Re: More information on MAS

[Bill Haneman <bill haneman sun com>]

> 
> Mike Andrews posted this to Slashdot with some information about the
> rationale behind MAS. 
> http://developers.slashdot.org/comments.pl?sid=52708&cid=5220114
> 
> They haven't managed to fix their webpage yet with the 'only works on
> high resoltions that I mailed Mike about, but I guess you can't win em
> all ;)
> 
> Christian
> 
> Also as a sidenote, Zeeshan Ali has already begun working on a set of
> MAS source and sinks for GStreamer, the first code for this is already
> checked into the head branch, but if I understood Zeeshan correctly he
> needs some more info from Mike to make it work right.

One of the main benefits of MAS is its ability to support
synchronization.  This is required before we can do anything with SMIL
(which Janina Sajika recently enquired about).  In order to support good
quality synchronization of multiple media streams, you need good latency
information, completion notifications, etc. and my understanding is that
this is something MAS was designed to handle and which is
difficult/impossible to get right with out other media sinks.

A general example is synchronized audio and video; particularly for
codecs that don't support interleaving of audio and video.  And most of
our multimedia formats don't have any kind of sideband or side-channel
for captioning, so captioning, descriptive audio, subtitles, etc. can't
reliably be synchronized with the 'primary' AV stream.  This can be a
problem even on a desktop machine, but it really gets nasty if you are
doing anything with streamed content or remote AV applications, etc. 
It's even a problem for something as apparently-simple as scrolling
captions and braille output, since the text stream needs to pause and
resync if the audio stream pauses, glitches, or just has latency issues.

regards,

Bill


-- 
Bill Haneman <bill haneman sun com>