Recherche avancée

Sur d’autres sites (11694)

• How to write HEVC frames to file using FFMpeg ?

  2 mai 2018, par boneill

  I have the following code used to output H264 frames to an mp4 file and this works fine :

  typedef struct _AvFileStreamContext
  
  {
  
      AVStream                 *pStreams[AV_FRAME_MAX];
  
      AVCodecContext           *streamCodec;
  
      AVFormatContext          *pAvContext;    // initialised with avformat_alloc_output_context2 for mp4 container
  
  
  
  }_AvFileStreamContext;
  
  
  
  static void WriteImageFrameToFile(const unsigned char * frame,
  
                                    const int frameSize,
  
                                    const struct timeval *frameTime,
  
                                    AvFileStreamContext *pContext,
  
                                    int keyFrame)
  
  {
  
      AVStream *stream pContext->pStreams[AV_FRAME_VIDEO];
  
      AVPacket pkt;
  
  
  
      av_init_packet(&pkt);
  
      if (keyFrame)
  
      {
  
          pkt.flags |= AV_PKT_FLAG_KEY;
  
      }
  
      pkt.stream_index = stream->index;
  
      pkt.data = (unsigned char*)frame;
  
      pkt.size = frameSize;
  
  
  
      int ptsValue = round((float)( ( (frameTime->tv_sec - pContext->firstFrameTime.tv_sec ) * 1000000 +
  
                                      (frameTime->tv_usec - pContext->firstFrameTime.tv_usec)) * pContext->streamCodec->time_base.den ) / 1000000);
  
  
  
      // Packets PTS/DTS must be in Stream time-base units before writing so
  
      // rescaling between coder and stream time bases is required.
  
      pkt.pts =  av_rescale_q(ptsValue, pContext->streamCodec->time_base, stream->time_base);
  
      pkt.dts =  av_rescale_q(ptsValue, pContext->streamCodec->time_base, stream->time_base);
  
  
  
      av_interleaved_write_frame(pContext->pAvContext, &pkt);
  
  }

  Once all frames have been received I call the following :

  av_write_trailer(pContext->pAvContext);
  
  avio_close(pContext->pAvContext->pb);

  The above function is supplied from a circular buffer of frames where each entry in the buffer represents a frame for H264. I am trying to understand how I can adapt this to handle H265/HEVC frames. When I blindly try and use this for H265 frames I end up with an mp4 file where each frame only contains a third of a complete frame i.e.

  
  The video continues to play for the correct duration but each frame is only a third of a complete frame. The implementation for receiving frames is the same as H264 and it is my understanding that with H265 each of the buffers I am receiving represents a ’tile’. In my case these are tile columns of which 3 tiles make up one frame. That said, it would seem that the above function would need to be adapted to combine 3 tiles until an end of frame marker is received. I have trawled the FFMpeg v3.3 documentation to find out how I can achieve this but have had limited luck.
  I have tried to use the following function call to combine frames :

  uint8_t * outputBuffer;
  
  unsigned int bufferSize;
  
  stream->parser = av_parser_init (AV_CODEC_ID_HEVC);
  
  int rc = av_parser_parse2(stream->parser, pContext->pAvContext,
  
                            &outputBuffer, &bufferSize,
  
                            frame, frameSize,
  
                            pkt.pts, pkt.dts, -1);

  It seems that the above call will ultimately call ;

  static int hevc_parse(AVCodecParserContext *s,
  
                        AVCodecContext *avctx,
  
                        const uint8_t **poutbuf, int *poutbuf_size,
  
                        const uint8_t *buf, int buf_size)

  Followed by :

  int ff_combine_frame(ParseContext *pc, int next,
  
                       const uint8_t **buf, int *buf_size)

  So it seems this is the correct path, however when I plug this all in the resulting mp4 file is not playable under gstreamer with the following errors :

  Prerolling...
  
  (gst-play-1.0:11225): GStreamer-WARNING **: gstpad.c:4943:store_sticky_event: Sticky event misordering, got 'segment' before 'caps'
  
  Redistribute latency...
  
  
  
  (gst-play-1.0:11225): GStreamer-WARNING **: gstpad.c:4943:store_sticky_event: Sticky event misordering, got 'segment' before 'caps'

  And I get the following errors (snippet of errors) from VLC where the frames appear to be correct in terms of height and width but are corrupt or incomplete during playback :

  [hevc @ 0x7f8128c30440] PPS changed between slices.
  
