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• Encoding H.264 CBR videos with FFmpeg

  3 février 2018, par Cornstalks

  I’m trying to encode a video with ffmpeg into H.264 (via the libx264 library) with a constant bit rate. I know, I know, VBR is often preferred, but for this specific job I’m required to use CBR (just as long as it’s so many kilobytes per second ; it doesn’t have to be an exact kilobytes per frame, afaik). My sample video I’m using to test is from here : http://a1408.g.akamai.net/5/1408/1388/2005110403/1a1a1ad948be278cff2d96046ad90768d848b41947aa1986/sample_iTunes.mov.zip (it comes from http://support.apple.com/kb/HT1425)

  I can get a constant bit rate when encoding the video with MPEG-4 Video (using the commands ffmpeg -i sample_iTunes.mov -b 819968 -minrate 819968 -maxrate 819968 out.mov), and the bit rate is as expected. Reading the video’s specs via the QuickTime Inspector, it’s got a data rate of 844.94 kbit/s. Cool.

  However, when I change the codec to libx264, it seems to completely ignore my bitrate requests ! The command I’m trying is "ffmpeg -i sample_iTunes.mov -vcodec libx264 -vpre medium -b 819968 -vb 819968 -minrate 819968 -maxrate 819968 -bufsize 400000 test.mov". But when I check the video’s specs via the QuickTime Inspector, it’s got a data rate of 254.74 kbit/s. WTF ? That’s not even close !

  I’ve tried changing so many parameters and adding tons of different things, and I’ve spent 2 days googling this, but I can’t seem to get it to work. If I encode the video with the MainConcept H.264 encoder, I can get a constant bitrate, but I need this to work with ffmpeg.

  If someone can help me figure out how to do CBR H.264 encoding with FFmpeg, I will love you forever !

• Encoding H.264 CBR videos with FFmpeg

  3 février 2018, par Cornstalks

  I’m trying to encode a video with ffmpeg into H.264 (via the libx264 library) with a constant bit rate. I know, I know, VBR is often preferred, but for this specific job I’m required to use CBR (just as long as it’s so many kilobytes per second ; it doesn’t have to be an exact kilobytes per frame, afaik). My sample video I’m using to test is from here : http://a1408.g.akamai.net/5/1408/1388/2005110403/1a1a1ad948be278cff2d96046ad90768d848b41947aa1986/sample_iTunes.mov.zip (it comes from http://support.apple.com/kb/HT1425)

  I can get a constant bit rate when encoding the video with MPEG-4 Video (using the commands ffmpeg -i sample_iTunes.mov -b 819968 -minrate 819968 -maxrate 819968 out.mov), and the bit rate is as expected. Reading the video’s specs via the QuickTime Inspector, it’s got a data rate of 844.94 kbit/s. Cool.

  However, when I change the codec to libx264, it seems to completely ignore my bitrate requests ! The command I’m trying is "ffmpeg -i sample_iTunes.mov -vcodec libx264 -vpre medium -b 819968 -vb 819968 -minrate 819968 -maxrate 819968 -bufsize 400000 test.mov". But when I check the video’s specs via the QuickTime Inspector, it’s got a data rate of 254.74 kbit/s. WTF ? That’s not even close !

  I’ve tried changing so many parameters and adding tons of different things, and I’ve spent 2 days googling this, but I can’t seem to get it to work. If I encode the video with the MainConcept H.264 encoder, I can get a constant bitrate, but I need this to work with ffmpeg.

  If someone can help me figure out how to do CBR H.264 encoding with FFmpeg, I will love you forever !

• ffmpeg : Image2 => Error while opening encoder

  29 mai 2019, par user1844282

  I get the following error ffmpeg.

  Error while opening encoder for output stream #0:0 - maybe incorrect parameters such as bit_rate, rate, width or height

  ffmpeg -f image2 -i %05d.jpg -vcodec libx264 foo.mp4

  I’m pretty sure I’ve used this exact command before and it’s been fine. This is my terminal output. Any help would be appreciated.

  $ ffmpeg -f image2 -i %05d.jpg -vcodec libx264 foo.mp4
  
  ffmpeg version 1.0 Copyright (c) 2000-2012 the FFmpeg developers
  
    built on Nov 22 2012 17:59:05 with Apple clang version 4.1 (tags/Apple/clang-421.11.66) (based on LLVM 3.1svn)
  
    configuration: --prefix=/opt/local --enable-swscale --enable-avfilter --enable-libmp3lame --enable-libvorbis --enable-libopus --enable-libtheora --enable-libschroedinger --enable-libopenjpeg --enable-libmodplug --enable-libvpx --enable-libspeex --enable-libfreetype --mandir=/opt/local/share/man --enable-shared --enable-pthreads --cc=/usr/bin/clang --arch=x86_64 --enable-yasm --enable-gpl --enable-postproc --enable-libx264 --enable-libxvid
  
    libavutil      51. 73.101 / 51. 73.101
  
  
  
    libavcodec     54. 59.100 / 54. 59.100
  
  
  
    libavformat    54. 29.104 / 54. 29.104
  
  
  
    libavdevice    54.  2.101 / 54.  2.101
  
  
  
    libavfilter     3. 17.100 /  3. 17.100
  
  
  
    libswscale      2.  1.101 /  2.  1.101
  
  
  
    libswresample   0. 15.100 /  0. 15.100
  
  
  
    libpostproc    52.  0.100 / 52.  0.100
  
  
  
  Input #0, image2, from '%05d.jpg':
  
    Duration: 00:00:04.44, start: 0.000000, bitrate: N/A
  
      Stream #0:0: Video: mjpeg, yuvj420p, 1201x900 [SAR 1:1 DAR 1201:900], 25 fps, 25 tbr, 25 tbn, 25 tbc
  
  [libx264 @ 0x7fab0881aa00] width not divisible by 2 (1201x900)
  
  Output #0, mp4, to 'foo.mp4':
  
      Stream #0:0: Video: h264, yuvj420p, 1201x900 [SAR 1:1 DAR 1201:900], q=-1--1, 90k tbn, 25 tbc
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (mjpeg -> libx264)
  
  Error while opening encoder for output stream #0:0 - maybe incorrect parameters such as bit_rate, rate, width or height