[vlc-devel] SoC 2010: ASF and other demuxer/muxer improvements

David Glaude david.glaude at gmail.com
Wed Jun 2 01:52:15 CEST 2010

Here are various ASF related VLC misbehaviour.

Set your prefered EU language such as "French":
Tools > Preferences > Show settings: All > Input /Codecs > Track settings >
Audio language
fill in "fr"

Be ready to paste the folowing URLs to VLC "Open Network Stream":
(2) mms://
It is the same file wich countain a multi-bitrate-video + multi-language
The first URL is an http download from an Apache (should be the same
behaviour as a local file).
The second URL is streaming by a Windows Media Streaming Server.

Now you are ready to experience various "problem":

A) If you take the http:// URL, VLC does start 3 video rather that one, but
play audio in your prefered language.
This might be considered as a "feature" but in fact it is properly writen in
the file and VLC knows that the 3 video track are mutualy excluding each

asf debug: found object guid: 0xa08649cf-0x4775-0x4670-0x8a166e35357566cd
asf debug: read "advanced mutual exclusion object"
asf debug:   - stream=24
asf debug:   - stream=25
asf debug:   - stream=26

VLC should choose (based on wich criteria) to only display one of the video.
VLC should have a way for the user to specify the available bandwidth (or
try to autodetect).
This behaviour can be found in Windows Media Player "Connection Speed"
The behaviour of the "Video > Video Track" is rather strange. Only one video
track seems to be enable (even if you see 3 copies of the video).
You can switch video track, but it does not change anything.
However, you can disable the video, then select one video track and only
that one appear.
But then, if you select an additionnal video track, you get two tracks where
you would have expect a "radio button" behaviour where you switch from one
track to another.

On the Audio side, it work perfectly, your prefered language is playing, you
can change audio track and only one audio is playing at a time.

B) If you take the mms:// URL, VLC does start a single video (GOOD) but the
audio track is track number 1 "Zulu".

Somehow, VLC does not let you:
B1) get the audio track you prefer
B2) see the list of available audio track
B3) change audio track
B4) see the list of available video track
B5) change video track

VLC know very well about the ASF format and the special GUID to talk about
mutual exclusion, but something is missing to fully use this information.

main debug: selected audio language[0] fr
main debug: selected audio language[1] any

access_mms info: selecting stream[0x1] audio (38 Kib/s)
access_mms info: ignoring stream[0x2] audio (38 Kib/s)
access_mms info: ignoring stream[0x3] audio (38 Kib/s)
access_mms info: selecting stream[0x18] video (528 Kib/s)
access_mms info: ignoring stream[0x19] video (278 Kib/s)
access_mms info: ignoring stream[0x1a] video (153 Kib/s)

asf debug: found object guid: 0x7c4346a9-0xefe0-0x4bfc-0xb229393ede415c85
asf debug: read "language list object" 23 entries
asf debug:   - 'en-gb'
asf debug:   - 'zu'
asf debug:   - 'fr'

If you have plan to work on ASF, you may want to look into those easy to
reproduce (maybe not to fix) issues.
If needed I can fill bug in the trac of vlc.

David Glaude
2010/5/31 Juho Vähä-Herttua <juhovh at iki.fi>

> Hello,
> Sorry for writing this introduction a bit late, I've written some other
> emails on this list though. I am a student of Aalto University School of
> Science and Technology (formerly known as Helsinki University of Technology)
> from Finland and finishing my 7th year graduating soon.
> I've worked with the ASF format and some other demuxers before and my main
> project now is to review and improve the ASF demuxer and muxer of VLC. Since
> I don't have so specific plan, if anyone on this list has anything remotely
> related that would need to be improved, I'd be very happy to know. Other
> than that I'll probably go through the bug tracker and see around. Since I'm
> mostly using Mac OS X, I'll be probably testing some Mac related things as
> well.
> I'm "juhovh" on IRC and hang out there pretty much always when I'm on
> computer, so contacting through IRC is probably most convenient. I'm happy
> to get to know all of you guys, hope we can get this to work.
> Project page can be found from:
> http://wiki.videolan.org/SoC_2010_ASF_Demuxer
> Git repository is in github:
> http://github.com/juhovh/vlc
> Juho
> _______________________________________________
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