Mt32-pi tutorial?

Pisound
1

Is there a tutorial for using mt32-pi with Pisound?

For instance, what settings do I need to use in mt32-pi’s config.txt?

Thanks,
-d

2

Hi, check out this page: https://github.com/dwhinham/mt32-pi/wiki/I²S-DACs

It says to use with Pisound, you must modify the sample rate to 48000, 96000 and 192000. No other configuration is mentioned. Let us know how it goes. :slight_smile:

3

Thanks for the link, I looked all over that Wiki and I didn’t see that.

48000 and 96000 worked for me, 192000 did not (sounded like mt32emu was OK, but Fluidsynth sounded like it was playing samples at twice the speed).

I was using mt32-pi 0.9.1

In [system], setting
output_device = i2s
Would then properly map mt32emu and Fluidsnyth to use the DAC on the Pisound.

I left the other values in [system] to their defaults, not sure if they have any relevance to Pisound:
chunk_size = 256
i2c_dac_address = 4c
i2c_dac_init = none

In [system], setting
output_device = pwm
Then it uses the headphone jack of the RPi but it sounds awful (lots of pops and scratches).

In the [control] section you can also set
scheme = simple_buttons
And the Pisound button will swap between Fluidsynth and mt32emu. That’s because Pisound’s button maps to m32-pi button #1.

It goes without saying (but leaving it here in case someone else has questions about using Pisound with mt32-pi) the volume and gain knob on the Pisound only work when output_device = i2s, because those pots are wired to the DAC of the Pisound. The knobs have no effect if using PWM for output device.

In the [system] I did set
usb = off
Not sure if it matters. Pisound doesn’t use USB, and I had no need for it.

1 Like
4

They might be missing setting the OSR pins as required for Pisound to control the sampling rate, but for most purposes 48kHz or 96kHz are good enough. :slight_smile:

The I²C settings are irrelevant for Pisound.

chunk_size is controlling the audio buffer size - the lower the value, the lower the latency, but also lower stability. :slight_smile: