[FFmpeg-user] How can I force a 360kHz time base?

[Jim DeLaHunt]

On 2021-02-26 17:24, Mark Filipak (ffmpeg) wrote:

> On 2021-02-26 20:05, Jim DeLaHunt wrote:
>> Does input1.mkv in fact have a constant frame rate of 24/1.001 
>> frames/second?
>
> No, it has a constant frame rate of 30/1.001 frames/second.

Sorry, my mistake.  I should have said, "Does input1.mkv in fact have a 
constant frame rate of 30/1.001 frames/second?"


> 'ffmpeg -i input.mkv -vf "showinfo" -codec:a copy -codec:s copy -dn 
> output.mkv'
>
> [Parsed_showinfo_0 @ 0000013c877124c0] n:   1 pts:     33 
> pts_time:0.033   pos:    10052 fmt:yuv420p sar:32/27 s:240x236 i:P 
> iskey:0 type:B checksum:3CF10BFE plane_checksum:[64208370 00B13226 
> C5775659] mean:[25 126 131 ] stdev:[12.8 6.1 1.6 ]
> [Parsed_showinfo_0 @ 0000013c877124c0] n:   2 pts:     67 
> pts_time:0.067   pos:     9213 fmt:yuv420p sar:32/27 s:240x236 i:P 
> iskey:0 type:B checksum:23A8A65F plane_checksum:[90DC2AA6 37E908C8 
> 779972F1] mean:[27 125 132 ] stdev:[14.8 7.1 1.9 ]
> [Parsed_showinfo_0 @ 0000013c877124c0] n:   3 pts:    100 
> pts_time:0.1     pos:    11086 fmt:yuv420p sar:32/27 s:240x236 i:P 
> iskey:0 type:B checksum:1CDF7A80 plane_checksum:[089DE80E C537F4C0 
> 8C4E9D94] mean:[29 125 132 ] stdev:[15.2 6.6 2.3 ]
> …[elided for brevity]…
> [Parsed_showinfo_0 @ 0000013c877124c0] n:  28 pts:    934 
> pts_time:0.934   pos:    45167 fmt:yuv420p sar:32/27 s:240x236 i:P 
> iskey:0 type:B checksum:8D724A43 plane_checksum:[CD1CE198 DC377EA5 
> 3D51E9E8] mean:[70 113 148 ] stdev:[46.3 11.6 11.5 ]
> [Parsed_showinfo_0 @ 0000013c877124c0] n:  29 pts:    968 
> pts_time:0.968   pos:    40163 fmt:yuv420p sar:32/27 s:240x236 i:P 
> iskey:0 type:P checksum:8F6C0D42 plane_checksum:[385DA9F1 7EA37D5A 
> AD78E5D9] mean:[70 113 148 ] stdev:[46.6 11.6 11.5 ]
> [Parsed_showinfo_0 @ 0000013c877124c0] n:  30 pts:   1001 
> pts_time:1.001   pos:    50467 fmt:yuv420p sar:32/27 s:240x236 i:P 
> iskey:0 type:B checksum:B511B7BA plane_checksum:[9C9A49A0 B1D583BA 
> FA0EEA51] mean:[70 113 148 ] stdev:[46.5 11.4 11.6 ]


This output shows a stream which has a varying frame rate. The change in 
pts_time is not constant from frame to frame.

Can you get some output which shows the timebase value, or the frame 
times, of input1.mkv, showing that there is a timebase which is a 
multiple of 1.001/30, or showing that the time value of each frame 
increments by a constant amount?

So far, the output you show is consistent with an input1.mkv which has a 
varying frame rate that is 30/1.001 fps, distorted to fit a 1/1000 
timebase. Can you show a diagnostic which eliminates that possibility?

     —Jim DeLaHunt