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• Should H.264 bit rate be multiples of 8 ?

  31 août 2016, par Dan Sharp

  I’m working on a video platform receiving H.264 video and building an HLS stream (transmuxing the H.264 to Mpeg2 TS segments via calls to ffmpeg).

  I wanted to set the bit rate to be about 2000 kbps, but I’m wondering : does it matter if it’s 2000 or 2048 ?

  In other words, do things calculate better if the bit rate is multiples of 8, like 512 or 2024 or 2048 ?

  I don’t know enough about how the bit rate is used, either on the sending side (camera) or on the processing side (ffmpeg).

  From tests... I can’t see any noticeable difference between 2000 and 2048, but maybe one is slightly better than another for the transmuxing and segmenting ?

  I welcome any thoughts/advice.

• FFMPEG wmv conversion to flv

  25 novembre 2012, par Brandon Grossutti

  anyone using ffmpeg

  I have a fairly simple wmv exported by a user from movie maker with standard output and want to convert to .flv using

  C :>ffmpeg -i "E :\Jab Core 4 Recounters.wmv" -vcodec flv "C :\Net Projects\SVN\IntegratedAlgorithmics\src\MediaAdmin\MediaAdmin\bin\Debug\Movies\Jab Core 4 Recounters.flv" -ar 44100

  the output / error i receive is

  FFmpeg version 0.5, Copyright (c) 2000-2009 Fabrice Bellard, et al.
  
    configuration: --enable-gpl --enable-postproc --enable-swscale --enable-avfilt
  
  er --enable-avfilter-lavf --enable-pthreads --enable-avisynth --enable-libfaac -
  
  -enable-libfaad --enable-libmp3lame --enable-libspeex --enable-libtheora --enabl
  
  e-libvorbis --enable-libxvid --enable-libx264 --enable-memalign-hack
  
    libavutil     49.15. 0 / 49.15. 0
  
    libavcodec    52.20. 0 / 52.20. 0
  
    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 16 2009 16:09:18, gcc: 4.2.4 [Sherpya]
  
  [wmv3 @ 0x1c0d490]Extra data: 8 bits left, value: 0
  
  
  
  Seems stream 1 codec frame rate differs from container frame rate: 1000.00 (1000
  
  /1) -> 30.00 (30/1)
  
  Input #0, asf, from 'E:\Jab Core 4 Recounters.wmv':
  
    Duration: 00:01:55.99, start: 5.000000, bitrate: 813 kb/s
  
      Stream #0.0: Audio: wmav2, 48000 Hz, stereo, s16, 192 kb/s
  
      Stream #0.1: Video: wmv3, yuv420p, 640x480, 586 kb/s, 30 tbr, 1k tbn, 1k tbc
  
  
  
  Output #0, flv, to 'C:\Net Projects\SVN\IntegratedAlgorithmics\src\MediaAdmin\Me
  
  diaAdmin\bin\Debug\Movies\Jab Core 4 Recounters.flv':
  
      Stream #0.0: Video: flv, yuv420p, 640x480, q=2-31, 200 kb/s, 90k tbn, 30 tbc
  
  
  
      Stream #0.1: Audio: libmp3lame, 48000 Hz, stereo, s16, 64 kb/s
  
  Stream mapping:
  
    Stream #0.1 -> #0.0
  
    Stream #0.0 -> #0.1
  
  [wmv3 @ 0x1c0d490]Extra data: 8 bits left, value: 0
  
  [libmp3lame @ 0x1c0d8d0]flv does not support that sample rate, choose from (4410
  
  0, 22050, 11025).
  
  Could not write header for output file #0 (incorrect codec parameters ?)

  i added th -ar switch when i got the error the first time

  the codec info i have on the file is as follows

  General
  
  Complete name                    : E:\Jab Core 4 Recounters.wmv
  
  Format                           : Windows Media
  
  File size                        : 11.3 MiB
  
  Duration                         : 2mn 0s
  
  Overall bit rate mode            : Variable
  
  Overall bit rate                 : 780 Kbps
  
  Maximum Overall bit rate         : 949 Kbps
  
  Encoded date                     : UTC 2009-03-07 07:02:41.121
  
  Writing application              :  6.0.6000.16386 / Windows Movie Maker
  
  Application                      : Windows Movie Maker 6.0.6000.16386
  
  
  
