame audio_frame;    AVStream *video_st;    PacketQueue videoq;    int audio_hw_buf_size;    double frame_timer;    double frame_last_pts;    double frame_last_delay;    double video_clock; ///<pts of last decoded frame / predicted pts of next decoded frame    VideoPicture pictq[VIDEO_PICTURE_QUEUE_SIZE];    int pictq_size, pictq_rindex, pictq_windex;    SDL_mutex *pictq_mutex;    SDL_cond *pictq_cond;    SDL_Thread *parse_tid;    SDL_Thread *video_tid;    AVIOContext *io_ctx;    struct SwsContext *sws_ctx;    char filename[1024];    int quit;} VideoState;/* Since we only have one decoding thread, the Big Struct can be global in case we need it. */VideoState *global_video_state;void packet_queue_init(PacketQueue *q) {    memset(q, 0, sizeof(PacketQueue));    q->mutex = SDL_CreateMutex();    q->cond = SDL_CreateCond();}int packet_queue_put(PacketQueue *q, AVPacket *pkt) {    AVPacketList *pkt1;    if (av_dup_packet(pkt) < 0) {        return -1;    }    pkt1 = av_malloc(sizeof(AVPacketList));    if (!pkt1)        return -1;    pkt1->pkt = *pkt;    pkt1->next = NULL;    SDL_LockMutex(q->mutex);    if (!q->last_pkt)        q->first_pkt = pkt1;    else        q->last_pkt->next = pkt1;    q->last_pkt = pkt1;    q->nb_packets++;    q->size += pkt1->pkt.size;    SDL_CondSignal(q->cond);    SDL_UnlockMutex(q->mutex);    return 0;}static int packet_queue_get(PacketQueue *q, AVPacket *pkt, int block) {    AVPacketList *pkt1;    int ret;    SDL_LockMutex(q->mutex);    for (;;) {        if (global_video_state->quit) {            ret = -1;            break;        }        pkt1 = q->first_pkt;        if (pkt1) {            q->first_pkt = pkt1->next;            if (!q->first_pkt)                q->last_pkt = NULL;            q->nb_packets--;            q->size -= pkt1->pkt.size;            *pkt = pkt1->pkt;            av_free(pkt1);            ret = 1;            break;        } else if (!block) {            ret = 0;            break;        } else {            SDL_CondWait(q->cond, q->mutex);        }    }    SDL_UnlockMutex(q->mutex);    return ret;}double get_audio_clock(VideoState *is) {    double pts;    int hw_buf_size, bytes_per_sec, n;    pts = is->audio_clock; /* maintained in the audio thread */    hw_buf_size = is->audio_buf_size - is->audio_buf_index;    bytes_per_sec = 0;    n = is->audio_st->codec->channels * 2;    if (is->audio_st) {        bytes_per_sec = is->audio_st->codec->sample_rate * n;    }    if (bytes_per_sec) {        pts -= (double) hw_buf_size / bytes_per_sec;    }    return pts;}int audio_decode_frame(VideoState *is, double *pts_ptr) {    int len1, data_size = 0, n;    AVPacket *pkt = &is->audio_pkt;    double pts;    for (;;) {        while (is->audio_pkt_size > 0) {            int got_frame = 0;            len1 = avcodec_decode_audio4(is->audio_st->codec, &is->audio_frame,                    &got_frame, pkt);            if (len1 < 0) {                /* if error, skip frame */                is->audio_pkt_size = 0;                break;            }            if (got_frame) {                data_size = is->audio_frame.linesize[0];                /*av_samples_get_buffer_size(NULL,                 is->audio_st->codec->channels,                 is->audio_frame.nb_samples,                 is->audio_st->codec->sample_fmt, 1);*/                memcpy(is->audio_buf, is->audio_frame.data[0], data_size);            }            is->audio_pkt_data += len1;            is->audio_pkt_size -= len1;            if (data_size <= 0) {                /* No data yet, get more frames */                continue;            }            pts = is->audio_clock;            *pts_ptr = pts;            n = 2 * is->audio_st->codec->channels;            is->audio_clock += (double) data_size                    / (double) (n * is->audio_st->codec->sample_rate);            /* We have data, return it and come back for more later */            return data_size;        }        if (pkt->data)            av_free_packet(pkt);        if (is->quit) {            return -1;        }        /* next packet */        if (packet_queue_get(&is->audioq, pkt, 1) < 0) {            return -1;        }        is->audio_pkt_data = pkt->data;        is->audio_pkt_size = pkt->size;        /* if update, update the audio clock w/pts */        if (pkt->pts != AV_NOPTS_VALUE) {            is->audio_clock = av_q2d(is->audio_st->time_base) * pkt->pts;        }    }    return 0;}void audio_callback(void *userdata, Uint8 *stream, int len) {    VideoState *is = (VideoState *) userdata;    int len1, audio_size;    double pts;    while (len > 0) {        if (is->audio_buf_index >= is->audio_buf_size) {            /* We have already sent all our data; get more */            audio_size = audio_decode_frame(is, &pts);            if (audio_size < 0) {                /* If error, output silence */                is->audio_buf_size = 1024;                memset(is->audio_buf, 0, is->audio_buf_size);            } else {                is->audio_buf_size = audio_size;            }            is->audio_buf_index = 0;        }        len1 = is->audio_buf_size - is->audio_buf_index;        if (len1 > len)            len1 = len;        memcpy(stream, (uint8_t *) is->audio_buf + is->audio_buf_index, len1);        len -= len1;        stream += len1;        is->audio_buf_index += len1;    }}static Uint32 sdl_refresh_timer_cb(Uint32 interval, void *opaque) {    SDL_Event event;    event.type = FF_REFRESH_EVENT;    event.user.data1 = opaque;    SDL_PushEvent(&event);    return 0; /* 0 means stop timer */}/* schedule a video refresh in 'delay' ms */static void schedule_refresh(VideoState *is, int delay) {    SDL_AddTimer(delay, sdl_refresh_timer_cb, is);}void video_display(VideoState *is) {    SDL_Rect rect;    VideoPicture *vp;    float aspect_ratio;    int w, h, x, y;    vp = &is->pictq[is->pictq_rindex];    if (vp->bmp) {        if (is->video_st->codec->sample_aspect_ratio.num == 0) {            aspect_ratio = 0;        } else {            aspect_ratio = av_q2d(is->video_st->codec->sample_aspect_ratio)                    * is->video_st->codec->width / is->video_st->codec->height;        }        if (aspect_ratio <= 0.0) {            aspect_ratio = (float) is->video_st->codec->width                    / (float) is->video_st->codec->height;        }        h = screen->h;        w = ((int) rint(h * aspect_ratio)) & -3;        if (w > screen->w) {            