What frame rates are permitted in MPEG?
A limited set is available for the choosing in MPEG-1 and the currently defined set of Profiles and Levels of MPEG-2, although “tricks” could be played with Systems-layer Time Stamps to convey non-standard picture rates. The set is: 23.976 Hz (3-2 pulldown NTSC), 24 Hz (Film), 25 Hz (PAL/SECAM or 625/60 video), 29.97 (NTSC), 30 Hz (drop-frame NTSC or component 525/60), 50 Hz (double-rate PAL), 59.97 Hz (double rate NTSC), and 60 Hz (double-rate, drop-frame NTSC/component 525/60 video). Only 23.976, 24, 25, 29.97, and 30 Hz are within the conformance space of Constrained Parameter Bitstreams and Main Level Thanks to MPEG’s top_field_first and repeat_first_field, it is technically possible to have somehow irregular coded frame rates and still have a constant display frame rate. But watch out for VBV compliance! What areas can be improved upon to create a better syntax than MPEG? As more number crunching cycles become available with improvements in semiconductors, several improvements can