  Video
  
  ID                               : 2
  
  Format                           : VC-1
  
  Format profile                   : MP@ML
  
  Codec ID                         : WMV3
  
  Codec ID/Info                    : Windows Media Video 9
  
  Codec ID/Hint                    : WMV3
  
  Duration                         : 2mn 0s
  
  Bit rate mode                    : Variable
  
  Bit rate                         : 587 Kbps
  
  Width                            : 640 pixels
  
  Height                           : 480 pixels
  
  Display aspect ratio             : 4/3
  
  Frame rate                       : 30.000 fps
  
  Resolution                       : 24 bits
  
  Scan type                        : Progressive
  
  Bits/(Pixel*Frame)               : 0.064
  
  Stream size                      : 8.46 MiB (75%)
  
  Language                         : en-us
  
  
  
  Audio
  
  ID                               : 1
  
  Format                           : WMA2
  
  Format profile                   : L3
  
  Codec ID                         : 161
  
  Codec ID/Info                    : Windows Media Audio 2
  
  Description of the codec         : Windows Media Audio 9.2 - VBR Quality 90, 48 kHz, stereo 1-pass VBR
  
  Duration                         : 2mn 0s
  
  Bit rate mode                    : Variable
  
  Bit rate                         : 186 Kbps
  
  Channel(s)                       : 2 channels
  
  Sampling rate                    : 48.0 KHz
  
  Resolution                       : 16 bits
  
  Stream size                      : 2.68 MiB (24%)
  
  Language                         : en-us

  i see alot of people with this issue with so solution or cause

  any ideas would be helpful
  thanks in advance

• Use opencv to encode into flv, playable by flash player

  13 février 2012, par Hemang Shah

  I've compiled ffmpeg with libx264 using configure options given at 1.

  This results in the following codecs being available in ffmpeg :

  $ ffmpeg -codecs | grep "264\|flv"
  
  ffmpeg version 0.10 Copyright (c) 2000-2012 the FFmpeg developers
  
  built on Feb 10 2012 13:54:15 with gcc 4.6.1
  
  configuration: --enable-gpl --enable-libfaac --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libtheora --enable-libvorbis --enable-libx264 --enable-nonfree --enable-postproc --enable-version3 --enable-x11grab
  
  libavutil      51. 34.101 / 51. 34.101
  
  libavcodec     53. 60.100 / 53. 60.100
  
  libavformat    53. 31.100 / 53. 31.100
  
  libavdevice    53.  4.100 / 53.  4.100
  
  libavfilter     2. 60.100 /  2. 60.100
  
  libswscale      2.  1.100 /  2.  1.100
  
  libswresample   0.  6.100 /  0.  6.100
  
  libpostproc    52.  0.100 / 52.  0.100
  
  DEVSD  flv             Flash Video (FLV) / Sorenson Spark / Sorenson H.263
  
  D V D  h264            H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10
  
  D V D  h264_vdpau      H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10 (VDPAU acceleration)
  
  EV    libx264         libx264 H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10
  
  EV    libx264rgb      libx264 H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10 RGB

  After this, I compiled opencv. Here is partial cmake result :

  --   Video I/O:
  
  --     DC1394 1.x:                 NO
  
  --     DC1394 2.x:                 NO
  
  --     FFMPEG:                     YES
  
  --       codec:                    YES
  
  --       format:                   YES
  
  --       util:                     YES
  
  --       swscale:                  YES
  
  --       gentoo-style:             YES
  
  --     GStreamer:                  YES
  
  --     UniCap:                     NO
  
  --     PvAPI:                      NO
  
  --     V4L/V4L2:                   /1
  
  --     Xine:                       NO

  Now, using opencv's VideoWriter, I tried to encode into flv with the following FOURCC codes :
  FLV1, X264

  While the FLV1 results in a video file not playable by flash player, but playabe by vlc ; X264 produces no results at all.
  Here is the console output for X264, resulting in a 0 byte file.

  Output #0, flv, to 'd.flv' :
  Stream #0.0 : Video : [0][0][0][0] / 0x0000, yuv420p, 320x240, q=2-31, 4915 kb/s, 90k tbn, 24 tbc

  Do you see anything amiss or incorrect ?
  thanks,