[FFmpeg-user] Why are these different?

[Mark Filipak]

Hi Carl,

On 07/02/2024 13.56, Carl Zwanzig wrote:
> On 2/7/2024 10:34 AM, Mark Filipak wrote:
>> Okay. Why are they different?
> 
> Because the containers are different? An mp4 container is not the same as an mkv (or avi or mpeg), 
> they must have different demuxers.

They are the same source, same container. The only difference is command.

ffmpeg -ss 20.061708333 -copyts -i %SOURCE% -map 0 -c copy -sn -dn -muxdelay 0 %TARGET%
ffmpeg -copyts -i %SOURCE% -map 0 -ss 20.061708333 -c copy -sn -dn -muxdelay 0 %TARGET%

Why do the results differ? They're not a little different. They're very different. The DTSs differ. 
The PTSs differ. The cutting points differ by a couple hundred frames. Even some of the packet 
lengths differ! This is serious.

I can't tell if the GOPs differ -- DTS-sorted v PTS-sorted -- because it's impossible to correlate 
'framecrc' results and 'showinfo' results.

--Mark.