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• ffmpeg / libav encoding 264 from YUV420P [on hold]

  4 janvier 2017, par MrSmith

  I am having issues getting this thing to encode correctly. Either I get the container wrong or the content it seems.
  This code encodes a file just fine, but viewing it with VLC or Totem will just yield the first picture, not the remaining 100 frames.
  This is a step up from before as I dont get warnings that my container (mp4) is borked, however now the video wont play at all.. at least it played before :).

  If someone could put a finger somewhere on this code and call me a dumbass, that would be nice :)

  void encode_video(char *carrarr[]){
  
  av_log_set_level(AV_LOG_DEBUG);
  
  av_register_all();
  
  avcodec_register_all();
  
  AVCodec *codec = avcodec_find_encoder(AV_CODEC_ID_H264);
  
  AVOutputFormat * outputFormat = av_guess_format("mp4", NULL, NULL);
  
  
  
  int test = avformat_alloc_output_context2(&outFmtCtx, outputFormat, NULL, NULL);
  
  if(test<0) exit(-1);
  
  
  
  AVStream * outStrm = avformat_new_stream(outFmtCtx, codec);
  
  avcodec_get_context_defaults3(outStrm->codec, codec);
  
  
  
  outStrm->codec->codec_id = AV_CODEC_ID_H264;
  
  outStrm->codec->coder_type = AVMEDIA_TYPE_VIDEO;
  
  
  
  outStrm->codec->bit_rate = 400000;
  
  outStrm->codec->width = 320;
  
  outStrm->codec->height = 240;
  
  outStrm->codec->time_base= (AVRational){1,25};
  
  outStrm->time_base=(AVRational){1,25};
  
  outStrm->codec->gop_size = 10; // emit one intra frame every ten frames
  
  outStrm->codec->max_b_frames=1;
  
  outStrm->codec->pix_fmt = AV_PIX_FMT_YUV420P;
  
  outStrm->codec->flags |= AV_CODEC_FLAG_GLOBAL_HEADER;
  
  // FOR H264 ONLY
  
  test = av_opt_set(outStrm->codec->priv_data, "preset", "slow", 0);
  
  if(test<0) exit(-2);
  
  test = avcodec_open2(outStrm->codec, codec, NULL);
  
  if(test<0) exit(-3);
  
  test = avio_open2(&outFmtCtx->pb, "myoutputfile.avi", AVIO_FLAG_WRITE, NULL, NULL);
  
  if(test<0) exit(-4);
  
  
  
  test = avformat_write_header(outFmtCtx, NULL);
  
  if(test<0) exit(-5);
  
  AVFrame * frame = avcodec_alloc_frame();
  
  if (!frame) exit(-6);
  
  
  
  frame->format = outStrm->codec->pix_fmt;
  
  frame->width  = outStrm->codec->width;
  
  frame->height = outStrm->codec->height;
  
  
  
  ret = av_image_alloc(frame->data, frame->linesize, frame->width, frame->height, outStrm->codec->pix_fmt, 32);
  
  if (ret < 0) exit(-7);
  
  
  
  av_init_packet(&pkt);
  
  pkt.data = NULL;
  
  pkt.size = 0;
  
  
  
  int yrange = 240*320;
  
  int vrange = 240*320*0.25;
  
  
  
  for(int i=0;i<100;i++){
  
      char *carr = carrarr[i];
  
  
  
      char* Y = carr;
  
      char* U = carr+yrange;
  
      char* V = carr+yrange+vrange;
  
      frame->data[0] = (uint8_t*)Y;
  
      frame->data[1] = (uint8_t*)U;
  
      frame->data[2] = (uint8_t*)V;
  
      frame->pts = i;
  
  
  
      ret = avcodec_encode_video2(outStrm->codec, &pkt, frame, &got_output);
  
      if (ret < 0) {
  
          fprintf(stderr, "Error encoding frame\n");
  
          exit (EXIT_FAILURE);
  
      }
  
      if (got_output) {
  
          printf("Write frame %3d (size=%5d)\n", i, pkt.size);
  
          //fwrite(pkt.data, 1, pkt.size, file_encoded_video);
  
          av_interleaved_write_frame(outFmtCtx, &pkt);
  
          av_free_packet(&pkt);
  
      }
  
  }
  
  av_write_trailer(outFmtCtx);
  
  avio_close(outFmtCtx->pb);
  
  }

  carrarr is holding 100 frames of nice valid YUV420P data, I know this cause I’ve encoded it before AND I can output it to screen with SDL.

  Any ideas welcome. Thanks !

• Error in video streaming using libavformat : VBV buffer size not set, muxing may fail

  18 octobre 2017, par Blue Sky

  I stream a video using libavformat as follows :

  static AVStream *add_stream(AVFormatContext *oc, AVCodec **codec,
  
                          enum AVCodecID codec_id)
  
  {
  
  AVCodecContext *c;
  
  AVStream *st;
  
  /* find the encoder */
  
  *codec = avcodec_find_encoder(codec_id);
  
  if (!(*codec)) {
  
      fprintf(stderr, "Could not find encoder for '%s'\n",
  
              avcodec_get_name(codec_id));
  
      exit(1);
  
  }
  
  st = avformat_new_stream(oc, *codec);
  
  if (!st) {
  
      fprintf(stderr, "Could not allocate stream\n");
  
      exit(1);
  
  }
  
  st->id = oc->nb_streams-1;
  
  c = st->codec;
  
  switch ((*codec)->type) {
  
  case AVMEDIA_TYPE_AUDIO:
  
      c->sample_fmt  = (*codec)->sample_fmts ?
  
