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基于FFMPEG封装aac及h264为FargmentMP4

时间:2021-02-23 14:31:57      阅读:0      评论:0      收藏:0      [点我收藏+]

标签:格式   flags   bre   cat   sign   case   http   str   end   

FargmentMP4是一种特殊的MP4,这边他的特点及格式,不再详细说明 ,网上资料不少可以进行参考。

这边说下基于FFMPEG封装aac及h264为FargmentMP4的步骤:

  1.  
    关键代码:
  2.  
    1、创建两个输入对象和一个输出对象并打开。
  3.  
    AVFormatContext *ifmt_ctx_v = NULL, *ifmt_ctx_a = NULL, *ofmt_ctx = NULL;
  4.  
    if ((ret = avformat_open_input(&ifmt_ctx_a, in_filename_a, NULL, NULL)) < 0) {
  5.  
    printf("Could not open input file.");
  6.  
    goto end;
  7.  
    }
  8.  
    // printf("=====2========RET:%d\n",ret);
  9.  
    if ((ret = avformat_find_stream_info(ifmt_ctx_a, 0)) < 0) {
  10.  
    printf("Failed to retrieve input stream information");
  11.  
    if (acc_length > 0)
  12.  
    goto end;
  13.  
    }
  14.  
     
  15.  
    if ((ret = avformat_open_input(&ifmt_ctx_v, in_filename_v, NULL, NULL)) < 0) {
  16.  
    printf("Could not open input file:%d\n", ret);
  17.  
    goto end;
  18.  
    }
  19.  
    if ((ret = avformat_find_stream_info(ifmt_ctx_v, 0)) < 0) {
  20.  
    printf("Failed to retrieve input stream information");
  21.  
    goto end;
  22.  
    }
  23.  
    avformat_alloc_output_context2(&ofmt_ctx, NULL, NULL, out_filename);
  24.  
    if (!ofmt_ctx) {
  25.  
    printf("Could not create output context\n");
  26.  
    ret = AVERROR_UNKNOWN;
  27.  
    goto end;
  28.  
    }
  29.  
    ofmt = ofmt_ctx->oformat;
  30.  
     
  31.  
    2、初始化过滤器 因为aac打包到mp4需要去掉adts头。
  32.  
    const AVBitStreamFilter *absFilter = av_bsf_get_by_name("aac_adtstoasc");
  33.  
    AVBSFContext *absCtx = NULL;
  34.  
    av_bsf_alloc(absFilter, &absCtx);
  35.  
     
  36.  
    3、获取视频流信息并拷贝相应编码格式
  37.  
    for (i = 0; i < ifmt_ctx_v->nb_streams; i++) {
  38.  
    //Create output AVStream according to input AVStream
  39.  
    if (ifmt_ctx_v->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_VIDEO) {
  40.  
    AVStream *in_stream = ifmt_ctx_v->streams[i];
  41.  
    AVCodec *avcodec = avcodec_find_decoder(in_stream->codecpar->codec_id);
  42.  
    AVStream *out_stream = avformat_new_stream(ofmt_ctx, avcodec);
  43.  
    videoindex_v = i;
  44.  
    if (!out_stream) {
  45.  
    printf("Failed allocating output stream\n");
  46.  
    ret = AVERROR_UNKNOWN;
  47.  
    goto end;
  48.  
    }
  49.  
    videoindex_out = out_stream->index;
  50.  
    AVCodecContext *codec_ctx = avcodec_alloc_context3(avcodec);
  51.  
    ret = avcodec_parameters_to_context(codec_ctx, in_stream->codecpar);
  52.  
    if (ret < 0) {
  53.  
    printf("Failed to copy context from input to output stream codec context\n");
  54.  
    goto end;
  55.  
    }
  56.  
    codec_ctx->codec_tag = 0;
  57.  
    if (ofmt_ctx->oformat->flags & AVFMT_GLOBALHEADER)
  58.  
    codec_ctx->flags |= AV_CODEC_FLAG_GLOBAL_HEADER;
  59.  
     
  60.  
    ret = avcodec_parameters_from_context(out_stream->codecpar, codec_ctx);
  61.  
    int q = 0;
  62.  
    }
  63.  
    }
  64.  
     
