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• How do I extract color matrix from MP4 an x264 stream in Media Foundation

  23 août 2016, par Jules

  I am playing a video (mp4 containing x264 encoded video stream) with a custom player using media foundation.

  When I convert the YUV information into RGB I need to account for the color matrix and range used at encode time.

  Some of my videos have this information, I can use MediaInfo.exe or FFMPEG to see that it is present.

  However, for such videos if I look at the relevant Media Foundation properties (Extended Color Information) the properties are not present in the files.

  So, somehow I need to find a way to access the information.

  Media Foundation does provide access to MF_MT_MPEG4_SAMPLE_DESCRIPTION and MF_MT_MPEG_SEQUENCE_HEADER for the video stream but I can’t find descriptions of what these contain.

  I noticed that the MF_MT_MPEG_SEQUENCE_HEADER is much longer for the videos with the information present and this (MPEG Headers Quick Reference) seems to suggest headers might contain the information I need.

  I’m looking for Color Range (limited/full), Color Primaries, Transfer Characteristics and Matrix Coefficients (BT.709 etc).

  I’d greatly appreciate any help finding this information from a Media Foundation video stream.

  Thanks

  Jules

  ---

  Update - Sequence Header

  The sequence header appears to be a subset of MPEG4 sample description, though I can’t find anything that indicates what either bits of data actually contains / doesn’t contain specifically.

  The sequence header appears to contain data structured as an MP4 byte stream as described in the H264 Standards Document and includes the VUI (Video Usability Information - Annex E of document) which may then include the colour information I’m interested in.

  Given that it’s a byte stream I need to know where it starts and whether there’s some existing code I could use to decode it.

  In FFMPEG in libavcodec/h264_ps.c there is a function called ff_h264_decode_seq_parameter_set which ends up calling decode_vui_parameters. It seems possible that seq_parameter_set maps to MF_MT_MPEG_SEQUENCE_HEADER and it may be possible to use that code to decode the data.

  If anyone one has any direct experience with decoding this data it would be very useful.

  Thanks again

  ---

  Update - Related posts

  I found this How to decode sprop-parameter-sets in a H264 SDP ? and Possible Locations for Sequence/Picture Parameter Set(s) for H.264 Stream which are fairly helpful.

  The sequence header would appear to be Sequence or picture parameter set (pps) and the parameters I want are the VUI extension subset.

  Plus this post H.264 stream structure gives the high level of how the stream data is structured, and the MF_MT_MPEG_SEQUENCE_HEADER appears to start with a NAL 0x00 0x00 0x01 so I’m guessing it is a NAL containing the PPS.

• How to install libx265 for ffmpeg on Mac OSX

  20 mars 2016, par Spencer

  I have tried multiple guides here (search for "Building libx265") and here with no success. Both times I made sure I uninstalled ffmpeg first, went through the guides, then ran

  brew install ffmpeg --with-fdk-aac --with-freetype --with-libass --with-libvpx --enable-libx265

  No matter what when I go to run a command like

  ffmpeg -i source.mkv -c:v libx265 test1.mkv

  I get the error :

  Unknown encoder 'libx265'

  Has anyone had success building libx265 for use with ffmpeg on OSX and can you please share how you did it ?

  P.S. I am running OSX 10.11.3

• format unknown error with ffmpeg

  6 février 2016, par Rambo Actionha

  I’m trying to convert .webm to .mp4 using :

  ffmpeg -fflags +genpts -i 1.webm -r 24 1.mp4

  it doesn’t work , this is what I get :

  C:\Users\mahmoud\Desktop\ffmpeg>ffmpeg -fflags +genpts -i v.webm -r 24 1.mp4
  
  FFmpeg version SVN-r18639, Copyright (c) 2000-2009 Fabrice Bellard, et al.
  
    configuration: --enable-memalign-hack --enable-postproc --enable-gpl --enable-
  
  libfaac --enable-libfaad --enable-libgsm --enable-libmp3lame --enable-libvorbis
  
  --enable-libtheora --enable-libx264 --enable-libxvid --disable-ffserver --enable
  
  -avisynth --enable-pthreads
  
    libavutil     50. 3. 0 / 50. 3. 0
  
    libavcodec    52.27. 0 / 52.27. 0
  
    libavformat   52.32. 0 / 52.32. 0
  
    libavdevice   52. 2. 0 / 52. 2. 0
  
    libswscale     0. 7. 1 /  0. 7. 1
  
    libpostproc   51. 2. 0 / 51. 2. 0
  
    built on Apr 21 2009 13:44:38, gcc: 4.2.4 (TDM-1 for MinGW)
  
  v.webm: Unknown format

  any one can help ?