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

Kamaldeep Tumkur kamaldeep.tumkur at gmail.com
Mon Apr 13 15:30:03 CEST 2015

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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