[FFmpeg-user] the trim filter

Mark Filipak markfilipak.imdb at gmail.com
Fri Jul 5 00:08:47 EEST 2024


I meant the "broken non-IDR frame".

On 04/07/2024 17.04, Mark Filipak wrote:
> 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.
>>
>>
> 
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