[gst-devel] media-info, and old streaminfo tags

[Mathrick]

W liście z śro, 10-03-2004, godz. 15:57, Benjamin Otte pisze: 
> Quoting Martin Soto <soto at informatik.uni-kl.de>:
> 
> > Well, as I explained, I'm usually sending sound, so I really need and
> > audio sink. It is just that every now and then there are passages
> > without sound, and I have to handle them as well. My older player tries
> > to modify the pipeline in such cases to disconnect the audio component,
> > and believe me, doing that raises more issues than it solves. The main
> > problem is that it is very hard to touch the pipeline without disrupting
> > the data flow. You unlink a pad a bit too early, and you may prevent
> > some important data from reaching its intended destination. This may
> > result in all sorts of funny behavior, specially in DVD menus.
> > 
> I think the correct behaviour would be to send silence in that case. Or invent 
> some sort of event to tell the stream there's nothing there. But just not 
> sending anything doesn't work. (We've got to solve the same problem for MIDI 
> btw)

I'm kinda restating the obvious, but sending silence is nothing more
than a crude hack, and no solution at all. Not only it's ugly, it also
is format specific (many formats treat "no signal" and "signal of level
0" differently, and some, like subtitles, have no "0 level" at all) and
prevents us completely from authoring such formats (so bye bye DVD
creation, and subtitle (re/en)coding, and variable fps AVIs [1])

Cheers,
Maciej

[1] OK, I admit variable fps in AVIs is actually an _evil_ hack itself,
and yes, I know we all should use matroska and let AVIs die. But for
now, there are hacks like this one. It basically consists of 120
(multiply of 24 and 30 [2]) fps stream, with 4/5 or 5/6 frames marked as
dropped respectively. The only tool that does such files is magic
Japanese piece of software, but it would be cool to be able to do this
with gst :). Maybe then Avery Lee [3] will get convinced media
frameworks aren't such a bad things ;)

[2] Yes, you guessed it, these are PAL and NTSC framerates. It's
actually used for encoding many new anime, which often have such a mixed
content (24fps is normal episode animation, and 30fps is CG opening for
example).

[3] Virtual Dub author, he attempted to port VD to DirectShow once, but
gave it up, as he hasn't been able to do many of his insider AVI tricks
VD traditionally used.

-- 
"Tautologizm to coś tautologicznego"
   Maciej Katafiasz <mnews2 at wp.pl>
       http://mathrick.blog.pl