[mythtv-commits] Ticket #9577: CEA-708 captions sometimes spontaneously reset

MythTV noreply at mythtv.org
Sun Feb 13 01:48:41 UTC 2011


#9577: CEA-708 captions sometimes spontaneously reset
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     Reporter:  Clayton Smith <argilo@…>          |      Owner:  danielk
         Type:  Bug Report                        |     Status:  new
     Priority:  minor                             |  Milestone:  unknown
    Component:  MythTV - ATSC                     |    Version:  0.24-fixes
     Severity:  medium                            |   Keywords:  cea-708
Ticket locked:  0                                 |
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 Sometimes the CEA-708 closed caption decoder resets the caption display
 spontaneously, making the captions unreadable.  Upon investigation, I
 found that the code which detects reset (RST) and delay cancel (DLC)
 commands in the parse_cc_service_stream function is incorrect.  It should
 only inspect command bytes, but it actually scans parameter bytes as well.
 These parameter bytes may coincide with RST and DLC, causing an undesired
 reset in the former case, or a premature delay cancel in the latter.

 To solve this problem, I added code to skip over parameter bytes.  The
 list of commands and their corresponding number of parameter bytes were
 taken from the CEA-708 specification.  I tested the code on a number of
 shows, and it now correctly skips over parameter bytes (verified with
 printf debugging), and the spontaneous resets are gone.

-- 
Ticket URL: <http://code.mythtv.org/trac/ticket/9577>
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