[mythtv-users] Lossless transcoding became really slow

[Jim Stichnoth]

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?

Jim