w = screen->w;            h = ((int) rint(w / aspect_ratio)) & -3;        }        x = (screen->w - w) / 2;        y = (screen->h - h) / 2;        rect.x = x;        rect.y = y;        rect.w = w;        rect.h = h;        SDL_DisplayYUVOverlay(vp->bmp, &rect);    }}void video_refresh_timer(void *userdata) {    VideoState *is = (VideoState *) userdata;    VideoPicture *vp;    double actual_delay, delay, sync_threshold, ref_clock, diff;    if (is->video_st) {        if (is->pictq_size == 0) {            schedule_refresh(is, 1);        } else {            vp = &is->pictq[is->pictq_rindex];            delay = vp->pts - is->frame_last_pts; /* the pts from last time */            if (delay <= 0 || delay >= 1.0) {                /* if incorrect delay, use previous one */                delay = is->frame_last_delay;            }            /* save for next time */            is->frame_last_delay = delay;            is->frame_last_pts = vp->pts;            /* update delay to sync to audio */            ref_clock = get_audio_clock(is);            diff = vp->pts - ref_clock;            /* Skip or repeat the frame. Take delay into account             FFPlay still doesn't "know if this is the best guess." */            sync_threshold =                    (delay > AV_SYNC_THRESHOLD) ? delay : AV_SYNC_THRESHOLD;            if (fabs(diff) < AV_NOSYNC_THRESHOLD) {                if (diff <= -sync_threshold) {                    delay = 0;                } else if (diff >= sync_threshold) {                    delay = 2 * delay;                }            }            is->frame_timer += delay;            /* computer the REAL delay */            actual_delay = is->frame_timer - (av_gettime() / 1000000.0);            if (actual_delay < 0.010) {                /* Really it should skip the picture instead */                actual_delay = 0.010;            }            schedule_refresh(is, (int) (actual_delay * 1000 + 0.5));            /* show the picture! */            video_display(is);            /* update queue for next picture! */            if (++is->pictq_rindex == VIDEO_PICTURE_QUEUE_SIZE) {                is->pictq_rindex = 0;            }            SDL_LockMutex(is->pictq_mutex);            is->pictq_size--;            SDL_CondSignal(is->pictq_cond);            SDL_UnlockMutex(is->pictq_mutex);        }    } else {        schedule_refresh(is, 100);    }}void alloc_picture(void *userdata) {    VideoState *is = (VideoState *) userdata;    VideoPicture *vp;    vp = &is->pictq[is->pictq_windex];    if (vp->bmp) {        // we already have one make another, bigger/smaller        SDL_FreeYUVOverlay(vp->bmp);    }    // Allocate a place to put our YUV image on that screen    vp->bmp = SDL_CreateYUVOverlay(is->video_st->codec->width,            is->video_st->codec->height, SDL_YV12_OVERLAY, screen);    vp->width = is->video_st->codec->width;    vp->height = is->video_st->codec->height;    SDL_LockMutex(is->pictq_mutex);    vp->allocated = 1;    SDL_CondSignal(is->pictq_cond);    SDL_UnlockMutex(is->pictq_mutex);}int queue_picture(VideoState *is, AVFrame *pFrame, double pts) {    VideoPicture *vp;    //int dst_pix_fmt;    AVPicture pict;    /* wait until we have space for a new pic */    SDL_LockMutex(is->pictq_mutex);    while (is->pictq_size >= VIDEO_PICTURE_QUEUE_SIZE && !is->quit) {        SDL_CondWait(is->pictq_cond, is->pictq_mutex);    }    SDL_UnlockMutex(is->pictq_mutex);    if (is->quit)        return -1;    // windex is set to 0 initially    vp = &is->pictq[is->pictq_windex];    /* allocate or resize the buffer! */    if (!vp->bmp || vp->width != is->video_st->codec->width            || vp->height != is->video_st->codec->height) {        SDL_Event event;        vp->allocated = 0;        /* we have to do it in the main thread */        event.type = FF_ALLOC_EVENT;        event.user.data1 = is;        SDL_PushEvent(&event);        /* wait until we have a picture allocated */        SDL_LockMutex(is->pictq_mutex);        while (!vp->allocated && !is->quit) {            SDL_CondWait(is->pictq_cond, is->pictq_mutex);        }        SDL_UnlockMutex(is->pictq_mutex);        if (is->quit) {            return -1;        }    }    /* We have a place to put our picture on the queue */    /* If we are skipping a frame, do we set this to null     but still return vp->allocated = 1? */    if (vp->bmp) {        SDL_LockYUVOverlay(vp->bmp);        //dst_pix_fmt = PIX_FMT_YUV420P;        /* point pict at the queue */        pict.data[0] = vp->bmp->pixels[0];        pict.data[1] = vp->bmp->pixels[2];        pict.data[2] = vp->bmp->pixels[1];        pict.linesize[0] = vp->bmp->pitches[0];        pict.linesize[1] = vp->bmp->pitches[2];        pict.linesize[2] = vp->bmp->pitches[1];        // Convert the image into YUV format that SDL uses        sws_scale(is->sws_ctx, (const uint8_t * const *) pFrame->data,                pFrame->linesize, 0, is->video_st->codec->height, pict.data,                pict.linesize);        SDL_UnlockYUVOverlay(vp->bmp);        vp->pts = pts;        /* now we inform our display thread that we have a pic ready */        if (++is->pictq_windex == VIDEO_PICTURE_QUEUE_SIZE) {            is->pictq_windex = 0;        }        SDL_LockMutex(is->pictq_mutex);        is->pictq_size++;        SDL_UnlockMutex(is->pictq_mutex);    }    return 0;}int main(int argc, char *argv[]) {    return EXIT_SUCCESS;}
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六、同步video_clock

