[vdr] Problems playing ongoing recordings?

Artur Skawina art_k at o2.pl
Wed Apr 2 13:37:52 CEST 2008


JJussi wrote:
> On Wednesday, 2. Aprilta 2008 05:11:37 VDR User wrote:
> 
>> Playback is faster then watching live tv?!  Maybe if you skip past the
>> commercials or something!  I've started playing back a recording many
>> times before it was finished and never had a problem with lockup or
>> that the playback was going faster then live tv!
> 
> Yes.. Check that attached message OR search subtitle "Playback to fast.." from 
> archives.
> Clements Kirchgatterer said that, that's normal...

Small drift is expected -- the clock used as reference for playback (on
dvb/dxr card etc) is not synced to the one used by the broadcaster. 
It's a similar problem to trying to record audio using one sound card
and playing it back using another card in real time -- at some point you
will get either over- or underruns because the sample rates are not 100%
identical.

I suspect some of the issues when playing ongoing recordings just after
they are extended are caused by the recorder telling the system to drop
the recently written data and this is interfering with the readahead
done by the player, which then has to wait for the data to be refetched
from disk. O_DIRECT helps here (by not using the cache at all), OTOH
it could cause playback problems at the very end (due to the small delay
and larger chunks used when extending the file)

artur



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