Recherche avancée

Sur d’autres sites (13992)

• Evolution #2727 (Fermé) : forcer type=’MyISAM’ sur les tables MySQL

  25 octobre 2014, par cedric -

  Appliqué par commit r21697.

• avformat_write_header produces invalid header (resulting MPG broken)

  24 janvier 2013, par TheSHEEEP

  I am rendering a video file from input pictures that come from a 3D engine at runtime (I don't pass an actual picture file, just RGB memory).
  This works perfectly when outputting MP4 using CODEC_ID_H264 as video codec.

  But when I want to create an MPG file using CODEC_ID_MPEG2VIDEO, the resulting file is simply broken. No player can play the video correctly and when I then want to concatenate that MPG with another MPG file, and transform the result MP4 in another step, the resulting .mp4 file has both videos, but many frames from the original MPG video (and only video ! Sound works fine) are simply skipped.

  At first I thought the MPG -> MP4 conversion was the problem, but then I noticed that the initial MPG, which comes from the video render engine, is already broken, which would speak for broken headers. Not sure if it is the system or sequence headers that are broken, though.
  Or if it could be something totally different.

  If you want to have a look, here is the file :
  http://www.file-upload.net/download-7093306/broken.mpg.html

  Again, the exact same muxing code works perfectly fine when directly creating an MP4 from the video render engine, so I'm pretty sure the input data, swscale(), etc. is correct. The only difference is that CODEC_ID_H264 is used and some additional variables (like qmin, qmax, etc.) are set, which are all specific to H264 so should not have an impact.

  Also, neither avformat_write_header nor av_write_trailer report an error.

  As an additional info, when viewing the codec data of the MPG in VLC player, it is not able to show the FPS, resolution and format (should show 640x360, 30 fps and 4:2:0 YUV).

  I am using a rather new (2-3 months old, maybe) FFmpeg version, which I compiled from sources with MinGW.

  Any ideas on how to resolve this would be welcome. Currently, I am out of those :)

• av_write_frame fails when encoding a larger audio file to .mpg

  27 novembre 2012, par TheSHEEEP

  I am encoding live rendered video data and an existing .wav file into an mpg-file.

  To do that I first write all audio frames, and then the video frames as they come in from the render engine. For smaller .wav files (< 25 seconds), everything works perfectly fine. But as soon as I use a longer .wav file, av_write_frame (when writing the audio frame) just returns -1 after having written some 100 frames. It is never the same frame at which it fails, also it is never the last frame.
  All test files can be played perfectly with any player I tested.

  I am following the muxing example (more or less).

  Here is my function that writes an audio frame :

  void write_audio_frame( Cffmpeg_dll * ptr, AVFormatContext *oc, AVStream *st, int16_t sample_val )
  
  {
  
  AVCodecContext *c;
  
  AVPacket pkt = { 0 }; // data and size must be 0;
  
  AVFrame *frame = avcodec_alloc_frame();
  
  int got_packet;
  
  
  
  av_init_packet(&pkt);
  
  c = st->codec;
  
  
  
  get_audio_frame(ptr, ptr->samples, ptr->audio_input_frame_size, c->channels);
  
  frame->nb_samples =  ptr->audio_input_frame_size;
  
  int result = avcodec_fill_audio_frame(frame, c->channels, c->sample_fmt,
  
                          (uint8_t *) ptr->samples,
  
                           ptr->audio_input_frame_size *
  
                          av_get_bytes_per_sample(c->sample_fmt) *
  
                          c->channels, 0);
  
  if (result != 0)
  
  {
  
      av_log(c, AV_LOG_ERROR, "Error filling audio frame. Code: %i\n", result);
  
      exit(1);
  
  }
  
  
  
  result = avcodec_encode_audio2(c, &pkt, frame, &got_packet);
  
  if (result != 0)
  
  {
  
      av_log(c, AV_LOG_ERROR, "Error encoding audio. Code: %i\n", result);
  
      exit(1);
  
  }
  
  
  
  
  
  if (c->coded_frame && c->coded_frame->pts != AV_NOPTS_VALUE)
  
      pkt.pts= av_rescale_q(c->coded_frame->pts, c->time_base, st->time_base);
  
  pkt.flags |= AV_PKT_FLAG_KEY;
  
  
  
  pkt.stream_index= st->index;
  
  av_log(c, AV_LOG_ERROR, "Got? %i Pts: %i Dts: %i Flags: %i Side Elems: %i Size: %i\n", 
  
          got_packet, pkt.pts, pkt.dts, pkt.flags, pkt.side_data_elems, pkt.size);
  
  
  
  /* write the compressed frame in the media file */
  
  result = av_write_frame(oc, &pkt);
  
  if (result != 0) 
  
  {
  
      av_log(c, AV_LOG_ERROR, "Error while writing audio frame. Result: %i\n", result);
  
      exit(1);
  
  }
  
  }

  So "Error while writing audio frame. Result : -1" is what I always get after some frames.

  And here is my get_audio_frame function :

  void get_audio_frame( Cffmpeg_dll* ptr, int16_t* samples, int frame_size, int nb_channels, int16_t sample_val ) 
  
  {
  
      fread( samples, sizeof( int16_t ), frame_size * nb_channels, ptr->fp_sound_input );
  
  };

  And finally, this is the loop in which I write all audio frames (don't worry about the .wav header, I skipped it before that loop) :

  while (!feof(ptr->fp_sound_input))
  
      {
  
          write_audio_frame( ptr, ptr->oc, ptr->audio_st, -1 );
  
      }

  As you can see, I'm outputting almost everything in the packet and check for any possible error. Other than av_write_frame failing after some time when I am encoding a longer audio file, everything seems perfectly fine. All the packet values I am tracking are 100% the same for all frames (except the data pointer, obviously). Also, as stated, the same procedure works flawlessly for shorter fp_sound_input files. avcodec_encode_audio2() and avcodec_fill_audio_frame() also never fail.

  The codecs I use for encoding are CODEC_ID_MPEG2VIDEO (video) and CODEC_ID_MP2 (audio). The .wav files are saved in PCM 16 LE (all use the exact same encoding).

  What could be wrong here ?