[FFmpeg-user] Why are these different?

Mark Filipak markfilipak.imdb at gmail.com
Mon Feb 12 00:08:09 EET 2024

On 11/02/2024 16.42, Paul B Mahol wrote:
> Codec copy with -ss before -i and after -i is not documented that it gives
> different results

Does that make sense? I think it's not documented because no one knows how to explain the results.

> because once you do not decode everything from start you basically can not
> expect to get
> always (for any container and for any input) frame-accurate results in both
> cases.

I don't think decoding is being done. The cutting/trimming can be by dropping packets & remuxing. 
The packets have to be 'opened' to read the PTSs, but I don't think there's actual decoding.

'-ss'-before-'-i' is cutting at the right point.
'-i'-before-'-ss' is cutting at the wrong point.

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