I'll try to answer some.
This is a bunch of follow-up questions I feel both users and
occasionally builders want easy clarified without to much research or
experiments. I neither say these cannot be partly answered in nor
derived from the manual documentation. Additional questions may appear ;)
Q1
What capabilites/features does the pre-build Cingg AppImage and/vs the
package build (ex. RPM) have?
especially with regards to ffmeg, multimedia codecs, encoders etc.
Q2
Is the AppImage static linked and RPM dynamic linked or combined
dynamic/staticvwith regards to libs?
Appimage uses mix of statically-added thirdparty libs embedded in "cin" binary and system's dynamic libs put into self-extracting squashfs archive. RPM depends on those dynamic libs from system to be present and compatible between build system and system rpm ran on.
Q3
Does the AppImage use the thirdparty ffmpeg and the RPM the local system
ffmpeg?
or are both static builds with third party ffmpeg
I think both uses statically-linked thirdparty ffmpeg. (our default due to patching)
Q4
Where is possibly the ffmpeg binary for the extracted AppImage and
installed RPM?
for own build ffmpeg binary is found in
cinelerra-5.1/thirdparty/ffmpeg-8.0/ffmpeg
it is not packaged/installed.
Q5
Who make and maintain the thirdparty ffmpeg and what extra codecs are added?
At this moment it seems that I try to maintain it. I mostly added giant array of pixelformats to yuv4mpeg so cin can show that in GUI. Other patches carrying from earlier versions, dealing with seeking, mpegts muxing for BluRay disks, some gopro-specific cases for hw acceleration and may be something else
Q6
What are the configure scripts for the AppImage vs RPM?
Q7
What extra capabilites/features may be achieved and justified with own
custom build?
what config elements?
I for example link with system's libdav1d instead of built-in older version.
For both cinelerra-gg and ffmpeg you can ran ./configure --help and see various supported switches. A lot of them, and for ffmpeg they vary per release.
Q8
How often is it needed or suggested to download (or update if possible)
the source repo via git clone?
I use either web interface or "git pull -r / git log" to see if anything new arrived into repo. Or just look for emails from Phyllis to list describing newly-added changes ;)
I think we still aim at "end of the month" release, so I guess you can update monthly, but obviously testing new patches may happen earlier.