[FFmpeg-user] Why are these different?

[Paul B Mahol]

On Sun, Feb 11, 2024 at 8:54 PM Vincent Deconinck <vdeconinck at gmail.com>
wrote:

> Hi,
>
> I will probably get flamed because I'm for jumping into this conversation
> while being a complete newbie :-), but I think nobody replied with an
> answer to Mark's question "why".
>
> All I know is the ffmpeg page on seeking -
> https://trac.ffmpeg.org/wiki/Seeking - ends with a paragraph saying:
> "Using -ss as input/output option *together with -c:v copy might not be
> accurate* since ffmpeg is forced to only use/split on i-frames" (emphasis
> mine)
> The page also states that:
> "As of FFmpeg 2.1, when transcoding with ffmpeg (*i.e. not stream
> copying*),
> -ss is now also "frame-accurate" even when used as an input option"
> My understanding is thus that with input seeking, the requested start time
> will not be satisfied without transcoding; while with output seeking, the
> requested start time will always be guaranteed correct, even with -c copy.
>
>
Yes, but "frame-accurate" (and if no bugs exist) is very slow when seeking
away from start of video.

But I might be wrong ;-)
>
> Peace.
>
> Vincent
>
> On Sun, Feb 11, 2024 at 8:29 PM Paul B Mahol <onemda at gmail.com> wrote:
>
> > On Sun, Feb 11, 2024 at 7:12 PM Mark Filipak <markfilipak.imdb at gmail.com
> >
> > wrote:
> >
> > > On 11/02/2024 13.09, Bouke / Videotoolshed wrote:
> > > > So do you, so why ask the question?
> > > > Now go away!
> > >
> > > I do not know the answer.
> > >
> >
> > In most cases you will get in most times different results for those 2
> > variants.
> >
> > Only for perfect containers and perfect implementations it will give same
> > result in every case.
> > For last one I do not have any example ffmpeg command to show you. (And
> I'm
> > not sure if it even exist)
> >
> >
> > >
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