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• ffmpeg : avfilter's anull says "Rematrix is needed between stereo and 0 channels but there is not enough information to do it"

  12 juillet 2017, par kuanyui

  I’m trying to write a transcoder according to FFMpeg’s official example with ffmpeg 3.2.4 (official prebuild Win32), and try to transcode a video with stereo audio stream source (from avformat’s dshow).

  In the example code, which passes anull into avfilter_graph_parse_ptr() for audio stream, and "time_base=1/44100:sample_rate=44100:sample_fmt=s16:channels=2:channel_layout=0x3" is passed into avfilter_graph_create_filter(), occurs error in the following avfilter_graph_config() :

  [auto-inserted scaler 0 @ 32f77600] w:iw h:ih flags:'bilinear' interl:0
  
  [Parsed_null_0 @ 2e9d79a0] auto-inserting filter 'auto-inserted scaler 0' between the filter 'in' and the filter 'Parsed_null_0'
  
  [swscaler @ 3331bfe0] deprecated pixel format used, make sure you did set range correctly
  
  [auto-inserted scaler 0 @ 32f77600] w:1920 h:1080 fmt:yuvj422p sar:1/1 -> w:1920 h:1080 fmt:yuv420p sar:1/1 flags:0x2
  
  [libmp3lame @ 2e90a360] Channel layout not specified
  
  [in @ 3866e8a0] tb:1/44100 samplefmt:s16 samplerate:44100 chlayout:0x3
  
  [Parsed_anull_0 @ 330e8820] auto-inserting filter 'auto-inserted resampler 0' between the filter 'in' and the filter 'Parsed_anull_0'
  
  [auto-inserted resampler 0 @ 330e8dc0] [SWR @ 3809b620] Rematrix is needed between stereo and 0 channels but there is not enough information to do it
  
  [auto-inserted resampler 0 @ 330e8dc0] Failed to configure output pad on auto-inserted resampler 0

  I’ve googled for days but didn’t find any clue for it. Doesn’t what anull do is only "Pass the audio source unchanged to the output", why libav want to resample stereo to 0 channel ? What’s going wrong ?

• avfilter's anull says "Rematrix is needed between stereo and 0 channels but there is not enough information to do it"

  24 mai 2017, par kuanyui

  I’m trying to write a transcoder according to FFMpeg’s official example with ffmpeg 3.2.4 (official prebuild Win32), and try to transcode a video with stereo audio stream source (from avformat’s dshow).

  In the example code, which passes anull into avfilter_graph_parse_ptr() for audio stream, and "time_base=1/44100:sample_rate=44100:sample_fmt=s16:channels=2:channel_layout=0x3" is passed into avfilter_graph_create_filter(), occurs error in the following avfilter_graph_config() :

  [auto-inserted scaler 0 @ 32f77600] w:iw h:ih flags:'bilinear' interl:0
  
  [Parsed_null_0 @ 2e9d79a0] auto-inserting filter 'auto-inserted scaler 0' between the filter 'in' and the filter 'Parsed_null_0'
  
  [swscaler @ 3331bfe0] deprecated pixel format used, make sure you did set range correctly
  
  [auto-inserted scaler 0 @ 32f77600] w:1920 h:1080 fmt:yuvj422p sar:1/1 -> w:1920 h:1080 fmt:yuv420p sar:1/1 flags:0x2
  
  [libmp3lame @ 2e90a360] Channel layout not specified
  
  [in @ 3866e8a0] tb:1/44100 samplefmt:s16 samplerate:44100 chlayout:0x3
  
  [Parsed_anull_0 @ 330e8820] auto-inserting filter 'auto-inserted resampler 0' between the filter 'in' and the filter 'Parsed_anull_0'
  
  [auto-inserted resampler 0 @ 330e8dc0] [SWR @ 3809b620] Rematrix is needed between stereo and 0 channels but there is not enough information to do it
  
  [auto-inserted resampler 0 @ 330e8dc0] Failed to configure output pad on auto-inserted resampler 0

  I’ve googled for days but didn’t find any clue for it. Doesn’t what anull do is only "Pass the audio source unchanged to the output", why libav want to resample stereo to 0 channel ? What’s going wrong ?

• ffmpeg using MediaCodec, avcodec_open2 says error code :-1 (0xffffffff) text : "Operation not permitted"

  11 mai 2017, par Miguel Del Amor

  I’m trying to use the Android API MediaCoded that have been supported by ffmpeg but while I try to open the codec I got "Operation not permitted" all times, I’ve tried some changes and I’ve tried to find examples without not luck.

  This is what I’m doing

  av_jni_set_java_vm(QAndroidJniEnvironment::javaVM(), NULL);
  
  
  
  av_register_all();
  
  avcodec_register_all();
  
  
  
  AVCodec *_codec(nullptr);
  
  AVCodecContext *_codecContext(nullptr);
  
  
  
  if (_codec == nullptr)
  
      _codec = avcodec_find_decoder_by_name("h264_mediacodec");
  
  
  
  if (_codecContext == nullptr)
  
      _codecContext = avcodec_alloc_context3(_codec);
  
  
  
  int ret = 0;
  
  if( (ret = avcodec_open2(_codecContext, _codec, NULL)) < 0 ) {
  
  
  
      char str[AV_ERROR_MAX_STRING_SIZE];
  
      memset(str, 0, sizeof(str));
  
      av_strerror(ret, str, sizeof(str));
  
  
  
      qDebug("avcodec_open2 \"%s\" error[code:%d text:\"%s\"]",_codec->long_name, ret, str);
  
  }

  And I’m getting this output

  avcodec_open2 "H.264 Android MediaCodec decoder" error[code:-1 text:"Operation not permitted"]

  What I’m doing wrong ?