Video on Linux 101 (was Re:new microsoft software bug reporting tool could really result in higher quality at MS)

[Evan Leibovitch]

ted leslie wrote: 

>http://tinyurl.com/76stb
>
>i had to view on my mac,
>aside from a wine based app, anyone got a way to view asf's on Linux,
>

billt-lxSQFCZeNF4 at public.gmane.org answered:

>I have been using both mplayer and xine to watch asf files without a problem.
>  
>
You're both right.

The issue is not in the players themselves, but in the file formats 
themselves and what they contain. Multimedia encodings and compressions 
are a hodgepodge of proprietary IP, of which most is not voluntarily 
made available in an open source form. The term "codec" is used for the 
format-specific drivers needed to play or encode a file; each video file 
uses one codec for video and one for audio.

Compounding the problem is that the file extension doesn't itself always 
give enough information on the codecs the file will need. I looked at 
two ASF files that people had sent me; both used Windows Media Audio 2 
for their audio codec, but for video one used Windows Media 7 and other 
MPEG-4. The file in the URL sent by Ted uses yet a third video codec, 
Windows Media 9. In my experience these problems happen not just in ASF 
files but also in WMV files. Some will play, some won't -- it all 
depends on the codecs they use inside.

Open source application support for all these codecs is substantial but 
not complete. In many cases, the codec technique is known and codable 
for open source players but protected by patents, trade secrets, etc. In 
other cases the technique isn't even known, so if it can't be 
reverse-engineered we must get and use the original Windows-binary 
codecs files.

A full list of codecs in use, and their current status under open source 
systems and players, can be found at: 
http://www.mplayerhq.hu/DOCS/codecs-status.html . You'll notice that the 
WMV9 codec used in the Microsoft video file Ted is trying to watch is 
under the "not yet working" list for the open source native version; 
it's only supported through the Windows-binary codec. Such files are 
usually located in the /usr/lib/win32/ directory of a Linux or BSD 
system. Even so, there may still be some WMV9 files that are not 
playable; the status page says that "FFmpeg M$ WMV3/WMV9" codecs are not 
yet working.

Because of the IP entanglements, distributions that may include the open 
source multimedia players such as xine and mplayer might not include 
many necessary codec files. This is similar to the issues involved in 
being able to play commercial DVDs on your open source system.

To get these codecs, see 
http://www1.mplayerhq.hu/homepage/design7/codecs.html from which you can 
download a gzip file containing the binary codecs.

Ubuntu information on getting w32codec deb packages is at
http://ubuntuforums.org/archive/index.php/t-75278.html
RPMS for Mandriva are available at the Penguin Liberation Front 
(http://plf.zarb.org)
and RPMS for Fedora and other RPM-using distros are here:
http://rpm.greysector.net/mplayer/downloads-optional.html

It doesn't surprise me -- and is likely no accident -- that the 
Microsoft-made video Ted wants to watch is one of the most difficult to 
do under an open source platform.

- Evan

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