[mythtv-users] Trying to Understand mythcommflag --rebuild

[Michael T. Dean]

On 02/13/2009 03:45 PM, Drew Tomlinson wrote:
> I'm experimenting with removing commercials by following the
> instructions at http://www.mythtv.org/wiki/Script_-_RemoveCommercials. 
> In an attempt to understand the script, I have been running the commands
> manually on a HD recording of local news captured via ATSC. 
>
> The news cast is one hour in length.  However after running
> mythtranscode and mythcommflag --rebuild, the show is now reported as 17
> min 23 seconds.  The show is still there in its entirety but pressing
> the 30 sec skip forward button actually moves forward around 2 minutes. 
> It is my understanding that the "mythcommflag --rebuild" command is
> supposed to fix this by rebuilding the seek table.  Is this correct? 
> And if so, what might I check to determine why mythcommflag is not
> rebuilding properly.  I've tried using both the "-f $DIR/$FILENAME" as
> in the wiki and with "-c CHANID -s STARTTIME".  Neither helps.  I'm
> running 0.21-fixes.
>
> Here is the output of my mythcommflag --rebuild command:
>
> mythtv at mythfe01 /tv0/record $ mythcommflag --rebuild -c 2581 -s
> 20090213080000
> 2009-02-13 12:29:54.515 Using runtime prefix = /usr
> 2009-02-13 12:29:54.516 Empty LocalHostName.
> 2009-02-13 12:29:54.524 New DB connection, total: 1
> 2009-02-13 12:29:54.528 Closing DB connection named 'DBManager0'
> 2009-02-13 12:29:54.528 mythcommflag version: 0.21.20080304-1 www.mythtv.org
> 2009-02-13 12:29:54.528 Enabled verbose msgs: important
>
> MythTV Commercial Flagger, started at Fri Feb 13 12:29:54 2009
> Rebuilding SeekTable(s) for:
> ChanID  Start Time      Title                                      Status
> ------  --------------  -----------------------------------------  ------
> 2009-02-13 12:29:54.531 New DB connection, total: 2
> 2581    20090213080000  KCRA 3 News at 8am                        
> 2009-02-13 12:29:54.546 Using protocol version 40
> 2009-02-13 12:29:55.744 RingBuf(/tv1/record/2581_20090213080000.mpg):
> Waited 1.0 seconds for data to become available...
> 2009-02-13 12:29:56.757 RingBuf(/tv1/record/2581_20090213080000.mpg):
> Waited 2.0 seconds for data to become available...
> 2009-02-13 12:31:42.928 RingBuf(/tv1/record/2581_20090213080000.mpg):
> Waited 1.0 seconds for data to become available...
> 2009-02-13 12:31:43.938 RingBuf(/tv1/record/2581_20090213080000.mpg):
> Waited 2.0 seconds for data to become available...
> Rebuilt     
>
> Finished commercial break flagging at Fri Feb 13 12:31:44 2009

In 0.21-fixes and below, mythcommflag --rebuild does not work for much 
of any MPEG-2.  It /might/ work on some PVR-x50 MPEG-2, but I've had a 
lot of even that that it couldn't process.  It's virtually guaranteed to 
fail on any broadcast digital video (ATSC, DVB-T/C/S).

You need to use mythtranscode --buildindex --mpeg2 (which does /not/ 
transcode the show) after (what I'm assuming is lossless) transcoding.

Read http://www.mythtv.org/wiki/Repairing_the_Seektable for information 
and help fixing the seektable.

The broken seektable would cause the length issue you described.

Note that mythcommflag --rebuild is working in trunk for all known MPEG-2.

Mike