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• Muxing H264 packets into a MPEGTS container using libav*

  30 avril 2024, par Lucen

  I'm writing a C++ program where I need to encode packets in h264 format and mux them to a MPEG TS container. For the encoding part, I based my code on the encode_video example (https://ffmpeg.org/doxygen/trunk/encode_video_8c-example.html#a9) provided in FFMPEG documentation, and it seems to work fine. In particular, I generate a std::vector of packets which I sequentially write to an output .ts file for debug. Such .ts file plays fine with SMPlayer, and a ffproba command gives

  


  >> ffprobe  -print_format json -show_format -show_streams out.ts
Input #0, h264, from 'out.ts':
  Duration: N/A, bitrate: N/A
    Stream #0:0: Video: h264 (Main), yuv420p(progressive), 640x480 [SAR 1:1 DAR 4:3], 25 fps, 25 tbr, 1200k tbn, 50 tbc
    "streams": [
        {
            "index": 0,
            "codec_name": "h264",
            "codec_long_name": "H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10",
            "profile": "Main",
            "codec_type": "video",
            "codec_time_base": "1/50",
            "codec_tag_string": "[0][0][0][0]",
            "codec_tag": "0x0000",
            "width": 640,
            "height": 480,
            "coded_width": 640,
            "coded_height": 480,
            "has_b_frames": 1,
            "sample_aspect_ratio": "1:1",
            "display_aspect_ratio": "4:3",
            "pix_fmt": "yuv420p",
            "level": 30,
            "chroma_location": "left",
            "field_order": "progressive",
            "refs": 1,
            "is_avc": "false",
            "nal_length_size": "0",
            "r_frame_rate": "25/1",
            "avg_frame_rate": "25/1",
            "time_base": "1/1200000",
            "bits_per_raw_sample": "8",
            "disposition": {
                "default": 0,
                "dub": 0,
                "original": 0,
                "comment": 0,
                "lyrics": 0,
                "karaoke": 0,
                "forced": 0,
                "hearing_impaired": 0,
                "visual_impaired": 0,
                "clean_effects": 0,
                "attached_pic": 0,
                "timed_thumbnails": 0
            }
        }
    ],
    "format": {
        "filename": "out.ts",
        "nb_streams": 1,
        "nb_programs": 0,
        "format_name": "h264",
        "format_long_name": "raw H.264 video",
        "size": "435443",
        "probe_score": 51
    }
}



  


  The dts and pts timestamps are also set.
However, if I try to mux them in MPEG TS format, using as a base the example mux.c (https://ffmpeg.org/doxygen/trunk/mux_8c-example.html), it doesn't work. A shortened version of my muxing code is as follows : (the variables ending with "_" are class fields)

  


  int MyProcessing::Mux(const std::string outputFilename) {
    AVFormatContext *muxingContest;
    avformat_alloc_output_context2(&muxingContest, NULL, NULL, m_output.c_str());

    auto outFormat = muxingContest->oformat;
    outFormat->video_codec = AV_CODEC_ID_H264;

    AVStream *outStream;
    const AVCodec *codec;

    Mux_AddStream(&outStream, muxingContest, &codec, outFormat->video_codec);

    AVDictionary *opt = nullptr;
    Mux_OpenVideo(muxingContest, codec, outStream, opt);
 
    if (!(muxingContest->flags & AVFMT_NOFILE)) {
      avio_open(&muxingContest->pb, m_output.c_str(), AVIO_FLAG_WRITE);
    }
    avformat_write_header(muxingContest, &opt);

    auto muxOk = true;
    size_t countMuxedFrames = 0;
    while ((muxOk) && (countMuxedFrames < packets_.size())) {
        muxOk = !MuxPacket(muxingContest, outStream, packets_[countMuxedFrames], &opt);
        countMuxedFrames++;
    }

    av_write_trailer(muxingContest);
    if (!(muxCodecContextPtr_->flags & AVFMT_NOFILE)) avio_closep(&muxingContest->pb);
 
    return 0;
}


int MyProcessing::Mux_AddStream(AVStream **stream, AVFormatContext *format, const AVCodec **codec, enum AVCodecID codecId) {
    *codec = avcodec_find_encoder(codecId);
    muxPacketTmpPtr_ = av_packet_alloc();
    *stream = avformat_new_stream(format, *codec);
    (*stream)->time_base = (AVRational){ 1, STREAM_FRAME_RATE };
    (*stream)->id = format->nb_streams-1;
    (*stream)->index = 0;
    muxCodecContextPtr_ = avcodec_alloc_context3(*codec);
    Mux_FillCodecContext(*muxCodecContextPtr_, codecId, **stream);
    if (format->oformat->flags & AVFMT_GLOBALHEADER)
        muxCodecContextPtr_->flags |= AV_CODEC_FLAG_GLOBAL_HEADER;
    return 0;
}


