Len,
Thanks for the feedback.
On Wed, Feb 17, 2021 at 10:30 AM Len Ovens <len@xxxxxxxxxxxxx> wrote:
On Wed, 17 Feb 2021, drew Roberts wrote:
> I am not 100% sure I understand it all correctly, but here is what I am
> working on in my effort to help:
>
> "I have program Audio that will be coming in as AES to the input of the
> Audio Science card (ASI6644)"
AES3 I presume. So stereo program.
I guess. I have never played in that field.
> This comes into the machine with the ASI card and gets sent back out to a
> speaker as analog audio. It is intended to play without stopping.
OK
> At 10 minutes past every hour, it should be faded down and specific files
> played out to the same speaker.
The ASI6644 Has Linux alsa drivers, why not use amixer to change the level
of the program audio going into the card (and out if needed).
Ignorant question: How would you script that? How do you detect when the file playback ends and turn the regular volume back up?
> I initially thought of liquidsoap. I get so far and then my skills fail me.
> It seems it should be easy but it is stumping me. I have one more thought to
> perhaps annotate things somehow or whatever.
Unless you actually need a streaming capability to extend across a network
(you say aes3 in and audio out so no)
I see no mention of the need to stream. Or perhaps he knows how to do that part "outside" of this.
> So, I now have a jack graph.
Basically you are using jackd to mix the two signals then which is ok. I
am not sure what other options are available and jack is probably easiest
to do. I am not that familiar with the ASI6644 (or any audio science card)
as they are out of my price range :) but I think it may be possible to mix
two sets of playback channels in the card itself as it seems to have a
matrix mixer on the card. This would eliminate the use of jack all
together. I do not know if the ALSA driver has all the control showing in
ALSA or if a more direct control is needed. The card does have an API to
allow custom control applications to be set up.
You also mentioned something about a R-pi... My first question for that
would be, does the R-pi have a PCIe slot?
He has the nice card, I have the R-pi... ~;-)
I know that some SOC cards do
but my old R-pi 2 most certainly does not :) However, if you are testing
on a R-pi then I would assume you have a USB device...
I do have an inexpensive ub, no capture controls, 1 playback (PCM).
many of these do
not have mixer controls available to ALSA, using real knobs instead. The
very cheap USB dongles with mic in and headphone out do have ALSA mixer
controls and might be better for testing.
I still have the feeling that someone who knows what they are doing in liquidsoap could to it all there very easily.
I have asked something in #savonet on irc. No response yet.
I am learning a lot in this process that may be useful later so I am happy enough to experiment...
--
Len Ovens
www.ovenwerks.net
all the best,
drew
Enjoy the Paradise Island Cam playing
Bahamian Or Nuttin - https://www.paradiseislandcam.com/
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