2-in, 8-out DSP platform using the Raspberry Pi + HATs

[katariat]

Thanks @CharlieLaub.

This might be another naïve/ dumb question

the HAT (Suptronix 7.1 channel board) fits the RK3328 board like the pi. I know the HAT also has its own 5v power input and if I power the audio extractor HAT, the pi gets powered by it

in the case of the HAT + RK3288 board combo....if i power the RK3288 board, then i am guessing it will be able to power the audio extractor HAT...just wanted to confirm

Thanks

[katariat]

Hi All,

been trying to tinker and hopefully i think i have made some progress. On my RK3288 SBC running Armbian Ubuntu desktop with the subtronics HAT (X6000) - ran the following

tdk@rock64:~$ aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: rockchiprk3328 [rockchip,rk3328], device 0: ff000000.i2s-i2s-hifi i2s-hifi-0 [ff000000.i2s-i2s-hifi i2s-hifi-0]
Subdevices: 1/1
Subdevice #0: subdevice #0
card 0: rockchiprk3328 [rockchip,rk3328], device 1: ff010000.i2s-rk3328-hifi ff410000.codec-1 [ff010000.i2s-rk3328-hifi ff410000.codec-1]
Subdevices: 1/1
Subdevice #0: subdevice #0
card 0: rockchiprk3328 [rockchip,rk3328], device 2: ff030000.spdif-dit-hifi dit-hifi-2 [ff030000.spdif-dit-hifi dit-hifi-2]
Subdevices: 1/1
Subdevice #0: subdevice #0

I guessed that hw0,0 might be the HDMI and when i run the dump params i get the following

tdk@rock64:~$ aplay -D hw:0,0 --dump-hw-params /dev/zero
Playing raw data '/dev/zero' : Unsigned 8 bit, Rate 8000 Hz, Mono
HW Params of device "hw:0,0":
--------------------
ACCESS: MMAP_INTERLEAVED RW_INTERLEAVED
FORMAT: S16_LE S24_LE S32_LE
SUBFORMAT: STD
SAMPLE_BITS: [16 32]
FRAME_BITS: [32 256]
CHANNELS: [2 8]
RATE: [32000 192000]
PERIOD_TIME: (41 2048000]
PERIOD_SIZE: [8 65536]
PERIOD_BYTES: [256 1900800]
PERIODS: [2 16384]
BUFFER_TIME: (83 4096000]
BUFFER_SIZE: [16 131072]
BUFFER_BYTES: [256 524288]
TICK_TIME: ALL
--------------------
aplay: set_params:1299: Sample format non available
Available formats:
- S16_LE
- S24_LE
- S32_LE

i see the channels as [2,8]...I am hoping that this is what we were trying to enable on the pi as well i.e get the HAT to play all 8 channels thru HDMI

[gordoste]

Yes, my understanding is that the format of the parameter dump is [MIN MAX]

The stupid thing about the Pi is that all of the hardware supports 8 channels, but the driver is specifically written to have a maximum of 2 channels.

[phofman]

8ch HDMI has been enabled in 5.4y kernel bcm2835-pcm.c: Support multichannel audio * raspberrypi/linux@9a47172 * GitHub . Should be part of the latest raspbian Raspberry Pi OS - Wikipedia Download Raspberry Pi OS for Raspberry Pi

[gordoste]

Unfortunately while Model 3 Pi’s now work out of the box, the changes made so far don’t add multichannel HDMI audio support for Model 4 Pi’s, go to page 10 of this thread for the necessary additional changes.
I commented on the commit and the committer replied maybe we can get this change into Raspbian.

[phofman]

IMO either something like bcm2835-pcm: Fix up multichannel pcm audio by popcornmix * Pull Request #3933 * raspberrypi/linux * GitHub which requires recompiling the kernel, or using the enable_compat_alsa module param the other way than used in stock RPiX config e.g. linux/bcm2711-rpi-cm4.dts at 7fec469409de5a3af543043771f57ab70ddec2a4 * raspberrypi/linux * GitHub . Perhaps removing and loading the snd_bcm2835 module with module params 'enable_compat_alsa=1 enable_hdmi=0 enable_headphones=0' would fix the problem

[challenge]

Hello, is anyone running it in a stable conf with raspy 4b?
I'm getting back at it after having just tried it one month ago.

I've modded the kernel and it detects and plays all the 8 channels, but I have a big issue now:
channel positions/mappings are swapping randomly.

