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• file size increasing when while uploading and converting video to flv with ffmpeg

  20 avril 2013, par Dhirendra Singh Dhabhai

  I need to upload and convert video from any format to flv. i'm doing this with ffmpeg and using this ffmpeg command

  ffmpeg -i input.mp4 -vcodec flv -sameq -ar 22050  -f flv output.flv

  this command is running fine but the problem is the file size of output file is 5 times grater than the original input file and if i reduce it it reduces the quality also, need help.

• X264 encoding using Opencv

  29 novembre 2011, par user573193

  I am working with a high resolution camera : 4008x2672. I a writing a simple program which grabs frame from the camera and sends the frame to a avi file. For working with such a high resolution, I found only x264 codec that could do the trick (Suggestions welcome). I am using opencv for most of the image handling stuff. As mentioned in this post http://doom10.org/index.php?topic=1019.0 , I modified the AVCodecContext members as per ffmpeg presets for libx264 (Had to do this to avoid broken ffmpeg defaults settings error). This is output I am getting when I try to run the program

  libx264 @ 0x992d040]non-strictly-monotonic PTS 
  
  1294846981.526675 1 0 //Timestamp camera_no frame_no
  
  1294846981.621101 1 1
  
  1294846981.715521 1 2
  
  1294846981.809939 1 3
  
  1294846981.904360 1 4
  
  1294846981.998782 1 5
  
  1294846982.093203 1 6
  
      Last message repeated 7 times
  
  [avi @ 0x992beb0]st:0 error, non monotone timestamps 
  
  -614891469123651720 >= -614891469123651720
  
  
  
   OpenCV Error: Unspecified error (Error while writing video frame) in
  
   icv_av_write_frame_FFMPEG, file 
  
  /home/ajoshi/ext/OpenCV-2.2.0/modules/highgui/src/cap_ffmpeg.cpp, line 1034
  
  terminate called after throwing an instance of 'cv::Exception'
  
   what():  /home/ajoshi/ext/OpenCV-2.2.0/modules/highgui/src/cap_ffmpeg.cpp:1034:
  
  error: (-2) Error while writing video frame in function icv_av_write_frame_FFMPEG

  Aborted

  Modifications to the AVCodecContext are :

  if(codec_id == CODEC_ID_H264)
  
  {
  
      //fprintf(stderr, "Trying to parse a preset file for libx264\n");
  
      //Setting Values manually from medium preset
  
      c->me_method = 7;
  
      c->qcompress=0.6;
  
      c->qmin = 10;
  
      c->qmax = 51;
  
      c->max_qdiff = 4;
  
      c->i_quant_factor=0.71;
  
      c->max_b_frames=3;
  
      c->b_frame_strategy = 1;
  
      c->me_range = 16;<br />
  
      c->me_subpel_quality=7;
  
      c->coder_type = 1;
  
      c->scenechange_threshold=40;
  
      c->partitions = X264_PART_I8X8 | X264_PART_I4X4 | X264_PART_P8X8 | X264_PART_B8X8;
  
      c->flags = CODEC_FLAG_LOOP_FILTER;
  
      c->flags2 = CODEC_FLAG2_BPYRAMID | CODEC_FLAG2_MIXED_REFS | CODEC_FLAG2_WPRED | CODEC_FLAG2_8X8DCT | CODEC_FLAG2_FASTPSKIP;
  
      c->keyint_min = 25;
  
      c->refs = 3;
  
      c->trellis=1;
  
      c->directpred = 1;
  
      c->weighted_p_pred=2;
  
  }

  I am probably not setting the dts and pts values which I believed ffmpeg should be setting it for me.

  Any sugggestions welcome.
  Thanks in advance
  

• What codec do I need to convert .wav to .mp3 with ffmpeg ?

