使用FFmpeg实现的转码器

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头文件

#include "stdafx.h"#include <windows.h>extern "C" { #include <libavcodec/avcodec.h> #include <libavdevice/avdevice.h> #include <libavformat/avformat.h> #include <libavfilter/avfilter.h> #include <libavutil/avutil.h> #include <libswscale/swscale.h>#include <stdlib.h> #include <stdio.h> #include <string.h> #include <math.h>} class rtsp2mp4{public:    int inputFile(char *file);    int outputFile(char *file);    int transStart();    int decode();    int encode();    int transEnd();private:    int init();    int unit();    int prepare();    int rtsp2mp4 :: flush_encoder(AVFormatContext *fmt_ctx, unsigned int stream_index);    void ResolutionChange(AVCodecContext *pCodecCtx,AVFrame *pFrame,AVFrame *pNewFrame,int pNewWidth,int pNewHeight);    AVFormatContext *in_fmt_ctx;    AVStream *in_video_stream;    AVFrame *frame;    AVFormatContext *out_fmt_ctx;    AVStream *out_video_stream;    char *rtsp_url;    char *name_path;    int width;    int height;    int64_t pts, dts;    int last_pts;    int last_dts;    int video_index;    int got_frame;    int got_picture;    int frame_index;    int i;};

具体函数实现

#include "rtsp2mp4.h"/*卸载函数：释放内存*/int rtsp2mp4 :: unit(){    if (out_fmt_ctx && !(out_fmt_ctx->oformat->flags & AVFMT_NOFILE)) {        avio_close(out_fmt_ctx->pb);    }       avcodec_close(out_fmt_ctx->streams[0]->codec);    av_freep(&out_fmt_ctx->streams[0]->codec);    av_freep(&out_fmt_ctx->streams[0]);    avformat_free_context(in_fmt_ctx);    avformat_free_context(out_fmt_ctx);    return 0;}/*输入读取文件的地址，这是读取的是rtsp流地址，在之后的进行一点修改就可以转码普通格式*/int rtsp2mp4 :: inputFile(char *file){    rtsp_url = file;    return 0;}/*输出文件名*/int rtsp2mp4 :: outputFile(char *file){    name_path = file;    return 0;}/*FFmpeg组件的注册与一些初始化操作*/int rtsp2mp4 :: init(){    av_register_all();    avformat_network_init();    in_fmt_ctx = NULL;    out_fmt_ctx = NULL;    width = 800;    height = 600;    video_index = -1;    pts = -3600;    dts = -3600;    i = 0;    frame_index = 0;    return 0;}/*准备和一些参数的设定*/int rtsp2mp4 :: prepare(){    int ret = 0;    /*下面四行为rtsp流通过TCP协议读取的操作*/    AVDictionary *avdic=NULL;    char option_key[]="rtsp_transport";    char option_value[]="tcp";    av_dict_set(&avdic,option_key,option_value,0);    /*如果输入的不是rtsp流地址，把avformat_open_input(&in_fmt_ctx,rtsp_url,NULL,&avdic)改为：avformat_open_input(&in_fmt_ctx,rtsp_url,NULL,NULL);*/    if(ret = avformat_open_input(&in_fmt_ctx,rtsp_url,NULL,&avdic) < 0) {        printf("无法打开文件\n");        return ret;    }    if(ret = avformat_find_stream_info(in_fmt_ctx,0) < 0) {        printf("无法找到流信息\n");        return ret;    }    av_dump_format(in_fmt_ctx,0,rtsp_url,0);    for(unsigned i =0;i < in_fmt_ctx->nb_streams;i ++) {        if(in_fmt_ctx->streams[i]->codec->coder_type == AVMEDIA_TYPE_VIDEO) {            in_video_stream = in_fmt_ctx->streams[i];            video_index = i;            break;        }    }    /*寻找与打开解码器*/    if(0 > avcodec_open2(in_video_stream->codec, avcodec_find_decoder(in_video_stream->codec->codec_id), NULL)) {        printf("无法找到解码器\n");    }    /*创建输出文件*/      avformat_alloc_output_context2(&out_fmt_ctx,NULL,NULL,name_path);    if(!out_fmt_ctx) {          printf("不能创建输出文件\n");        ret = AVERROR_UNKNOWN;        return ret;    }    /*创建输出流*/    out_video_stream = avformat_new_stream(out_fmt_ctx, NULL);    if (!out_video_stream) {        printf("无法创造新流\n");        ret = AVERROR_UNKNOWN;        return ret;    }    /*参数设置—开始*/     out_video_stream->codec->codec = avcodec_find_encoder(out_fmt_ctx->oformat->video_codec);    out_video_stream->codec->height = height;    out_video_stream->codec->width = width;    out_video_stream->codec->time_base.num = in_fmt_ctx->streams[i]->avg_frame_rate.den;    out_video_stream->codec->time_base.den = in_fmt_ctx->streams[i]->avg_frame_rate.num;    out_video_stream->codec->sample_aspect_ratio = in_video_stream->codec->sample_aspect_ratio;    out_video_stream->codec->pix_fmt = in_video_stream->codec->pix_fmt;    out_video_stream->codec->pix_fmt = out_video_stream->codec->codec->pix_fmts[0];    out_video_stream->codec->bit_rate = 500000;    out_video_stream->codec->codec_type = AVMEDIA_TYPE_VIDEO;    /*按照命令输出的文件修改*/    out_video_stream->codec->thread_count = 6;    out_video_stream->codec->max_b_frames = 3;    out_video_stream->codec->b_frame_strategy = 1;    out_video_stream->codec->gop_size = 250;    out_video_stream->codec->keyint_min = 25;    out_video_stream->codec->trellis = 1;    out_video_stream->codec->me_subpel_quality = 7;    out_video_stream->codec->refs = 3;    out_video_stream->codec->me_method = ME_HEX;    out_video_stream->codec->coder_type = FF_CODER_TYPE_AC;    out_video_stream->codec->me_range = 16;    out_video_stream->codec->max_qdiff = 4;    out_video_stream->codec->qmin = 0;    out_video_stream->codec->qmax = 69;    out_video_stream->codec->qcompress = 0.6;    out_video_stream->codec->flags |= CODEC_FLAG_GLOBAL_HEADER;    /*参数设置—结束*/    /*寻找编码器*/    if (!out_video_stream->codec->codec) {        printf("找不到编码器\n");        ret = AVERROR_UNKNOWN;        return ret;    }    AVDictionary *param = 0;      av_dict_set(¶m, "profile", "baseline", 0);    av_opt_set(out_video_stream->codec->priv_data, "preset", "fast", 0);    av_opt_set(out_video_stream->codec->priv_data, "tune", "zerolatency", 0);    /*打开编码器*/    if ((avcodec_open2(out_video_stream->codec, out_video_stream->codec->codec, NULL)) < 0) {        printf("无法打开编码器\n");        ret = AVERROR_UNKNOWN;        return ret;    }    if(video_index == -1) {        printf("没找到视频流\n");        ret = AVERROR_UNKNOWN;        return ret;    }    return 0;}/*转码之前的准备，写头文件等*/int rtsp2mp4 :: transStart(){    init();    prepare();    avio_open(&out_fmt_ctx->pb,name_path,AVIO_FLAG_WRITE);    AVDictionary *opt = NULL;    av_dict_set_int(&opt,"video_track_timescale",25,0);    avformat_write_header(out_fmt_ctx,&opt);    return 0;}/*解码一帧*/int rtsp2mp4 :: decode(){    AVFrame *old_frame;    old_frame = av_frame_alloc();    frame = av_frame_alloc();    int size = avpicture_get_size(out_video_stream->codec->pix_fmt, width,height);    uint8_t* frame_buf = (uint8_t *)av_malloc(size);    avpicture_fill((AVPicture *)frame, frame_buf, out_video_stream->codec->pix_fmt, width, height);    frame->format = AV_PIX_FMT_YUV420P;    frame->width = width;    frame->height = height;    AVPacket *pkt_in = NULL;    int y_size = out_video_stream->codec->width * out_video_stream->codec->height;    pkt_in = (AVPacket *)av_malloc(sizeof(AVPacket));    av_new_packet(pkt_in, y_size);    int ret = 0;    got_frame = -1;    if (av_read_frame(in_fmt_ctx, pkt_in) < 0) {        