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• FFMpeg/video4linux2,v4l2 : The v4l2 frame is 46448 bytes, but 153600 bytes are expected (Webcam capture not fast enough ?)

  30 août 2013, par user763410

  I am trying to capture webcam output in linux/ubuntu. I have a chicony webcam (lenovo laptop). I am running inside a VMWARE virtual machine. The capture is not proceeding beyond 10 seconds. can you please help.

  The command I used is :

  $ ffmpeg -y  -f video4linux2 -r 20 -s 160x120 -i /dev/video0 -acodec libfaac -ab 128k  /tmp/web.avi

  The most important message I am getting is :

  [video4linux2,v4l2 @ 0x9e43fa0] The v4l2 frame is 46448 bytes, but 153600 bytes are expected

  Complete message from ffmpeg :

  ffmpeg version N-55159-gf118b41 Copyright (c) 2000-2013 the FFmpeg developers
  
    built on Aug 18 2013 09:09:13 with gcc 4.6 (Ubuntu/Linaro 4.6.3-1ubuntu5)
  
    configuration: --enable-libass --prefix=/opt/ffmpeg --enable-debug --enable-libfreetype
  
    libavutil      52. 40.100 / 52. 40.100
  
    libavcodec     55. 19.100 / 55. 19.100
  
    libavformat    55. 12.102 / 55. 12.102
  
    libavdevice    55.  3.100 / 55.  3.100
  
    libavfilter     3. 82.100 /  3. 82.100
  
    libswscale      2.  4.100 /  2.  4.100
  
    libswresample   0. 17.103 /  0. 17.103
  
  [video4linux2,v4l2 @ 0x9e43fa0] The V4L2 driver changed the video from 160x120 to 320x240
  
  [video4linux2,v4l2 @ 0x9e43fa0] The driver changed the time per frame from 1/20 to 1/15
  
  Input #0, video4linux2,v4l2, from '/dev/video0':
  
    Duration: N/A, start: 6424.338678, bitrate: 18432 kb/s
  
      Stream #0:0: Video: rawvideo (YUY2 / 0x32595559), yuyv422, 320x240, 18432 kb/s, 15 fps, 15 tbr, 1000k tbn, 1000k tbc
  
  Codec AVOption ab (set bitrate (in bits/s)) specified for output file #0 (/tmp/web.avi) has not been used for any stream. The most likely reason is either wrong type (e.g. a video option with no video streams) or that it is a private option of some encoder which was not actually used for any stream.
  
  Output #0, avi, to '/tmp/web.avi':
  
    Metadata:
  
      ISFT            : Lavf55.12.102
  
      Stream #0:0: Video: mpeg4 (FMP4 / 0x34504D46), yuv420p, 320x240, q=2-31, 200 kb/s, 20 tbn, 20 tbc
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (rawvideo -> mpeg4)
  
  Press [q] to stop, [?] for help
  
  [video4linux2,v4l2 @ 0x9e43fa0] The v4l2 frame is 46448 bytes, but 153600 bytes are expected
  
  /dev/video0: Invalid data found when processing input
  
  frame=   29 fps= 14 q=3.5 Lsize=      87kB time=00:00:01.45 bitrate= 490.0kbits/s    
  
  video:80kB audio:0kB subtitle:0 global headers:0kB muxing overhead 7.760075%
  
  [video4linux2,v4l2 @ 0x9e43fa0] Some buffers are still owned by the caller on close.

• Playing audio file using libavcodec and libao

  21 août 2013, par sarah john

  Myself trying to play an audio file using libavcodec in qt5 .While trying to play i am unable to play the the file.
  while decoding the file using av_read_frame()
  audioStream->index=0
  and packet.stream_index is some higher nos .so avcodec_decode_audio4() is not getting executed.Why is it so ?
  I am getting output as
  My output

  ---

  File Opend

  Input #0, ogg, from '/home/tel/Downloads/desktop-login.ogg':
  
  Duration: 00:00:07.72, start: 0.000000, bitrate: 108 kb/s
  
  Stream #0:0: Audio: vorbis, 44100 Hz, stereo, fltp, 112 kb/s
  
  audioStream 0x88b3f20
  
  Stream id: 0
  
  Codec ptr: 0x88b4100
  
  Codec Opened
  
  DRIVER ID 1
  
  Sample format 3
  
  Sample format:AV_SAMPLE_FMT_FLT 32
  
  Sample format channels 0
  
  Sample format rate 0
  
  Sample format  4
  
  buffersize  192008

  This is my program. My output is also given below.Please help me in solving this.

  for(i=0; i < container->nb_streams; i++){
  
  
  
      if(container->streams[i]->codec->codec_type==AVMEDIA_TYPE_AUDIO){
  
           stream_id=i;
  
           audioStream=container->streams[i];
  
  
  
           qWarning() <<"audioStream"<streams[stream_id]->codec;
  
  qWarning() <<"Codec ptr:"<< ctx;
  
  AVCodec *codec=avcodec_find_decoder(ctx->codec_id);
  
  if(codec==NULL){
  
          die("cannot find codec!");
  
  }
  
  
  
  if(avcodec_open2(ctx,codec,NULL)<0){
  
          die("Codec cannot be opended!");
  
  }
  
  else
  
          qWarning()<<"Codec Opened";
  
  
  
  
  
          ao_initialize();
  
          driver = ao_default_driver_id();
  
          qWarning()<<"DRIVER ID" <sample_fmt;
  
          qWarning()<<"Sample format"<channels;
  
     qWarning()<<"Sample format channels"<sample_rate;
  
    qWarning()<<"Sample format rate"<codec;
  
    while(av_read_frame(container,&packet)>=0)
  
    {
  
  
  
          if(packet.stream_index==audioStream->index){
  
          len=avcodec_decode_audio4(ctx,frame,&frameFinished,&packet);
  
          qWarning()<<"Enterd if loop";
  
  
  
          if(frameFinished){
  
              qWarning()<<"PLAYING";
  
              ao_play(audio_device, (char*)frame->extended_data[0],frame->linesize[0] );
  
          }
  
    }

• Merge commit 'ca62236a89f47bd871eaf69d8d9e837c93c55a6c'

  26 septembre 2017, par James Almer

  Merge commit 'ca62236a89f47bd871eaf69d8d9e837c93c55a6c'
  * commit 'ca62236a89f47bd871eaf69d8d9e837c93c55a6c' :
  
    vaapi_encode : Add VP8 support
  
    vaapi_encode : Pass framerate parameters to driver
  
    vaapi_h264 : Enable VBR mode
  
    vaapi_encode : Support VBR mode
  This commit is a noop, see
  
  ceb28c3cc4c7921935b48904db3c559eed1597fe
  
  2201c02e6dc9f9652a8e27dec194915f05954ad0
  
  be6546a4ff592785d039df6cbdd7659781d30b2c
  
  d1acab8293054151157910eb081d5edcc7496e13
  Merged-by : James Almer <jamrial@gmail.com>