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/* ============================================================================ Name        : VideoDecodeTutorial5_1.c Author      : clarck Version     : Copyright   : Your copyright notice Description : Hello World in C, Ansi-style ============================================================================ */#include <stdio.h>#include <stdlib.h>#include <math.h>#include <libavcodec/avcodec.h>#include <libavformat/avformat.h>#include <libavformat/avio.h>#include <libswscale/swscale.h>#include <libavutil/avstring.h>#include <SDL/SDL.h>#include <SDL/SDL_thread.h>#ifdef __MINGW32__#undef main /* Prevents SDL from overriding main() */#endif#define SDL_AUDIO_BUFFER_SIZE 1024#define MAX_AUDIOQ_SIZE (5 * 16 * 1024)#define MAX_VIDEOQ_SIZE (5 * 256 * 1024)#define AV_SYNC_THRESHOLD 0.01#define AV_NOSYNC_THRESHOLD 10.0#define FF_ALLOC_EVENT   (SDL_USEREVENT)#define FF_REFRESH_EVENT (SDL_USEREVENT + 1)#define FF_QUIT_EVENT (SDL_USEREVENT + 2)#define VIDEO_PICTURE_QUEUE_SIZE 1#define AVCODEC_MAX_AUDIO_FRAME_SIZE 192000 // 1 second of 48khz 32bit audiotypedef struct PacketQueue {    AVPacketList *first_pkt, *last_pkt;    int nb_packets;    int size;    SDL_mutex *mutex;    SDL_cond *cond;} PacketQueue;typedef struct VideoPicture {    SDL_Overlay *bmp;    int width, height; /* source height & width */    int allocated;    double pts;} VideoPicture;typedef struct VideoState {    AVFormatContext *pFormatCtx;    int videoStream, audioStream;    double audio_clock;    AVStream *audio_st;    PacketQueue audioq;    uint8_t audio_buf[(AVCODEC_MAX_AUDIO_FRAME_SIZE * 3) / 2];    unsigned int audio_buf_size;    unsigned int audio_buf_index;    AVPacket audio_pkt;    uint8_t *audio_pkt_data;    int audio_pkt_size;    AVFrame audio_frame;    AVStream *video_st;    PacketQueue videoq;    int audio_hw_buf_size;    double frame_timer;    double frame_last_pts;    double frame_last_delay;    double video_clock; ///<pts of last decoded frame / predicted pts of next decoded frame    VideoPicture pictq[VIDEO_PICTURE_QUEUE_SIZE];    int pictq_size, pictq_rindex, pictq_windex;    SDL_mutex *pictq_mutex;    SDL_cond *pictq_cond;    SDL_Thread *parse_tid;    SDL_Thread *video_tid;    AVIOContext *io_ctx;    struct SwsContext *sws_ctx;    char filename[1024];    int quit;} VideoState;/* Since we only have one decoding thread, the Big Struct can be global in case we need it. */VideoState *global_video_state;void packet_queue_init(PacketQueue *q) {    memset(q, 0, sizeof(PacketQueue));    q->mutex = SDL_CreateMutex();    q->cond = SDL_CreateCond();}int packet_queue_put(PacketQueue *q, AVPacket *pkt) {    AVPacketList *pkt1;    if (av_dup_packet(pkt) < 0) {        return -1;    }    pkt1 = av_malloc(sizeof(AVPacketList));    if (!pkt1)        return -1;    pkt1->pkt = *pkt;    pkt1->next = NULL;    SDL_LockMutex(q->mutex);    if (!q->last_pkt)        q->first_pkt = pkt1;    else        q->last_pkt->next = pkt1;    q->last_pkt = pkt1;    q->nb_packets++;    q->size += pkt1->pkt.size;    SDL_CondSignal(q->cond);    SDL_UnlockMutex(q->mutex);    return 0;}static int packet_queue_get(PacketQueue *q, AVPacket *pkt, int block) {    AVPacketList *pkt1;    int ret;    SDL_LockMutex(q->mutex);    for (;;) {        if (global_video_state->quit) {            ret = -1;            break;        }        pkt1 = q->first_pkt;        if (pkt1) {            q->first_pkt = pkt1->next;            if (!q->first_pkt)                q->last_pkt = NULL;            q->nb_packets--;            q->size -= pkt1->pkt.size;            *pkt = pkt1->pkt;            av_free(pkt1);            ret = 1;            break;        } else if (!block) {            ret = 0;            break;        } else {            SDL_CondWait(q->cond, q->mutex);        }    }    SDL_UnlockMutex(q->mutex);    return ret;}double get_audio_clock(VideoState *is) {    double pts;    int hw_buf_size, bytes_per_sec, n;    pts = is->audio_clock; /* maintained in the audio thread */    hw_buf_size = is->audio_buf_size - is->audio_buf_index;    bytes_per_sec = 0;    n = is->audio_st->codec->channels * 2;    if (is->audio_st) {        bytes_per_sec = is->audio_st->codec->sample_rate * n;    }    if (bytes_per_sec) {        pts -= (double) hw_buf_size / bytes_per_sec;    }    return pts;}int audio_decode_frame(VideoState *is, double *pts_ptr) {    int len1, data_size = 0, n;    AVPacket *pkt = &is->audio_pkt;    double pts;    for (;;) {        while (is->audio_pkt_size > 0) {            int got_frame = 0;            len1 = avcodec_decode_audio4(is->audio_st->codec, &is->audio_frame,                    &got_frame, pkt);            if (len1 < 0) {                /* if error, skip frame */                is->audio_pkt_size = 0;                break;            }            if (got_frame) {                data_size = is->audio_frame.linesize[0];                /*av_samples_get_buffer_size(NULL,                 is->audio_st->codec->channels,                 is->audio_frame.nb_samples,                 is->audio_st->codec->sample_fmt, 1);*/                memcpy(is->audio_buf, is->audio_frame.data[0], data_size);            }            is->audio_pkt_data += len1;            is->audio_pkt_size -= len1;            if (data_size <= 0) {                /* No data yet, get more frames */                continue;            }            pts = is->audio_clock;            *pts_ptr = pts;            n = 2 * is->audio_st->codec->channels;            is->audio_clock += (double) data_size                    / (double) (n * is->audio_st->codec->sample_rate);            /* We have data, return it and come back for more later */            return data_size;        }        if (pkt->data)            av_free_packet(pkt);        if (is->quit) {            return -1;        }        /* next packet */        if (packet_queue_get(&is->audioq, pkt, 1) < 0) {            return -1;        }        is->audio_pkt_data = pkt->data;        is->audio_pkt_size = pkt->size;        /* if update, update the audio clock w/pts */        if (pkt->pts != AV_NOPTS_VALUE) {            is->audio_clock = av_q2d(is->audio_st->time_base) * pkt->pts;        }    }    return 0;}void audio_callback(void *userdata, Uint8 *stream, int len) {    VideoState *is = (VideoState *) userdata;    int len1, audio_size;    double pts;    while (len > 0) {        if (is->audio_buf_index >= is->audio_buf_size) {            /* We have already sent all our data; get more */            audio_size = audio_decode_frame(is, &pts);            if (audio_size < 0) {                /* If error, output silence */                is->audio_buf_size = 1024;                memset(is->audio_buf, 0, is->audio_buf_size);            } else {                is->audio_buf_size = audio_size;            }            is->audio_buf_index = 0;        }        len1 = is->audio_buf_size - is->audio_buf_index;        if (len1 > len)            len1 = len;        memcpy(stream, (uint8_t *) is->audio_buf + is->audio_buf_index, len1);        len -= len1;        stream += len1;        is->audio_buf_index += len1;    }}static Uint32 sdl_refresh_timer_cb(Uint32 interval, void *opaque) {    SDL_Event event;    event.type = FF_REFRESH_EVENT;    event.user.data1 = opaque;    SDL_PushEvent(&event);    return 0; /* 0 means stop timer */}/* schedule