[FFmpeg-user] Why are these different?

[Paul B Mahol]

On Wed, Feb 7, 2024 at 2:43 AM Mark Filipak <markfilipak.imdb at gmail.com>
wrote:

> Why are these different?
>
> Looking only at the first 5 video frames:
>
> ffmpeg -ss 20.061708333 -copyts -i %SOURCE% -map 0 -c copy -sn -dn
> -muxdelay 0 %TARGET%
> produces this:
> 0,    2846606,    2854113,     3753,   640646, 0x3a5a0c45
> 0,    2850360,    2850360,     3753,   640646, 0xfed1d09a <== error
> 0,    2854113,    2861621,     3753,   640646, 0x02208727
>
> 0,    2857867,    2857867,     3753,   640646, 0x108abb16
> 0,    2861621,    2869128,     3753,   640646, 0xfd51ca41
>
> ffmpeg -copyts -i %SOURCE% -map 0 -ss 20.061708333 -c copy -sn -dn
> -muxdelay 0 %TARGET%
> produces this:
> 0,      50062,      61323,     3753,   640646, 0x12a26bc2
> 0,      53816,      53816,     3753,   415846, 0xb16fcb71 <== error
> 0,      57569,      57569,     3753,   123879, 0xf2721eb8 <== error
> 0,      61323,      68831,     3753,   126929, 0xe73f80e5
> 0,      65077,      65077,     3753,   124619, 0x20a2a8d5
>
> They have the same '-copyts'. They should have the same DTSs & PTSs. They
> don't.
> They have the same '-muxdelay 0'. They should both have no delay. The 2nd
> has delay.
> The packet with CRC=0x3a5a0c45 is packet 0 in the first and packet 264 in
> the second.
>
> 'showinfo' shows only frames and uses bogus PTSs. 'framecrc' shows only
> packets, not frames. So it
> doesn't seem possible to correlate their information.
>
>
This is all about seeking, and that depends 100000% on internal demuxer
implementation of container.


> --Mark.
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