local files - is syncing re-downloading?

[spicycabbage]

so here's what I know:

the only way to play local files on spotify is to put your local files in one playlist and download that playlist. even if you have bought/downloaded music files on your phone, spotify cannot play them unless they are uploaded to your computer, put in a spotify playlist, and then 'synced' or downloaded.

and here's my question:

if i have music files already downloaded on my phone but want to listen to them on spotify, and so 'sync' the files, am I re-downloading them? will I be using twice as much space?

not sure if this is a silly/easy question but i couldn't find the info anywhere on the website/forum. thanks.

[spicycabbage]

OH and if i sync a playlist from spotify does that mean i can use those synced local files and play them on a different app? or are they 'synced' in that they are only available through spotify?

[neo-x]

If you have files such as MP3 files on your devices memory as files (.mp3 etc) and you Sync the files from Spotify, They are then twice in the device after the "sync" / download. You can find your synced tracks with the file browser
from (my example: /sdcard/external_sd/Android/data/com.spotify.mobile.android.ui/cache/Users/userid-user/LocalSync .

(I have set my cache to go to my SD card)