Re: [gfvs] cdda backend

[Bastien Nocera <hadess hadess net>]

On Mon, 2007-12-17 at 10:56 -0500, David Zeuthen wrote:
> On Mon, 2007-12-17 at 10:42 +0000, Bastien Nocera wrote:
> > > It seems the main objections to that new cdda module for gnome-vfs were
> > > 
> > >  - would pull gstreamer into the client apps 
> > 
> > Which client app would want to deal with audio CD data without pulling
> > in some sort of multimedia framework?
> 
> The problem, AFAIK, was that *any* application linking in
> libgnome-vfs.so would pull in gstreamer. I understood from Alex's second
> reply that was the main problem.

That's rubbish. Either the build system was seriously broken, or I
didn't quite understand the concept of plugins...

<snip>
> > > However, that ignores several fundamental problems
> > > 
> > >  - libcdio / libparanoia isn't the API application programmers
> > >    should use (however, gio is)
> > 
> > GStreamer is, to deal with sound data.
> 
> Sure, and I agree we should all be using GStreamer and all the apps we
> all use should be using it. But a number apps still don't and there are
> multiple competing frameworks etc.

Then they're probably using another way of accessing the data, probably
through plugins for that particular framework, certainly not using gvfs.

>  Then again, a lot of us (and our
> technical users) run command line tools and it's just damn handy to have
> the PCM data available in ~/.gvfs.

Most tools you'd want to use also take in stdin.

> > How will you export the (very as-hoc) errors from the underlying
> > libraries? 
> 
> We could return G_IO_ERROR_SCRATCHED and have the app do the moral
> equivalent of an ioctl() on the GFile to set the retries. But I think
> that's crazy and I'm not sure apps want to deal with error handling
> _anyway_ so hiding it in the backend is fine (other fs drives don't do
> this). 
> 
> I think instead the backend just skips over the scratched area and puts
> up a libnotify notification (or other out-of-band signal) to notify the
> user it's skipping over the scratched area (that's how DVD Player in Mac
> OS X 10.5 does it)

That's not a bad idea for playback, but certainly not of any use for
ripping.

> > How do you export the MusicBrainz Disc ID, or FreeDB one?
> 
> As metadata in the WAV container (see the patch for details; search for
> "Jailhouse"; it's fine, we can choose another container for the PCM data
> if you want (AIFF?)

How will you get the metadata? You'll need to use musicbrainz, or
similar, data which won't carry over to changes in applications.

> > I think that's a bad idea. And it eats the cdda:/ MRL space for
> > GStreamer.
> 
> I'm not sure these namespaces are similar anyway.

We'll need to blacklist cdda:/ from the gvfs GStreamer plugin to get it
handled by the proper CDDA plugin from GStreamer, so they do overlap.