a video refresh in 'delay' ms */static void schedule_refresh(VideoState *is, int delay) {    SDL_AddTimer(delay, sdl_refresh_timer_cb, is);}void video_display(VideoState *is) {    SDL_Rect rect;    VideoPicture *vp;    float aspect_ratio;    int w, h, x, y;    vp = &is->pictq[is->pictq_rindex];    if (vp->bmp) {        if (is->video_st->codec->sample_aspect_ratio.num == 0) {            aspect_ratio = 0;        } else {            aspect_ratio = av_q2d(is->video_st->codec->sample_aspect_ratio)                    * is->video_st->codec->width / is->video_st->codec->height;        }        if (aspect_ratio <= 0.0) {            aspect_ratio = (float) is->video_st->codec->width                    / (float) is->video_st->codec->height;        }        h = screen->h;        w = ((int) rint(h * aspect_ratio)) & -3;        if (w > screen->w) {            w = screen->w;            h = ((int) rint(w / aspect_ratio)) & -3;        }        x = (screen->w - w) / 2;        y = (screen->h - h) / 2;        rect.x = x;        rect.y = y;        rect.w = w;        rect.h = h;        SDL_DisplayYUVOverlay(vp->bmp, &rect);    }}void video_refresh_timer(void *userdata) {    VideoState *is = (VideoState *) userdata;    VideoPicture *vp;    double actual_delay, delay, sync_threshold, ref_clock, diff;    if (is->video_st) {        if (is->pictq_size == 0) {            schedule_refresh(is, 1);        } else {            vp = &is->pictq[is->pictq_rindex];            delay = vp->pts - is->frame_last_pts; /* the pts from last time */            if (delay <= 0 || delay >= 1.0) {                /* if incorrect delay, use previous one */                delay = is->frame_last_delay;            }            /* save for next time */            is->frame_last_delay = delay;            is->frame_last_pts = vp->pts;            /* update delay to sync to audio */            ref_clock = get_audio_clock(is);            diff = vp->pts - ref_clock;            /* Skip or repeat the frame. Take delay into account             FFPlay still doesn't "know if this is the best guess." */            sync_threshold =                    (delay > AV_SYNC_THRESHOLD) ? delay : AV_SYNC_THRESHOLD;            if (fabs(diff) < AV_NOSYNC_THRESHOLD) {                if (diff <= -sync_threshold) {                    delay = 0;                } else if (diff >= sync_threshold) {                    delay = 2 * delay;                }            }            is->frame_timer += delay;            /* computer the REAL delay */            actual_delay = is->frame_timer - (av_gettime() / 1000000.0);            if (actual_delay < 0.010) {                /* Really it should skip the picture instead */                actual_delay = 0.010;            }            schedule_refresh(is, (int) (actual_delay * 1000 + 0.5));            /* show the picture! */            video_display(is);            /* update queue for next picture! */            if (++is->pictq_rindex == VIDEO_PICTURE_QUEUE_SIZE) {                is->pictq_rindex = 0;            }            SDL_LockMutex(is->pictq_mutex);            is->pictq_size--;            SDL_CondSignal(is->pictq_cond);            SDL_UnlockMutex(is->pictq_mutex);        }    } else {        schedule_refresh(is, 100);    }}void alloc_picture(void *userdata) {    VideoState *is = (VideoState *) userdata;    VideoPicture *vp;    vp = &is->pictq[is->pictq_windex];    if (vp->bmp) {        // we already have one make another, bigger/smaller        SDL_FreeYUVOverlay(vp->bmp);    }    // Allocate a place to put our YUV image on that screen    vp->bmp = SDL_CreateYUVOverlay(is->video_st->codec->width,            is->video_st->codec->height, SDL_YV12_OVERLAY, screen);    vp->width = is->video_st->codec->width;    vp->height = is->video_st->codec->height;    SDL_LockMutex(is->pictq_mutex);    vp->allocated = 1;    SDL_CondSignal(is->pictq_cond);    SDL_UnlockMutex(is->pictq_mutex);}int queue_picture(VideoState *is, AVFrame *pFrame, double pts) {    VideoPicture *vp;    //int dst_pix_fmt;    AVPicture pict;    /* wait until we have space for a new pic */    SDL_LockMutex(is->pictq_mutex);    while (is->pictq_size >= VIDEO_PICTURE_QUEUE_SIZE && !is->quit) {        SDL_CondWait(is->pictq_cond, is->pictq_mutex);    }    SDL_UnlockMutex(is->pictq_mutex);    if (is->quit)        return -1;    // windex is set to 0 initially    vp = &is->pictq[is->pictq_windex];    /* allocate or resize the buffer! */    if (!vp->bmp || vp->width != is->video_st->codec->width            || vp->height != is->video_st->codec->height) {        SDL_Event event;        vp->allocated = 0;        /* we have to do it in the main thread */        event.type = FF_ALLOC_EVENT;        event.user.data1 = is;        SDL_PushEvent(&event);        /* wait until we have a picture allocated */        SDL_LockMutex(is->pictq_mutex);        while (!vp->allocated && !is->quit) {            SDL_CondWait(is->pictq_cond, is->pictq_mutex);        }        SDL_UnlockMutex(is->pictq_mutex);        if (is->quit) {            return -1;        }    }    /* We have a place to put our picture on the queue */    /* If we are skipping a frame, do we set this to null     but still return vp->allocated = 1? */    if (vp->bmp) {        SDL_LockYUVOverlay(vp->bmp);        //dst_pix_fmt = PIX_FMT_YUV420P;        /* point pict at the queue */        pict.data[0] = vp->bmp->pixels[0];        pict.data[1] = vp->bmp->pixels[2];        pict.data[2] = vp->bmp->pixels[1];        pict.linesize[0] = vp->bmp->pitches[0];        pict.linesize[1] = vp->bmp->pitches[2];        pict.linesize[2] = vp->bmp->pitches[1];        // Convert the image into YUV format that SDL uses        sws_scale(is->sws_ctx, (const uint8_t * const *) pFrame->data,                pFrame->linesize, 0, is->video_st->codec->height, pict.data,                pict.linesize);        SDL_UnlockYUVOverlay(vp->bmp);        vp->pts = pts;        /* now we inform our display thread that we have a pic ready */        if (++is->pictq_windex == VIDEO_PICTURE_QUEUE_SIZE) {            is->pictq_windex = 0;        }        SDL_LockMutex(is->pictq_mutex);        is->pictq_size++;        SDL_UnlockMutex(is->pictq_mutex);    }    return 0;}double synchronize_video(VideoState *is, AVFrame *src_frame, double pts) {    double frame_delay;    if (pts != 0) {        /* if we have pts, set video clock to it */        is->video_clock = pts;    } else {        /* if we aren't given a pts, set it to the clock */        pts = is->video_clock;    }    /* update the video clock */    frame_delay = av_q2d(is->video_st->codec->time_base);    /* if we are repeating a frame, adjust clock accordingly */    frame_delay += src_frame->repeat_pict * (frame_delay * 0.5);    is->video_clock += frame_delay;    return pts;}uint64_t global_video_pkt_pts = AV_NOPTS_VALUE;/* These are called whenever we allocate a frame * buffer. We use this to store the global_pts in * a frame at the time it is allocated. */int our_get_buffer(struct AVCodecContext *c, AVFrame *pic) {    int ret = avcodec_default_get_buffer(c, pic);    uint64_t *pts = av_malloc(sizeof(uint64_t));    *pts = global_video_pkt_pts;    pic->opaque = pts;    return ret;}void our_release_buffer(struct AVCodecContext *c, AVFrame *pic) {    if (pic)        av_freep(&pic->opaque);    avcodec_default_release_buffer(c, pic);}int video_thread(void *arg) {    VideoState *is = (VideoState *) arg;    AVPacket pkt1, *packet = &pkt1;    //int len1;    int frameFinished;    AVFrame *pFrame;    double pts;    pFrame = av_frame_alloc();    for (;;) {        if (packet_queue_get(&is->videoq, packet, 1) < 0) {            // means we quit getting packets            break;        }        pts = 0;        // Save global pts to be stored in pFrame in first call        global_video_pkt_pts = packet->pts;        // Decode video frame        //len1 =        avcodec_decode_video2(is->video_st->codec, pFrame, &frameFinished,                packet);        if (packet->dts == AV_NOPTS_VALUE && pFrame->opaque                && *(uint64_t*) pFrame->opaque != AV_NOPTS_VALUE) {            pts = *(uint64_t *) pFrame->opaque;        } else if (packet->dts != AV_NOPTS_VALUE) {            pts = packet->dts;        } else {            pts = 0;        }        pts *= av_q2d(is->video_st->time_base);        // Did we get a video frame?        if (frameFinished) {            pts = synchronize_video(is, pFrame, pts);            if (queue_picture(is, pFrame, pts) < 0) {                break;            }        }        av_free_packet(packet);    }    av_free(pFrame);    return 0;}int main(int argc, char *argv[]) {    return EXIT_SUCCESS;}
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七、视频的其余逻辑处理

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/* ============================================================================ Name        : player5.c Author      : clarck Version     : Copyright   : Your copyright notice Description : Hello World in C, Ansi-style ============================================================================ */// tutorial05.c// A pedagogical video player that really works!//// Code based on FFplay, Copyright (c) 2003 Fabrice Bellard,// and a tutorial by Martin Bohme (boehme@inb.uni-luebeckREMOVETHIS.de)// and another tutorial by Stephen Dranger (dranger at gmail dot com)// Tested on Gentoo, CVS version 5/01/07 compiled with GCC 4.1.1// Use//// gcc -o tutorial05 tutorial05.c -lavformat -lavcodec -lswscale -lz -lm `sdl-config --cflags --libs`// to build (assuming libavformat and libavcodec and libswscale are correctly installed,// and assuming you have sdl-config. Please refer to SDL docs for your installation.)//// Run using// tutorial05 myvideofile.mpg//// to play the video.#include <libavcodec/avcodec.h>#include <libavformat/avformat.h>#include <libavformat/avio.h>#include <libswscale/swscale.h>#include <libavutil/avstring.h>#include <SDL/SDL.h>#include <SDL/SDL_thread.h>#ifdef __MINGW32__#undef main /* Prevents SDL from overriding main() */#endif#include <stdio.h>#include <math.h>#define SDL_AUDIO_BUFFER_SIZE 1024#define MAX_AUDIOQ_SIZE (5 * 16 * 1024)#define MAX_VIDEOQ_SIZE (5 * 256 * 1024)#define AV_SYNC_THRESHOLD 0.01#define AV_NOSYNC_THRESHOLD 10.0#define FF_ALLOC_EVENT   (SDL_USEREVENT)#define FF_REFRESH_EVENT (SDL_USEREVENT + 1)#define FF_QUIT_EVENT (SDL_USEREVENT + 2)#define VIDEO_PICTURE_QUEUE_SIZE 1#define AVCODEC_MAX_AUDIO_FRAME_SIZE 192000 // 1 second of 48khz 32bit audiotypedef struct PacketQueue {    AVPacketList *first_pkt, *last_pkt;    int nb_packets;    int size;    SDL_mutex *mutex;    SDL_cond *cond;} PacketQueue;typedef struct VideoPicture {    SDL_Overlay *bmp;    int width, height; /* source height & width */    int allocated;    double pts;} VideoPicture;typedef struct VideoState {    AVFormatContext *pFormatCtx;    int videoStream, audioStream;    double audio_clock;    AVStream *audio_st;    PacketQueue audioq;    uint8_t audio_buf[(AVCODEC_MAX_AUDIO_FRAME_SIZE * 3) / 2];    unsigned int audio_buf_size;    unsigned int audio_buf_index;    AVPacket audio_pkt;    uint8_t *audio_pkt_data;    int audio_pkt_size;    AVFrame audio_frame;    AVStream *video_st;    PacketQueue videoq;    int audio_hw_buf_size;    double frame_timer;    double frame_last_pts;    double frame_last_delay;    double video_clock; ///<pts of last decoded frame / predicted pts of next decoded frame    VideoPicture pictq[VIDEO_PICTURE_QUEUE_SIZE];    int pictq_size, pictq_rindex, pictq_windex;    SDL_mutex *pictq_mutex;    SDL_cond *pictq_cond;    SDL_Thread *parse_tid;    SDL_Thread *video_tid;    AVIOContext *io_ctx;    struct SwsContext *sws_ctx;    char filename[1024];    int quit;} VideoState;SDL_Surface *screen;/* Since we only have one decoding thread, the Big Struct can be global in case we need it. */VideoState *global_video_state;void packet_queue_init(PacketQueue *q) {    memset(q, 0, sizeof(PacketQueue));    q->mutex = SDL_CreateMutex();    q->cond = SDL_CreateCond();}int packet_queue_put(PacketQueue *q, AVPacket *pkt) {    AVPacketList *pkt1;    if (av_dup_packet(pkt) < 0) {        return -1;    }    pkt1 = av_malloc(sizeof(AVPacketList));    if (!pkt1)        return -1;    pkt1->pkt = *pkt;    pkt1->next = NULL;    SDL_LockMutex(q->mutex);    if (!q->last_pkt)        q->first_pkt = pkt1;    else        q->last_pkt->next = pkt1;    q->last_pkt = pkt1;    q->nb_packets++;    q->size += pkt1->pkt.size;    SDL_CondSignal(q->cond);    SDL_UnlockMutex(q->mutex);    return 0;}static int packet_queue_get(PacketQueue *q, AVPacket *pkt, int block) {    AVPacketList *pkt1;    int ret;    SDL_LockMutex(q->mutex);    for (;;) {        if (global_video_state->quit) {            ret = -1;            break;        }        pkt1 = q->first_pkt;        if (pkt1) {            q->first_pkt = pkt1->next;            