          (*codec)->sample_fmts[0] : AV_SAMPLE_FMT_FLTP;
  
      c->bit_rate    = 64000;
  
      c->sample_rate = 44100;
  
      c->channels    = 2;
  
      break;
  
  case AVMEDIA_TYPE_VIDEO:
  
      c->codec_id = codec_id;
  
      c->bit_rate = 400000;
  
      /* Resolution must be a multiple of two. */
  
      c->width    = outframe_width;
  
      c->height   = outframe_height;
  
      /* timebase: This is the fundamental unit of time (in seconds) in terms
  
       * of which frame timestamps are represented. For fixed-fps content,
  
       * timebase should be 1/framerate and timestamp increments should be
  
       * identical to 1. */
  
      c->time_base.den = STREAM_FRAME_RATE;
  
      c->time_base.num = 1;
  
      c->gop_size      = 12; /* emit one intra frame every twelve frames at most */
  
      c->pix_fmt       = STREAM_PIX_FMT;
  
      if (c->codec_id == AV_CODEC_ID_MPEG2VIDEO) {
  
          /* just for testing, we also add B frames */
  
          c->max_b_frames = 2;
  
      }
  
      if (c->codec_id == AV_CODEC_ID_MPEG1VIDEO) {
  
          /* Needed to avoid using macroblocks in which some coeffs overflow.
  
           * This does not happen with normal video, it just happens here as
  
           * the motion of the chroma plane does not match the luma plane. */
  
          c->mb_decision = 2;
  
      }
  
  break;
  
  default:
  
      break;
  
  }
  
  /* Some formats want stream headers to be separate. */
  
  if (oc->oformat->flags & AVFMT_GLOBALHEADER)
  
      c->flags |= CODEC_FLAG_GLOBAL_HEADER;
  
  return st;
  
  }

  But when I run this code, I get the following error/warning :

  [mpeg @ 01f3f040] VBV buffer size not set, muxing may fail

  Do you know how I can set the VBV buffer size in the code ? In fact, when I use ffplay to display the streamed video, ffplay doesn’t show anything for short videos but for long videos, it start displaying the video immediately. So, it looks like ffplay needs a buffer to be filled up by some amount so that it can start displaying the stream. Am I right ?

• ffmpeg API muxing h264 endoced frames to mkv

  24 mars 2017, par Pawel K

  Hi I’m having some problems with muxing h264 encoded frames into mkv container using code of ffmpeg-3.2.4.
  I have ended up with the following code that is a mashup of code found on SO and muxing.c example of ffmpeg :
  (and yes I am aware that it is ugly, no errors checked etc. it is meant to be like that for clarity :) )

  char *filename = "out.mkv";
  
  const uint8_t SPS[] = { 0x67, 0x42, 0x40, 0x1F, 0x96, 0x54, 0x02, 0x80, 0x2D, 0xD0, 0x0F, 0x39, 0xEA };
  
  const uint8_t PPS[] = { 0x68, 0xCE, 0x38, 0x80 };
  
  int fps = 5;
  
  
  
  typedef struct OutputStream
  
  {
  
     AVStream *st;
  
     AVCodecContext *enc;
  
  
  
     /* pts of the next frame that will be generated */
  
     int64_t next_pts;
  
     int samples_count;
  
     AVFrame *frame;
  
     AVFrame *tmp_frame;
  
     float t, tincr, tincr2;
  
     struct SwsContext *sws_ctx;
  
     struct SwrContext *swr_ctx;
  
  } OutputStream;
  
  
  
  static void avlog_cb(void *s, int level, const char *szFmt, va_list varg)
  
  {
  
     vprintf(szFmt, varg);
  
  }
  
  
  
  void main()
  
  {
  
     AVOutputFormat *fmt;
  
     AVFormatContext *formatCtx;
  
     AVCodec *audio_codec;
  
     AVCodec *video_codec;
  
     OutputStream video_st = { 0 };
  
     OutputStream audio_st = { 0 };
  
     av_register_all();
  
  
  
     av_log_set_level(AV_LOG_TRACE);
  
     //av_log_set_callback(avlog_cb);
  
  
  
     //allocate output and format ctxs
  
     avformat_alloc_output_context2(&formatCtx, NULL, NULL, filename);
  
     fmt = formatCtx->oformat;
  
  
  
     //allocate streams
  
     video_codec = avcodec_find_encoder(fmt->video_codec);
  
     video_st.st = avformat_new_stream(formatCtx, NULL);
  
     video_st.st->id = 0;
  
  
  
