hifiberry_connect_devices

#!/bin/bash

SPDIF_D="hw:2,0"
USB_D="hw:1,0"
HDMI_D="hw:0,0"
FORMAT="-f S16_LE -c 2 --buffer-size=1024"
STDERR_SINK="/dev/null"
#STDERR_SINK="/dev/stderr"
QUERY_PERIOD=0.25
REGFILE=/proc/asound/sndrpihifiberry/registers

#try to terminate them. if that doesn't work, kill
reset_dump() {
    if [[ !(-z $(pgrep arecord) && -z $(pgrep aplay)) ]]; then
        killall arecord >$STDERR_SINK 2>&1
        killall aplay >$STDERR_SINK 2>&1
    fi
    sleep $QUERY_PERIOD
    while [[ !(-z $(pgrep arecord) && -z $(pgrep aplay)) ]]; do
        killall -9 arecord >$STDERR_SINK 2>&1
        killall -9 aplay >$STDERR_SINK 2>&1
    done
}


#get sample rate by probing SPDIF input for one second
dummy_rec() {
    if [[ ! -z $(pgrep arecord) ]]; then
        echo "Already recording"
        echo "Already recording" 2>$STDERR_SINK
    else
        arecord -D $SPDIF_D -f cd -d 1 2>$STDERR_SINK
    fi
}

get_sample_rate() {
    if [[ -z $1 ]]; then
        reset_dump
    fi
    dummy_rec | while read F; do 
        cat $REGFILE | awk '$0~/ind freq/{print $3*1000}$0~/ lock/{print $2}$0~/intstat/{print $2}'; 
        break; 
    done;
}

#the actual signal dumper
dump_signal() {
    if [[ (! -z $1) ]]; then
        SAMPLE_RATE=$1
        reset_dump
        arecord -D $SPDIF_D -r $SAMPLE_RATE $FORMAT 2>$STDERR_SINK | aplay -D $SPDIF_D -r $SAMPLE_RATE $FORMAT 2>$STDERR_SINK &
    fi
    sleep $QUERY_PERIOD
    cat $REGFILE >$STDERR_SINK
}

#main loop
while true; do
    SAMPLE_RATE_NEW=$(get_sample_rate $SAMPLE_RATE)
    if [[ $(echo "$SAMPLE_RATE_NEW" | wc -l) == 3 ]]; then
        CLOCK=$(echo "$SAMPLE_RATE_NEW" | head -n 1)
        INTSTAT=$(echo "$SAMPLE_RATE_NEW" | head -n 3 | tail -n 1)
        SAMPLE_RATE_NEW=$(echo "$SAMPLE_RATE_NEW" | head -n 2 | tail -n 1)
        echo A $SAMPLE_RATE $SAMPLE_RATE_NEW $CLOCK $INTSTAT $(($INTSTAT & 0xf8)) >$STDERR_SINK
        if [[ !(-z $SAMPLE_RATE_NEW) ]]; then
            if [[ -z $SAMPLE_RATE || !($SAMPLE_RATE_NEW == $SAMPLE_RATE) ]]; then
                SAMPLE_RATE=$SAMPLE_RATE_NEW
                echo "Switching to sample rate "$SAMPLE_RATE" "$FORMAT" device: "$SPDIF_D
                dump_signal $SAMPLE_RATE
            echo B $SAMPLE_RATE $SAMPLE_RATE_NEW $CLOCK $INTSTAT $(($INTSTAT & 0xf8)) >$STDERR_SINK
            fi
            if [[ !($CLOCK == "ON") || ($(($INTSTAT & 0xf8)) == 8) ]]; then
                echo $(($INTSTAT & 0xf8)) >$STDERR_SINK
                unset SAMPLE_RATE
            fi
        fi
    fi
    sleep $QUERY_PERIOD
done