This is a bit geeky, because WinMerge is generally a programmer's tool. Typically you open two different versions of a file or folder in WinMerge; it shows the differences in a left/right view, and lets you copy differences from one side to the other.
But that's exactly what you need to selectively sync a music collection from one place to another, like to an mp3 player.
What I do is to open my music collection folder (on my PC) and my mp3 player's music folder in WinMerge. It quickly scans for differences, then shows me
- which folders and files are on left or right only (e.g. not on the mp3 player).
- which folders and files are different (e.g. different folder contents or different file size)
- which files and folders are identical (i.e. in sync)
Because I'm a geek, I store my music collection on a mini Linux file server and access it using Samba over a wireless network. You do not have to do this! But just for interest, in this environment and using the setup below, WinMerge generates the diff view of my collection of around 5,000 tracks in about 3 seconds. Of course it will work just the same but faster with files stored on your PC.
The following instructions assume you have installed and launched WinMerge and have your mass storage class mp3 player connected to your PC. My player is a Sansa Clip.
1. Configure WinMerge to do fast scans of your music collection
Edit -> Options
Select the Compare category
Tick Ignore time differences less than 3 seconds
File Compare Method: Modified Date and Size
Changing the file compare method from Full Contents to Modified Date and Size is key to achieving fast scan times. You don't need a byte by byte comparison to sync your mp3s. Date and filesize comparison is fast and all you need.
2. Open your music collection and your mp3 player in WinMerge
In Select Files or Folders Dialog
Left: select music folder on your PC
Right: select music folder on your mp3 player
Tick Include Subfolders
3. Customize the view
You will want an Explorer tree view: View -> Tree mode
It can be handy to show file size differences:
Tools -> Customize Columns
Add left size and right size
4. Save all this as a WinMerge project
File -> Save Project
On this page you also have option to make one side read only. This is handy if you want to protect your music collection and only copy files in one direction - to your mp3 player.
Next time you want to sync files, just open the project. All your configuration steps are saved.
5. Start syncing
WinMerge is now showing your music collection in an Explorer tree view. Different icons in the tree clearly show you which folders and files are
- on left only (i.e. not on mp3 player):
- on right only (i.e. only on mp3 player)
- or different (e.g. different folder contents, different file size)
Right click the folder or file/s
Copy -> Left to Right
... or just hit the "Copy right" icon in the toolbar:
To check result of the merge, click refresh.