[mythtv-commits] Ticket #10793: CommFlagger improvements
MythTV
noreply at mythtv.org
Fri Oct 19 10:03:22 UTC 2012
#10793: CommFlagger improvements
-----------------------------------+-----------------------------
Reporter: markspieth | Owner: cpinkham
Type: Patch - Feature | Status: new
Priority: minor | Milestone: unknown
Component: MythTV - Mythcommflag | Version: Unspecified
Severity: medium | Resolution:
Keywords: | Ticket locked: 0
-----------------------------------+-----------------------------
Comment (by Wayne McDougall <waynemcdougall@…>):
In SubtitleChangeDetector.cpp there is the following code:
{{{
//subtitle.start_display_time; /* relative to packet pts,
in ms */
//subtitle.end_display_time; /* relative to packet pts, in ms
*/
//subtitle.pts; /* in AV_TIME_BASE, use frame
number * fps */
int start = frameNumber + subtitle.start_display_time * fps /
1000;
int end = frameNumber + subtitle.end_display_time * fps /
1000;
}}}
It seems to me this code assumes start_display_time and end_display_time
are relative times to the frame number. Instead in my recordings they are
absolutes timecodes in ms, directly related to the timecodes associated
with each video frame. And the above code yields incorrect framenumbers,
and subtitle detection fails.
I guess we could subtract the the initial frame's timecode, if we can
assume fps is constant for recordings. I'm not sure that is a safe
assumption. I suspect the time code wraps around to zero at some point,
and that would need to be handled.
Instead I think it would be safer to follow the pattern of
subtitlescreen.cpp which just compares the subtitle start and end
timecodes with the frame timecodes.
Presumably the current code works for some people, although I find it hard
to see how. It's entirely possible I'm not understanding something deeper
here. Comments welcome. But I'm hoping if I do a good job, the changed
code should still work correctly for them and also work for me.
--
Ticket URL: <http://code.mythtv.org/trac/ticket/10793#comment:6>
MythTV <http://code.mythtv.org/trac>
MythTV Media Center
More information about the mythtv-commits
mailing list