Audio Issues with DAC

Hey everyone, much love from Italy!
I am creating a headunit for my BMW E30. I need to get RCA output from the RPI (5) and i settled for the Hifiberry DAC+ ADC.
I set the correct DT overlays and everything, and i have audio output working on the RCAs.
The problem is that the audio quality on react-carplay is very bad. There is pretty much no bass, and i think its trying to output in stereo, while the physical output is actually mono of course.
Can i fix this somehow?

Also i modified the app by adding a dismissable splash screen so that instead of the interface and the loading icon i see the BMW logo, and i can hide it with ESC.
The problem is that with my custom app i have no audio output at all, while if using an image from github it works (badly, but it works)…

Oh and well, i have no audio input at all, not even using ALSA recording, so i feel like i am doing something wrong there, or the mic itself is not compatible with the ADC input of the board.

Thanks everyone!
Man.

Hi,

Would be great to see it in a retro like an e30!

There’s a few things to unpick from your post

  • Audio Quality - This is the first I have heard of this, so I suspect it may be more to do with your set up than the app itself. Do you have any kind of audio processing from the pi’s output? Usually when running it through aux to a headunit (or the built in amplifier) there is some kind of audio equaliser that may bring it to life a bit more. Are your RCAs feeding an amplifier direct? One thing to bare in mind is the voltage levels of the RCA output, I imagine they are quite low, it’s been a long time since I have meddled in after market audio, but from what I remember most car amps require quite a high driving voltage on the RCAs.
  • For the audio going when you have added your splash screen, have you tried compiling the app? If I remember correct some of the hosted paths are broken for audio when running it in dev mode
  • Mic - does a mic appear in the drop down in react-carplay? I am guessing if ALSA is not working then likely the board is not set up correctly, do you have a link to the exact HAT you are using? I am struggling to find one that has audio input aswell as RCA out

Oh great, the creator himself!
Well yeah, it’s kind of a big project since i am building everything custom, it’s gonna be a weird form factor too, pretty much a 1.5 DINs screen, so that it fits and fills completely the space in the dash.
Also i am going to build an HiFi system to hook up to the rasp and probably some security features in the future…

Any way, today i just read that the Hifiberry DAC+ ADC (analog-digital converter - aka analog input) does not support Bias power, and my MIC needs it, so i am out of luck. I just bought another mic from amazon, with a simple USB, so i dont have to deal with these problems ahaha.

The audio output problems seem to be linked to the audio channels…
I have only ALSA installed, and i dont want to use PulseAudio or other systems, pretty much because i dont need them. I tried switching to a mono RCA/aux converter (so single RCA pole to aux) and it seems to have great quality on my headphones (but its mono ofc). The problem was probably related to the app not knowing how to deal with channels… maybe because it sees more than 2 and separates the audio output for the different audio drivers.
Will have to test that with the actual car amp and speakers when they come in.

Yes, i compiled the app for armLinux, and i dont really know why the audio does not work in my version.
Right now i am testing the 4.0.3 beta1 to get the buttons working, and it seems to be stable and nice, but i will have to port my modifications from the other version…

Since you are already here, i would love to get some more info about the app settings, like Phone Work Mode, Format, and Ibox Version… i could not find any docs about and i dont really know how to set them up.
Also, i am using the Carlinkit CCPA, and if you happen to know the best settings to get smooth video/audio that would help me a lot, because right now it runs @ 60fps but it seems a bit delayed, which is not really the best experience yk

Thanks a lot,
Man.