#11188: ffmpeg_opt.c correct_input_start_times(void) calculates wrong ts_offset
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Reporter: Jens Viebig | Type: defect
Status: new | Priority: normal
Component: | Version:
undetermined | unspecified
Keywords: | Blocked By:
Blocking: | Reproduced by developer: 0
Analyzed by developer: 0 |
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Summary of the bug:
The abs_start_seek calculation in correct_input_start_times(void) is not
done correctly since the sum on the left is evaluated before the shorthand
if, giving unexecpected results
abs_start_seek = is->start_time + (ifile->start_time != AV_NOPTS_VALUE) ?
ifile->start_time : 0;
This expression almost always evaluates to "ifile->start_time" but is
expected to be evaluated to: is->start_time + ifile->start_time
As an example:
is->start_time = 10
ifile->start_time = 20
abs_start_seek = 10 + (20 != AV_NOPTS_VALUE) ? 20 : 0;
evaluates to
abs_start_seek = 10 + (true) ? 20 : 0;
then
abs_start_seek = 11 ? 20 : 0;
then
abs_start_seek = 20
We already submitted a patch for this issue, but it seems it was
misunderstood by the maintainers and is still not merged to the current
codebase
https://lists.ffmpeg.org/pipermail/ffmpeg-devel/2023-May/309555.html
With the patch the evaluation is corrected to:
abs_start_seek = is->start_time + ((ifile->start_time != AV_NOPTS_VALUE) ?
ifile->start_time : 0);
With the example, this evaluates to:
is->start_time = 10
ifile->start_time = 20
abs_start_seek = 10 + ((20 != AV_NOPTS_VALUE) ? 20 : 0);
evaluates to
abs_start_seek = 10 + ((true) ? 20 : 0);
then
abs_start_seek = 10 + 20;
then
abs_start_seek = 30;
--
Ticket URL: <https://trac.ffmpeg.org/ticket/11188>
FFmpeg <https://ffmpeg.org>
FFmpeg issue tracker
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