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• Thread count option in FFmpeg for FASTEST conversion to h264 ?

  5 septembre 2013, par Saptarshi Biswas

  I need to maximize speed while converting videos using FFmpeg to h264

  • Any input format of source videos
  • User's machine can have any number of cores
  • Power and memory consumption are non-issues

  Of course, there are a whole bunch of options that can be tweaked but this question is particularly about choosing the best -thread <count></count> option. I am trying to find an ideal thread count as a function of

  • no. of cores
  • input video format
  • h264-friendly values maybe ?
  • anything else missed above ?

  I am aware the default -thread 0 follows one-thread-per-core approach which is supposed to be optimal. But I am not sure if this is time or space-optimized. Also, on certain testcases, I've seen more threads (say 4 threads on my dual core test machine) finishes quicker than the default.

  Any other direction, say configure options w.r.t. threads, worth pursuing ?

• 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

• Recording a mp3 stream with FFMPEG and drop-outs

  14 mars 2013, par Rob Oliver

  I hope someone can give me pointer, I have a php script that runs the command below to record an live radio mp3 stream to create hour long mp3 recordings. It works very well for my purpose. The only issue is occasionally no recording is made. As far as I can tell its because the stream has dropped out and ffmpeg just aborts.

  /usr/local/bin/ffmpeg -i http://www.mystream.com:8000/radiostream.mp3 -t 60:00 -acodec copy /var/www/mydomain/audio/".$recorded_audio_title;

  So my question, is there anyway to tell ffmpeg to continuously record for the 60:00 minutes to make a recording even if their are drop outs ? I'd be happy with a odd bit of silence providing it completed the recording.

  I hope this makes sense and I'd appreciate even a pointer to a FFMPEG option or flag. Having Google'd I havnt seen anything that would fit the bill.

  Many thanks in advance

  rob