Added tool to measure the end to end latency in loopback configuratio…

…n to investigate #53

The script run_latency_test.sh can be used to run the test.
The latency utility measures the end to end latency by adding timestamps in the stream at playback time and checking the timestamps when the packets are received on the capture device.
The average measured end to end latency is printed at the end of the test.
The latency utility is based on a modified version of the original ALSA latency tool.

run_latency_test.sh

@@ -0,0 +1,137 @@
+#!/bin/bash
+#
+# Tested on Ubuntu 18.04
+#
+
+function cleanup {
+#kill and wait for previous daemon instances to exit
+  sudo killall -q ptp4l
+  killall -q aes67-daemon
+  while killall -0 aes67-daemon 2>/dev/null ; do
+    sleep 1
+  done
+}
+
+function usage {
+  echo 'Usage run_latenvy_test.sh sample_format sample_rate channels duration' >&2
+  echo '  sample_format can be one of S16_LE, S24_3LE, S32_LE' >&2
+  echo '  sample_rate can be one of 44100, 48000, 96000' >&2
+  echo '  channels can be one of 1, 2, 4' >&2
+  echo '  duration in seconds' >&2
+  exit 1
+}
+
+
+if [ "$#" -ne 4 ]; then
+  usage 
+fi
+
+if ! [ -x "$(command -v /usr/sbin/ptp4l)" ]; then
+  echo 'Error: ptp4l is not installed.' >&2
+  exit 1
+fi
+
+if ! [ -x "$(command -v arecord)" ]; then
+  echo 'Error: arecord is not installed.' >&2
+  exit 1
+fi
+
+if ! [ -x "$(command -v aplay)" ]; then
+  echo 'Error: aplay is not installed.' >&2
+  exit 1
+fi
+
+if ! [ -x "$(command -v ./daemon/aes67-daemon)" ]; then
+  echo 'Error: aes67-daemon is not compiled.' >&2
+  exit 1
+fi
+
+if ! [ -r "3rdparty/ravenna-alsa-lkm/driver/MergingRavennaALSA.ko" ]; then
+  echo 'Error: MergingRavennaALSA.ko module is not compiled.' >&2
+  exit 1
+fi
+
+cd test
+echo 'Compiling tools ...' >&2
+make
+cd ..
+
+SAMPLE_FORMAT=$1
+SAMPLE_RATE=$2
+CHANNELS=$3
+DURATION=$4
+
+if [ $SAMPLE_FORMAT == "S16_LE" ]; then
+  CODEC="L16"
+elif [ $SAMPLE_FORMAT == "S24_3LE" ]; then
+  CODEC="L24"
+elif [ $SAMPLE_FORMAT == "S32_LE" ] ; then
+  CODEC="AM824"
+else
+  usage
+fi
+
+if [ $SAMPLE_RATE == "44100" ]; then
+  PTIME="1.08843537415"
+elif [ $SAMPLE_RATE == "48000" ]; then
+  PTIME="1"
+elif [ $SAMPLE_RATE == "96000" ]; then
+  PTIME="0.5"
+else
+  usage
+fi
+
+MAP="[ "
+for (( ch=0; ch<$CHANNELS; ch++ ))
+do
+   MAP+=$ch
+   if (( ch != ($CHANNELS - 1) )); then
+     MAP+=","
+   fi
+done
+MAP+=" ]"
+
+echo 'Creating configuration files ..' >&2
+sed 's/48000/'"$SAMPLE_RATE"'/g;s/status.json/status_.json/g;' test/daemon.conf > test/daemon_.conf
+sed 's/\/2/\/'"$CHANNELS"'/g;s/48000/'"$SAMPLE_RATE"'/g;s/L24/'"$CODEC"'/g;s/ptime:1/ptime:'"$PTIME"'/;s/\[ 0, 1 \]/'"$MAP"'/g' test/status.json > test/status_.json
+
+trap cleanup EXIT
+
+#configure system parms
+sudo sysctl -w net/ipv4/igmp_max_memberships=66
+
+if [ -x /usr/bin/pulseaudio ]; then
+  #stop pulseaudio, this seems to open/close ALSA continuosly
+  echo autospawn = no > $HOME/.config/pulse/client.conf
+  pulseaudio --kill >/dev/null 2>&1
+  rm $HOME/.config/pulse/client.conf
+  #disable pulseaudio
+  systemctl --user stop pulseaudio.socket > /dev/null 2>&1
+  systemctl --user stop pulseaudio.sservice > /dev/null 2>&1
+fi
+
+#uninstall kernel module
+if sudo lsmod | grep MergingRavennaALSA > /dev/null 2>&1 ; then
+  sudo rmmod MergingRavennaALSA
+fi
+
+#install kernel module
+sudo insmod 3rdparty/ravenna-alsa-lkm/driver/MergingRavennaALSA.ko
+
+cleanup
+
+echo "Starting PTP master ..."
+sudo /usr/sbin/ptp4l -i lo -l7 -E -S &
+
+echo "Starting AES67 daemon ..."
+./daemon/aes67-daemon -c ./test/daemon_.conf &
+
+echo "Waiting for PTP slave to sync ..."
+sleep 30
+
+echo "Running 10 secs latency test"
+cd test
+./latency -P hw:RAVENNA -C hw:RAVENNA -f $SAMPLE_FORMAT -r $SAMPLE_RATE -c $CHANNELS -M 128 -m 128 -s $DURATION
+cd ..
+
+echo "Terminating processes ..."

test/Makefile

@@ -1,8 +1,11 @@
 CXX=g++
 CC=g++
-all: check createtest
+LIBS=-lpthread -lasound
+all: check createtest latency
 createtest: createtest.o
 check: check.o
+latency: latency.o
+	$(CXX) $< -o latency  $(LIBS)
 clean:
 	rm *.o
-	rm check createtest
+	rm check createtest latency