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29th April 2018, 04:11 | #1 | Link |
Registered User
Join Date: Feb 2017
Posts: 13
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Doubts about timing and lost frame/packet at the codec level
As far as I understand, the h264 codec holds information about the frame rate (within the NAL, of SEI's type, timing_info_present_flag -> time_scale) and with that plus the frames count a container can build up its timing scheme. (like PTS) Is that right?
Here are some other questions:
I saw an example at Internet with what seems to be a 29.97 (time_scale/num_units_in_tick)/2 but I downloaded the big bunny (30fps) and then I extracted the .h264 and there I noticed a time_scale valued with 60 and a num_units_in_tick of 1 but the video itself is 30fps, do I really need to half its value to get the right framerate? Why spend more bits where I could store its value? Last edited by leandro; 29th April 2018 at 04:25. |
3rd May 2018, 03:52 | #2 | Link |
Angel of Night
Join Date: Nov 2004
Location: Tangled in the silks
Posts: 9,559
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Did you check nuit_field_based_flag? The spec is obnoxiously bad at making it clear, but the actual framerate is
Code:
time_scale / (num_units_in_tick * (nuit_field_based_flag+1)) |
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