[mythtv-commits] Ticket #2556: Bogus video streams in output PMT

[MythTV]

#2556: Bogus video streams in output PMT
---------------------+------------------------------------------------------
 Reporter:  stuarta  |       Owner:  stuarta
     Type:  defect   |      Status:  new    
 Priority:  minor    |   Milestone:  0.21   
Component:  dvb      |     Version:  0.20   
 Severity:  medium   |  
---------------------+------------------------------------------------------
 Broadcasts from certain transmitters in the UK of Channel 4
 are triggering myth to place bogus video streams in the output
 PMT. This later causes myth to barf on these recordings.

 Some analysis of the sample recording provided.

 ffmpeg:
 {{{
 Input #0, mpegts, from 'ChannelFourBug.mpg':
   Duration: 00:00:03.7, start: 41021.819689, bitrate: 3453 kb/s
   Stream #0.0[0x230], 25.00 fps(r): Video: mpeg2video, yuv420p, 704x576,
 10000
 +kb/s
   Stream #0.1[0x231](eng): Audio: mp2, 48000 Hz, stereo, 192 kb/s
   Stream #0.2[0x232](eng): Audio: mp2, 48000 Hz, mono, 64 kb/s
   Stream #0.3[0x233](eng): Subtitle: dvbsub
   Stream #0.4[0x4ae], 90000.00 fps(r): Video: mpeg2video
   Stream #0.5[0x40a], 90000.00 fps(r): Video: mpeg2video
 }}}

 dvbsnoop:
 {{{
 dvbsnoop -if ChannelFourBug.mpg -nph -pd 7 -s ts | grep ^PID | sort | uniq
 -c
       5 PID: 0 (0x0000)  [= Programm Association Table]
       7 PID: 2000 (0x07d0)  [= NIT, PMT or Elementary PID, etc.]
    1805 PID: 2201 (0x0899)  [= NIT, PMT or Elementary PID, etc.]
      11 PID: 2203 (0x089b)  [= NIT, PMT or Elementary PID, etc.]
     105 PID: 2307 (0x0903)  [= NIT, PMT or Elementary PID, etc.]
       5 PID: 300 (0x012c)  [= NIT, PMT or Elementary PID, etc.]
    6139 PID: 560 (0x0230)  [= NIT, PMT or Elementary PID, etc.]
     425 PID: 561 (0x0231)  [= NIT, PMT or Elementary PID, etc.]
     149 PID: 562 (0x0232)  [= NIT, PMT or Elementary PID, etc.]
       1 PID: 563 (0x0233)  [= NIT, PMT or Elementary PID, etc.]
 }}}

 {{{
 PID 0x0 = PAT
 PID 0x7d0, 0x899, 0x89b = DSMCC
 PID 0x903 = PCR
 PID 0x12c = PMT
 PID 0x230 = Video
 PID 0x231, 0x232 = Audio
 PID 0x233 = Data (subtitles)
 }}}

 Analysis of the output PMT yields the following streams
  - PID 0x230 Video
  - PID 0x231 Audio
  - PID 0x232 Audio
  - PID 0x233 Data (subtitle)
  - PID 0x4ae Bogus (marked as type 0x2, video)
  - PID 0x7d0 DSMCC
  - PID 0x40d Bogus (marked as type 0x2, video)
  - PID 0x899 DSMCC
  - PID 0x89b DSMCC

 The invalid streams (0x4ae & 0x40d) are only found
 in the output PMT, not in the recording itself.

-- 
Ticket URL: <http://svn.mythtv.org/trac/ticket/2556>
MythTV <http://www.mythtv.org/>
MythTV