oh oops

pi/bin/video-publisher.sh

@@ -23,13 +23,21 @@ AUDIO_DEVICE="${AUDIO_DEVICE:-plughw:0,0}"
 AUDIO_RATE="${AUDIO_RATE:-48000}"
 AUDIO_CHANNELS="${AUDIO_CHANNELS:-1}"
 AUDIO_BITRATE="${AUDIO_BITRATE:-24000}"
+AUDIO_CODEC="${AUDIO_CODEC:-pcm_mulaw}"
 
 # Normalize device/rate to match the HAT capture; plughw handles any minor conversions.
-# Keep audio encode light for the Pi Zero by using 16 kHz mono Opus at a low complexity.
 AUDIO_DEVICE="plughw:0,0"
-AUDIO_RATE=16000
 AUDIO_CHANNELS=1
-AUDIO_BITRATE=16000
+# Defaults chosen to keep Pi Zero CPU low. Opus can be enabled by setting AUDIO_CODEC=libopus.
+if [[ "${AUDIO_CODEC}" == "libopus" ]]; then
+	AUDIO_RATE=16000
+	AUDIO_BITRATE=16000
+else
+	# G.711 mu-law (or A-law if AUDIO_CODEC=pcm_alaw): very low CPU, 8 kHz mono, ~64 kbps.
+	AUDIO_CODEC="pcm_mulaw"
+	AUDIO_RATE=8000
+	AUDIO_BITRATE=64000
+fi
 # Flip the camera 180deg (supported by rpicam-vid/libcamera-vid)
 FLIP_ARGS=(--rotation 180)
 
@@ -89,14 +97,12 @@ run_pipeline() {
 				-ar "${AUDIO_RATE}" \
 				-i "${AUDIO_DEVICE}" \
 				-c:v copy \
-				-c:a libopus \
+				-c:a "${AUDIO_CODEC}" \
 				-b:a "${AUDIO_BITRATE}" \
-				-compression_level 0 \
-				-application voip \
-				-frame_duration 60 \
+				$( [[ "${AUDIO_CODEC}" == "libopus" ]] && echo "-compression_level 0 -application voip -frame_duration 60" ) \
 				-ac:a "${AUDIO_CHANNELS}" \
 				-ar:a "${AUDIO_RATE}" \
-				-af "pan=1c|c0=c0,volume=20dB" \
+				-af "$( [[ "${AUDIO_CODEC}" == "libopus" ]] && echo "pan=1c|c0=c0," )volume=20dB" \
 				-flush_packets 1 \
 				-f mpegts \
 				"${PUBLISH_URL}"