[FFmpeg-trac] #1098(avfilter:open): ass subtitle are stretched
FFmpeg
trac at avcodec.org
Mon Mar 19 18:18:39 CET 2012
#1098: ass subtitle are stretched
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Reporter: fate | Owner:
Type: defect | Status: open
Priority: normal | Component: avfilter
Version: git-master | Resolution:
Keywords: ass | Blocked By:
Blocking: | Reproduced by developer: 1
Analyzed by developer: 1 |
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Comment (by dbuitenh):
Replying to [comment:7 saste]:
> The problem depends on the fact that vf_ass.c uses the same DAR of input
for rendering the subtitles, which is indeed a rather arbitrary behavior
(see line in vf_ass.c: ass_set_aspect_ratio(ass->renderer, dar, sar)).
>
> Possible fixes:
> set the DAR to 1.0, or allow the user to specify the DAR through an
option.
>
> In the second case I ask: does it make sense to be able to set such
value, or should be rather set in the ass file itself (assuming it is
possible)?
The thing that everyone who uses VSFilter on windows (thus defining the
behavior for other players and libs) has been doing since time immortal is
to manually set the x/y resize factors in the .ass file. i.e. something
with a 32:27 PAR -> x = (27 / 32) = 84.275%, y = 100 %. VSFilter then
applies these at a 1.0 DAR, and then the renderer resizes on playback as
the very last step.
To sum up: VSFilter always applies at 1.0 DAR.
--
Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/1098#comment:9>
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