void MyProcessing::Mux_FillCodecContext(AVCodecContext &cc, enum AVCodecID codecId, AVStream &stream) {
    cc.codec_id = codecId;
    cc.bit_rate = 400000;
    cc.width    = outputWidth_;
    cc.height   = outputHeight_;
    cc.time_base  = stream.time_base;
    cc.gop_size = 10;
    cc.max_b_frames = 1;
    cc.gop_size      = 12;
    cc.pix_fmt       = AV_PIX_FMT_YUV420P;
    if (cc.codec_id == AV_CODEC_ID_MPEG2VIDEO) cc.max_b_frames = 2;
    if (cc.codec_id == AV_CODEC_ID_MPEG1VIDEO)  cc.mb_decision = 2;
    av_opt_set(&cc, "preset", "slow", 0);
    av_opt_set(&cc, "tune", "zerolatency", 0);
}


int MyProcessing::Mux_OpenVideo(AVFormatContext *format, const AVCodec *codec, AVStream *stream, AVDictionary *opt_arg) {
    AVDictionary *opt = nullptr;
    av_dict_copy(&opt, opt_arg, 0);
    muxCodecContextPtr_->flags |= AV_CODEC_FLAG_GLOBAL_HEADER;
    avcodec_open2(muxCodecContextPtr_, codec, &opt);
    av_dict_free(&opt);
    avcodec_parameters_from_context(stream->codecpar, muxCodecContextPtr_);
    return 0;
}

int MyProcessing::MuxPacket(AVFormatContext *format, AVStream *stream, AVPacket &pkt, AVDictionary **opt) {
    AVBitStreamFilterContext *bsf = av_bitstream_filter_init("h264_mp4toannexb");
    AVPacket filteredPkt = pkt;
    auto filterResult = av_bitstream_filter_filter(bsf, format->streams[stream->index]->codec, NULL,
                                         &filteredPkt.data, &filteredPkt.size,
                                         pkt.data, pkt.size,
                                         pkt.flags & AV_PKT_FLAG_KEY);

    if (filterResult < 0) return filterResult;
    else {
        filteredPkt.buf = av_buffer_create(filteredPkt.data, filteredPkt.size,
                                       av_buffer_default_free, NULL, 0);
    }
    av_bitstream_filter_close(bsf);
    filteredPkt.stream_index = stream->index;
    filteredPkt.dts = filteredPkt.pts;
    filteredPkt.duration = ((double)stream->time_base.num / (double)stream->time_base.den) / STREAM_FRAME_RATE;
    av_packet_rescale_ts(&filteredPkt, muxCodecContextPtr_->time_base, stream->time_base); // rescale output packet timestamp values from codec to stream timebase
    auto writePktResult = av_write_frame(format, &filteredPkt);
   // auto writePktResult = av_interleaved_write_frame(format, &filteredPkt);
    return 0;
}



  


  The console error is

  


  [mpegts @ 0x55555736edc0] H.264 bitstream malformed, no startcode found, use the video bitstream filter 'h264_mp4toannexb' to fix it ('-bsf:v h264_mp4toannexb' option with ffmpeg)


  


  It Is telling me to apply the h264_mp4toannexb filter. As you see from the code, I've put the filtering accordingly, but the error message persists (unless I'm applying the filter in a wrong way).

  


  In the last lines of method MuxPacket(), if I uncomment the line with av_interleaved_write_frame() and comment the previous one, I get the same error, as well as a seg fault. Inspecting with GDB, the call stack for the seg fault is as follows :

  


  #0  __memmove_avx_unaligned_erms () at ../sysdeps/x86_64/multiarch/memmove-vec-unaligned-erms.S:440
#1  0x00007ffff67c7cb6 in av_packet_copy_props () at /lib/x86_64-linux-gnu/libavcodec.so.58
#2  0x00007ffff67c8447 in av_packet_ref () at /lib/x86_64-linux-gnu/libavcodec.so.58
#3  0x00007ffff7e2fa13 in  () at /lib/x86_64-linux-gnu/libavformat.so.58
#4  0x00007ffff7e2fb11 in  () at /lib/x86_64-linux-gnu/libavformat.so.58
#5  0x00007ffff7e30575 in av_interleaved_write_frame () at /lib/x86_64-linux-gnu/libavformat.so.58


  


  I tried to look at solutions online, but they are either old or they don't work. Some of the things I tried and didn't work :

  


  

  1. Putting the line

  


  


  muxCodecContextPtr_->flags |= AV_CODEC_FLAG_GLOBAL_HEADER;


  


  in Mux() after the call to avformat_alloc_output_context2.

