[FFmpeg-devel] Question on tbr, tbn, tbc

[Jean First]

On Mon Apr 13 2015 15:30:03 GMT+0200 (CEST), Kamaldeep Tumkur wrote:
> I have an mpeg4 transcoded from an mov source that has the following:
>
> Stream #0:0(eng): Video: h264 (Constrained Baseline) (avc1 / 0x31637661),
> yuv420p(tv, bt709), 480x270 [SAR 1:1 DAR 16:9], 462 kb/s, 25 fps, 25 tbr,
> 12800 tbn, 50 tbc (default)
>
> Why is tbn value so high? Why do the tbc and tbn values not match the tbr?
> And what kind of irregularities can this potentially cause during playback?
> How can it be corrected?
>
> When used in http based streaming with flash, this mp4 results in a black
> screen right at start up that continues till the end. On seeking, the video
> displays back again.
>
> Thanks for your inputs and guidance.
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Hi,

Please continue this conversation on the ffmpeg-user mailinglist !

The default value is set so high so you can combine multiple streams
with different timebases in the same container without having to worry
for offsets. It should not cause any problems during playback. If you
want to set it to a specific value during encoding you can set the
video_track_timescale option to a specific value.

Jean