[pulseaudio-discuss] ask about passthrough support

[Arun Raghavan]

On Thu, 2011-09-15 at 14:03 +0800, Lu Guanqun wrote:
> On Thu, Sep 15, 2011 at 01:58:41PM +0800, Arun Raghavan wrote:
> > On Thu, 2011-09-15 at 11:22 +0800, Lu Guanqun wrote:
> > > On Thu, Sep 08, 2011 at 02:19:41AM +0800, Arun Raghavan wrote:
> > > > On Wed, 2011-09-07 at 11:09 -0700, Arun Raghavan wrote:
> > > > > On Wed, 2011-09-07 at 14:20 +0800, Lu Guanqun wrote:
> > > > > > Hi Arun,
> > > > > > 
> > > > > > I have several things unclear about passthrough support:
> > > > > 
> > > > > I'm talking about this work at Linux Plumbers' Conference on Friday. If
> > > > > videos are available, I'll link to them -- hopefully that should make
> > > > > the motivation clear.
> > > > 
> > > > Oh, phew, no video -- I'm still happy to answer any questions you
> > > > have. :)
> > > 
> > > Hi Arun,
> > > 
> > > I've a dumb question... On my laptop, when I use pacat --passthrough
> > > <some-wav-file>, does it mean the passthrough mode is used? Though it's
> > > not the usual case as hardware decoding is not used.
> > 
> > Yes -- all the logic that works with passthrough streams goes via
> > pa_sink_input_is_passthrough(), which you will see checks if the stream
> > has non-PCM data OR has the PASSTHROUGH flag set (which is what
> > --passthrough does).
> 
> That's cool, thanks for the info. If this ALSA device can hard decode,
> then in this scenario, it can play, let's say, MP3 file on the fly. :)

Yes, if it's payloaded in IEC61937 format.

-- Arun