On Tue, Dec 18, 2001 at 01:05:07PM +0100, Peter Surda wrote:
> On Tue, Dec 18, 2001 at 12:40:26PM +0100, Zdenek Kabelac wrote:
> > I've read your post - but WITHOUT modified picture itself (e.g. some
> > > wait for #VBI 1 1 1 1 1 1 1 2 1 1 1 1 1 .....
> > Which is the best we can do without unmodified picture... :(
> No, this is the best we can do without modifying picture or SPEED.
Well as I see I'll have to put more light here :)
In the first place - PAL television refresh isn't 25Hz - but 50Hz - which
means each frame is being displayed twice - but in each pass only every second
line is displayed.
So now to the problem you are trying to solve in completely broken way.
(BTW - if your card just return only 25Hz interrupt then there is something
wrong with this card - so are you sure about 25Hz rate ?)
The proper solution would be to count the interrupt number
(which is made at least by my VBI driver in mga_vid)
and according to current number make necessary image transformation.
Actually if just some estimation would be enough I guess even the 400MHz
machine could handle that - as what we need in this case is to interleave
the two following images - but for the correct result we need to know
exact interrupt number - as sometimes we need to take odd and sometimes
even lines from the second image.
Again I'll repeat - if XFree will not have proper support and if linux
kernel is able to delay process scheduling for 30ms or more - it's hard
to fight with this problem (and I'll again mention the word Amiga here).
> > Well the sound card speed is considered - don't worry :)
> Yeah sure I remember how this happened and how I had to play with sound card
> sound driver to get sync working with "fscked" aviplay :-)
I'd say that about aviplay - but rather about broken cheap hardware you
have used...
> > transformation in realtime
> You probably didn't read it. My proposal is to add an option that will modify
> playback speed (both video and audio of course) to match video display fps,
> and to be able to maintain a fixed VBI count pattern. In case of 23.98, it
> will be played about 4% faster.
If you want to play the sound for 4% faster - you can already do that
just set resampling and set 44100 Hz playing rate and 45864 resampling rate
this is working for a long time...
Aviplay should stay in sync with this minor deviation - but again
this is seriously broken attemp to solve this problem...
> No big magic or horsepower needed and will imho look better. Don't forget that
> aviplay ALREADY DOES modify playback speed to match soundcard clock (your
> ideas about matching to cpu clock proved wrong), so there is no strong
It's not proved to be wrong - it's just that people are buying cheap & broken
hardware all the time... :)
Anyway maybe I'll take a look on this problem - but I'd like to
see the proper MGA TV Out support in the XFree - as the mga.o driver
runs with enabled Macrovision protection - what kind of id*ot enabled that
as I've my TV out connected directly to VCR and there is no way I could
contect this directly to TV receiver.
--
.''`. 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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