mpd music selection algorithm

client.py

#!/usr/bin/env python
# vim: ai ts=4 sw=4 sts=4 expandtab fileencoding=utf-8

from mpd import MPDClient

## SETTINGS
##
HOST = 'localhost'
PORT = '6600'
PASSWORD = False
###

def connect():
    client = MPDClient()
    client.connect(host=HOST, port=PORT)

    if PASSWORD:
        client.password(PASSWORD)

    return client

db.py

#!/usr/bin/env python
# vim: ai ts=4 sw=4 sts=4 expandtab fileencoding=utf-8

import lmdb
import os

## SETTINGS
##
MY_DIR = os.path.dirname(__file__)
DB_PATH = os.path.join(MY_DIR, "status.lmdb")
##

env = lmdb.open(DB_PATH, max_dbs=3)
lastqueued = env.open_db(b'lastqueued')
lastplayed = env.open_db(b'lastplayed')

keyof = lambda artist, title : ("%s\t%s" % (
        artist.replace("\t","\\t"),
        title.replace("\t","\\t")
)).encode("UTF-8")

gistfile1.txt

Music selection algorithm…

All my music files are arranged "by UUID"; so there's a UUID tag in the file metadata, which derives the file name,
which improves the efficiency of tools like `rsync` when synchronising music repositories as it avoids re-transferring whole
files when a file is renamed.

This directory is what MPD sees.

`monitor.py` is run in the background, and `randomtrack.py` is run periodically from `cron` to keep adding new files.

monitor.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-
# vim: ai ts=4 sw=4 sts=4 expandtab

# IMPORTS
from mpd import CommandError
from db import env, lastplayed, keyof
from client import connect
import logging
import time
import os


logging.basicConfig(level=logging.DEBUG)
client = connect()
log = logging.getLogger(os.path.basename(__file__))

while True:
    events = client.idle()
    if "player" not in events:
        continue

    current = client.currentsong()
    if current \
            and current.get("title") \
            and current.get("artist") \
            and current.get("file"):
        # Update now playing
        now = str(time.time())
        key = keyof(current["artist"], current["title"])
        client.sticker_set("song", current["file"], "lastplayed_unixtime", now)
        with env.begin(db=lastplayed, write=True) as txn:
            txn.put(key, now.encode("utf-8"))

client.disconnect()

randomtrack.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-
# vim: ai ts=4 sw=4 sts=4 expandtab

# IMPORTS
from mpd import CommandError
from random import choice
from db import env, lastqueued, lastplayed, keyof
from client import connect
import logging
import time
import datetime
import mutagen
import os
import argparse


## SETTINGS
##
HOST = 'localhost'
PORT = '6600'
PASSWORD = False

REPO_DIR = "/home/stuartl/music/.by-uuid"
MIN_DURATION = 86400 * 31   # ~ 1 month
###


logging.basicConfig(level=logging.DEBUG)
client = connect()
log = logging.getLogger(os.path.basename(__file__))

ap = argparse.ArgumentParser()
ap.add_argument("count", type=int, default=100, nargs="?")
args = ap.parse_args()

files = client.list("file")

TODAY = datetime.date.today()
NOW = time.time()
MAX_LAST = NOW - MIN_DURATION
IS_CHRISTMAS = (TODAY.month == 12) and (TODAY.day < 26)

refresh = NOW
status = client.status()
playlistlen = int(status['playlistlength'])

log.info("Playlist has %d tracks, %d expected", playlistlen, args.count)

while playlistlen < args.count:
    while True:
        file = choice(files)
        log.debug("Checking %r", file)
        filename = file["file"]
        last = 0.0

        for name in ("lastplayed_unixtime", "lastqueued_unixtime"):
            try:
                last = float(
                        client.sticker_get("song", filename, name)
                )
                break
            except CommandError as e:
                if not str(e).endswith("no such sticker"):
                    raise

        if last >= MAX_LAST:
            log.debug("Played too recently")
            continue

        path = os.path.join(REPO_DIR, filename)
        if not os.path.exists(path):
            log.debug("No longer on disk")
            continue

        fileobj = mutagen.File(path)
        if "GROUPING" in fileobj.tags:
            grouping = fileobj.tags["GROUPING"][0]
            log.debug("Special grouping: %r", grouping)
            if grouping.lower() == "christmas":
                # Is it December?
                if not IS_CHRISTMAS:
                    # No
                    log.debug("Christmas song not in December")
                    continue
            else:
                continue

        # Extract artist/title metadata
        artist = fileobj.tags.get("ARTIST", ["N/A"])[0]
        title = fileobj.tags.get("TITLE", ["N/A"])[0]

        # Compute a key for LMDB, then look up the last play time there
        key = keyof(artist, title)
        with env.begin(db=lastqueued) as txn:
            at_last = txn.get(key)
            if at_last is not None:
                at_last = float(at_last.decode())
                if at_last >= MAX_LAST:
                    # We played this album/title before
                    # (maybe another version)
                    log.debug("%s - %s has been queued recently", artist, title)
                    continue

        with env.begin(db=lastplayed) as txn:
            at_last = txn.get(key)
            if at_last is not None:
                at_last = float(at_last.decode())
                if at_last >= MAX_LAST:
                    # We played this album/title before
                    # (maybe another version)
                    log.debug("%s - %s has been played recently", artist, title)
                    continue

        log.info(
                "Adding %r: %s - %s [%s]",
                file, artist, title,
                fileobj.tags.get("ALBUM", ["N/A"])[0]
        )
        client.add(filename)

        # Mark as added
        client.sticker_set("song", filename, "lastqueued_unixtime", str(NOW))
        with env.begin(db=lastqueued, write=True) as txn:
            txn.put(key, str(NOW).encode("utf-8"))

        # Refresh length
        if refresh < (time.time() - 5):
            refresh = time.time()
            status = client.status()
            playlistlen = int(status['playlistlength'])
            log.info("Playlist has %d tracks, %d expected",
                    playlistlen, args.count)
        else:
            playlistlen += 1
        break

client.disconnect()