  [hevc @ 0x7f8128c42080] PPS changed between slices.
  
  [hevc @ 0x7f8128c53ce0] PPS changed between slices.
  
  [00007f8110293be8] freetype spu text error: Breaking unbreakable line
  
  [hevc @ 0x7f8128c1e0a0] First slice in a frame missing.
  
  [hevc @ 0x7f8128c1e0a0] First slice in a frame missing.
  
  [hevc @ 0x7f8128c1e0a0] Could not find ref with POC 7
  
  [hevc @ 0x7f8128c30440] PPS changed between slices.
  
  [hevc @ 0x7f8128c42080] PPS changed between slices.
  
  [hevc @ 0x7f8128c53ce0] PPS changed between slices.
  
  [hevc @ 0x7f8128c1e0a0] First slice in a frame missing.
  
  [hevc @ 0x7f8128c1e0a0] First slice in a frame missing.
  
  [hevc @ 0x7f8128c1e0a0] Could not find ref with POC 15
  
  [hevc @ 0x7f8128c30440] PPS changed between slices.
  
  [hevc @ 0x7f8128c42080] PPS changed between slices.
  
  [hevc @ 0x7f8128c53ce0] PPS changed between slices.
  
  [hevc @ 0x7f8128c1e0a0] First slice in a frame missing.
  
  [hevc @ 0x7f8128c1e0a0] First slice in a frame missing.
  
  [hevc @ 0x7f8128c1e0a0] Could not find ref with POC 23

  Here is an example frame from the VLC playback where you can just about see the outline of someone :
  

  It should be noted that when using the call to av_parser_parse2(), a frame is only passed to av_interleaved_write_frame() when outputBuffer is populated which seems to take a number of tiles (greater than 3) so I am possibly not setting something correctly.

  • Can I tell FFMpeg that a particular tile is an end of frame ?
  • Should I be using some other FFMpeg call to combine H265 tiles ?
  • Am I misunderstanding how HEVC operates ? (probably)
  • Once combined it the call to av_interleaved_write_frame() still valid ?
  • Note that use of libx265 is not possible.

  Any help appreciated.

• Use ffmpeg as external tool to stream 2 or more different sources via pipeline

  25 février 2021, par StackDOX

  I have an application running on an embedded system. This application has 2 video sources (and, theorically, 1 audio source). Concentrating to the video sources, I have 2 subprocess that computes different frames sets (unrelated each others). I want to send these frames to 2 differents streams.

  


  I would to avoid to write a lot of ffmpeg/libav code. I have ffmpeg compiled for the embeeded system and I can use it as tool. For example, I can write to the stdout the first frames set and pass it to the ffmpeg like this :

  


  ./my_app|ffmpeg -an -i - -vcodec copy -f rtp rtp://"remote_ip

  


  This basically works. But, now i would to send the other one frame set. How to do that ? Theorically I need anoter ffmpeg instance that read from another source that can't be the stdout of "my_app", because is already busy.

  


  ---

  


  I'm thinking to use 2 video files as support. I can record the 2 frames sets into 2 video files and then run 2 ffmpeg instances from these sources. In this case I think I need a way to limit the video files dimensions (like a circular buffer), because 2 streams can become really huge in time. It is a possibility ?
This can sound "weird" to me : I need to record a video source in realtime and stream it via ffmpeg (always in realtime). I don't know if it is a good idea, there are realtime problems for sure :

  


  loop:
my_app --write_into--> video_stream1.mp4 
ffmpeg <--read_from-- video_stream1.mp4

my_app --write_into--> video_stream2.mp4 
ffmpeg <--read_from-- video_stream2.mp4


  


  Have you some suggestion to address this kind of situation ?

  


  many thanks, bye.

  


• Evolution #4657 : Renommage du menu maintenance

  10 février 2021, par nicod _

  Maïeul Rouquette a écrit :

  Dans la même veine que #2835 et #4626. Le menu "maintenance" c’est forcément de la maintenance technique.

  Ma proposition :
  - renommer le menu "Maintenance" en "maintenance technique"

  "Maintenance" tout court n’est pas suffisant ? Sinon ça va passer sur deux lignes, ce serait moche.

  - changer la sous entrée "Maintenance technique" en "gestion des bases", et y regrouper aussi sauvegarde et restauration de la base
  - deporter de "Maintenance technique" tout ce qui concerne les statistique, dans une entrée "Historique des statistiques".

  Un peu de rangement, pourquoi pas :)