if (!q->first_pkt)                q->last_pkt = NULL;            q->nb_packets--;            q->size -= pkt1->pkt.size;            *pkt = pkt1->pkt;            av_free(pkt1);            ret = 1;            break;        } else if (!block) {            ret = 0;            break;        } else {            SDL_CondWait(q->cond, q->mutex);        }    }    SDL_UnlockMutex(q->mutex);    return ret;}double get_audio_clock(VideoState *is) {    double pts;    int hw_buf_size, bytes_per_sec, n;    pts = is->audio_clock; /* maintained in the audio thread */    hw_buf_size = is->audio_buf_size - is->audio_buf_index;    bytes_per_sec = 0;    n = is->audio_st->codec->channels * 2;    if (is->audio_st) {        bytes_per_sec = is->audio_st->codec->sample_rate * n;    }    if (bytes_per_sec) {        pts -= (double) hw_buf_size / bytes_per_sec;    }    return pts;}int audio_decode_frame(VideoState *is, double *pts_ptr) {    int len1, data_size = 0, n;    AVPacket *pkt = &is->audio_pkt;    double pts;    for (;;) {        while (is->audio_pkt_size > 0) {            int got_frame = 0;            len1 = avcodec_decode_audio4(is->audio_st->codec, &is->audio_frame,                    &got_frame, pkt);            if (len1 < 0) {                /* if error, skip frame */                is->audio_pkt_size = 0;                break;            }            if (got_frame) {                data_size = is->audio_frame.linesize[0];                /*av_samples_get_buffer_size(NULL,                 is->audio_st->codec->channels,                 is->audio_frame.nb_samples,                 is->audio_st->codec->sample_fmt, 1);*/                memcpy(is->audio_buf, is->audio_frame.data[0], data_size);            }            is->audio_pkt_data += len1;            is->audio_pkt_size -= len1;            if (data_size <= 0) {                /* No data yet, get more frames */                continue;            }            pts = is->audio_clock;            *pts_ptr = pts;            n = 2 * is->audio_st->codec->channels;            is->audio_clock += (double) data_size                    / (double) (n * is->audio_st->codec->sample_rate);            /* We have data, return it and come back for more later */            return data_size;        }        if (pkt->data)            av_free_packet(pkt);        if (is->quit) {            return -1;        }        /* next packet */        if (packet_queue_get(&is->audioq, pkt, 1) < 0) {            return -1;        }        is->audio_pkt_data = pkt->data;        is->audio_pkt_size = pkt->size;        /* if update, update the audio clock w/pts */        if (pkt->pts != AV_NOPTS_VALUE) {            is->audio_clock = av_q2d(is->audio_st->time_base) * pkt->pts;        }    }    return 0;}void audio_callback(void *userdata, Uint8 *stream, int len) {    VideoState *is = (VideoState *) userdata;    int len1, audio_size;    double pts;    while (len > 0) {        if (is->audio_buf_index >= is->audio_buf_size) {            /* We have already sent all our data; get more */            audio_size = audio_decode_frame(is, &pts);            if (audio_size < 0) {                /* If error, output silence */                is->audio_buf_size = 1024;                memset(is->audio_buf, 0, is->audio_buf_size);            } else {                is->audio_buf_size = audio_size;            }            is->audio_buf_index = 0;        }        len1 = is->audio_buf_size - is->audio_buf_index;        if (len1 > len)            len1 = len;        memcpy(stream, (uint8_t *) is->audio_buf + is->audio_buf_index, len1);        len -= len1;        stream += len1;        is->audio_buf_index += len1;    }}static Uint32 sdl_refresh_timer_cb(Uint32 interval, void *opaque) {    SDL_Event event;    event.type = FF_REFRESH_EVENT;    event.user.data1 = opaque;    SDL_PushEvent(&event);    return 0; /* 0 means stop timer */}/* schedule a video refresh in 'delay' ms */static void schedule_refresh(VideoState *is, int delay) {    SDL_AddTimer(delay, sdl_refresh_timer_cb, is);}void video_display(VideoState *is) {    SDL_Rect rect;    VideoPicture *vp;    float aspect_ratio;    int w, h, x, y;    vp = &is->pictq[is->pictq_rindex];    if (vp->bmp) {        if (is->video_st->codec->sample_aspect_ratio.num == 0) {            aspect_ratio = 0;        } else {            aspect_ratio = av_q2d(is->video_st->codec->sample_aspect_ratio)                    * is->video_st->codec->width / is->video_st->codec->height;        }        if (aspect_ratio <= 0.0) {            aspect_ratio = (float) is->video_st->codec->width                    / (float) is->video_st->codec->height;        }        h = screen->h;        w = ((int) rint(h * aspect_ratio)) & -3;        if (w > screen->w) {            w = screen->w;            h = ((int) rint(w / aspect_ratio)) & -3;        }        x = (screen->w - w) / 2;        y = (screen->h - h) / 2;        rect.x = x;        rect.y = y;        rect.w = w;        rect.h = h;        SDL_DisplayYUVOverlay(vp->bmp, &rect);    }}void video_refresh_timer(void *userdata) {    VideoState *is = (VideoState *) userdata;    VideoPicture *vp;    double actual_delay, delay, sync_threshold, ref_clock, diff;    if (is->video_st) {        if (is->pictq_size == 0) {            schedule_refresh(is, 1);        } else {            vp = &is->pictq[is->pictq_rindex];            delay = vp->pts - is->frame_last_pts; /* the pts from last time */            if (delay <= 0 || delay >= 1.0) {                /* if incorrect delay, use previous one */                delay = is->frame_last_delay;            }            /* save for next time */            is->frame_last_delay = delay;            is->frame_last_pts = vp->pts;            /* update delay to sync to audio */            ref_clock = get_audio_clock(is);            diff = vp->pts - ref_clock;            /* Skip or repeat the frame. Take delay into account             FFPlay still doesn't "know if this is the best guess." */            sync_threshold =                    (delay > AV_SYNC_THRESHOLD) ? delay : AV_SYNC_THRESHOLD;            if (fabs(diff) < AV_NOSYNC_THRESHOLD) {                if (diff <= -sync_threshold) {                    delay = 0;                } else if (diff >= sync_threshold) {                    delay = 2 * delay;                }            }            is->frame_timer += delay;            /* computer the REAL delay */            