[FFmpeg-user] the trim filter

[Mark Filipak]

Paul, if I find a way to change only the audio frame's PTSes, what would I change them to?
Don't I want to simply drop them, instead?
_But_ if I use -noise=drop, I'll drop the video packets, too, and the video decoder will malfunction 
because of the broken IDR frame.

This is not a simple problem, eh?

--Mark.

On 04/07/2024 16.25, Mark Filipak wrote:
> On 04/07/2024 14.22, Paul B Mahol wrote:
>> On Thu, Jul 4, 2024 at 8:05 PM Mark Filipak <markfilipak.imdb at gmail.com>
>> wrote:
>>
>>> Is there some secret to the trim filter?
>>>
>>> --filter_complex "split=2[i5][i6],
>>>    [i5]trim=start_frame=481:end_frame=134047[o5],
>>>    [i6]trim=start_frame=138745:end_frame=246719[o6],
>>>    [o5][o6]concat=n=2"
>>>
>>> I get "dup=481", instead, and wind up with 20.061708[3..] seconds of black
>>> frames preceding the
>>> segment I want, and the frame rate is 19.181 FPS.
>>>
>>>
>> You need to rewrite audio timestamps, otherwise you get 'empty' gaps.
> 
> Have you found an atrim expression that works?
> 
> I tried adding atrim=start=20.062. Now playback goes for 20.061708[3..] sec of black frames, then 
> freezes for another 20.061708[3..] sec, then continues as though nothing strange had happened.
> 
> Actually changing the audio frame's PTSes is going to be harder than hard.
> 
> --Mark.
> 
>