[ubuntu-mythtv] [SOLVED] Upgrade to 0.25 / recorded program sync problem

[Eric Shubert]

On 06/19/2012 01:23 AM, Steven Ellis wrote:
>
> On Wed, June 13, 2012 3:14 am, Eric Shubert wrote:
>> On 06/08/2012 08:07 PM, Eric Shubert wrote:
>>> On 06/08/2012 05:19 PM, Eric Shubert wrote:
>>>> I have a bit of a problem with 0.25.
>>>>
>>>> I have a BE and 2 FEs which were running 0.24. I upgraded the BE
>>>> (mythbuntu) and one FE (Lucid w/ mythbuntu repos) to 0.25 and they're
>>>> running fine.
>>>>
>>>> The other FE I (re)built from scratch on Precise. That FE works fine
>>>> for
>>>> live TV (using BE), but recorded programs have a problem. When playing
>>>> recorded programs, the audio lags the video by a couple seconds. This
>>>> happens on all recordings that were made with 0.24. Since upgrading
>>>> everything to 0.25, I have 3 programs recorded so far. Two play ok on
>>>> the problem host, but one plays out of sync like the 0.24 recordings.
>>>> It's the 2nd of the 3 recordings that plays out of sync.
>>>>
>>>> All hosts are up to date with the latest packages from the mythbuntu
>>>> repos.
>>>>
>>>> Anyone have any ideas where to look for a resolution? I'll be glad to
>>>> post any information which may be helpful.
>>>>
>>>> TIA.
>>>
>>> I've tried changing various settings, largely to no avail. Something has
>>> changed since yesterday though (updated pulseaudio-client package
>>> perhaps?) which has improve things slightly.
>>>
>>> I notice now that all 1080i recordings are playing normally. I know for
>>> certain that this was not the case yesterday. I also notice that all
>>> recordings which play with the audio sync problem (audio lags 1-2
>>> seconds, and the amount of lag appears to vary between recordings) are
>>> show 720p for resolution. On recordings that show nothing for
>>> resolution, some have the lag and some don't.
>>>
>>> So the scenario now appears to be unlrelated to which version made the
>>> recordings. The differentiating factor appears to go along with the
>>> broadcast resolution. IOW, when a program is broadcast in 1080i, the
>>> audio is X and it works, while with 720p broadcasts, the audio is Y
>>> which has the problem playing back.
>>>
>>> I'll try to get some more recordings to see if I can narrow things down
>>> a bit more. I haven't see this with any live TV programs, but that's not
>>> to say it can't happen.
>>>
>>> Any ideas are appreciated.
>>>
>>
>> For posterity. I tried a different tact, which was to install mythbuntu
>> first, then enable ubuntu desktop from the mythbuntu control center.
>> Audio sync is now flawless.
>>
>> I think the problem was related to pulse audio. With the new setup, I
>> configured with the alsa hdmi device instead of pulse. I did try
>> changing the former ubunutu/myth installation to the same hdmi device,
>> but I got no audio at all with that. I'm guessing that some of the other
>> audio adjustments I made trying to fix the problem caused it to not
>> work. I didn't see any point in chasing down that path further since I
>> have a working system now.
>>
>> P.S. FWIW, I'm running this frontend from an 8G USB drive. Booting is a
>> little slower than the HDD, and updates take a bit longer (not that
>> updates on the HDD were very fast). Normal/typical operation is
>> otherwise very nice though. $10 for 2 8G drives (one live, one backup)
>> vs $60 or more for a 2.5" HDD. I've opted for the former, and am very
>> happy with my decision. There are some tweaks I can make to reduce i/o
>> to the USB drive, but it's working nicely even w/out doing that yet.
>>
>
> Take a look at http://code.mythtv.org/trac/ticket/10797
>
> There is a thread on MythTV Users around a similar audio sync problem.
>
> Steve
>
> --------------------------------------------

I can't say for sure if that fix would have helped my situation or not, 
as I no longer have that drive/config to test with. I did check 
/proc/asound/card0/pcm1p/sub0/prealloc value, and it's 64 in my present 
setup that's working. I'm using an alsa hdmi device though now, instead 
of the pulse device which was giving me the sync problems. The sync in 
my present setup is absolutely flawless, and the sync happens 
instantaneously when skipping forward and backward. Very nice, 
especially compared to 0.24.

Thanks for the heads up, Steve.
-- 
-Eric 'shubes'