bug#43418: ffprobe/avprobe and ffmpeg/avconv should be added as dependencies of youtube-dl so it will function correctly

[Nathan Dehnel <ncdehnel@gmail.com>]

Ludovic wanted to add useflags to guix.
https://lists.gnu.org/archive/html/guix-devel/2019-05/msg00285.html
I don't know what became of it.

On Tue, Sep 15, 2020 at 2:44 PM raingloom <raingloom@riseup.net> wrote:
>
> On Tue, 15 Sep 2020 14:06:11 +0200
> Tobias Geerinckx-Rice via Bug reports for GNU Guix <bug-guix@gnu.org>
> wrote:
>
> > Hi Nathan,
> >
> > Nathan Dehnel 写道：
> > > bash-5.0$ youtube-dl -x
> > > https://www.youtube.com/watch?v=7Ijd_iN9Blk
> > > [youtube] 7Ijd_iN9Blk: Downloading webpage
> > > [download] Deadmau5 - Hit Save-7Ijd_iN9Blk.webm has already been
> > > downloaded
> > > [download] 100% of 15.45MiB
> > > ERROR: ffprobe/avprobe and ffmpeg/avconv not found. Please
> > > install one.
> >
> > It works fine without ‘-x’:
> >
> >   λ youtube-dl https://www.youtube.com/watch?v=7Ijd_iN9Blk
> >   [youtube] 7Ijd_iN9Blk: Downloading webpage
> >   [download] Destination: Deadmau5 - Hit Save-7Ijd_iN9Blk.mp4
> >   [download] 100% of 37.09MiB in 00:02
> >
> > This *is* functioning correctly in my view: that advanced options
> > optionally require run-time dependencies is not a bug but a
> > feature.  The programme clearly explains which package could be
> > installed to continue, and the user can chose which one they
> > prefer - including neither, which suffices for the majority of
> > youtube-dling.
> >
> > Matters would be different if the error message were less clear,
> > or perhaps if ffmpeg weren't so insanely great:
> >
> >   λ guix size youtube-dl | tail -n1
> >   total: 186.9 MiB
> >   λ guix size youtube-dl ffmpeg | tail -n1
> >   total: 811.2 MiB
> >
> > (!)
> >
> > Kind regards,
> >
> > T G-R
>
> Maybe it's time we added an "optional dependencies" field?
> There seems to be a bug report or help request like every week that
> just boils down to "this package has an undocumented dependency".