[FFmpeg-trac] #2616(avcodec:open): support matrox mpeg-2 I-frame with alpha codec (m704 fourcc)

[FFmpeg]

#2616: support matrox mpeg-2 I-frame with alpha codec (m704 fourcc)
-------------------------------------+-------------------------------------
             Reporter:  ami_stuff    |                    Owner:
                 Type:  defect       |                   Status:  open
             Priority:  normal       |                Component:  avcodec
              Version:  git-master   |               Resolution:
             Keywords:  matrox       |               Blocked By:
  mpeg2video alpha                   |  Reproduced by developer:  0
             Blocking:               |
Analyzed by developer:  0            |
-------------------------------------+-------------------------------------

Comment (by ami_stuff):

 Finally I was able to encode sample with a real alpha channel:

 http://www1.datafilehost.com/d/0436af02

 Attached file plays correctly in Adobe Premiere (no colorful artefacts and
 alpha
 works - see attached screenshot).
 Colorful artefacts are visible while playing the file in WMP/VirtualDub.

 It looks like this codec is designed especially for Adobe Premiere which
 knows how to identify alpha channel and use it:

 "When rendering compositions or animations that have an alpha channel, you
 can
 select a “+ Alpha” Matrox VFW codec to render to a Matrox uncompressed or
 MPEG-2 I-frame .
 avi
 file that contains the alpha-key information. This .
 avi
 file
 will be automatically keyed when you place the clip in an Adobe Premiere
 Pro
 sequence."

 http://www.matrox.com/video/media/pdf/support/windows/vfw_software_codecs/doc/en_Matrox_VFW_Software_Codecs_10.pdf

 input which I used to encode the file:

 http://samples.mplayerhq.hu/FLV/flash_with_alpha/300x180-Scr-f8-056alpha.flv

-- 
Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/2616#comment:14>
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