Hello all!
I have had success!I installed this on my Pi 3.Once I opened amixer from the console, and selected device 0 from the F menu, then I selected line in, and unmuted it. BOOM! it works! (and very well!)
Nice ! Great project idea, putting a speaker inside a guitar to
enhance the sound in different ways. What a concept!
-- So. here is my Question.
Is it possible to have the audio enabled earlier? Before I installed the Zero audio injector, a USB sound card starts working around 1/2 way through the boot. Same result with the on board sound. Using this Zero Audio Injector, it isn't active until around 3 seconds after the Os is fully loaded (console login).
Load comparison 1: 15~20 secondsA USB sound card would turn on and MODEP would be processing effects 1/2 way through the boot. The boot would continue for the next 15~20 seconds. This makes the project appear to be fully booted at 15 seconds. Being headless the only indication that the system is working, is that you can hear the effects ;-). Clearly MODEP is running at 15 seconds and just needs the sound card to respond to function.
When you look at dmesg output, what is the kernel time point at
which the audio driver reports itself loading ?
Load comparison 2: 30~35 secondsWith Zero Audio Injector installed, it doesn't process audio until a few seconds after the login is reached. I imagine this is because the ALSA mixer settings are applied at that point? that's my guess.
When you look at dmesg output, what is the kernel time point at
which the audio driver reports itself loading ? There will
probably be a few steps here ... I would imagine that first the
audio injector overlay must load, which triggers the audio drivers
to load (eventually). Part of loading the audio drivers is to load
the codec driver.
There must be a few different checkpoints to loading and starting the audio subsystem. First overlay loading, then driver loading. Alsamixer setup. Finally user space application startup.
Typically with USB audio, there is no codec driver to be loaded, just the USB UAC driver.
For Rasbian, which is based on Debian, you may want to add to your research pages relating to Debian, like this one :
https://wiki.debian.org/BootProcessSpeedup
Now that I have asked my question :-) some of you might ask.. why? who cares? lol.
Here is my story:
My build: Pi 3+ running Patchbox OS (raspian) with the module loaded "MODEP" effects emulator.I am placing the pi inside an acoutistc guitar with 2 contact / vibration speakers installed in the body. (this makes any effects sound like they are coming from the actual guitar. sounds really weird and cool. its my cheap DIY version of that "ToneWood amp" that just came out. Don't tell my wife I have spent as much as the real thing. DIY sometimes costs more initially as you get tools and test parts!!! LOL.
Parts used:Pi 3+ (mounted on battery pack internally)Zero Audio Injector.5 watt stereo amp (super small PCB)
AA battery pack (body mounted)2 x voltage regulators. (5.5v for the Pi, 7v for the amp)2 x contact / vibration speaker (glued inside the body)Clip on sound hole magnetic pickup2 potentiometers, one for output volume, one for balance.VU / Batt level indictor (cheap ebay DIY VU that can be used for batt level instead)Momentary button, (I want to wire this as a "sudo shutdown now" button.)
Software:Patchbox OS (raspian flavor made for audio processing)Module: MODEP (drag and drop pedals / effects via any http browser.)
(P.S, what I would kill for, is making the OS, or part of the OS "read only", so just turning it off without a shutdown won't corrupt the SD. I have seen this done on a few similar projects, but I don't know what parts of this particular project "need" writable access.)
Thank you for reading this!Let me know any tips or advice you have.
~Chris
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