audd

#!/bin/sh

# Use https://audd.io/ to detect audio currently playing through audio source.
# Requires curl, ffmpeg.

TMP_DIR="/tmp/audd"
[ ! -d "$TMP_DIR" ] && mkdir "$TMP_DIR"
AUDIO_FILE="$TMP_DIR/recording.mp3"
PID_FILE="$TMP_DIR/recordingpid"

API_TOKEN_FILE="${XDG_CONFIG_HOME:-$HOME/.config}/audd/api_token"
[ -f "$API_TOKEN_FILE" ] && API_TOKEN="$(cat "$API_TOKEN_FILE")"

err_msg_exit() {
    # Print an error to stderr and exit.
    printf "%s\n" "$*" >&2
    exit 1
}

type curl >/dev/null || err_msg_exit "'curl' not found."
type ffmpeg >/dev/null || err_msg_exit "'ffmpeg' not found."

usage() {
    printf "Usage: audd [OPTION]... [FILE]
Query the AudD music recognition API.

Get a free API token at: https://audd.io/

The API token can be read from file:
$ echo \"api-token\" > \"%s\"

If no FILE is provided, a recording is made using the AUDIO_SOURCE.

Usage:
    -h                    Show this message and exit.
    -a API_KEY            AudD API token.
    -s AUDIO_SOURCE       ffmpeg audio input source, (default: \"default\").
    -t RECORDING_TIME     Length of recording time, in seconds, (default: 3).
    -r API_RETURN         AudD API return parameter, see https://docs.audd.io/,
                          (default: \"apple_music,spotify\").
    -o                    Use the \"recognizeWithOffset\" endpoint.
" "$API_TOKEN_FILE"
}

start_recording() {
    ffmpeg \
        -hide_banner \
        -f pulse -i "$AUDIO_SOURCE" -ac 1 \
        -c:a mp3 \
        -y "$AUDIO_FILE" >/dev/null 2>&1 &
    printf "%s\n" "$!" >"$PID_FILE"
}

kill_recording() {
    # kill with SIGTERM, allowing finishing touches.
    local pid
    pid="$(cat "$PID_FILE")"
    kill "$pid"
    rm -f "$PID_FILE"
    # even after SIGTERM, ffmpeg may still run, so wait till it's done.
    while kill -0 "$pid" 2>/dev/null; do
        sleep 0.1
    done
}

record() {
    start_recording && sleep "$RECORDING_TIME" && kill_recording
}

query() {
    curl --silent "https://api.audd.io/$ENDPOINT" \
        -F api_token="$API_TOKEN" \
        -F file=@"$AUDIO_FILE" \
        -F return="$API_RETURN"
}

# Defaults
RECORDING_TIME=3 # in seconds
AUDIO_SOURCE="default"
API_RETURN="apple_music,spotify"
ENDPOINT=""

# Parse options
while getopts ":hoa:s:t:r:" opt; do
    case $opt in
        "h")
            usage
            exit 0
            ;;
        "a")
            API_TOKEN="$OPTARG"
            ;;
        "s")
            AUDIO_SOURCE="$OPTARG"
            ;;
        "t")
            RECORDING_TIME="$OPTARG"
            ;;
        "r")
            API_RETURN="$OPTARG"
            ;;
        "o")
            ENDPOINT="recognizeWithOffset/"
            ;;
        "?")
            usage >&2
            err_msg_exit "Invalid Option: -$OPTARG"
            ;;
    esac
done
shift $((OPTIND - 1))

[ -z "$API_TOKEN" ] && err_msg_exit "No API_TOKEN provided. Use the -a option or write it to \"$API_TOKEN_FILE\""

if [ -z "$1" ]; then
    record || exit
else
    if [ -f "$1" ]; then
        AUDIO_FILE="$1"
    else
        err_msg_exit "audd: File \"$1\" not found."
    fi
fi

[ -f "$AUDIO_FILE" ] && query