actual_delay = is->frame_timer - (av_gettime() / 1000000.0);            if (actual_delay < 0.010) {                /* Really it should skip the picture instead */                actual_delay = 0.010;            }            schedule_refresh(is, (int) (actual_delay * 1000 + 0.5));            /* show the picture! */            video_display(is);            /* update queue for next picture! */            if (++is->pictq_rindex == VIDEO_PICTURE_QUEUE_SIZE) {                is->pictq_rindex = 0;            }            SDL_LockMutex(is->pictq_mutex);            is->pictq_size--;            SDL_CondSignal(is->pictq_cond);            SDL_UnlockMutex(is->pictq_mutex);        }    } else {        schedule_refresh(is, 100);    }}void alloc_picture(void *userdata) {    VideoState *is = (VideoState *) userdata;    VideoPicture *vp;    vp = &is->pictq[is->pictq_windex];    if (vp->bmp) {        // we already have one make another, bigger/smaller        SDL_FreeYUVOverlay(vp->bmp);    }    // Allocate a place to put our YUV image on that screen    vp->bmp = SDL_CreateYUVOverlay(is->video_st->codec->width,            is->video_st->codec->height, SDL_YV12_OVERLAY, screen);    vp->width = is->video_st->codec->width;    vp->height = is->video_st->codec->height;    SDL_LockMutex(is->pictq_mutex);    vp->allocated = 1;    SDL_CondSignal(is->pictq_cond);    SDL_UnlockMutex(is->pictq_mutex);}int queue_picture(VideoState *is, AVFrame *pFrame, double pts) {    VideoPicture *vp;    //int dst_pix_fmt;    AVPicture pict;    /* wait until we have space for a new pic */    SDL_LockMutex(is->pictq_mutex);    while (is->pictq_size >= VIDEO_PICTURE_QUEUE_SIZE && !is->quit) {        SDL_CondWait(is->pictq_cond, is->pictq_mutex);    }    SDL_UnlockMutex(is->pictq_mutex);    if (is->quit)        return -1;    // windex is set to 0 initially    vp = &is->pictq[is->pictq_windex];    /* allocate or resize the buffer! */    if (!vp->bmp || vp->width != is->video_st->codec->width            || vp->height != is->video_st->codec->height) {        SDL_Event event;        vp->allocated = 0;        /* we have to do it in the main thread */        event.type = FF_ALLOC_EVENT;        event.user.data1 = is;        SDL_PushEvent(&event);        /* wait until we have a picture allocated */        SDL_LockMutex(is->pictq_mutex);        while (!vp->allocated && !is->quit) {            SDL_CondWait(is->pictq_cond, is->pictq_mutex);        }        SDL_UnlockMutex(is->pictq_mutex);        if (is->quit) {            return -1;        }    }    /* We have a place to put our picture on the queue */    /* If we are skipping a frame, do we set this to null     but still return vp->allocated = 1? */    if (vp->bmp) {        SDL_LockYUVOverlay(vp->bmp);        //dst_pix_fmt = PIX_FMT_YUV420P;        /* point pict at the queue */        pict.data[0] = vp->bmp->pixels[0];        pict.data[1] = vp->bmp->pixels[2];        pict.data[2] = vp->bmp->pixels[1];        pict.linesize[0] = vp->bmp->pitches[0];        pict.linesize[1] = vp->bmp->pitches[2];        pict.linesize[2] = vp->bmp->pitches[1];        // Convert the image into YUV format that SDL uses        sws_scale(is->sws_ctx, (const uint8_t * const *) pFrame->data,                pFrame->linesize, 0, is->video_st->codec->height, pict.data,                pict.linesize);        SDL_UnlockYUVOverlay(vp->bmp);        vp->pts = pts;        /* now we inform our display thread that we have a pic ready */        if (++is->pictq_windex == VIDEO_PICTURE_QUEUE_SIZE) {            is->pictq_windex = 0;        }        SDL_LockMutex(is->pictq_mutex);        is->pictq_size++;        SDL_UnlockMutex(is->pictq_mutex);    }    return 0;}double synchronize_video(VideoState *is, AVFrame *src_frame, double pts) {    double frame_delay;    if (pts != 0) {        /* if we have pts, set video clock to it */        is->video_clock = pts;    } else {        /* if we aren't given a pts, set it to the clock */        pts = is->video_clock;    }    /* update the video clock */    frame_delay = av_q2d(is->video_st->codec->time_base);    /* if we are repeating a frame, adjust clock accordingly */    frame_delay += src_frame->repeat_pict * (frame_delay * 0.5);    is->video_clock += frame_delay;    return pts;}uint64_t global_video_pkt_pts = AV_NOPTS_VALUE;/* These are called whenever we allocate a frame * buffer. We use this to store the global_pts in * a frame at the time it is allocated. */int our_get_buffer(struct AVCodecContext *c, AVFrame *pic) {    int ret = avcodec_default_get_buffer(c, pic);    uint64_t *pts = av_malloc(sizeof(uint64_t));    *pts = global_video_pkt_pts;    pic->opaque = pts;    return ret;}void our_release_buffer(struct AVCodecContext *c, AVFrame *pic) {    if (pic)        av_freep(&pic->opaque);    avcodec_default_release_buffer(c, pic);}int video_thread(void *arg) {    VideoState *is = (VideoState *) arg;    AVPacket pkt1, *packet = &pkt1;    //int len1;    int frameFinished;    AVFrame *pFrame;    double pts;    pFrame = av_frame_alloc();    for (;;) {        if (packet_queue_get(&is->videoq, packet, 1) < 0) {            // means we quit getting packets            break;        }        pts = 0;        // Save global pts to be stored in pFrame in first call        global_video_pkt_pts = packet->pts;        // Decode video frame        //len1 =        avcodec_decode_video2(is->video_st->codec, pFrame, &frameFinished,                packet);        if (packet->dts == AV_NOPTS_VALUE && pFrame->opaque                && *(uint64_t*) pFrame->opaque != AV_NOPTS_VALUE) {            pts = *(uint64_t *) pFrame->opaque;        } else if (packet->dts != AV_NOPTS_VALUE) {            pts = packet->dts;        } else {            pts = 0;        }        pts *= av_q2d(is->video_st->time_base);        // Did we get a video frame?        