[FFmpeg-user] telecine pattern 5555 - Judder-free, 60 FPS telecine (?)

Mark Filipak markfilipak.windows+ffmpeg at gmail.com
Mon Mar 30 11:54:16 EEST 2020


In order to make my 5-5-5-5 pull-down, anti-judder trick work with soft telecined content (see 
Details, below), I reckon I need to rewrite the 'frame_rate_code' nibble found in the MPEG PGC's 
SEQUENCE_HEADER (i.e., 0x000001B3), at offset = 7, bits 4-7 (big endian). I need to change bits 4-7 
from '0100' (i.e., 30/1.001 FPS) to '0001' (i.e., 24/1.001 FPS).

Do you have any ideas how/whether ffmpeg can do this?

The "telecine=pattern=5555" filter appears to look at 'frame_rate_code'. Since, for soft-telecined 
content, 'frame_rate_code' is set to '0100' (i.e., 30/1.001 -- which is bogus), the 'telecine' 
filter miscalculates PTS times and the resulting OUT.MKV runs fast (though audio is not affected). 
The target PTS times should be 20/8*(24/1.001) because the *actual* frames are at 24/1.001 FPS -- 
it's soft telecined! But because 'frame_rate_code' is set to '0100', 'telecine' instead calculates 
PTS times as 20/8*(30/1.001). So, instead of being made at 60/1.001 FPS, OUT.MKV is made at 75/1.001 

Thanks for any help/insight you can provide (and I'm sorry this is so obscure, but a rewrite fix of 
the source video is probably easier than trying to get the developers to modify 'telecine').


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