  65.  
    4、获取音频流信息并拷贝相应编码格式
  66.  
    for (i = 0; i < ifmt_ctx_a->nb_streams; i++) {
  67.  
    if (ifmt_ctx_a->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_AUDIO) {
  68.  
    AVStream *in_stream = ifmt_ctx_a->streams[i];
  69.  
    AVCodec *avcodec = avcodec_find_decoder(in_stream->codecpar->codec_id);
  70.  
    AVStream *out_stream = avformat_new_stream(ofmt_ctx, avcodec);
  71.  
    audioindex_a = i;
  72.  
    if (!out_stream) {
  73.  
    printf("Failed allocating output stream\n");
  74.  
    ret = AVERROR_UNKNOWN;
  75.  
    goto end;
  76.  
    }
  77.  
    audioindex_out = out_stream->index;
  78.  
    avcodec = avcodec_find_decoder(in_stream->codecpar->codec_id);
  79.  
     
  80.  
    avcodec_parameters_copy(absCtx->par_in, in_stream->codecpar);
  81.  
    av_bsf_init(absCtx);
  82.  
     
  83.  
    AVCodecContext *codec_ctx = avcodec_alloc_context3(avcodec);
  84.  
    ret = avcodec_parameters_to_context(codec_ctx, in_stream->codecpar);
  85.  
    if (ret < 0) {
  86.  
    printf("Failed to copy context from input to output stream codec context\n");
  87.  
    goto end;
  88.  
    }
  89.  
    codec_ctx->codec_tag = 0;
  90.  
    if (ofmt_ctx->oformat->flags & AVFMT_GLOBALHEADER)
  91.  
    codec_ctx->flags |= AV_CODEC_FLAG_GLOBAL_HEADER;
  92.  
     
  93.  
    ret = avcodec_parameters_from_context(out_stream->codecpar, codec_ctx);
  94.  
    out_stream->codecpar->extradata = (uint8_t*)av_malloc(2);
  95.  
    out_stream->codecpar->extradata_size = 2;
  96.  
    unsigned char dsi1[2];
  97.  
    unsigned int sampling_frequency_index = (unsigned int)get_sr_index(8000);
  98.  
    make_dsi(sampling_frequency_index, 1, dsi1);
  99.  
    memcpy(out_stream->codecpar->extradata, dsi1, 2);
  100.  
     
  101.  
    break;
  102.  
    }
  103.  
    }
  104.  
    5、打开MP4文件
  105.  
    if (!(ofmt->flags & AVFMT_NOFILE)) {
  106.  
    if (avio_open(&ofmt_ctx->pb, out_filename, AVIO_FLAG_WRITE) < 0) {
  107.  
    printf("Could not open output file ‘%s‘", out_filename);
  108.  
    goto end;
  109.  
    }
  110.  
    }
  111.  
    6、设置字典fmp4的关键
  112.  
    AVDictionary *movflags = nullptr;
  113.  
    const bool low_delay = true;
  114.  
    if (low_delay) {
  115.  
    // In case of low delay, set fragment duration to 200 ms.
  116.  
    av_dict_set(&movflags, "movflags", "empty_moov+default_base_moof", 0);
  117.  
    av_dict_set_int(&movflags, "frag_duration", 200 * 1000, 0);
  118.  
    }
  119.  
    else {
  120.  
    // Only produce fragment until we have next key frame.
  121.  
    av_dict_set(&movflags, "movflags", "empty_moov+default_base_moof+frag_keyframe", 0);
  122.  
    }
  123.  
    //avformat_open_input(&addofmt_ctx, addinputAacFileName, 0, &movflags);
  124.  
    ret = avformat_write_header(ofmt_ctx, &movflags);
  125.  
    if (ret < 0) {
  126.  
    fprintf(stderr, "Error occurred when opening output file\n");
  127.  
    goto end;
  128.  
    }
  129.  
    7、打包
  130.  
     
  131.  
    if ((ret = av_interleaved_write_frame(ofmt_ctx, &pkt)) < 0) {
  132.  
    printf("Error muxing packet\n");
  133.  
    break;
  134.  
    }

具体工程参考:https://download.csdn.net/download/venice0708/11434379

基于FFMPEG封装aac及h264为FargmentMP4

标签:格式   flags   bre   cat   sign   case   http   str   end   

原文地址:https://www.cnblogs.com/lidabo/p/14434470.html

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