[FFmpeg-user] Slow speed when sub-clipping .mxf

Cecil Westerhof Cecil at decebal.nl
Tue Jun 27 13:58:16 EEST 2023

MediaMouth <communque at gmail.com> writes:

>> On Jun 21, 2023, at 00:45, Cecil Westerhof via ffmpeg-user <ffmpeg-user at ffmpeg.org> wrote:
>> Try:
>>    ffmpeg  -ss startSecs -t outputDuration -i srcPath.mxf -timecode stmptTc -c copy destPath.mxf
>> For timecode you probably nee to use stmptTc - startSecs.
> Thanks Cecil,

I am glad I could help someone else for a change. ;-)

> The only difference I'm in your cli code is that you put -ss and -t before -i, correct?
> Curious how that affects the process / why would that make a difference?

If you put the -ss and -t after the -i the video is internally
streamed and everything until startSecs is thrown away.
If you put it before the -i the internal streaming is started at -ss
and nothing has to be thrown away. If startSecs is quite a bit into
the video, this will mean a significant amount of work which is done
in the first case does not have to be done in the second case.

>> For timecode you probably nee to use smpteTc - startSecs.
> Been using hh:mm:ss:ff format and it's been working. I assume that has
> no affect on the speed of the process?

As far as I know not. And seems to me quite unlikely.

Cecil Westerhof
Senior Software Engineer
LinkedIn: http://www.linkedin.com/in/cecilwesterhof

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