rpi-cast

A tool to automatically cast audio input from a Raspberry Pi.

Overview

This tool will:

1. Listen on the defined PulseAudio source (eg. a HiFiBerry DAC+ ADC 3.5mm jack) (-i, --input-source)
2. Upon detecting enough volume (amplitude) (-vt, --volume-threshold):
   1. Create a loopback for each defined PulseAudio loopback sink (eg. the HiFiBerry DAC+ ADC RCA jacks) (-l, --loopback-sink)
   2. Cast to the Chromecast device defined (-d, --device-name) or the first one found, with the defined bitrate (-b, --bitrate) and sample rate (-s, --sample-rate)
   3. Set the volume for each output sink (-v, --volume)
   4. Attempt to keep the cast as long as the silence timeout isn't met (-st, --silence-timeout)
3. Rinse, repeat!

Here's an example wiring diagram of how a HiFiBerry DAC+ ADC Pro can be used to cast audio from a turntable, as well as loopback output to a receiver:

Dependencies

This script assumes you have a typical Raspbian install with apt and normal tools. It will install everything else it needs to run.

Installation

wget https://raw.githubusercontent.com/emmercm/rpi-cast/main/rpi-cast && chmod +x rpi-cast

Usage

Usage: ./rpi-cast [OPTIONS]

Cast options:
  -d, --device-name string         Chromecast device name (eg. "Living Room TV")
                                   Default: the first device found, preferring
                                    groups over single devices

  -v, --volume number              Output volume percentage (can can exceed 100)
                                   Default: 100

  -st, --silence-timeout number    Stop casting after some seconds of silence
                                   Default: 300

  -vt, --volume-threshold number   Minimum volume threshold to start casting
                                   Default: 0.005

Quality options:
  -b, --bitrate string             Bitrate to use in kbps
                                   Default: 320 if not WAV/FLAC

  -c, --codec string               Audio codec to use
                                   Options: mp3, ogg, aac, opus, wav, flac
                                   Default: wav

  -s, --sample-rate string         Sample rate to use in Hz
                                   Default: 96000 if AAC/WAV/FLAC, otherwise 44100

Other options:
  -h, --hifiberry-overlay string   HiFiBerry overlay to configure
                                   Optional, only needs to be done once

  -i, --input-source string        Pattern for the PulseAudio sources to use
                                   Default: alsa_input

  -l, --loopback-sink string       Pattern for the PulseAudio sinks to loopback to
                                   Default: alsa_output

HiFiBerry overlays:
  hifiberry-dacplusadc
  hifiberry-dacplusadcpro

Examples

Set up the drivers for a new HiFiBerry device (only needs to be done once), and start casting to the first device found:

./rpi-cast -h 'hifiberry-dacplusadcpro'

Cast to the entire house:

./rpi-cast -d 'Entire House'

Cast to a specific Chromecast with boosted volume:

./rpi-cast -d 'Living Room TV' -v 125

Cast with a lossy codec to reduce bandwidth:

./rpi-cast -c mp3 -b 256

Automatic startup

To have rpi-cast automatically start on device boot, add the following to your /etc/rc.local file:

# (Optional) log all /etc/rc.local output to a temp file
exec &> /tmp/rc.local.log
set -x

# Start rpi-cast and log to a temp file
su pi -c '/home/pi/rpi-cast > /tmp/rpi-cast.log &'