[mythtv-users] ac3 passthrough results in accelerated video

[scram69]

On Thu, May 29, 2008 at 8:18 PM, John P Poet <jppoet at gmail.com> wrote:
> On Thu, May 29, 2008 at 8:24 PM, Craig Treleaven <ctreleaven at cogeco.ca> wrote:

>> Me too.  I'm running .21-fixes (from a couple of months ago) on a Core2Duo mini.  The problem recordings will play in accelerated mode one, two or three times in a row and then play fine.  Lots of recordings play fine.  I think I only see this problem with ABC, NBC and CBS; not with the Canadian networks.  BTW, all are recorded OTA via an HDHomerun.
>>
>> Also, the frontend hangs on exiting playback, sometimes.  I keep meaning to set up logging but haven't done it yet.
>>
>> Neither of these problems happened to any extent under .20-fixes.  As you might imagine, it is having a detrimental effect on the SAF (spousal approval factor).  Thanks to scram69 for pointing out the issue and the correlation with digital audio--I had no idea that was related!
>>
>> On the Mac, what is a good tool identify the types of audio and video data in a file?  VLC doesn't give any details.
>
>
> One *big* change between 0.20 and 0.21 is that once you turn on
> timestetch while watching a show, it never turns back off -- even if
> you go back to 1.0x speed.  As part of this, it *decodes* DD5.1,
> adjusts it's speed (if necessary), then re-encodes the audio back into
> DD5.1 (preserving the original channel allocation) and sends it out
> your S/PDIF.  This is actually all pretty cool, but it has introduced
> some new problems.
>
> If you are getting loud static popping, I wonder if it is not
> correctly re-encoding the DD5.1?  I have not tried this in a *long*
> time, but you used to be able to change to a different ac3 library by
> compiling with:
>
> configure --enable-liba52bin --disable-decoder=ac3 --enable-decoder=liba52
>
> Mark Spieth would have to comment on whether that still works.  Of
> course your problem might also be that no ac3/a52 library is being
> linked in at all...
>
>
> If timestretch is "on", then it can occasionally get confused by the
> audiostream and miss-detect "6 channels" as "2 channel", which results
> in a chipmunk sound.  For example see:
>
> http://svn.mythtv.org/trac/ticket/5126
>
>
> You can post a (possibly) useful log if you run mythfrontend with audio logging:
>
> mythfrontend -v audio,libav,playback -l somelogfile
>
>
> Hope some of this info is useful.
>
> John

John - quite useful and timely.  I was just searching through the
archives attempting to dredge up the flags necessary to target audio
logging.

Craig - my recordings are all cable, but also via HDHomerun.  The
troubleshooting was basic Murphy - I only bothered with the hassle of
upgrading in order to get AC-3 on my main home theater frontend -
therefore, when the problems started creeping up, AC-3 was the most
likely culprit :(

I'll get to work on the log-

Steve