  


  

  2. Setting

  


  


  packet.flags |= AV_PKT_FLAG_KEY;


  


  before the call to av_write_frame / av_interleaved_write_frame.

  


  


  3. Trying to write by hand to the file the starting code as described here Need to convert h264 stream from annex-b format to AVCC format.

     


  


  4. Playing with parameters in Mux_FillCodecContext().

     


  


  


• Crash on ffmpeg avcodec_encode_video in a Console app

  5 mars 2013, par Robel sharma

  I want make an encoder which encode a raw image into h263 format.But after loading and initializing ffmpeg library I got crash on avcodec_encode_video for a demo image.

  int _tmain(int argc, _TCHAR* argv[]) {
  
      avcodec_register_all();
  
      AVCodec *codec;
  
      AVCodecContext *c= NULL;
  
      int i, ret, x, y, got_output;
  
      FILE *f;
  
      AVFrame *frame;
  
      AVPacket pkt;
  
  
  
      int out_size, size, outbuf_size;
  
  
  
      AVFrame *picture;
  
      uint8_t *outbuf, *picture_buf;
  
  
  
      AVRational rp;   
  
  
  
      rp.den = 1;
  
      rp.num = 25;
  
      uint8_t endcode[] = { 0, 0, 1, 0xb7 };
  
  
  
      codec = avcodec_find_encoder(CODEC_ID_H263);
  
  
  
      c = avcodec_alloc_context3(codec);
  
      picture= avcodec_alloc_frame();
  
      c->bit_rate = 400000;
  
      /* resolution must be a multiple of two */
  
      c->width = 352;
  
      c->height = 288;
  
      /* frames per second */
  
      //c->time_base= (AVRational){1,25};
  
      c->time_base = rp;
  
      c->gop_size = 10; /* emit one intra frame every ten frames */
  
      c->max_b_frames=1;
  
      c->pix_fmt = PIX_FMT_YUV420P;
  
      avcodec_open(c, codec);
  
  
  
  
  
      outbuf_size = 100000;
  
      outbuf = (uint8_t*)malloc(outbuf_size);
  
      size = c->width * c->height;
  
      picture_buf = (uint8_t*)malloc((size * 3) / 2); /* size for YUV 420 */
  
  
  
      picture->data[0] = picture_buf;
  
      picture->data[1] = picture->data[0] + size;
  
      picture->data[2] = picture->data[1] + size / 4;
  
      picture->linesize[0] = c->width;
  
      picture->linesize[1] = c->width / 2;
  
      picture->linesize[2] = c->width / 2;
  
  
  
      /* encode 1 second of video */
  
      for(i=0;i<25;i++) {
  
          fflush(stdout);
  
          /* prepare a dummy image */
  
          /* Y */
  
          for(y=0;yheight;y++) {
  
              for(x=0;xwidth;x++) {
  
                  picture->data[0][y * picture->linesize[0] + x] = x + y + i * 3;
  
              }
  
          }
  
          /* Cb and Cr */
  
          for(y=0;yheight/2;y++) {
  
              for(x=0;xwidth/2;x++) {
  
                  picture->data[1][y * picture->linesize[1] + x] = 128 + y + i * 2;
  
                  picture->data[2][y * picture->linesize[2] + x] = 64 + x + i * 5;
  
              }
  
          }
  
          /* encode the image */
  
  
  
          **Crash is here** --->                 ///////////////////////////////////////////////////
  
          out_size = avcodec_encode_video(c, outbuf, outbuf_size, picture);
  
  
  
          printf("encoding frame %3d (size=%5d)\n", i, out_size);
  
          fwrite(outbuf, 1, out_size, f);
  
      }
  
      /* get the delayed frames */
  
      for(; out_size; i++) {
  
          fflush(stdout);
  
          out_size = avcodec_encode_video(c, outbuf, outbuf_size, NULL);
  
          printf("write frame %3d (size=%5d)\n", i, out_size);
  
          fwrite(outbuf, 1, out_size, f);
  
      }
  
      /* add sequence end code to have a real mpeg file */
  
      outbuf[0] = 0x00;
  
      outbuf[1] = 0x00;
  
      outbuf[2] = 0x01;
  
      outbuf[3] = 0xb7;
  
      fwrite(outbuf, 1, 4, f);
  
      fclose(f);
  
      free(picture_buf);
  
      free(outbuf);
  
  
  
      avcodec_close(c);
  
      av_free(c);
  
      av_free(picture);
  
      printf("\n");
  
      return 0;
  
  }

• FFMPEG Segmenting skips when m3u8 changes file

  25 septembre 2012, par user792164

  I am attempting to segment a large video file in to segments. When streamed (even locally) by opening the m3u8 file it will jump forward in time by some period of time less than 1 second.

