clip-recorder

Pirate Audio Dual Mic Recording Utility

Installing

Pre-requisites

Install the LADSPA plugins:

sudo apt install ladspa-sdk invada-studio-plugins-ladspa

Basic Audio Config

Dual Mic needs some config to enable the microphone and boost the input gain.

Add the following to /boot/config.txt to enable Dual Mic as an audio input:

dtoverlay=adau7002-simple

The following config uses a LADSPA plugin (Invada High-Pass Stero Filter) to remove DC bias and amplify the input from the microphone.

Add it to ~/.asoundrc or /etc/asound.conf:

pcm.mic_hw{
    type hw
    card adau7002
    format S32_LE
    rate 48000
    channels 2
}
pcm.mic_rt{
    type route
    slave.pcm mic_hw
    ttable.0.0 1
    ttable.0.1 0
    ttable.1.0 0
    ttable.1.1 1
}
pcm.mic_plug {
    type plug
    slave.pcm mic_rt
}
pcm.mic_filter {
    type ladspa
    slave.pcm mic_plug
    path "/usr/lib/ladspa";
    plugins [
    {
        label invada_hp_stereo_filter_module_0_1
        input {
	    controls [
                50   # Cut off frequency (Hz)
                30   # Gain (dB)
                1    # Soft Clip (on/off)
            ]
	}
    }
    ]
}
pcm.mic_out {
    type plug
    slave.pcm mic_filter
}

The device for recording is mic_out, and mic_hw is the raw, unfiltered input.

To test the microphone setup, use arecord like so:

arecord -Dmic_out -c2 -r48000 -fS32_LE -twav -d5 -R10000 -Vstereo test.wav

The ASCII VU meter should correspond to what the microphone is picking up.

Preparing to run these examples

Install Pulseaudio

Pulse audio supplies an "upmix" output device which allows cliprecord.py to play back lower samplerate (smaller) recording without handling resampling.

sudo apt install pulseaudio

Enable SPI

sudo raspi-config nonint do_spi 0

Install for Python 3

sudo apt install python3-pip python3-rpi.gpio python3-spidev python3-numpy python3-pil python3-pil.imagetk libportaudio2
sudo python3 -m pip install fonts font-roboto ST7789 sounddevice

Run

python3 cliprecord.py