[FFmpeg-user] Framerate automatically increased while cropping

Ulf Zibis Ulf.Zibis at CoSoCo.de
Tue Aug 24 15:03:47 EEST 2021

Am 24.08.21 um 13:51 schrieb Ulf Zibis:
> Am 23.08.21 um 07:15 schrieb Adam Nielsen via ffmpeg-user:
>>> why is the framerate automatically changed here from 29.98 fps to 120
>>> fps, and how can I prevent from this ?
>>>     Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1280x720, 2508 kb/s, 29.98 fps, 120 tbr, 90k tbn, 2k tbc (default)
>>  From what I can find, "tbr" is the target framerate the media is
>> indicating it wants.
> This is interesting. Thanks for the info. I would interpret this as meant for the playback of the video, e.g. for the ffplay. And why isn't it abreviated with "tfr" ?
>>    So ffmpeg is just respecting that value.
> With that contract I do hard, because in result I get a video with 15 % more bitrate and with lower quality, q=33.0 instead q=29.0. So I think, ffmpeg should retain the original bitrate and just propagate the tbr to be interpreted by the player.
>> I guess you could use the -r option to override this and force a
>> specific framerate if you want something different?
> Yes, this works fine. But I would appreciate, if I could use something like -r=inputrate or --keep_framerate

But with "-r 29.98" I get "tbr=29.98" instead the original 120, which I think would be correct.


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