[mythtv-users] HELP: What is meaning of "NVP: Video is 16.2157 frames ahead of audio, doubling video frame interval to slow down."

James Crow james at ultratans.com
Fri Dec 5 21:19:54 UTC 2008

On Fri, 2008-12-05 at 15:44 -0500, Jeffrey J. Kosowsky wrote:

>  > Did you try enabling extra audio buffering in tv playback general settings?
> Yes - it didn't help at all.
> And I don't think it should since this is not a 1-time buffering
> problem - but rather seems to be a continual one whereby the sound is
> waiting for the "slow" video to catch up.
> i.e. observationally, it seems like the sound plays at normal speed
> until it gets too far AHEAD (say 1/3 - 1/2 second) of the slower video
> then it pauses to wait for the video to "catch up". But then it
> immediately continues to get ahead of the video again and the cycle
> repeats...
> So I don't think any amount of buffering will help.
> I need to understand why the video is playing "slow" and what I can do
> to speed it up (I tried with/without XvMC and with/without
> interlacing). 
> I know my CPU is old but it is not getting 100% usage -- and in fact,
> on my old Nvidia 4600 card the total CPU usage was higher even if with
> analog TV.
> Also, I still don't understand the error message: 
> 	  Video is 16.2157 frames ahead of audio, doubling video frame
> 	  interval to slow down.
> Since it seems like the video is BEHIND -- hence the slow-mo video and
> the pause in audio while waiting for video to catch up.
> Interestingly, in mplayer, the sound and video play smoothly (under
> XvMC) though the audio gets gradually further ahead of the video. This
> despite the fact that mplayer is only using 35-40% of CPU, X using
> 10-15% and pulseaudio 5-8% -- so total CPU usage is about 60%.
> It seems like the problem is worse now with the new 6200 card than
> with my old 4600 card (without XvMC) when total CPU usage was closer
> to 100%.
> I tried both the 96.43.07 and the 173.14.12 atrpms drivers.

I am having the exact same problem with WLOS ABC-HD from Asheville, NC
with Charter ClearQAM. My system is very capable of playing back Mpeg2
HD. I can play all other HD feeds (NBC, FOX, PBS, and CBS) without

Try to play the video with mplayer. When I played one of my problem
files mplayer said it jumped frame rates from 59.xx to 47.xx every
couple of secs.

I am not sure if the file is damaged or something else is going on. I
want to put up an antenna so I can grab the OTA ATSC signal and see if
it has problems as well. Might get to it this weekend, but it may wait
until after the holidays.


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