[Mp4-tech] Frame rate in h.264

[John Cox]

Glenn
You can get the info from the VUI (in SPS) from the timing_info fields
(num_units in tick, time_scale, fixed_frame_rate_flag).  Unfortunately
these fields are optional and very few encoders fill them in.  Indeed in
the only recent example I've seen where they were filled in the encoder
had got the value wrong by a factor of two. num_units_in_tick/time_scale
should yield field time (or half frame time if progressive) rather than
frame time.
John Cox
SJ Consulting Ltd
>In MPEG-2 you could just parse the SEQ header and pull out some bits to 
>determine if the frame rate is 29.97/NTSC or 25/PAL or whatever.
>
>I don't see any obvious way to determine this from a .264 stream, other 
>than by figuring it out based on the number of frames and the time 
>elapsed, but given that there could be repeats that might be more 
>complex than I'd like.  
>
>Thanks,
>Glenn
>
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