Re: [Rhythmbox-devel] Bypass software mixer?

[Jonathan Matthew <notverysmart gmail com>]

On Sat, Jun 21, 2008 at 07:24:14AM -0700, Grant wrote:
> >> Can I bypass the software mixer to leave the audio untouched until it
> >> hits the DAC?
> >
> > If you disable crossfading in rhythmbox,
> 
> Will that disable gapless playback?

Yes.  The gapless/crossfading player backend converts everything to
44100Hz 16bit stereo, regardless of input or output format capabilities.
If the streams you're playing are already in that format, and your
output device supports that format, then no conversion will be done.  At
least, rhythmbox and gstreamer won't do any conversion.  I can't speak
for ALSA here.

> > set the rhythmbox volume control to full volume,
> 
> Sounds like faith-based mixer bypassing. :)  Any way to prevent the
> volume slider from affecting the volume at all?  My ALSA silders don't
> affect the volume with my USB DAC.

Not at all.  If the volume control is at full volume, the corresponding
GStreamer element goes into passthrough mode.

> > data written to ALSA will be about as untouched as you're going to get.
> 
> For me there's a big difference between untouched and "as untouched as
> you're going to get".  Is there no clear way to get the sound through
> the system without molesting it when using rhythmbox?

I said "as untouched as you're going to get" because I'm not going to
offer you any guarantees.  If it turns out there is still some format
conversion, resampling, scaling, or whatever going on, then you'll have
some serious work to do to fix it.

> > Other than that, it's not particularly clear what you mean by 'the
> > software mixer'.  The term 'mixer' means a number of different things,
> > and just about everything in the picture is 'software'.
> 
> I want the exact same digital information in the decoded FLAC file to
> hit the DAC.  High-quality computer audio is really coming of age and
> I think this type of thing will be requested more and more.

What type of thing?  A placebo "[ ] disable software mixer" setting?  It
sounds like that's all it would take to satisfy you.