[mythtv-users] Lossless transcoding became really slow

[Dale Pontius]

Jim Stichnoth wrote:
> On Sat, Jun 27, 2009 at 11:29 PM, Yeechang Lee<ylee at pobox.com> wrote:
>> Jim Stichnoth <stichnot at gmail.com> says:
>>> Lately my lossless (commercial-removing) transcodes have become
>>> exceptionally slow.
>> In mythtv-setup, what CPU level is the backend set to run
>> mythtranscode at? Perhaps you were at Medium before, and now are at
>> Low?
> 
> I haven't looked at that setting in ages.  It was set to Low, which is
> most likely how I originally wanted it.  I tried setting it to High,
> but there was no change in the lossless transcoding performance.
> 
> Then it occurred to me to check the logs while one of these transcodes
> was going on.  There were tons of lines being added to the backend log
> like this:
> 
> 2009-06-28 01:42:23.196 Id:1 00:01:18.368 V:170 EXT: 180 184 180
> 2009-06-28 01:42:23.204 Id:3 00:01:18.368 V:170 EXT: 179 184 180
> 2009-06-28 01:42:23.212 Id:2 00:01:18.375 V:170 EXT: 179 184 179
> 2009-06-28 01:42:23.220 PTS discrepency: 7068745 != 7067897 on B-Type (0)
> 2009-06-28 01:42:23.228 PTS discrepency: 7070247 != 7069398 on B-Type (1)
> 2009-06-28 01:42:23.236 PTS discrepency: 7071748 != 7070899 on I-Type (2)
> 2009-06-28 01:42:23.244 Id:0 00:01:18.574 V:170 EXT: 179 183 179
> 2009-06-28 01:42:23.252 Id:0 00:01:18.532 V:169 EXT: 179 183 179
> 2009-06-28 01:42:23.260 Id:0 00:01:18.548 V:168 EXT: 179 183 179
> 2009-06-28 01:42:23.268 PTS discrepency: 7073250 != 7072400 on B-Type (3)
> 2009-06-28 01:42:23.276 PTS discrepency: 7074751 != 7073901 on B-Type (4)
> 2009-06-28 01:42:23.284 PTS discrepency: 7076253 != 7075402 on P-Type (5)
> 2009-06-28 01:42:23.292 Id:0 00:01:18.625 V:167 EXT: 179 183 179
> 
> Then I remembered that I had changed the backend log settings to help
> diagnose some unrelated problem.  I was running mythbackend with "-v
> important,general,channel,record".  I switched it back to
> "important,general" and the transcoding speed went back to normal.
> 
> Except for the latest recording I'm trying to transcode.  About 75% of
> the way in, it slows down again and the backend log fills with
> messages like this:
> 
> 2009-06-28 01:53:09.485 No more queue slots!
> 2009-06-28 01:53:09.493 No more queue slots!
> 2009-06-28 01:53:09.501 No more queue slots!
> 2009-06-28 01:53:09.509 No more queue slots!
> 2009-06-28 01:53:09.517 No more queue slots!
> 2009-06-28 01:53:09.525 No more queue slots!
> 2009-06-28 01:53:09.533 No more queue slots!
> 2009-06-28 01:53:09.541 No more queue slots!
> 2009-06-28 01:53:09.549 No more queue slots!
> 2009-06-28 01:53:09.557 No more queue slots!
> 
> More than 250,000 of these lines!  A web search shows that it's
> probably some flaw or irregularity in the recording, rather than some
> misconfiguration on my part.
> 
> Thanks to everyone for the advice.  BTW, where do I find the SMART logs?
> 
First make sure you have smartmontools installed, configured, and
running.  Then for a normal/standard setup "grep smartd
/var/log/messages".  There tends to be a lot of chatter, some of it bad
looking, so don't get too worried at first blush.

Dale Pontius