if (frameFinished) {            pts = synchronize_video(is, pFrame, pts);            if (queue_picture(is, pFrame, pts) < 0) {                break;            }        }        av_free_packet(packet);    }    av_free(pFrame);    return 0;}int stream_component_open(VideoState *is, int stream_index) {    AVFormatContext *pFormatCtx = is->pFormatCtx;    AVCodecContext *codecCtx;    AVCodec *codec;    SDL_AudioSpec wanted_spec, spec;    if (stream_index < 0 || stream_index >= pFormatCtx->nb_streams) {        return -1;    }    // Get a pointer to the codec context for the video stream    codecCtx = pFormatCtx->streams[stream_index]->codec;    if (codecCtx->codec_type == AVMEDIA_TYPE_AUDIO) {        // Set audio settings from codec info        wanted_spec.freq = codecCtx->sample_rate;        wanted_spec.format = AUDIO_S16SYS;        wanted_spec.channels = codecCtx->channels;        wanted_spec.silence = 0;        wanted_spec.samples = SDL_AUDIO_BUFFER_SIZE;        wanted_spec.callback = audio_callback;        wanted_spec.userdata = is;        if (SDL_OpenAudio(&wanted_spec, &spec) < 0) {            fprintf(stderr, "SDL_OpenAudio: %s\n", SDL_GetError());            return -1;        }        is->audio_hw_buf_size = spec.size;    }    codec = avcodec_find_decoder(codecCtx->codec_id);    if (!codec || (avcodec_open2(codecCtx, codec, NULL) < 0)) {        fprintf(stderr, "Unsupported codec!\n");        return -1;    }    switch (codecCtx->codec_type) {    case AVMEDIA_TYPE_AUDIO:        is->audioStream = stream_index;        is->audio_st = pFormatCtx->streams[stream_index];        is->audio_buf_size = 0;        is->audio_buf_index = 0;        memset(&is->audio_pkt, 0, sizeof(is->audio_pkt));        packet_queue_init(&is->audioq);        SDL_PauseAudio(0);        break;    case AVMEDIA_TYPE_VIDEO:        is->videoStream = stream_index;        is->video_st = pFormatCtx->streams[stream_index];        is->sws_ctx = sws_getContext(is->video_st->codec->width,                is->video_st->codec->height, is->video_st->codec->pix_fmt,                is->video_st->codec->width, is->video_st->codec->height,                AV_PIX_FMT_YUV420P, SWS_FAST_BILINEAR, NULL, NULL, NULL);        is->frame_timer = (double) av_gettime() / 1000000.0;        is->frame_last_delay = 40e-3;        packet_queue_init(&is->videoq);        is->video_tid = SDL_CreateThread(video_thread, is);        codecCtx->get_buffer = our_get_buffer;        codecCtx->release_buffer = our_release_buffer;        break;    default:        break;    }    return 0;}int decode_interrupt_cb(void *opaque) {    return (global_video_state && global_video_state->quit);}int decode_thread(void *arg) {    VideoState *is = (VideoState *) arg;    AVFormatContext *pFormatCtx = NULL;    AVPacket pkt1, *packet = &pkt1;    int video_index = -1;    int audio_index = -1;    int i;    is->videoStream = -1;    is->audioStream = -1;    AVIOInterruptCB interupt_cb;    global_video_state = is;    // will interrupt blocking functions if we quit!    interupt_cb.callback = decode_interrupt_cb;    interupt_cb.opaque = is;    if (avio_open2(&is->io_ctx, is->filename, 0, &interupt_cb, NULL)) {        fprintf(stderr, "Cannot open I/O for %s\n", is->filename);        return -1;    }    // Open video file    if (avformat_open_input(&pFormatCtx, is->filename, NULL, NULL) != 0)        return -1; // Couldn't open file    is->pFormatCtx = pFormatCtx;    // Retrieve stream information    if (avformat_find_stream_info(pFormatCtx, NULL) < 0)        return -1; // Couldn't find stream information    // Dump information about file onto standard error    av_dump_format(pFormatCtx, 0, is->filename, 0);    // Find the first video stream    for (i = 0; i < pFormatCtx->nb_streams; i++) {        if (pFormatCtx->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO                && video_index < 0) {            video_index = i;        }        if (pFormatCtx->streams[i]->codec->codec_type == AVMEDIA_TYPE_AUDIO                && audio_index < 0) {            audio_index = i;        }    }    if (audio_index >= 0) {        stream_component_open(is, audio_index);    }    if (video_index >= 0) {        stream_component_open(is, video_index);    }    if (is->videoStream < 0 || is->audioStream < 0) {        fprintf(stderr, "%s: could not open codecs\n", is->filename);        goto fail;    }    // main decode loop    for (;;) {        if (is->quit) {            break;        }        // seek stuff goes here        if (is->audioq.size > MAX_AUDIOQ_SIZE                || is->videoq.size > MAX_VIDEOQ_SIZE) {            SDL_Delay(10);            continue;        }        if (av_read_frame(is->pFormatCtx, packet) < 0) {            if (is->pFormatCtx->pb->error == 0) {                SDL_Delay(100); /* no error; wait for user input */                continue;            } else {                break;            }        }        // Is this a packet from the video stream?        if (packet->stream_index == is->videoStream) {            packet_queue_put(&is->videoq, packet);        } else if (packet->stream_index == is->audioStream) {            packet_queue_put(&is->audioq, packet);        } else {            av_free_packet(packet);        }    }    /* all done - wait for it */    while (!is->quit) {        SDL_Delay(100);    }    fail: {        SDL_Event event;        event.type = FF_QUIT_EVENT;        event.user.data1 = is;        SDL_PushEvent(&event);    }    return 0;}int main(int argc, char *argv[]) {    SDL_Event event;    VideoState *is;    is = av_mallocz(sizeof(VideoState));    char filePath[] = "./src/a.mp4";    // Register all formats and codecs    av_register_all();    if (SDL_Init(SDL_INIT_VIDEO | SDL_INIT_AUDIO | SDL_INIT_TIMER)) {        fprintf(stderr, "Could not initialize SDL - %s\n", SDL_GetError());        exit(1);    }    // Make a screen to put our video#ifndef __DARWIN__    screen = SDL_SetVideoMode(640, 480, 0, 0);#else    screen = SDL_SetVideoMode(640, 480, 24, 0);#endif    if (!screen) {        fprintf(stderr, "SDL: could not set video mode - exiting\n");        exit(1);    }    av_strlcpy(is->filename, filePath, sizeof(is->filename));    is->pictq_mutex = SDL_CreateMutex();    is->pictq_cond = SDL_CreateCond();    schedule_refresh(is, 40);    is->parse_tid = SDL_CreateThread(decode_thread, is);    if (!is->parse_tid) {        av_free(is);        return -1;    }    for (;;) {        SDL_WaitEvent(&event);        switch (event.type) {        case FF_QUIT_EVENT:        case SDL_QUIT:            SDL_CondSignal(is->audioq.cond);            SDL_CondSignal(is->videoq.cond);            is->quit = 1;            SDL_Quit();            exit(0);            break;        case FF_ALLOC_EVENT:            alloc_picture(event.user.data1);            break;        case FF_REFRESH_EVENT:            video_refresh_timer(event.user.data1);            break;        default:            break;        }    }    return 0;}
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