Investigating: "Unchanged" disposition selects "default"

[webdevpythonicenthusiast]

In the Disposition dropdown, clicking "Unchanged" appears to select "Default" (which is the default selected option). All other disposition options (e.g., "Original," "Remove," etc.) are selectable and function correctly.

I'm trying to understand the intended behavior/functionality of the "Default" disposition. Is there any processing involved that might modify the stream data (even if not full re-encoding)? Or is it possible that "Default" internally uses the same stream handling logic as "Unchanged"? If so, that might explain why selecting "Unchanged" doesn't visually change the selection from "Default" (just what I thought, I'm not a developer).

As a workaround, I'm wondering if the "Original" disposition option can reliably substitute "Unchanged" in cases where the source file does not contain duplicate streams.

OS: Windows 10
App Version: v3.64.0

[mifi]

Hi. Unfortunately I'm not 100% sure how the internals of ffmpeg work, but they have documented some of it here:

https://ffmpeg.org/ffmpeg.html#toc-Main-options (see -disposition).

In LosslessCut the different values mean:

• Remove: sends to ffmpeg -disposition:stream_specifier 0. This means "clear disposition" according to ffmpeg docs. So this means explicitly remove the disposition value
• Unchanged: Special LosslessCut choice that allows you to unset/reset the disposition to its initial value. E.g. if you've selected original from the list, original will be forced as the value for this track (see below), but if you want to unset/clear this, choose "Unchanged".
• All other values (including original and default) are values passed directly to ffmpeg, e.g.:
  • -disposition:stream_specifier default
  • -disposition:stream_specifier original
  • -disposition:stream_specifier ...

Here's what ffmpeg says about default:

If no -disposition options were specified for an output file, ffmpeg will automatically set the ’default’ disposition flag on the first stream of each type, when there are multiple streams of this type in the output file and no stream of that type is already marked as default.

So default is used to set the default track that should be played.

original doesn't seeem to be documented in ffmpeg docs.