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• How to tell if ffmpeg errored ?

  12 septembre 2011, par Eric

  The Situation :
  I'm using ffmpeg (via php) to convert video files. I configured my convert script to return the output (as the $error array) from the exec() command. My assumption was that if no error occurred, $error would be an empty array.

  The Problem :
  The problem is that, the script returns output even if there was no error in conversion. (I can tell that there was no error because a playable video file is output.)

  The Question :
  How does ffmpeg format its errors/output ? I want to be able to parse this and determine if an error occurred and what error it was.

  Thanks !

  Code :
  *An example of a non-error output :

  FFmpeg version git-N-29201-g37c0a44, Copyright (c) 2000-2011 the FFmpeg developers|  built on Sep  9 2011 23:29:21 with gcc 4.1.2 20080704 (Red Hat 4.1.2-50)|  configuration: --prefix=/usr/local/hgffmpeg --enable-shared --enable-nonfree --enable-avfilter --enable-filter=movie --enable-gpl --enable-pthreads --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libfaac --enable-libmp3lame --enable-libtheora --enable-libvorbis --enable-libx264 --enable-libxvid --extra-cflags=-I/usr/local/hgffmpeg/include/ --extra-ldflags=-L/usr/local/hgffmpeg/lib --enable-decoder=ac3 --enable-decoder=asv1 --enable-decoder=asv2 --enable-decoder=flac --enable-decoder=wmv1 --enable-decoder=wmv2 --enable-decoder=wmv3 --enable-decoder=mpeg1video --enable-decoder=mpeg2video --enable-decoder=flv --enable-decoder=fraps --enable-decoder=h263 --enable-decoder=h264 --enable-decoder=libgsm --enable-decoder=mjpeg --enable-decoder=mpeg4 --enable-decoder=mpeg4aac --enable-decoder=mpegvideo --enable-decoder=mpeg4aac --enable-decoder=msmpeg4v1 --enable-decoder=msmpeg4v2 --enable-decoder=msmpeg4v3 --enable-decoder=pcm_alaw --enable-decoder=pcm_mulaw --enable-encoder=ac3 --enable-encoder=asv1 --enable-encoder=asv2 --enable-encoder=flac --enable-encoder=h263 --enable-encoder=flashsv --enable-encoder=flv --enable-encoder=libgsm --enable-encoder=mjpeg --enable-encoder=msmpeg4v3 --enable-encoder=pcm_alaw --enable-encoder=pcm_mulaw --enable-encoder=mpeg1video --enable-encoder=mpeg2video --enable-encoder=mpeg4 --enable-encoder=msmpeg4v1 --enable-encoder=msmpeg4v2 --enable-encoder=rv10 --enable-encoder=rv20 --enable-encoder=vorbis --enable-encoder=wmav1 --enable-encoder=wmav2 --enable-encoder=wmv1 --enable-encoder=wmv2 --disable-demuxer=v4l --disable-demuxer=v4l2 --enable-version3|  libavutil    50. 40. 1 / 50. 40. 1|  libavcodec   52.120. 0 / 52.120. 0|  libavformat  52.108. 0 / 52.108. 0|  libavdevice  52.  4. 0 / 52.  4. 0|  libavfilter   1. 79. 1 /  1. 79. 1|  libswscale    0. 13. 0 /  0. 13. 0|[mpeg1video @ 0x1f6d030] skipped MB in I frame at 5 0|[mpeg1video @ 0x1f6d030] Warning MVs not available|[mpeg1video @ 0x1f6d030] concealing 260 DC, 260 AC, 260 MV errors|[mpegvideo @ 0x1f6a660] Estimating duration from bitrate, this may be inaccurate|Input #0, mpegvideo, from '../uploads/test_vid/unencodedVideo.mpg':|  Duration: 00:00:00.01, bitrate: 104860 kb/s|    Stream #0.0: Video: mpeg1video, yuv420p, 320x200 [PAR 1:1 DAR 8:5], 104857 kb/s, 23.98 fps, 23.98 tbr, 1200k tbn, 23.98 tbc|WARNING: The bitrate parameter is set too low. It takes bits/s as argument, not kbits/s|File '../uploads/test_vid/video.flv' already exists. Overwrite ? [y/N] Not overwriting - exiting

• During transcoding, does output quality of a video improve when i give output bitrate more than input video's bitrate ?

