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View Full Version : Google Play Music Matching - how does it work?



d6jg
2016-01-20, 13:47
I "backup" my FLACS to Google Play in addition to a proper backup.
The upload via their Music Manager software does a couple of things
1) it transcodes FLACS to MP3
2) in the event that a track matches an item in their library the file isn't uploaded instead it uses the Google track
Does anyone know anything more about the matching system. It seems hit and miss to me but there is no log of what's going on.
I know that some of the files are Google's as some of my FLACs are ripped from vinyl and despite the "clean up" software still carry the odd pop or crackle. In some cases the Google MP3 clearly does not have any such noise so must be a match from their library but in other cases the pops etc are still there. It seems entirely random as I ripped a bunch of Eric Clapton vinyl albums a month or two ago. 461 on Google is clean but One In Every Crowd is just a transcode of my vinyl.
Does anyone know more about how it works? I have Googled but info is thin on the subject.

pippin
2016-01-20, 14:21
I think it just uses tags

d6jg
2016-01-20, 14:37
I think it just uses tags

So you think if a tag doesn't exactly match their database it doesn't work for a whole album?

At what level would you imagine the comparison is - album or track?

I can't see how I could of tagged the Artist / Album wrongly for Eric Clapton / Backless which is one that isn't matched. Maybe at track level there could be a typo or other difference.

Your theory does make sense as I have a vinyl copy of Best Of Cream which never made it to CD. Not at all rare but it is the only Cream album which carries the single version of White Room. All others carry the full album version.

The album in question is scratchy but Google have replaced my FLACs with a clean MP3 except that White Room is the full album version which proves it is a match!

In some cases I am going to replace my scratchy FLACs with Google mp3s. Some of my wife's albums really have been abused to a degree where a 256kbps MP3 is better than a vinyl rip to FLAC. This may also be the case for Best of Cream but I really would like the single version of White Room - a bit OCD is me.

d6jg
2016-01-21, 03:35
I did some tests this AM.

I chose one of my Eric Clapton albums which wasn't "matched". It was There's One In Every Crowd ripped from vinyl to FLAC.

I found that one track has a slightly different title to what appeared in Wikipedia and on Amazon so I changed the tag on my FLAC to match. Deleted the album from Google play and re-uploaded. It is now a clean matched mp3 without the scratchy intro.

This tells me that Google operate the matching at a folder/track level i.e. if one file in a folder is wrongly tagged then the whole folder is physically uploaded and the whole album is simply a transcoded version of my FLAC scratches and all.

In this case the error was simple to spot - the track in question was tagged as We've Been Told (Jesus Coming Soon) when it apparently should be We've Been Told (Jesus Is Coming Soon). EDIT Eric & Yvonne never sing the "Is"

Blondie's Plastic Letters is also unmatched and a quick scan of the tracks suggests to me that the culprit is (I'm Always Touched by Your) Presence Dear which should be (I'm Always Touched by Your) Presence, Dear

Capitalisation seems to have been accounted for in the algorithm but not missing characters.

I wonder what would happen if I took a bunch of say 10 random mp3s or FLACs stuck them together into one folder and tagged them as the ten tracks from say Abbey Road. If the tagging was correct would Google present me a nice hires set of mp3s that were actually Abbey Road ? Dare I ?

Note. Before someone says surely the track length matters. No. I mentioned Best of Cream and White Room earlier. The track Google give you is the album version at over 4 mins but their library says it is the 3 minute something single version. When you play it the track continues playing after the track end point !!