[FFmpeg-devel] [PATCH 3/3] lavf/utils: add flag to fill unset timestamps from wallclock offset

Rodger Combs rodger.combs at gmail.com
Sun Dec 10 13:14:08 EET 2017

> On Dec 10, 2017, at 05:07, Nicolas George <george at nsup.org> wrote:
> Rodger Combs (2017-12-07):
>> ---
>> libavformat/avformat.h      |  1 +
>> libavformat/internal.h      |  5 +++++
>> libavformat/options_table.h |  1 +
>> libavformat/utils.c         | 12 ++++++++++++
>> 4 files changed, 19 insertions(+)
> Can you give an example of scenario where this option would be useful?
> I mean with some level of details about the problem and the solution.

The goal is to use this in conjunction with the previous patches in the set to deal with live broadcast streams coming off a tuner. The first patch sets the CORRUPT flag when the TEI bit is set in a TS packet (indicating that the tuner detected uncorrectable errors), the second clears the PTS and DTS in response to that flag (since a bit flip that causes a too-high timestamp can throw off the whole stream, since ffmpeg.c enforces monotonicity), and the third re-generates DTSs by interpolating from the previous packet's receipt time.

> Also, the timestamp would need to be filtered for scheduling
> fluctuations.

In my target use-case, being slightly off due to scheduling fluctuations isn't particularly problematic, since this is expected to only occur in the case of corruption anyway, so the whole thing is best-effort.

> Regards,
> -- 
>  Nicolas George
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