[mythtv-users] XvMC on NVidia with Myth .20 (Anyonegetting goodHD off a P4 3

Brad Fuller bradallenfuller at yahoo.com
Mon Jan 8 21:08:42 UTC 2007



Drew Bernat wrote:
> On Jan 8, 2007, at 2:30 PM, Brad Fuller wrote:
>
>> XvMC, AFAIK, is a mechanism to offload IDCT and motion compensation 
>> chores to the GPU. Right?
>> Thus, by definition mpeg2 streams from OTA HD are going to be different 
>> than mpeg2 streams from your PVR card that does the mpeg2 encoding.  So, 
>> the decoding of a stream from OTA HD and from you PVR card are going to 
>> be different.
>>
>> What do you mean "XvMC doesn't work"? What leads you to this conclusion
>
> Piles and piles of prebuffering errors, skipping playback - the same 
> thing that I was seeing with HD before the latest NVidia drivers (and 
> turning off sync to vblank). 
>
> I was guessing it was file format. It's kind of annoying, since I can 
> play both HD and SD but have to flip the configuration between the 
> two. Here's some output:
>
> 2007-01-07 20:11:36.371 NVP: prebuffering pause
> 2007-01-07 20:11:36.394 NVP: Waiting for prebuffer.. 0 uADDDuLD
> 2007-01-07 20:11:36.793 NVP: Video is 3.20878 frames behind audio (too 
> slow), skipping A/V wait.
>
> and
>
> 2007-01-07 20:11:36.797 WriteAudio: buffer underrun
> 2007-01-07 20:11:37.143 WriteAudio: buffer underrun
> 2007-01-07 20:11:37.412 NVP: Video is 3.22094 frames ahead of audio,
>                         doubling video frame interval to slow down.
> 2007-01-07 20:11:37.560 NVP: Video is 3.50962 frames ahead of audio,
>                         doubling video frame interval to slow down.
> 2007-01-07 20:11:37.728 NVP: prebuffering pause
> 2007-01-07 20:11:37.750 NVP: Waiting for prebuffer.. 0 DDAuDLUu
> 2007-01-07 20:11:38.113 NVP: prebuffering pause
> 2007-01-07 20:11:38.133 NVP: Waiting for prebuffer.. 0 AuDLDADU
> 2007-01-07 20:11:38.411 NVP: Video is 3.09489 frames behind audio (too 
> slow), skipping A/V wait.
>
> Very similar to what I was seeing with HD before tweaking my NVidia 
> setup.
What's the result when you try  xvmc-enabled mplayer on your OTA and 
PVR-encoded mpeg?



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