[Jack-Devel] How does --hwmix work?

[Ralf Mardorf]

On Tue, 02 May 2017 21:59:48 +0200, David Kastrup wrote:
>I have an RME Hammerfall DSP, a card that I believe supports --hwmix on
>jackd.  How does this work?  Does this require special support by the
>application?  If so, which applications exist using it via Jack?

Hi,

I don't know what this option should do [1], maybe you are confusing
it with hwmon. IIUC HWMIX is a feature to use a sound card without a
sound server, but since jack is a sound server, this option might be
irrelevant. I might be mistaken ;).

However, if you want a hardware mixer, you don't need a jack option,
instead try running   hdspmixer   . I suspect hdspmixer doesn't work
with all RME cards.

Regards,
Ralf

[1]
[rocketmouse at archlinux ~]$ man jackd | grep hwmix -A3
[rocketmouse at archlinux ~]$ man jackd | grep hwmon -A3
       -H, --hwmon
              Enable hardware monitoring of capture ports.  This is a
method for obtaining "zero latency" mon‐ itoring  of  audio  input.
It requires support in hardware and from the underlying ALSA device
driver. --
              (M-Audio  Delta  series,  Terratec,  and  others) support
--hwmon.  In the future, some consumer cards may also be supported by
modifying their mixer settings.

              Without --hwmon, port monitoring requires JACK to read
              audio into system memory,  then  copy  it back  out  to
              the  hardware  again,  imposing  the  basic JACK system
              latency determined by the --period and --nperiods
              parameters.

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