     AVCodecContext *codecCtx =  avcodec_alloc_context3(video_codec);
  
     fmt->video_codec = AV_CODEC_ID_H264;
  
     video_st.enc = codecCtx;
  
  
  
     codecCtx->codec_id = fmt->video_codec;
  
     codecCtx->bit_rate = 400000;
  
     codecCtx->width  = 1080;
  
     codecCtx->height = 720;
  
     codecCtx->profile = FF_PROFILE_H264_CONSTRAINED_BASELINE;
  
     codecCtx->level = 31;
  
  
  
     video_st.st->time_base = (AVRational){ 1, fps };
  
     codecCtx->time_base = video_st.st->time_base;
  
     codecCtx->gop_size = 4;
  
     codecCtx->pix_fmt = AV_PIX_FMT_YUV420P;
  
  
  
     //open video codec
  
     codecCtx->extradata_size = 24;
  
     codecCtx->extradata = (uint8_t *)av_malloc(codecCtx->extradata_size);
  
     uint8_t extra_data_array[] = { 0x01, SPS[1], SPS[2], SPS[3], 0xFF, 0xE1, 0xc0, 0, 0x42, 0x40, 0x1F, 0x96, 0x54, 0x02, 0x80, 0x2D, 0xD0, 0x0F, 0x39, 0xEA, 0x03, 0xCE, 0x38, 0x80 };
  
     memcpy(codecCtx->extradata, extra_data_array, codecCtx->extradata_size);
  
  
  
     AVCodecContext *c = video_st.enc;
  
     AVDictionary *opt = NULL;
  
     avcodec_open2(c, video_codec, &opt);
  
     avcodec_parameters_from_context(video_st.st->codecpar, c);
  
  
  
     //open output file
  
     avio_open(&formatCtx->pb, filename, AVIO_FLAG_WRITE);
  
  
  
     //write header
  
     int res = avformat_write_header(formatCtx, NULL);
  
  
  
     //write frames
  
  
  
     // get the frames from file
  
     uint32_t u32frameCnt = 0;
  
  
  
     do
  
     {
  
        int8_t i8frame_name[64] = "";
  
  
  
        uint8_t  *pu8framePtr = NULL;
  
        AVPacket pkt = { 0 };
  
  
  
        av_init_packet(&pkt);
  
        sprintf(i8frame_name, "frames/frame%d.bin", u32frameCnt++);
  
        //reading frames from files
  
        FILE *ph264Frame = fopen(i8frame_name, "r");
  
        if(NULL == ph264Frame)
  
        {
  
           goto leave;
  
        }
  
  
  
        //get file size
  
        fseek(ph264Frame, 0L, SEEK_END);
  
        uint32_t u32file_size = 0;
  
        u32file_size = ftell(ph264Frame);
  
        fseek(ph264Frame, 0L, SEEK_SET);
  
  
  
        pu8framePtr = malloc(u32file_size);
  
        uint32_t u32readout = fread(pu8framePtr, 1, u32file_size, ph264Frame);
  
  
  
        //if the read frame is a key frame i.e. nalu hdr type = 5 set it as a key frame
  
        if(0x65 == pu8framePtr[4])
  
        {
  
           pkt.flags = AV_PKT_FLAG_KEY;
  
        }
  
        pkt.data = (uint8_t *)pu8framePtr;
  
        pkt.size = u32readout;
  
        pkt.pts  = u32frameCnt;
  
        pkt.dts  = pkt.pts;
  
  
  
        av_packet_rescale_ts(&pkt, c->time_base, video_st.st->time_base);
  
        pkt.stream_index = video_st.st->index;
  
        av_interleaved_write_frame(formatCtx, &pkt);
  
        free(pu8framePtr);
  
        fclose(ph264Frame);
  
     }
  
     while(1);
  
  leave:
  
  
  
     av_write_trailer(formatCtx);
  
     av_dump_format(formatCtx, 0, filename, 1);
  
     avcodec_free_context(&video_st.enc);
  
     avio_closep(&formatCtx->pb);
  
     avformat_free_context(formatCtx);
  
  }

  It can be compiled with the following command line (after adding headers) :

  gcc file.c -o test_app -I/usr/local/include -L/usr/local/lib -lxcb-shm -lxcb -lX11 -lx264 -lm -lz -pthread -lswresample -lswscale -lavcodec -lavformat -lavdevice -lavutil

  The files that are read are valid annexB stream (valid as in it’s playable in vlc after concatenating into file) it is a Constrained Baseline 3.1 profile H264 and it comes from an IPcam’s interleaved RTCP/RTP stream (demuxed)

  The result is ... well I don’t see the picture. I get only black screen with the progress bar and timer running. I don’t know if I do something wrong with setting up the codecs and streams, or it’s just wrong timestamps.
  I know I got them wrong in some manner but I don’t understand that fully yet (how to calculate the correct presentation times), i.e. the stream and the codec both contain time_base field, and then I know that the sample rate of the video is 90kHz and the frame rate is 5 fps

  On top of it all the examples I’ve found have to some extend deprecated parts that change the flow/meaning of the application and that doesn’t help at all so thus If anyone could help I would appreciate it (I think not only me I would guess)

  Regards, Pawel