Steven Hartland (12022-07-02):
> I'm using concat to join multiple files from a GoPro camera including the
> three metadata streams, with the early return it fails as the metadata
> stream information is missing so map fails.

> I believe the reason for the failure is that this early return prevents the
> metadata from being preserved.

You are trying to trick concat into merging files with different streams
and match streams between them. It is not how concat is designed to
work, it might work in your particular test case but will not work in
more complex cases and will break other use cases.

For example, with your change, if you concatenate a file with metadata
"start_time=12:00" and another with "start_time=12:01", it will generate
a file with both metadata entries instead of just the first one as would
be desirable.

Implementing your feature is not completely trivial: look how it is done
for subtitles streams in DVD structures. The concat stream defines all
the streams it expects to find in the file and specifies a condition to
match them, "exact_stream_id".

> On Sun, 19 Jun 2022 at 21:18, Marton Balint <cus@passwd.hu> wrote:

Please remember that top-posting is forbidden on this mailing-list. If
you do not know what it mean, look it up.

Regards,

-- 
  Nicolas George