[mythtv-commits] Ticket #10794: [PATCH] ffmpeg: Dont discard PES sections split across a TS packet

MythTV noreply at mythtv.org
Sun Jun 3 14:57:53 UTC 2012

#10794: [PATCH] ffmpeg: Dont discard PES sections split across a TS packet
     Reporter:  Lawrence Rust <lvr@…>  |      Owner:  danielk
         Type:  Patch - Bug Fix        |     Status:  new
     Priority:  minor                  |  Milestone:  unknown
    Component:  MythTV - DVB           |    Version:  0.25-fixes
     Severity:  medium                 |   Keywords:  MHEG 'red button'
Ticket locked:  0                      |
 In libavformat/mpegts.c, if a TS packet has a pointer field which marks
 the boundary of a PES section then the first section will be discarded if
 a second section is started in the remainder of the TS packet.

 This fix adds a check for a completed section and if present, appends the
 2nd section table to the 1st.

 This bug is most noticeable on the BBC MHEG text (red button) service
 which often will not start because the boot application or essential files
 have missing blocks.  Currently, it is often impossible to view the BBC
 'red button' service on FreeSat because of this bug.

 The attached patch is for fixes/0.25 and is also applicable to fixes/0.24.
 The same bug also affects git master but ffmpeg has been updated since and
 has changed considerably in this area.

 I take it that this bug has been around for a long time and has caused
 problems for text and subtitle users for a similarly long time.

 The bug and fix can be tested on this sample (16MB) recorded from Freesat
 BBC1 on the 25-May with mythtv fixes/0.24:

Ticket URL: <http://code.mythtv.org/trac/ticket/10794>
MythTV <http://code.mythtv.org/trac>
MythTV Media Center

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