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• ffmpeg : Setting GOP structure, Picture structure when converting to MPEG-2 [on hold]

  27 juin 2017, par Jude

  I have a yuv file named src9_ref__625.yuv from the following website :
  ftp://vqeg.its.bldrdoc.gov/SDTV/VQEG_PhaseI/TestSequences/Reference/

  It contains 720 pixels (1440 bytes) per horizontal line and has 576 active lines per frame. Each line is in multiplexed 4:2:2 component video format as follows : Cb Y Cr Y ... 720 Y bytes per line, 360 Cb bytes per line, 360 Cr bytes per line.

  How to convert that file to MPEG-2 with following coding parameters :

  • GOP Structure : Automatic
  • Picture Structure : Alw Frame
  • Profile/Level : MP@ML

  ...as suggested in this article :
  http://iie.fing.edu.uy/publicaciones/2009/JL09/JL09.pdf

• ffmpeg problem in ubuntu (libavcodec.so)

  7 décembre 2016, par lyuba

  I run Ubuntu and try to use the ffmpeg wrapper in Java from here :
  http://code.google.com/p/javacv/

  It seems to work fine on other systems, but in Ubuntu the project crashes
  with the following mistake :
  Exception in thread "main" java.lang.UnsatisfiedLinkError : Error looking up
  function ’avcodec_decode_video2’ : /usr/lib/i686/cmov/libavcodec.so :
  undefined symbol : avcodec_decode_video2

  ffmpeg is working great from the command line, though.

  JavaCV author recommended me to check this link :
  http://linux-tipps.blogspot.com/2009/05/pretending-package-is-installed-by.html

  Probably I’m doing something wrong, but it cannot reinstall libavcodec51
  like this.

  So the questions are :
  1. Is those solution above a good one so I should bring it to success
  somehow ?
  2. What are the other ways to solve the problem ?

  Thank you for your suggestions in advance !

• 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.