I mean I run speaker-test or ecasound, I mark down the alsa numbers to real speaker mappings, I close it, re run right after and speakers are shuffled in another combination. e.g. 1 is not front left anymore for example etc
sometimes they are offset by one, like what on previous run was on 1, now becomes 2 etc, sometime seems more random?

raspy 4b, 7.1ch board

[gordoste]

I don't think mine was doing that. I haven't fired it up for a while (working on other projects) but it is nearly time to start working on this again.
Are you just using alsa (no pulse/other stuff)? Try running speaker-test -s1 a few times to see if it varies.

[challenge]

thank you for the answer, I parked/abandoned this project (life got busy), still have the board but not planning to use it really soon.
The issue was happening only on a specific modded distribution (moode), it doesn't happen on vanilla raspbios.
Board works fine on raspbios. I was trying to trace the root of the issue with moode, but ran out of time.

[Stretchie]

My setup: Pi 3b (no+), X6000K-7.1CH, HiFiBarry DAC+ADC.

In 2-way configuration the unit works just fine and clean. With the 3-way setup I hear crackling in all 3 channels, the quieter the program is the less crackling you can hear. No change if I reduce the gain of pre1 to -20db and increase the buffer size to 2048 or set output to -f:16,6,44100.

Ecasound output:

**************************************************************************
*        ecasound v2.9.1 (C) 1997-2014 Kai Vehmanen and others    
**************************************************************************
(eca-chainsetup-parser) Buffering mode 'rt' selected.
(eca-chainsetup-parser) Setting buffersize to (samples) 2048.
(eca-chainsetup-parser) Disabling extra buffering on realtime devices.
(eca-chainsetup-parser) Enabling 'sum' mixmode.
(eca-chainsetup) Chainsetup "untitled-chainsetup"
(eca-chainsetup) Multitrack-mode enabled.
(eca-chainsetup) "rt" buffering mode selected.
(eca-chainsetup) Opened input "alsa", mode "read". Format: s16_le, channels
... 2, srate 44100, interleaved.
(eca-chainsetup) NOTE: using existing audio parameters -f:f32_le,2,44100
... for object 'loop' (tried to open with -f:s16_le,2,44100).
(eca-chainsetup) Opened input "loop", mode "read". Format: f32_le, channels
... 2, srate 44100, interleaved (locked params).
(eca-chainsetup) NOTE: using existing audio parameters -f:f32_le,2,44100
... for object 'loop' (tried to open with -f:s16_le,2,44100).
(eca-chainsetup) Opened output "loop", mode "write". Format: f32_le,
... channels 2, srate 44100, interleaved (locked params).
(eca-chainsetup) Opened input "loop", mode "read". Format: f32_le, channels
... 2, srate 44100, interleaved (locked params).
(eca-chainsetup) Opened output "loop", mode "write". Format: f32_le,
... channels 2, srate 44100, interleaved (locked params).
(eca-chainsetup) Opened output "alsa", mode "write". Format: s24_le,
... channels 6, srate 44100, interleaved.
- [ Connected chainsetup: "untitled-chainsetup" ] ------------------------
- [ Controller/Starting batch processing ] -------------------------------
- [ Engine - Driver start ] ----------------------------------------------

3-way ecasound chain, with crackling:

ecasound -B:rt -b:2048 -z:mixmode,sum \
        -a:pre1 -i:alsa,hw:3,1 -pf:/pre1.ecp -o:loop,1 \
        -a:pre2,woofer -i:loop,1 \
        -a:mid,tweeter -i:loop,2 \
        -a:pre2 -pf:/pre2.ecp -o loop,2 \
        -a:woofer -pf:/woofer.ecp -chorder:1,2,0,0,0,0 \
        -a:mid -pf:/mid.ecp -chorder:0,0,1,2,0,0 \
        -a:tweeter -pf:/tweeter.ecp -chorder:0,0,0,0,1,2 \
        -a:woofer,mid,tweeter -f:24,6,96000 -o:alsa,hw:0,0

2-way chain with clean sound:

ecasound -z:mixmode,sum -B:rt \
         -a:pre -i:alsa,hw:3,1 -pf:/pre.ecp -o:loop,1 \
         -a:woofer,tweeter -i:loop,1 \
         -a:woofer -pf:/woofer.ecp -chorder:1,2,0,0 \
         -a:tweeter -pf:/tweeter.ecp -chorder:0,0,1,2 \
         -a:woofer,tweeter -f:24,4,96000 -o:alsa,hw:0,0

Any ideas? Do I need the 3B+ board??

Regards