[Jack-Devel] Don't ever bother with bridging JACK with ALSA or Pulseaudio.

Chris Caudle chris at chriscaudle.org
Thu Sep 12 19:16:19 CEST 2019

On Thu, September 12, 2019 8:05 am, crocket wrote:
> I've spent months on perfecting the bridge between JACK and ALSA.

I think you have created the most complex monitor controller ever.  This
is that system that has S/PDIF from the motherboard audio to digital input
on a USB connected interface that you described earlier?

--> is a connection that doesn't cross the boundary of a computer.
==> is a connection that occurs between two computers.

Anything that doesn't cross ==> occurs on my desktop computer. Anything
that happens after ==> occurs on Raspberry Pi 3 B+.
netjack1 runs on my desktop computer. Ethernet cable is the only cable
that connects two machines.

1. ALSA dmix --> SPDIF out of Realtek ALC887 onboard soundcard --> SPDIF
In of X-Fi HD USB --(alsa_in or zita-a2j)--> netjack1 ==(ethernet
cable)==> ALSA jack backend --> I2S Amplifier(HiFiBerry Amp2) --> Speakers

2. netjack1 --(alsa_out or zita-j2a)--> headphone jack of X-Fi HD USB on
my desktop computer --> headphones


Is this being used for music production, or just listening to audio files?
PulseAudio can do something similar in a self-contained fashion, at the
expense of higher latency and the occasional dropped sample.  And of
course the old fashioned way to do it would be with an analog monitor
controller or small mixer.  The more modern audio production focused way
would be to use Dante or similar if you really want network connectivity,
or the ability to add and remove devices, have large distance separation,

My recollection is that the questions you posed were somewhat isolated,
and mostly how to accomplish various specific tasks with jackd or alsa. 
It may have been better to start with a more general description of what
you were trying to accomplish and ask about the best way to get to that
result, because I can't imagine anyone recommending that convoluted signal
chain just for listening to audio from your desktop and a separate
computer (RPi in your case) at the same time.  Using an on board audio
interface just to send audio over S/PDIF to a USB interface to drive
headphones seems pretty bizarre, I never could make sense of what you were
trying to accomplish with that rather than just sending audio to the USB
interface to start with.

Chris Caudle

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