multiroom: update snapcast to v0.22 and various improvements

- Update snapcast to v0.22.0-r0
- Replace FIFO stream source with ALSA which significantly reduces CPU and I/O usage (fixes #294)
- Add SOUND_INPUT_LATENCY and SOUND_OUTPUT_LATENCY env vars (also helps with #294)
- Reduce multiroom-server image with multi stage builds for a slimmer image
- Reduce verbose level for both multiroom services

Connects-to: #294
Change-type: minor
Signed-off-by: Tomás Migone <tomas@balena.io>

core/audio/balena-sound.pa

@@ -3,13 +3,13 @@
 # Create balena-sound sinks
 load-module module-null-sink sink_name=balena-sound.input
 load-module module-null-sink sink_name=balena-sound.output
-load-module module-pipe-sink file=/var/cache/snapcast/snapfifo sink_name=snapcast format=s16le rate=44100
+load-module module-null-sink sink_name=snapcast
 
 # Route audio internally, loopback sinks depend on configuration. See start.sh for details:
 # balena-sound.input: For multiroom it's routed to snapcast sink, for standalone directly wired to balena-sound.output
 # balena-sound.output: Set to audio sink specified by audio block
-load-module module-loopback source="balena-sound.input.monitor" %INPUT_SINK%
-load-module module-loopback source="balena-sound.output.monitor" %OUTPUT_SINK%
+load-module module-loopback latency_msec=%INPUT_LATENCY% source="balena-sound.input.monitor" %INPUT_SINK%
+load-module module-loopback latency_msec=%OUTPUT_LATENCY% source="balena-sound.output.monitor" %OUTPUT_SINK%
 
 # Route all plugin input to the default sink
 set-default-sink balena-sound.input

core/audio/start.sh

@@ -5,6 +5,14 @@ set -e
 CONFIG_TEMPLATE=/usr/src/balena-sound.pa
 CONFIG_FILE=/etc/pulse/balena-sound.pa
 
+# Set loopback module latency
+function set_loopback_latency() {
+  local LOOPBACK="$1"
+  local LATENCY="$2"
+
+  sed -i "s/%$LOOPBACK%/$LATENCY/" "$CONFIG_FILE"
+}
+
 # Route "balena-sound.input" to the appropriate sink depending on selected mode
 # Either "snapcast" fifo sink or "balena-sound.output"
 function route_input_sink() {
@@ -72,11 +80,17 @@ while ! curl --silent --output /dev/null "$SOUND_SUPERVISOR/ping"; do sleep 5; e
 SOUND_SUPERVISOR="$(ip route | awk '/default / { print $3 }'):3000"
 MODE=$(curl --silent "$SOUND_SUPERVISOR/mode" || true)
 
+# Get latency values
+SOUND_INPUT_LATENCY=${SOUND_INPUT_LATENCY:-200}
+SOUND_OUPUT_LATENCY=${SOUND_OUTPUT_LATENCY:-200}
+
 # Audio routing: route intermediate balena-sound input/output sinks
 echo "Setting audio routing rules. Note that this can be changed after startup."
 reset_sound_config
 route_input_sink "$MODE"
 route_output_sink
+set_loopback_latency "INPUT_LATENCY" "$SOUND_INPUT_LATENCY"
+set_loopback_latency "OUTPUT_LATENCY" "$SOUND_OUPUT_LATENCY"
 if [[ -n "$SOUND_ENABLE_SOUNDCARD_INPUT" ]]; then
   route_input_source
 fi

core/multiroom/client/Dockerfile.template

@@ -1,13 +1,15 @@
-FROM balenalib/%%BALENA_MACHINE_NAME%%-alpine:3.12
+# Minimum snapcast version for ALSA stream source is v0.21
+# Currently Alpine 3.12 is pinned to snapcast v0.19 so we need to use Alpine edge
+FROM balenalib/%%BALENA_MACHINE_NAME%%-alpine:edge
+WORKDIR /usr/src
 
 RUN install_packages snapcast-client
 
 # Audio block setup
-RUN curl --silent https://raw.githubusercontent.com/balenablocks/audio/master/scripts/alsa-bridge/alpine-setup.sh | sh
 ENV PULSE_SERVER=tcp:audio:4317
 ENV PULSE_SINK=balena-sound.output
+RUN curl --silent https://raw.githubusercontent.com/balenablocks/audio/master/scripts/alsa-bridge/alpine-setup.sh | sh
 
-WORKDIR /usr/src
 COPY start.sh .
 
