On Tue, Dec 18, 2001 at 09:59:43AM -0800, Billy Biggs wrote:
> I don't know what you're saying here at all:
>
> > current linux possibilities - it simply can't be better (for now we
> > are not talking about interlaced TV output) and it works without any
> > external interrupt driver
>
> It works without any external interrupt driver? What's mga_vid? :)
Well mga_vid could be only used with Matrox card owners - which
is rather minority I would say - so it's really not a general
solution and avifile is not just MGA video player :)
So yes it works very well even without interrupt driver with
just poor linux scheduler - but of course tearing is unvoidable in this
case...
> Yes, I am working to avoid judder at refres rates less than 85hz! For
> example, many CRT projectors can run at 72hz which is great for 24fps
> video. To ensure a 3-3-3-3 pattern we must have a vsync device.
I would say we need better kernel :)
Again - if you have such device - avifile will use - but if you don't have
the current solution from avifile couldn't be made better in my eyes...
(if you will enable export AVIPLAY_DEBUG=1 you will see sync messages
and you will also see how the linux scheduler behaves - from time to time
it will miss the timer wakeup point by more then 15ms)
> Even worse, consider playback of 60fps material at 85hz. Judder is
Well I do not have 60fps material :) I do use 29.97Hz movies...
I'm currious what do you mean by 60fps material - do you use
some high speed video cammeras :) in my eyes there is no such thing like
60fps video - movie has 23.97, PAL 25, NTSC 29.97
>
> Dude, my sentence begins with 'Given we need a vsync device'. I say
> here that we need BOTH. Don't you agree?
Well not just 'BOTH' of us - almost every video app needs such device :)
> > odd/even frame for TV (might be used the HZ 4byte sign bit) but
> > generaly I would expect XFree driver would be doing this itself if it
> > possible...
>
> Do what itself? Tell you if you're on an odd or even field?
No I mean - I'll give two following images and video card would be doing
proper interlacing...
> > kernel problems here :) - you simply need kernel device to use
> > interrupts
>
> I was just suggesting. LKM gets too much traffic, and this is
> definitely a video issue. I think you'll find more interested people
> there.
Well there is no point to disuccess this on Xpert - as long as Linus
will be mostly ignoring any improvements in scheduling
(I think I do have somewhere his sentence where he said that 1.5GHz
CPU should be fast for every video application thus we do not need
to modify kernel :) to fix latency problems
I think that the need for vsync device is know for a long time and
yet there has nothing (except for my completely ignored attemp)
> I don't think DVD support belongs in 'avifile'. I like it as a
> library for reading/writing AVI files, but I think you should split off
> your player if you want to go further. I think avifile handles too
It's not usable just for player :)
> Regardless, it's lots of fun to write your own player. I think it's
> important that we work on common libraries but there is much fun in
> learning by writing your own.
yeap - but you might safe yourself a lot of time which you could spend
elsewhere...
> > and few other tweaks - around 3 or 4 of them - you may check the
> > source. The code is designed in such a way it will work with/without
> > VSYNC device.
>
> Showing the frame on the next refresh is fine so long as you are woken
> up at an appropriate time, but 10ms scheduling can screw you otherwise.
>
> Your other heuristics sound like quite a hack. :)
Yeap but they are necessary to fight with the problem you have just
described above.
I would be currious if you will find better solution :)
BTW - do you see any 'judder' problem with avifile ??
--
.''`. Which fundamental human right do you want to give up today?
: :' : Debian GNU/Linux maintainer - www.debian.{org,cz}
`. `' Zdenek Kabelac kabi@{debian.org, users.sf.net, fi.muni.cz}
`- Resistance is futile. You all will be packaged
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