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