[mythtv-commits] Ticket #10984: Improve closed caption performance
MythTV
noreply at mythtv.org
Tue Aug 6 15:57:32 UTC 2013
#10984: Improve closed caption performance
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Reporter: stichnot | Owner: stichnot
Type: Developer Task | Status: new
Priority: minor | Milestone: 0.28
Component: MythTV - Captions | Version: Master Head
Severity: medium | Resolution:
Keywords: | Ticket locked: 0
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Comment (by stichnot):
A fundamental issue here is that the amount of work to render one subtitle
can vary wildly, depending on the number of differently-formatted chunks
in the subtitle, and the complexity of formatting in osd_subtitle.xml.
For the latter, larger fonts, shadows, and outlines make rendering more
expensive.
Since there are always many video frames between different subtitles, the
processing time for one subtitle may cause a dropped frame, even when the
average per-frame overhead is small.
The best way to deal with this may be to offload as much processing as
possible into a helper thread, being careful to avoid non-thread-safe
MythUI work in the helper thread. Performance-tuning the single-subtitle
work is also worthwhile, but probably can't be the only approach since we
are largely at the mercy of the subtitle provider, the themer
(osd_subtitle.xml complexity), and the user (subtitle zoom factor in the
Playback OSD).
--
Ticket URL: <http://code.mythtv.org/trac/ticket/10984#comment:3>
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