  19 septembre 2011, par LedZeppelin

  I am able to convert from .mp3 files to .wav files.

  me@me-desktop:~$ ffmpeg -i Desktop/input.mp3 Desktop/output.wav
  
  FFmpeg version SVN-r0.5.1-4:0.5.1-1ubuntu1.1, Copyright (c) 2000-2009 Fabrice Bellard, et al.
  
    configuration: --extra-version=4:0.5.1-1ubuntu1.1 --prefix=/usr --enable-avfilter --enable-avfilter-lavf --enable-vdpau --enable-bzlib --enable-libgsm --enable-libschroedinger --enable-libspeex --enable-libtheora --enable-libvorbis --enable-pthreads --enable-zlib --disable-stripping --disable-vhook --enable-runtime-cpudetect --enable-gpl --enable-postproc --enable-swscale --enable-x11grab --enable-libdc1394 --enable-shared --disable-static
  
    libavutil     49.15. 0 / 49.15. 0
  
    libavcodec    52.20. 1 / 52.20. 1
  
    libavformat   52.31. 0 / 52.31. 0
  
    libavdevice   52. 1. 0 / 52. 1. 0
  
    libavfilter    0. 4. 0 /  0. 4. 0
  
    libswscale     0. 7. 1 /  0. 7. 1
  
    libpostproc   51. 2. 0 / 51. 2. 0
  
    built on Mar 31 2011 18:53:20, gcc: 4.4.3
  
  [mp3 @ 0x9449510]mdb:511, lastbuf:0 skipping granule 0
  
      Last message repeated 1 times
  
  [mp3 @ 0x9449510]mdb:511, lastbuf:0 skipping granule 1
  
      Last message repeated 1 times
  
  Input #0, mp3, from 'Desktop/input.mp3':
  
    Duration: 00:04:45.31, start: 0.000000, bitrate: 256 kb/s
  
      Stream #0.0: Audio: mp3, 48000 Hz, stereo, s16, 256 kb/s
  
  Output #0, wav, to 'Desktop/output.wav':
  
      Stream #0.0: Audio: pcm_s16le, 48000 Hz, stereo, s16, 1536 kb/s
  
  Stream mapping:
  
    Stream #0.0 -> #0.0
  
  Press [q] to stop encoding
  
  [mp3 @ 0x9449510]mdb:511, lastbuf:0 skipping granule 0
  
      Last message repeated 1 times
  
  [mp3 @ 0x9449510]mdb:511, lastbuf:0 skipping granule 1
  
  size=   42944kB time=229.03 bitrate=1536.0kbits/s    
  
  video:0kB audio:42944kB global headers:0kB muxing overhead 0.000100%

  However when I try to convert the same .wav file back to an .mp3 I get the following error : Unsupported codec for output stream #0.0

  me@me-desktop:~$ ffmpeg -i Desktop/output.wav Desktop/output2.mp3
  
  FFmpeg version SVN-r0.5.1-4:0.5.1-1ubuntu1.1, Copyright (c) 2000-2009 Fabrice Bellard, et al.
  
    configuration: --extra-version=4:0.5.1-1ubuntu1.1 --prefix=/usr --enable-avfilter --enable-avfilter-lavf --enable-vdpau --enable-bzlib --enable-libgsm --enable-libschroedinger --enable-libspeex --enable-libtheora --enable-libvorbis --enable-pthreads --enable-zlib --disable-stripping --disable-vhook --enable-runtime-cpudetect --enable-gpl --enable-postproc --enable-swscale --enable-x11grab --enable-libdc1394 --enable-shared --disable-static
  
    libavutil     49.15. 0 / 49.15. 0
  
    libavcodec    52.20. 1 / 52.20. 1
  
    libavformat   52.31. 0 / 52.31. 0
  
    libavdevice   52. 1. 0 / 52. 1. 0
  
    libavfilter    0. 4. 0 /  0. 4. 0
  
    libswscale     0. 7. 1 /  0. 7. 1
  
    libpostproc   51. 2. 0 / 51. 2. 0
  
    built on Mar 31 2011 18:53:20, gcc: 4.4.3
  
  Input #0, wav, from 'Desktop/output.wav':
  
    Duration: 00:03:49.03, bitrate: 1536 kb/s
  
      Stream #0.0: Audio: pcm_s16le, 48000 Hz, stereo, s16, 1536 kb/s
  
  Output #0, mp3, to 'Desktop/output2.mp3':
  
      Stream #0.0: Audio: 0x0000, 48000 Hz, stereo, s16, 64 kb/s
  
  Stream mapping:
  
    Stream #0.0 -> #0.0
  
  Unsupported codec for output stream #0.0

  I've already tried installing unstripped-51 per a suggestion from a previous question but I am still unable to convert from .wav to .mp3