shazam

#!/usr/bin/env bash

# Use https://rapidapi.com/apidojo/api/shazam/ to detect audio currently playing through audio source.
# Requires curl, ffmpeg

TMP_DIR="/tmp/shazam"
[ ! -d "$TMP_DIR" ] && mkdir "$TMP_DIR"
AUDIO_FILE="$TMP_DIR/recording.dat"
AUDIO_B64_FILE="$TMP_DIR/recording_b64.dat"
PID_FILE="$TMP_DIR/recordingpid"

API_KEY_FILE="${XDG_CONFIG_HOME:-$HOME/.config}/shazam-cli/key"
[ -f "$API_KEY_FILE" ] && API_KEY="$(<"$API_KEY_FILE")"

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

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

Get free API access at: https://rapidapi.com/apidojo/api/shazam/

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

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

Usage:
    -h                    Show this message and exit.
    -a API_KEY            API token.
    -s AUDIO_SOURCE       ffmpeg audio input source, (default: \"default\").
    -t RECORDING_TIME     Length of recording time, in seconds, (default: 5).
" "$API_KEY_FILE"
}

start_recording() {
    # should be mono signed 16 bit little endian
    ffmpeg \
        -hide_banner \
        -f pulse -i "$AUDIO_SOURCE" \
        -ac 1 -f s16le -acodec pcm_s16le -ar 44100 \
        -y "$AUDIO_FILE" >/dev/null 2>&1 &
    printf "%s\n" "$!" >"$PID_FILE"
}

kill_recording() {
    # kill with SIGTERM, allowing finishing touches.
    local pid
    pid="$(<"$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
}

convert() {
    # convert audio file to 44100 Hz 16 bit signed little endian mono
    ffmpeg -i "$AUDIO_FILE" -ac 1 -f s16le -acodec pcm_s16le -ar 44100 -y "/tmp/shazam/converted.dat" >/dev/null 2>&1
    AUDIO_FILE="/tmp/shazam/converted.dat"
}

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

query() {
    base64 $AUDIO_FILE >$AUDIO_B64_FILE
    curl --silent -X POST \
        'https://shazam.p.rapidapi.com/songs/v2/detect' \
        --header 'content-type: text/plain' \
        --header 'x-rapidapi-host: shazam.p.rapidapi.com' \
        --header "x-rapidapi-key: $API_KEY" \
        --data "@$AUDIO_B64_FILE"
}

# Defaults
RECORDING_TIME=5 # in seconds
AUDIO_SOURCE="default"

# Parse options
while getopts ":ha:s:t:" opt; do
    case $opt in
    "h")
        usage
        exit 0
        ;;
    "a")
        API_KEY="$OPTARG"
        ;;
    "s")
        AUDIO_SOURCE="$OPTARG"
        ;;
    "t")
        RECORDING_TIME="$OPTARG"
        ;;
    "?")
        usage >&2
        err_msg_exit "Invalid Option: -$OPTARG"
        ;;
    esac
done
shift $((OPTIND - 1))

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

[ -z "$API_KEY" ] && err_msg_exit "shazam: No API_KEY provided. Use the -a option or write it to \"$API_KEY_FILE\""

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

[ -f "$AUDIO_FILE" ] && query