[Libav-user] SEI picture timing message and timestamp in decoded frame, h264 es

[Michal Rybinski]

Hi there,

I'm a bit newbie to ffmpeg API and still didn't get a grasp where to look
in ffmpeg code for some answers. I hope for some guideline/explanation. If
this is more suitable for ffmpeg-user mailing list, just let me know.

Case:
Playing back a video (using ffmpeg API of course), a h264 elementary
stream. It is possible, that every frame gets additional SEI picture timing
message in that stream. FFMPEG is compiled without "--enable-gpl" and
without "--enable-nonfree" flags (so it's not using x264 in my case).
Reading frames and controlling their displaying using AVFrame
best_effort_timestamp value.

Question:
Is FFMPEG taking into account SEI picture timing message contents when
establishing timestamp (pts or best effort timestamp) when my app reads
decoded AVFrame (basically looking into pts and best_effort_timestamp
fields)? If yes - is clockTimestamp calculated from SEI picture timing
overruling/overwriting any other values or is it more complicated? Where
should I look to understand how SEI picture timing message influences
timestamp (and which one in terms of AVFrame fields) when h264/es frame
gets decoded via ffmpeg?

Best Regards
Michał
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