[LAU] Can netjack1/2 over a direct ethernet connection substitute for local ALSA audio?
len at ovenwerks.net
Thu Mar 28 08:06:15 CET 2019
On 2019-03-27 22:35, crocket wrote:
> I have a desktop computer and Raspberry Pi 3 B+.
> I want Raspberry Pi to control my speakers and share my speakers with
> my desktop over a direct ethernet connection.
Netjack can do that yes. Or zita-njbridge.
> USB microphone is going to be connected to Raspberry Pi and be shared
> with the desktop computer over the ethernet connection, too.
Jack can not use two devices. speakers (via some kind of on board audio
device I assume) and the usb mic will not be in sync and so clicks and
pops would be assured. Some kind of sample rate conversion would be
needed. zita-ajbridge or alsa-in would work for that.
> Can netjack1/2 over a direct ethernet connection substitute for local
> ALSA audio?
No, not really. Many applications can talk to jack directly but many do
not... but then there are more and more that do not talk to alsa either.
Most linux desktop audio is not alsa (surprise) but pulse. Bridging
pulse to jack will allow desktop audio to feed jack directly. Pulse does
present an alsa port for things that do not know about pulse.
> Will video and audio synchronize if netjack was used over a direct
> ethernet connection?
No, but that is not a given with almost anything anyway. Your TV may
have video and audio in sync, but that sync will change just by moving
your chair closer or farther away. Audio can lag video by quite a lot
without being noticeable. Leading, not so much. Some video players (like
VLC) have a control to move the timing of the audio with respect to the
video. in this case, just changing the buffer size in jack will add more
delay. I think what you really want to know is if there will be a
noticeable difference between when the person on screen moves their lips
and their voice happens
However, without knowing what your expectations are and what your use
is, it is hard to know what to suggest. Pulse also has a plugin that
allows audio over ethernet and that may be all you need and simpler to
install. A usb mic is not a serious recording device though maybe ok for
podcast types of things. I won't say you can't use it for music as great
recordings have been made with sm57 mics after using them as hammers
too... but live recordings are more about being there than quality
sound. crowd noise etc. covers a lot.
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