[FFmpeg-user] Quicktime - Specify a Movie Header timescale of 24000
mwjburton at gmail.com
Thu Mar 8 18:58:08 EET 2018
On 8 Mar 2018, at 16:38, Carl Eugen Hoyos <ceffmpeg at gmail.com> wrote:
> 2018-03-08 15:57 GMT+01:00, Mark Burton <mwjburton at gmail.com>:
>> Understood. A better option would no doubt be the ability to specify this
>> value in the same way we can specify the video_track_timescale value.
> If it would not fix your issue why would it be a good option?
Fair enough. The current ffmpeg default is 1000. This is not divisible by 24, 30 or 60fps. The default in the Quicktime specification is 600. This is cleanly divisible by 24, 25, 30, 50, 60, so is a very good value for the majority of professional fixed frame rates. I accept these do not represent all fixed frame rates, but it is evidently a better value than 1000.
"Media Time Scale
A QuickTime movie always has a time scale, expressed in units per second. You can specify a time scale when you create a movie, but the time scale cannot be changed once a movie exists. When you perform operations on a QuickTime movie, you frequently need to specify a point in the movie timeline at which to begin the operation; this is specified using a time value, expressed in movie time scale units. You may also need to specify a duration; this is also expressed in movie time scale units. The default movie time scale is 600…"
>> Since I don’t have the know how to make changes to the FFmpeg code
>> (changing MOV_TIMESCALE to a higher value in libavformat/movenc.h),
> Sorry, this is not an acceptable answer:
> movenc.h is a textfile that can be changed with any text editor.
I understand that, but I do not yet know how to bring the files locally, edit the values and then compile everything into a binary. I have absolutely tried this a number of ways, following the Compilation Guide https://trac.ffmpeg.org/wiki/CompilationGuide <https://trac.ffmpeg.org/wiki/CompilationGuide>, but I did not manage to do it successfully. I would love to get there though and so any help is hugely appreciated. I’m very determined and will do my utmost to be able to contribute a complete answer to this issue.
>> or even better, build a binary for me to test with.
> Could you elaborate why you cannot compile yourself?
> FFmpeg is supposed to build out-of-the-box on every common
> operating system and an a few very uncommon OS's.
> This is the right mailing list for compilation help.
Thanks. I have managed to compile a usable ffmpeg using brew (I work exclusively on macOS), but I have not figured out how I would be able to edit the libavformat/movenc.h file before compiling using this method. It seems I would need to go down the route, so any help to get that far would be so welcome.
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