[FFmpeg-user] Towards better trims & concatenations

[Jim DeLaHunt]

On 2024-01-07 18:54, Mark Filipak wrote:
> On 1/7/24 20:24, Jim DeLaHunt wrote:
>>>> Also, what does "h:\BDMV\STREAM\00305.m2ts" refer to?
>>>
>>> That's the mother video from which the clone and sons are made.
>>>
>>>> Is that a standard video which I can get a copy of somewhere?
>>>
>>> Nope.
>>>
>> That presents an obstacle...
>
> The 'mother' is an M2TS. I'll try trimming it '-to 34.076' while 
> leaving the beginning intact. The problem is that ffmpeg changes the 
> DTSs and PTSs of the copy.
> …How can I trim 00305.m2ts '-to 34.076' without altering the TSs and 
> other things?

How about a different approach: look for reference videos which also 
demonstrate the problems you see with your videos, and which others can 
also retrieve or construct.

For instance, this command:

 > ffmpeg  -f lavfi -i "testsrc" -to 1:00 testpat.m2ts

generates a 60-second video with a test pattern. Anyone with recent 
FFmpeg can generate a video like this, though perhaps not identical. If 
you use this as your "mother" video, and apply your test method to it, 
does ffmpeg demonstrate the same bugs? If yes, then you can include 
instructions to generate that video in your bug reports.

Best regards,
     —Jim DeLaHunt