 CMD [ "/bin/bash", "/usr/src/start.sh" ]

core/multiroom/client/start.sh

@@ -21,10 +21,7 @@ echo "Target snapcast server: $SNAPSERVER"
 
 # Start snapclient
 if [[ "$MODE" == "MULTI_ROOM" || "$MODE" == "MULTI_ROOM_CLIENT" ]]; then
-  # Start snapclient and filter out those pesky chunk logs
-  # grep filter can be removed when we get snapcast v0.20
-  # see: https://github.com/badaix/snapcast/issues/559#issuecomment-615874719
-  /usr/bin/snapclient --host $SNAPSERVER $LATENCY | grep -v "\[Info\] (Stream) Chunk"
+  /usr/bin/snapclient --host $SNAPSERVER $LATENCY --logfilter *:notice
 else
   echo "Multi-room client disabled. Exiting..."
   exit 0

core/multiroom/server/Dockerfile.template

@@ -1,12 +1,30 @@
-FROM balenalib/%%BALENA_MACHINE_NAME%%-alpine:3.12
+# Build snapweb separately
+FROM balenalib/%%BALENA_MACHINE_NAME%%-alpine-node:latest as web-builder
+WORKDIR /usr/src
+
+RUN install_packages git make npm
+
+RUN git clone https://github.com/badaix/snapweb.git snapweb
+RUN npm install --global --no-save typescript
+RUN cd snapweb && make
 
+# Minimum snapcast version for ALSA stream source is v0.21
+# Currently Alpine 3.12 is pinned to snapcast v0.19 so we need to use Alpine edge
+FROM balenalib/%%BALENA_MACHINE_NAME%%-alpine:edge
 WORKDIR /usr/src
 
-RUN install_packages snapcast-server git make npm
+# Install snapweb
+RUN mkdir -p /var/www
+COPY --from=web-builder /usr/src/snapweb/dist/* /var/www/
+
+# Install snapcast
+RUN install_packages snapcast-server
 COPY snapserver.conf /etc/snapserver.conf
 COPY start.sh .
-RUN git clone https://github.com/badaix/snapweb.git snapweb
-RUN npm install --global --no-save typescript
-RUN cd snapweb && make && mkdir -p /var/www && mv dist/* /var/www
+
+# Audio block setup
+ENV PULSE_SERVER=tcp:audio:4317
+ENV PULSE_SOURCE=snapcast.monitor
+RUN curl --silent https://raw.githubusercontent.com/balenablocks/audio/master/scripts/alsa-bridge/alpine-setup.sh| sh
 
 CMD [ "/bin/bash", "/usr/src/start.sh" ]

core/multiroom/server/snapserver.conf

@@ -8,6 +8,8 @@ port = 1780
 doc_root = /var/www/
 
 [stream]
-stream = pipe:///var/cache/snapcast/snapfifo?name=balenaSound
+stream = alsa://?name=balenaSound&device=pulse
 sampleformat = 44100:16:2
 
+[logging]
+filter = *:notice

docker-compose.yml

@@ -2,7 +2,6 @@ version: '2'
 
 volumes:
   spotifycache:
-  snapcast:
 
 services:
 
@@ -14,8 +13,6 @@ services:
       io.balena.features.dbus: 1
     ports:
       - 4317:4317
-    volumes:
-      - snapcast:/var/cache/snapcast
 
   sound-supervisor:
     build: ./core/sound-supervisor
@@ -32,8 +29,6 @@ services:
       - 1704:1704
       - 1705:1705
       - 1780:1780
-    volumes:
-      - snapcast:/var/cache/snapcast
 
   multiroom-client:
     build: ./core/multiroom/client

docs/03-customization.md

@@ -23,6 +23,9 @@ The following environment variables apply to balenaSound in general, modifying i
 | SOUND_VOLUME | Output volume level at startup. | 0 - 100, integer value without the `%` symbol. | 75 |
 | SOUND_DEVICE_NAME / BLUETOOTH_DEVICE_NAME | Device name to be advertized by plugins (AirPlay device list, Spotify Connect and UPnP). For bluetooth use `BLUETOOTH_DEVICE_NAME` | Any valid string. | `balenaSound <plugin> <xxxx>`, where:<br>- `<plugin>` is `Spotify, AirPlay, UPnP`<br>- `<xxxx>` the first 4 chars of the device UUID. |
 | AUDIO_OUTPUT | Select the default audio output interface. See [audio block](https://github.com/balenablocks/audio/blob/master/README.md#environment-variables). | For all device types: <br>- `AUTO`: Automatic detection. Priority is `USB > DAC > HEADPHONES > HDMI`<br>- `DAC`: Force default output to be an attached GPIO based DAC<br><br> For Raspberry Pi devices: <br>- `RPI_AUTO`: Official BCM2835 automatic audio switching as described [here](https://www.raspberrypi.org/documentation/configuration/audio-config.md) <br>- `RPI_HEADPHONES`: 3.5mm audio jack <br>- `RPI_HDMI0`: Main HDMI port <br>- `RPI_HDMI1`: Secondary HDMI port (only Raspberry Pi 4) <br><br> For Intel NUC: <br>- NUCs have automatic output detection and switching. If you plug both the HDMI and the 3.5mm audio jack it will use the latter. | `AUTO` |
+| SOUND_INPUT_LATENCY | Input loopback latency in milliseconds. Useful when experiencing frequent audio stuttering due to underruns. Note that this is only a friendly request, the actual latency might be higher. | 1 - 2000. | 200 |
+| SOUND_OUTPUT_LATENCY | Output loopback latency in milliseconds. Note that this is only a friendly request, the actual latency might be higher. | 1 - 2000. | 200 |
+
 
 ## Multi-room