  19 septembre 2013, par Jobin Jose

  I use ffmpeg for converting videos.
  As i understand, the bitrate of a video stream is the number of bits which constitute the video over 1 second of time.
  What happens when i specify the output video bitrate to be more than the input video's bitrate ?
  For example :
  If bitrate of "Input.mp4" is 2000KBps and i want to convert it to "Output.mp4" with output bitrate set to 3000KBps.
  How will the converter create the extra 1000 bits(3000-2000) for every second of video ?

• ffmpeg : convert audio-only flv to swf

  5 octobre 2011, par Michael Brewer-Davis

  My Flex application records audio-only FLV files using red5—I'd like to convert these to SWF files so I can embed them in other SWF files. (I could also convert to MP3 and then embed them into SWFs myself, but I'd prefer a one step solution.)

  Anyone have experience doing this ?

  What I've tried :

  The following naive ffmpeg command fails :

  > ffmpeg -i 3139747641.flv -vn movie.swf
  
  FFmpeg version SVN-r21751-snapshot, Copyright (c) 2000-2010 Fabrice Bellard, et al.
  
    built on Feb 11 2010 09:15:42 with gcc 4.2.1 (SUSE Linux)
  
    configuration: --enable-gpl --enable-nonfree
  
    libavutil     50. 9. 0 / 50. 9. 0
  
    libavcodec    52.53. 0 / 52.53. 0
  
    libavformat   52.52. 0 / 52.52. 0
  
    libavdevice   52. 2. 0 / 52. 2. 0
  
    libswscale     0.10. 0 /  0.10. 0
  
  [flv @ 0x8a5e3a0]Could not find codec parameters (Video: 0x0000)
  
  [flv @ 0x8a5e3a0]Estimating duration from bitrate, this may be inaccurate
  
  Input #0, flv, from '3139747641.flv':
  
    Metadata:
  
      audiocodecid    : -1
  
      duration        : 0
  
      videocodecid    : -1
  
      canSeekToEnd    : true
  
    Duration: 00:00:14.88, start: 0.000000, bitrate: N/A
  
      Stream #0.0: Video: 0x0000, 1k tbr, 1k tbn, 1k tbc
  
      Stream #0.1: Audio: nellymoser, 8000 Hz, mono, s16
  
  Output #0, swf, to 'movie.swf':
  
      Stream #0.0: Audio: 0x0000, 8000 Hz, mono, s16, 64 kb/s
  
  Stream mapping:
  
    Stream #0.1 -> #0.0
  
  Encoder (codec id 86017) not found for output stream #0.0

  I've tried adding a dummy video, but this also failed :

  > ffmpeg -i dummy.mov -i 3139747641.flv movie.swf
  
      
  
  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'dummy.mov':
  
    Metadata:
  
      major_brand     : qt  
  
      minor_version   : 512
  
      compatible_brands: qt  
  
      encoder         : Lavf52.52.0
  
      encoder-eng     : Lavf52.52.0
  
    Duration: 00:00:00.10, start: 0.000000, bitrate: 62 kb/s
  
      Stream #0.0(eng): Video: mpeg4, yuv420p, 10x10 [PAR 1:1 DAR 1:1], 1 kb/s, 10 fps, 10 tbr, 10 tbn, 10 tbc
  
  [flv @ 0x8a67fa0]Could not find codec parameters (Video: 0x0000)
  
  [flv @ 0x8a67fa0]Estimating duration from bitrate, this may be inaccurate
  
  Input #1, flv, from '3139747641.flv':
  
    Metadata:
  
      audiocodecid    : -1
  
      duration        : 0
  
      videocodecid    : -1
  
      canSeekToEnd    : true
  
    Duration: 00:00:14.88, start: 0.000000, bitrate: N/A
  
      Stream #1.0: Video: 0x0000, 1k tbr, 1k tbn, 1k tbc
  
      Stream #1.1: Audio: nellymoser, 8000 Hz, mono, s16
  
  picture size invalid (0x0)
  
  Cannot allocate temp picture, check pix fmt