  The following commands are executed :

  First mp4 —> ts :

  ffmpeg -i input_file.mp4 -bsf:v h264_mp4toannexb -acodec libfaac -vcodec libx264 -f mpegts -threads 0 output.ts

  Then I split using :

  ffmpeg -i output.ts -vcodec copy -acodec copy -map 0 -f segment -segment_time 30 -segment_list output.m3u8 -segment_list_type m3u8 -segment_format mpegts output%03d.ts 

  Note : Changing segment time has no effect on issue.

  Generated manifest :

  #EXTM3U
  
  #EXT-X-VERSION:4
  
  #EXTINF:30.947578,
  
  output000.ts
  
  #EXTINF:30.155111,
  
  output001.ts
  
  ...
  
  #EXTINF:24.023989,
  
  output082.ts
  
  #EXT-X-TARGETDURATION:37
  
  #EXT-X-ENDLIST

  ---

  Meta Data :

  $> ffmpeg -version
  
  ffmpeg version git-2012-08-19-a93c221
  
  built on Aug 19 2012 13:18:58 with gcc 4.4.5 (Debian 4.4.5-8)
  
  configuration: --prefix=/usr --bindir=/usr/bin --datadir=/usr/share/ffmpeg --incdir=/usr/include/ffmpeg --libdir=/usr/lib/ --mandir=/usr/share/man --extra-cflags='-O3 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions \ -fstack-protector --param=ssp-buffer-size=4 -mtune=generic' --enable-gpl --enable-shared --enable-nonfree --enable-version3 --enable-libfaac --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-librtmp --enable-libtheora --enable-libvorbis --enable-libvpx --enable-libx264 --enable-pthreads --enable-libxvid --enable-postproc --enable-libgsm --enable-libspeex --enable-avfilter --disable-decoder=libdirac --enable-libfreetype --enable-libschroedinger --disable-decoder=libschroedinger --enable-libopenjpeg --disable-ffplay --disable-ffserver
  
  libavutil      51. 70.100 / 51. 70.100
  
  libavcodec     54. 53.100 / 54. 53.100
  
  libavformat    54. 25.104 / 54. 25.104
  
  libavdevice    54.  2.100 / 54.  2.100
  
  libavfilter     3. 11.101 /  3. 11.101
  
  libswscale      2.  1.101 /  2.  1.101
  
  libswresample   0. 15.100 /  0. 15.100
  
  libpostproc    52.  0.100 / 52.  0.100

  -

  $> ffprobe input_file.mp4
  
  
  
  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'input_file.mp4':
  
  Metadata:
  
  major_brand     : isom
  
  minor_version   : 1
  
  compatible_brands: isom
  
  creation_time   : 2011-09-08 11:43:25
  
  Duration: 00:41:31.00, start: 0.000000, bitrate: 1146 kb/s
  
  Stream #0.0(und): Video: h264 (High), yuv420p, 720x404 [PAR 1:1 DAR 180:101], 1015 kb/s,    23.98 fps, 23.98 tbr, 24k tbn, 47.95 tbc
  
  Metadata:
  
    creation_time   : 2011-09-08 11:43:25
  
  Stream #0.1(und): Audio: aac, 48000 Hz, stereo, s16, 124 kb/s
  
  Metadata:
  
    creation_time   : 2011-09-08 11:43:25

  -

  $> ffprobe output_file.ts
  
  Input #0, mpegts, from 'output_file.ts':
  
  Duration: 00:41:30.98, start: 1.400000, bitrate: 807 kb/s
  
  Program 1 
  
  Metadata:
  
    service_name    : Service01
  
    service_provider: FFmpeg
  
  Stream #0.0[0x100]: Video: h264 (High), yuv420p, 720x404 [PAR 1:1 DAR 180:101], 23.98 fps, 23.98 tbr, 90k tbn, 47.95 tbc
  
  Stream #0.1[0x101](und): Audio: aac, 48000 Hz, stereo, s16, 141 kb/

  ---

  Is it possible to remove this jump, if so, what encoding parameters or incorrect assumptions have I made ? Thanks.