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

[Drew Tomlinson]

Michael T. Dean wrote:
> 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).

Thanks for the explanation.

> 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.

I tried this but the result was a 0 byte file.  What would cause that? 
My specific command was the one you mention above plus "-i
</path/filename>".

> The broken seektable would cause the length issue you described.
>
> Note that mythcommflag --rebuild is working in trunk for all known
> MPEG-2.

I may have to try that.  :)

Thanks,

Drew

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