[Mp4-tech] Frame rate in h.264

[Tuukka Toivonen]

On Wed, 13 Jul 2005, Glenn Connery wrote:
>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.

See VUI parameters (Appendix E.1.1 in the standard, I believe).
Interesting values include these:
analyze: READ timing_info_present_flag                 : [1] 1
analyze: READ num_units_in_tick                        : [32] 1000
analyze: READ time_scale                               : [32] 25000
analyze: READ fixed_frame_rate_flag                    : [1] 1
(from my H.264 stream analyzer)
The frame rate here is 25 fps--it would be 25000/1000.
Furthermore, fixed_frame_rate_flag probably tells that there
is a fixed frame rate, anyway (but check the standard).
>From my memory, I believe VUI parameters are optional.
At least x264 writes them, I don't think JM does
(I could be wrong).