Video JACK?, was Re: [linux-audio-dev] What about OpenML? Some questions

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Subject: Video JACK?, was Re: [linux-audio-dev] What about OpenML? Some questions
From: Jelle (jelle_AT_defekt.nl)
Date: Tue Oct 16 2001 - 14:18:54 EEST


On Mon, Oct 15, 2001 at 06:57:27PM -0400, Paul Davis wrote:

> >If and how could it be fit into LADSPA or JACK? Or should OpenML be the
> >graph-host and host LADSPA plugins (so you may get hardware benefits)?
>
> LADSPA and JACK are completely orthogonal to one another. LADSPA can
> exist without JACK, and vice versa. What they share in common is no
> more (or less) than they share with every other callback based media API.

I am aware of that.

But I was looking at it this way. OpenGL provides many h/w functions,
duplicated in s/w, that give you great speed advantages if you use them.

I was suggesting that maybe OpenML could provide some processing
advantages if it was integrated in a LADSPA host, by for example,
letting all the mixing and equalizing be done by hardware... (ignoring
OpenML's lack of callback model and latency issues, zero-copy gone etc)

but thanks.

> >And while I'm at it, can JACK transport other than audio signals, and
> >at another clock rate (say video)?
>
> In theory yes. The current reference implementation isn't complete,
> and so in practice, no. This will change soon. Note, however, that
> there is only one reference clock signal in a JACK system. If other
> clock rates are not integer multiples of the reference clock, then its
> difficult to make things work correctly. This is almost certainly true
> for audio/video integration.

to be honest, I'd rather have a mixed callback and streamed system. It's
likely that video doesn't run at a fixed rate, but rather (eg.) as fast
as possible. (I'm writing software which integrates audio and video, and
the video can be switched between fixed_rate and variable_rate.)

Streaming is probably beyond the scope of JACK, but it doesn't seem usefull
to create another system for just transferring variable rate video (or
whatever).

would you, at all, be interested in extending JACK to mediate video
connections between software (even with variable clock rates)?

same question for LADSPA (i'm working on a extended "video"-version)

cheers

-- 
jelle herold (defekt)   http://defekt.nl/
seeing digital          http://channelthree.net/


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