调通了ffmpeg tutorial例程

来源：互联网发布：酒店网络怎么布置编辑：程序博客网时间：2024/04/30 13:24
参考http://m.oschina.net/blog/56616调通了ffmpeg例程
gcc test_decode_frames.c -I/usr/local/include -lavcodec -lavformat -lswscale -lavutil
#include <stdlib.h>#include <stdio.h>#include <libavformat/avformat.h>#include <libavcodec/avcodec.h>#include <libswscale/swscale.h>static void SaveFrame(AVFrame *pFrame, int width, int height, int iFrame){    FILE *pFile;    char szFilename[32];    int y;    sprintf(szFilename, "frame%d.ppm", iFrame);    pFile = fopen(szFilename, "wb");    if (!pFile)        return;    fprintf(pFile, "P6\n%d %d\n255\n", width, height);    for (y = 0; y < height; y++)        fwrite(pFrame->data[0] + y * pFrame->linesize[0], 1, width * 3, pFile);    fclose(pFile);}int main(int argc, char* argv[]){    AVFormatContext *pFormatCtx = NULL;    int             i           = 0;    int             videoStream = 0;    AVCodecContext  *pCodecCtx  = 0;    AVCodec         *pCodec     = NULL;    AVFrame         *pFrame     = 0;    AVFrame         *pFrameRGB  = NULL;    AVPacket        packet;    int             gotPic      = 0;    int             bytesUsed   = 0;    int             numBytes    = 0;    uint8_t         *buffer     = NULL;    // 注册所有 muxer/demuxer, encoder/decoder    av_register_all();    // 打开一个文件, 读文件头    if (avformat_open_input(&pFormatCtx, argv[1], NULL, NULL) != 0)        return -1;    // 获取文件中的流信息    if (avformat_find_stream_info(pFormatCtx, NULL ) < 0)        return -1;    // 输出文件信息到终端    av_dump_format(pFormatCtx, -1, argv[1], 0);    // 找到第一个视频流    videoStream = -1;    for (i = 0; i < pFormatCtx->nb_streams; i++)    {        if (pFormatCtx->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO)        {            videoStream = i;            break;        }    }    if (videoStream == -1)        return -1;    // 打开解码器    pCodecCtx = pFormatCtx->streams[videoStream]->codec;    pCodec = avcodec_find_decoder(pCodecCtx->codec_id);    if (pCodec == NULL)        return -1;    if (avcodec_open2(pCodecCtx, pCodec, NULL) < 0)        return -1;    // 申请帧缓存    pFrame = avcodec_alloc_frame();    if (pFrame == NULL)        return -1;    pFrameRGB = avcodec_alloc_frame();    if (pFrameRGB == NULL)        return -1;    numBytes = avpicture_get_size(PIX_FMT_RGB24, pCodecCtx->width,                                  pCodecCtx->height);    buffer = av_malloc(numBytes);    avpicture_fill((AVPicture *)pFrameRGB, buffer, PIX_FMT_RGB24,                   pCodecCtx->width, pCodecCtx->height);    // 读取帧数据==>解码==>色彩空间转换==>保存PPM文件    i = 0;    while (av_read_frame(pFormatCtx, &packet) >= 0)    {        if (packet.stream_index == videoStream)        {            gotPic = 0;            bytesUsed = 0;            bytesUsed = avcodec_decode_video2(pCodecCtx, pFrame, &gotPic, &packet);            if (gotPic &&  (bytesUsed > 0))            {                struct SwsContext *img_convert_ctx = NULL;                img_convert_ctx = sws_getCachedContext(img_convert_ctx, pCodecCtx->width,                                                       pCodecCtx->height, pCodecCtx->pix_fmt,                                                       pCodecCtx->width, pCodecCtx->height,                                                       PIX_FMT_RGB24, SWS_BICUBIC,                                                       NULL, NULL, NULL);                if (!img_convert_ctx)                {                    fprintf(stderr, "Cannot initialize sws conversion context\n");                    exit(1);                }                sws_scale(img_convert_ctx, (const uint8_t * const*)pFrame->data,                          pFrame->linesize, 0, pCodecCtx->height, pFrameRGB->data,                          pFrameRGB->linesize);                if (i++ < 50)                    SaveFrame(pFrameRGB, pCodecCtx->width, pCodecCtx->height, i);            }        }    }    av_free(buffer);    av_free(pFrameRGB);    av_free(pFrame);    avcodec_close(pCodecCtx);    avformat_close_input(&pFormatCtx);    return 0;}