[linux-audio-user] hardware mixing - what it _actually_ is?

[Mark Knecht]

On 1/22/07, Lee Revell <rlrevell at joe-job.com> wrote:
> On 1/22/07, Mark Knecht <markknecht at gmail.com> wrote:
> > On 1/22/07, Lee Revell <rlrevell at joe-job.com> wrote:
> > <SNIP>
> > >
> > > Basically nothing supports hardware mixing these days except the
> > > emu10k1 devices and some VIA onboard chipsets, because the hardware is
> > > designed around Windows which does software mixing in the kernel.
> > >
> >
> > RME HDSP series?
>
> I don't have the hardware to check, but judging from the driver code
> this device does not support hardware mixing - the call to
> snd_pcm_new() in snd_hdsp_create_pcm() from hdsp.c specifies 1
> playback and 1 capture substream.
>
> Lee
>

The device does support hardware mixing. I can take inputs coming into
the card and mix them directly with outputs coming from Alsa to create
an output stream going to my monitors in real time with no latency
with or without sending the inputs to Alsa for other uses.

The magic is created by the hdspmixer application written with love
and care by Thomas Charbonnel and initially debugged by Thomas &
myself back in 2004 I think. (Maybe 2003)

Hardware mixing  works identically (well, very closely) for Win XP and Linux.

Note that the big difference between the Hammerfall and HDSP lines was
the addition of hardware mixing.

Hope this clarifies things a bit.

- Mark