mythtv at cvs
Jul 31, 2010, 11:58 AM
Post #1 of 4
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Re: Ticket #7978: Seektable built during recording is broken; fixed by rebuilding seektable
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#7978: Seektable built during recording is broken; fixed by rebuilding seektable
---------------------------------------------+------------------------------
Reporter: Ian Macdonald <ian@…> | Owner: ijr
Type: defect | Status: new
Priority: major | Milestone: 0.24
Component: MythTV - General | Version: 0.22-fixes
Severity: medium | Resolution:
Mlocked: 0 |
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Comment(by OliHenning):
Ok, there, i can also confirm this problem.
I have a Hauppauge PVR-500 (double-Tuner, Analog-TV, OnBoard-MPEG-Enocder)
I'm in Switzerland, so i'm using PAL 50HZ.
I analyzed a bit and observed, that mythbackend is making entries in the
MySQL-Table "recordedseek" '''while''' the recording is running. It makes
seek-entries of type '9' which means 'GOP' (Group of Pictures).
Info: With this Information in the table, mythfrontend is able to seek
quickly to a specific timepoint in a recording, as every MPEG-Decoding has
to start at the beginning of a GOP (we have to hit the 'exact' Byte-
Position in the Multi-100-Megabytes-MPEG-File !).
Additionally, mythfrontend can quickly calculate the length of the movie
in hh:mm:ss (simply make a
{{{
SELECT max(mark) FROM seektable WHERE type=9 AND chanid=... AND
starttime=...
}}}
or so)
'''BUT:''' These seektable-entries 'while-recording' are wrong. I dumped
the entries of a recording right after the recording, then i did a rebuild
of these seek-entries as follows:
{{{
mythtranscode -b -i 1004_20100731012300.mpg
}}}
and then i dumped the entries again. And there are differendes:
After ''Recording'': 3936 Rows[[BR]]
After ''Transcode'': 3996 Rows
After ''Recording'': mark-values (=25Hz Frames) from 0 to 47403[[BR]]
After ''Transcode'': mark-values (=25Hz Frames) from 0 to 47940
After ''Recording'': Recording-Length min:sec = 31:34 (=47403/25
Seconds)[[BR]]
After ''Transcode'': Recording-Length min:sec = 31:56 (=47940/25 Seconds)
After ''Recording'': delta between two mark-values: random (between 1 and
42, but mostly 12)[[BR]]
After ''Transcode'': delta between two mark-values: ALWAYS 12
So, in my optinion, mythbackend (while recording running) is not able to
identify the GOP-Frames in the MPEG-Stream correctly while mythtranscode
does.
what do you mean
Greeting from switzerland
--
Ticket URL: <http://svn.mythtv.org/trac/ticket/7978#comment:10>
MythTV <http://www.mythtv.org/>
MythTV
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