[mythtv] ivtv buffer overflow

Isaac Richards ijr at case.edu
Mon Dec 12 16:50:56 EST 2005


On Monday 12 December 2005 16:47, Niels den Otter wrote:
> Isaac Richards wrote:
> >>I have been experiencing problems with corrupt ivtv recordings and
> >>the buffer overflow messages since around September.  I thought that
> >>these were linked to an ivtv upgrade, but now that I look at the
> >>commit date of the bufferSize changes (09/21/05) in
> >>mpeg_recorder.cpp, it looks like this corresponds almost exactly with
> >>the start of my corruption.  I have changed the bufferSize to 32768
> >>as you suggested on ivtv-devel and I am currently recompiling to test
> >>the results.  I notice that prior to this change, the bufferSize was
> >>256,000.  What is the reason for such a drastic reduction, it wasn't
> >>mentioned in the commit message.  Would setting it back to 256,000 be
> >>better than 32768?  I'll play around with it a bit and let you know
> >>the results.
> >
> > Smaller reads make ivtv more responsive on channel changes & startup.
>
> I have tried a bufferSize of both 32768 and 256000, but the problem is
> still there. Strange thing is that it only happens when a recording
> starts while watching LiveTV.  The recording is in the list, but the
> ivtv driver keeps spewing the 'Overflow' messages and the image in the
> recording is black.
>
> If I quit LiveTV just before the recording starts all goes well. Is
> there anything different in the path LiveTV->recording and
> LiveTV->none->recording that could cause this?

Livetv -> recording is currently broken.

Isaac


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