[FFmpeg-user] Better way to cut parts out of a long video?

[Cecil Westerhof]

Rob Hallam <ffmpeg at roberthallam.com> writes:

> On Mon, 13 Jun 2022 at 11:26, Cecil Westerhof via ffmpeg-user
> <ffmpeg-user at ffmpeg.org> wrote:
>> That could very seldom work, but is certainly not a general solution.
>> In the past I was told to do it like this because it was faster. Then
>> I got problems with the output and was told how iframes work.
>
> What problems, exactly? Do they still occur with modern versions of
> ffmpeg, and with the inputs and outputs you are using?

I am not sure. I think I had the problem about half a year ago.
Because I use Debian the version of ffmpeg would have been a little
older.

There where two problems:
- The created video started most of the time to early.
- Sometimes the timestamps where incorrect.

I could try again of-course.


> I wrote a small script a while ago to "find the nearest keyframe in
> the input video before the point I want the output video to start" so
> that ti could be used for input seeking. However, that was a long time
> ago, and for the purposes of stream-copied (ie not re-encoded) output.
> I have not had any reason to use it recently.

I try the other options, but if that does not work for me, would you
be willing to share it?


> You could try 'combined seeking':
> https://trac.ffmpeg.org/wiki/Seeking#Combinedseeking

That looks very interesting and is what I was asking about. :-D


> My understanding is that seeking after input requires reading (and
> decoding?) frames, which is why it is much slower.

Yes, that is the problem. But if that is the price I have to pay for a
right cut …


Thanks for the hints.


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