[mythtv-commits] Ticket #2849: Problem finding keyframes in some recordings

MythTV mythtv at cvs.mythtv.org
Fri Dec 29 17:19:03 UTC 2006

#2849: Problem finding keyframes in some recordings
 Reporter:  doug at ties.org  |       Owner:  ijr    
     Type:  defect         |      Status:  new    
 Priority:  minor          |   Milestone:  unknown
Component:  mythtv         |     Version:  0.20   
 Severity:  medium         |  
 I have some ATSC (OTA, DVB drivers) recordings whose seektable was written
 incorrectly -- the entries point to packets in the file that are not even
 picture start, and there are a whole lot more entries than should exist.

 'mythcommflag --rebuild' on one of these files picks up most (but not all)
 of the keyframes correctly, but the frame number is incorrect.  Both of
 these problems cause trouble seeking.

 Recordings from other stations, and some other recordings from the same
 station, are fine.

 This is with 0.20-fixes, but I don't see that a whole lot has changed in
 dtvrecorder since that time.

 I have debugged this problem as far as I am able for the time being.  I've
 put a bunch of data at http://www.parkercat.org/doug/wgbh-weird/ (behind a
 cable modem, so please go easy):
  * wgbh-weird.ts -- first 200MB of an example bad recording
  * before-commflag.gnumeric -- recordedseek entries for this recording,
 imported to Gnumeric
  * after-commflag.gnumeric -- recordedseek entries after 'mythcommflag
  * wgbh-weird-gopdump.txt -- slightly-formatted dump of the GOP-containing
 TS packets, as reported by:
  * tsdump and tsdump.C -- my old program to do minimal parsing on MPEG2-TS
 files for debug (Linux binary & source)

Ticket URL: <http://svn.mythtv.org/trac/ticket/2849>
MythTV <http://www.mythtv.org/>

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