[mythtv] [mythtv-commits] Ticket #5552: AC3 passthrough causes accelerated playback on OSX 0.21 frontend

Michael T. Dean mtdean at thirdcontact.com
Fri Jul 18 04:37:29 UTC 2008

On 07/17/2008 12:45 AM, MythTV wrote:
> #5552: AC3 passthrough causes accelerated playback on OSX 0.21 frontend
>  When AC3 passthrough is selected on the OSX frontend, occasionally the
>  video an audio begin playing at an accelerated rate.  This usually happens
>  when the show is not bookmarked - i.e. playback starts from the beginning
>  of the file.  It never happens if AC3 passthrough is un-checked.
>  I've attached a log file.  The accelerated playback session begins at the
>  top of the file and ends at 21:29:24.  The normal playback session begins
>  immediately afterward at 21:29:25.  The most obvious difference between
>  the two is the appearance of a slew of " NVP: Video is x.xxxx frames
>  behind audio (too slow), dropping frame to catch up." messages once
>  playback begins in the first case.

Are you sure the broadcaster isn't switching to 32kHz AC-3 at that 
location and your sound card is continuing to read data at 48kHz?  Most 
all computer-based sound cards work only with 48kHz AC-3.



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