[FFmpeg-user] Image2 demuxer on Synology

[Moritz Barsnick]

On Fri, Jan 04, 2019 at 11:31:43 +0000, Stuart Bruce wrote:
> The Synology is about 18 months old and completely 'vanilla', with no
> maintenance or updates, and it's still running the 2015-era version of
> FFmpeg that was preinstalled on it.

I found this thread:
https://github.com/SynoCommunity/spksrc/issues/3000
which indicates there exists a special repository for Synology
packages. It provides this:
https://github.com/chanfried/spksrc/releases/tag/ffmpeg-3.4
which is at least a bit newer. The point is: Perhaps its build didn't
disable your required stuff. (I can't find the package's build options
to check.)

> - On a Synology system, what do I need to do to get the image2 muxer
> enabled? Can I change the config of the existing set-up, or do I need to do
> a re-install or update of the FFmpeg build?

You cannot change the existing setup. The availability of features is
within the ffmpeg binary (or rather binary plus ffmpeg libav* libraries).

> - If I need to reinstall or update, I'm not familiar with Synology systems-
> is there such a thing as a simple guide for FFmpeg installations on
> Synology? Google didn't show me any.

You may to able to add the quoted repository, or somehow manually
install the provided spk file. (New search terms for Google. ;-))

OTOH, I just noticed that your Synology is an x64_64 system? Just grab
a binary from here:
https://johnvansickle.com/ffmpeg/
(left column, git builds, preferred).

Otherwise, you need to compile ffmpeg for your Synology. Whether you
can compile natively (i.e. on the machine), or you need to
cross-compile, I do not know. (Too lazy to google.) And you may also
need to provide (cross-) compilations of other dependant stuff, if
external libraries are required for your particular features.

> - With the image2 demuxer disabled, is there a method for getting the
> preinstalled version of FFmpeg to export a JPEG file anyway?

We would need to see the output of
$ ffmpeg -encoders
$ ffmpeg -muxers

With the existing options of your ffmpeg binary, you *may* be able to
create a JPEG file with the mjpeg muxer and the mjpeg2jpeg bitstream
filter:

$ ffmpeg -i input -frames:v 1 -bsf mjpeg2jpeg -f mjpeg output.jpg

(I did test this, but not sure whether the result is a proper JPEG
file, or rather an MJPEG stream with a single frame.)

No chance for a PNG though, as far I can tell.

HTH,
cheers,
Moritz