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List:       kde-multimedia
Subject:    Re: KDE/aRts strategy meeting
From:       Jason Wood <jasonwood () blueyonder ! co ! uk>
Date:       2002-06-26 15:05:08
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On Wednesday 26 Jun 2002 1:58 pm, Neil Stevens wrote: 
> I didn't see any interest in writing a framework for video editing at that
> last meeting.  If there had been interest, then we'd have heard from
> someone working on it by now...

I am currently working on a non-linear video editing application for KDE. I am 
concentrating on the user interface for the moment and progress is slow, but 
when I am satisfied that it is working well, I will start working on whatever 
video framework exists in arts at the time to make it capable of what I want 
it to do. That's at least a couple of months away at least though.

> > 3. My interest in a video framework is as a library user. I want to
> > write a video codec that is integrated in some multiplexed, multi-codec
> > format like AVI with minimum effort. And I want to write apps
> > record&playback that video. I also want the perspective that there will
> > be apps like video editors in the future that can use my codec without
> > requiring me to port it first.
>
> Then you know what?  Why don't you propose something that will make your
> life as a library user easier, and get the ball rolling with some coding
> to begin implementing it.
>
> Don't just roll out the ball and say let's "talk."  Lay it on the line, say
> what you'd like to see.... 

From my point of view as an app developer, I would like to be able to :

1. have access to multiple decoders without having to worry about the internal 
workings of them.
2. have acces to multiple encoders without having to worry about the internal 
workings of them.
3. have effects modules which can accept one or more video streams and output 
one or more video streams.
4. Be able to pipe streams from one module to another in the same way that is 
possible with arts sound.
5. Have the synchronisation of video streams with sound handled for me.
6. Have the ability to "play" streams either in realtime, where frames can be 
dropped to sustain playback, or in non-realtime, which guarantees that the 
file is decoded and encoded correctly.

Moving aside from video for the moment, the aRts sound api as it stands is 
inadequate in some important aspects:

a) some objects such as arts:TraderQuery fail spectacularly (i.e. crash the 
program) if the correct arts objects have not been set up beforehand. It 
would be nice if there were safeguards against this happening, even if the 
program just crashes out with an intelligable error message, as it is a major 
pain in the ass when you are new to arts and can't figure out which objects 
you haven't initialised properly.

b) Some api functions need to be more rigorously defined, or extended so that 
they produce the expected functionality. The one that springs to mind is that 
the overallTime function for a play object returns a bogus time unless the 
object has already started playing and has "been playing for long enough for 
it to have been initialised properly". For me, this function is next to 
useless until it works on play objects without needing to play them first, 
and I don't believe there is any way to get the overall time of a file in 
arts without starting to play it first.

As I mentioned earlier though, I am a good couple of months away from being 
able to look at any of this myself, which is why I haven't brought it up 
before.

> ... keeping in mind that you may not care about C++, but KDE is full of C++
> coders who aren't going to hassle with a limited low-level language like
> C, nor waste time with an API that is C-like.  Unless your wrapper is a
> reasonably idiomatic C++ API that allows for extending and using the
> environment as fully as in C, you won't win converts from aRts.

I agree. 

Cheers,
Jason

-- 
Jason Wood
I don't give up, I lose interest
Homepage : www.uchian.pwp.blueyonder.co.uk

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