[mythtv-users] Playback causes recording stream corruption

[Tony Lill]

"Ben Rigby" <benrigby at gmail.com> writes:

> Hi,
>
> I've recently upgraded to 0.19 (via atrpms) on my FC3 myth box and run
> into a problem. The problem might not be new, or necessarily causes by
> 0.19 but it does seem to be exacerbated by it.
>
> My problem is that watching a recording (or Live TV) seems to cause
> some sort of corruption in any recordings being made. When the myth
> box is not in use for playback, and recordings are near perfect (very
> occasional video or audio artifacts). When a recording is made while
> I'm watching it or something else previously recorded, then there are
> significant artifacts. Often the recording is completely unwatchable
> for sections lasting up to 3 minutes. The corruption definitely seems
> to be occuring on the recording side of things, not the playback side
> of things beacuse I can go back later and play it again and the same
> corruption will occur.

It could be that your backend just can't keep up with the video
stream. I get the following messages a lot more since going to 0.19:

Mar 29 05:01:16 freevo kernel: ivtv0: All encoder MPEG stream buffers are full. Dropping data.
Mar 29 05:01:16 freevo kernel: ivtv0: Cause: the application is not reading fast enough.

The real cause seems to be that while recording, the same thread
that's reading from the device is also inserting rows in the
recoredemarkup table. Lately, after a lot of monkeying to make other
things not run during recording, I've found that I get these errors
whenever a recording starts. Coincidently, for the first 30 seconds of
a recording, the inserts are done every 5 seconds and after, every 30.

I'm working on a patch that will spin those database updates into
their own thread. If it works, it might fix you too.
--
Tony Lill,                         Tony.Lill at AJLC.Waterloo.ON.CA
President, A. J. Lill Consultants        fax/data (519) 650 3571
539 Grand Valley Dr., Cambridge, Ont. N3H 2S2     (519) 241 2461
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