[vdr] Advice on new motherboard, xineliboutput, vdpau, hdmi video & audio, etc.

jori.hamalainen at teliasonera.com jori.hamalainen at teliasonera.com
Fri Aug 20 10:08:39 CEST 2010


>> > Computer hardware usually cannot provide 50.000Hz, 59.940Hz or 
>> > 23.976Hz outputs to your TV/Monitor. This will cause some judder on 
>> > display output as MPEG/AVC input-stream is not synchronized to output
framerate.
> 
>> do you mean that all nvidia vdpau cards with existing drivers from 
>> Nvidia can't provide exact 50.000Hz, 59.940Hz or 23.976Hz ??

> There is no graphics card, BD/DVD player or other standalone device that
outputs 
> those rates exactly. I don't know how much they deviate, but I'd guess
it's usually 
> something like 0.01 % (50.005 Hz instead of 50 Hz), as Jori said.

If you can find a modeline what your output is currently using you can use
online services
to check framerates it provides.

You can use this link "Or give Xfree86 modeline to import"-option
http://www.epanorama.net/faq/vga2rgb/calc.html

For example Xorg server with log verbosity > 6 will print modes the X-server
is validating.
But I am not sure (too busy to check and remove from my VDR) if it writes
actual modelines out.

**

These framerate/synch issues are so complicated (and uninteresting to most)
that we 
can just made a conclusion that video/audio should be properly synched,
otherwise a 
quality declarating will occour. 

With VDR's FF card I have never seen such problems. But with softdevice
based outputs
I can see a lot of them. The video does not seem to be as smooth as on
dedicated players 
(BD, popcorn hour etc).

It does not help using direct Toslink-output from VDR which mostly prohibits
resampling
of audio. And why would you like to have audio decompressed, speeded up 1%
and then 
recompressed.

Just to avoid your output software to duplicate or drop frames. Synch
perfectly..
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