av_frame_free(&frame);        av_frame_free(&old_frame);        ret = AVERROR_UNKNOWN;        av_free_packet(pkt_in);        return ret;    }    if(pkt_in->stream_index == video_index) {        if (avcodec_decode_video2(in_fmt_ctx->streams[video_index]->codec, old_frame, &got_frame, pkt_in) < 0) {            av_frame_free(&frame);            av_frame_free(&old_frame);            av_free_packet(pkt_in);            printf("无法解码\n");            ret = AVERROR_UNKNOWN;            return ret;        }    }    printf("got_frame:%d\n",got_frame);    av_free_packet(pkt_in);    if(got_frame > 0) {        ResolutionChange(in_fmt_ctx->streams[video_index]->codec,old_frame,frame,width,height);    }    av_frame_free(&old_frame);    return ret;}/*编码一帧*/int rtsp2mp4 :: encode(){    AVPacket pkt_out;    av_init_packet(&pkt_out);    int ret = 0;    got_picture = -1;    if (got_frame > 0) {        frame->pts = i++;        pkt_out.data = NULL;        pkt_out.size = 0;        if (avcodec_encode_video2(out_video_stream->codec, &pkt_out, frame, &got_picture) < 0) {            av_free_packet(&pkt_out);            av_frame_free(&frame);            printf("无法编码\n");            ret = AVERROR_UNKNOWN;            return ret;        }           if (got_picture > 0) {            printf("成功编码 %5d\t大小:%5d\n",frame_index,pkt_out.size);          printf("dts:%10d\tpts:%6d\n",pkt_out.dts,pkt_out.pts);            frame_index++;            av_write_frame(out_fmt_ctx, &pkt_out);            av_free_packet(&pkt_out);        }    }    av_free_packet(&pkt_out);    av_frame_free(&frame);    return ret;}/*释放内存内的帧并且写尾文件*/int rtsp2mp4 :: transEnd(){    int ret = flush_encoder(out_fmt_ctx, video_index);    if (ret < 0) {        printf("释放失败\n");        return -1;    }    avformat_close_input(&in_fmt_ctx);    av_write_trailer(out_fmt_ctx);    unit();    return 0;}int rtsp2mp4 :: flush_encoder(AVFormatContext *fmt_ctx, unsigned int stream_index){    int ret;    int got_frame;    AVPacket enc_pkt;    if (!(fmt_ctx->streams[stream_index]->codec->codec->capabilities &CODEC_CAP_DELAY)) {        return 0;    }    while(1) {        enc_pkt.data = NULL;        enc_pkt.size = 0;        av_init_packet(&enc_pkt);        ret = avcodec_encode_video2(fmt_ctx->streams[stream_index]->codec, &enc_pkt, NULL, &got_frame);        av_frame_free(NULL);        if (ret < 0) {            break;        }        if (!got_frame) {            ret = 0;            break;        }        printf("释放编码数据: 成功编码 1 帧!\tsize:%5d\n",enc_pkt.size);        ret = av_write_frame(fmt_ctx, &enc_pkt);        if (ret < 0)            break;    }    return ret;}void rtsp2mp4 :: ResolutionChange(AVCodecContext *pCodecCtx,AVFrame *pFrame,AVFrame *pNewFrame,int pNewWidth,int pNewHeight){    pNewFrame->linesize[0] = pNewWidth;    pNewFrame->linesize[1] = pNewWidth/2;    pNewFrame->linesize[2] = pNewWidth/2;    //用 sws_getContext函数 得到 sws_scale函数 运行的上下文，之后用 sws_scale函数 将图形缩放    struct SwsContext *pSwsCtx = NULL;    pSwsCtx = sws_getContext(pCodecCtx->width,pCodecCtx->height,AV_PIX_FMT_YUV420P,pNewWidth,pNewHeight,AV_PIX_FMT_YUV420P,SWS_SINC,NULL,NULL,NULL);    if(pSwsCtx == NULL)        return ;    sws_scale(pSwsCtx,pFrame->data,pFrame->linesize,0,pCodecCtx->height,pNewFrame->data,pNewFrame->linesize);    sws_freeContext(pSwsCtx);}

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