Discovering recordings

There are LOTS of platforms that stream recordings of classical music. They differ in the nature and source of the recordings and the economic model. They all offer text search on composer and title. Some offer additional search and discovery features, as described below.

Commercial

Some platforms stream commercially licensed recordings (i.e. from record companies). They offer free access with ads, or no-ad access for a $10-15 monthly subscription.

• Idagio: classical focus, with an emphasis on 'relaxing' background music. Free with ads; $10/month otherwise. Recordings from major record labels like DG. You can 'like' tracks, artists etc.; this adds them your 'collections'. No social features. No metadata. There's a 'Discover New Music' link, but it's not personalized; the word 'curated' appears everywhere. Curated 'playlists' for various moods and occasions. For example, they have 'top 20' lists of recordings in various categories. In the list of piano pieces, the top 3 are 'Fur Elise', 'Rondo alla Turca', and 'The Entertainer'.
• Spotify, Pandora, iTunes etc. These typically have a discovery tool where you list a few tracks, and it plays an infinite stream of tracks that are related by (I assume) social linkage or attribute linkage. They may use some form of collaborative filtering; it's not revealed.
• YouTube Music is pretty much like Spotify. Thumb up/down ratings, and 'Save to Library'. They make recommendations based on your listening history and ratings (on YouTube as well as YouTube Music). You can choose between 'Familiar' and "Discover'. Odd UI - you have to listen to the recommendations in order. Minimal metadata. No social features.
• Apple Music is (more or less) the new name for iTunes. Some metadata and linkage. No social features. Everything is a 'song'. Playlists and 'radio stations' based on what you've already listened to.
• Apple Music Classical (included with Apple Music) is an iPhone app that provides better metadata and search for classical. Commercial releases only. No discovery features as far as I can tell. $11/month.
• Amazon music unlimited. $17/month. The usual 'radio station' features.
• AllMusic. This is essentially a directory of commercial albums. It doesn't do streaming, but has links to Amazon. They have lots of editorial material - reviews, ratings, artist bios, descriptive tags - supplied by their own staff (not by the public). They also have user-supplied ratings, but use them only for 'average user ratings', not collaborative filtering. They have primitive discovery tools, based on these materials; you can search by arbitrary combinations of genre, dates, ratings, tags, etc. They focus mostly on rock and jazz. They list classical albums but have little editorial material. They show TONS of ads. It's not clear to me who uses their platform, or why.

Semi-commercial

Platforms that essentially act as record companies: they vet performers, then sell their recordings and pay the performers. Some of them host content from record labels.

• Tidal: $11-$20/month. Multi-genre, mostly popular. Classical searches yield mostly MIDI/synth versions. 100M songs (?) and 650K videos. I'm not sure what their discovery tools are. They have 'expert-curated playlists', track-level "add to collection" and "block", artist "follow", and the ability to 'track and share your listening habits'.
• Soundcloud. Mostly popular, some classical. Discovery tools (mostly social linkage): 'related tracks' (not sure of the criteria; seems to be new unrelated stuff); 'In playlists': the playlists this recording is in; 'Likes': see who liked this recording; 'Reposts': not sure what this is; 'Following': you can follow other users; 'comments' (on tracks). No classical metadata.
• prestomusic. Classical, jazz.
• Muziekweb.nl. Dutch, multi-genre, government-funded.
• Classical Music Archive.

Non-commercial

Platforms where anyone can upload recordings.

• audio.com. Text search only.

Hybrid

Sites that have commercial music and also allow arbitrary user uploads.

• YouTube has made it possible to hear obscure music, and lots of renditions of less obscure music, including historical performances, performances by class B/C/D musicians, recordings with video, and recordings with superimposed scores.

  In addition to text search, YouTube provides lists of recommended videos. I'm not sure what the algorithm is, but this is not a bad discovery tool. If you listen to music by a particular obscure composer, you'll get recommendations for related obscure composers.

• Bandcamp. Some classical, no metadata. They have a discover feature which seems to be based on user-supplied tags. You can search on combinations of tags.
• IMSLP has streamable MP3s for many compositions. These are mostly supplied by record companies, but users can upload them also. This provides some attribute search capabilities, albeit with a clumsy interface.

Also:

• Patreon. musicians can upload recordings and get paid by people who like them. Not geared toward classical music.

Most of these platforms don't have good metadata or attribute-based search. Few of them, for example, let you click on a track and see all recordings of that work.

As mentioned, some of them (Spotify, YouTube) make recommendations based on what you've listened to. These mechanisms are incomplete. Typically, they steer you towards music that's already achieved some level of success - it's been commercially published, or commercially recorded, or lots of people have listened to it on the platform. They steer you toward the middle of the taste distribution, not the edges.

Spotify offers a Web API getting 'recommendations' based on 'seed items': tracks, artists, genres, and also with bounds on acoustic parameters like tempo, timbre, etc. It's not personalized.