Constant framerate setting doesn't work at 59.94fps

[Hanbrakeur]

Hello, when setting framerate to 59.94 in constant framerate, mp4/m4v, it results in variable framerate.

The problem was reported here https://github.com/HandBrake/HandBrake/issues/3183 but the bug has been marked as duplicate and no solution was provided.

Does anyone know a workaround ? This problem is very serious because the video becomes out of sync overtime when dubbing it on a software editing program like Sony Vegas. Should I encode to 50fps or is there a way to get 59.94 CFR ?

Thanks for your help,


Cédric.

[Deleted User 11865]

MediaInfo is wrong, the video bitstream is CFR. MediaInfo reports VFR because it's not possible to have an exact frame duration on a 90 KHz timebase given a 24000/1001 or 60000/1001 frame rate (3,753.75 and 1,501.5 ticks per frame, respectively).

You could probably remux using different software and a different time base, but it's more likely Vegas has desync issues because of edit lists and B-frames, in my opinion. IIRC, musicvid is more familiar with Vegas specifically, so he may have some advice to work around this issue.

[Hanbrakeur]

Thanks for your quick reply.

[Deleted User 13735]

When the reported "Variable" frame rate is very close, e.g., 59.920 / 59.960, which is a factor of only 0.001, then it is actually constant frame rate. Since integer math can't deal with an irrational outcome (60/1001/90000), we call this the rounding error or "jitter," and it is present in all kinds of calculations.

True variable frame rate often looks like this, a difference of 3% or quite a bit more, even 2 fps with stills:

Code: Select all

Frame rate mode             : Variable
Frame rate                  : 59.369 FPS
Minimum frame rate          : 58.215 FPS
Maximum frame rate          : 60.647 FPS

[Hanbrakeur]

Thanks for clarifying this.