music-transfer

A small utility to seamlessly transfer music playback between two computers.

Before you get too excited - no, there isn't any fancy over-the-network music streaming going on. music-transfer is basically just a wrapper around the Spotify Connect API (for music handoff) + a simple client/server app to sync system volume.

music-transfer was designed with display-switch in mind, as I wanted seamless spotify handoff between my work/personal PC.

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NOTE: At the moment, cross-computer volume sync is only implemented on Windows!

If you'd like to contribute volume sync functionality for MacOS/Linux/etc, PRs are more than welcome!

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Example: Using music-transfer alongside display-switch

As mentioned earlier, music-transfer was designed to integrate nicely with display-switch.

Here's a copy of the display-switch.ini that I use to achieve seamless music handoff as part of the KVM switch.

usb_device = "1532:005C"
on_usb_connect = "DisplayPort1"
on_usb_disconnect = "Hdmi1"

on_usb_connect_execute = "'C:\\Users\\daprilik\\bin\\music-transfer.exe' --config-path 'C:\\Users\\daprilik\\bin\\music_transfer_config.json' --spotify-token-cache-path 'C:\\Users\\daprilik\\bin\\.spotify_token_cache.json' transfer local --sync-volume --spotify"
on_usb_disconnect_execute = "'C:\\Users\\daprilik\\bin\\music-transfer.exe' --config-path 'C:\\Users\\daprilik\\bin\\music_transfer_config.json' --spotify-token-cache-path 'C:\\Users\\daprilik\\bin\\.spotify_token_cache.json' transfer remote --sync-volume --spotify"

Note that you could avoid explicitly passing --config-path and --spotify-token-cache-path by figuring out which working directory display-switch.exe is run from, but I prefer to be explicit over implicit.

Setup

Run cargo build --release, and a binary will pop out at <repo>/target/release/music-transfer.

Spotify Authentication

The first time you want to do something spotify related with music-transfer, you'll need to go through the Spotify authentication flow.

I suggest running music-transfer list-spotify-devices, as that's a quick and easy way to validate that you can talk to the Spotify API.

After running this command, a browser window will pop up asking you to login to Spotify. Upon successful login, you'll be redirected to a webpage specified in "spotify_redirect_uri", the URL of which you'll need to copy-paste into the CLI window.

At this point, you should see a list of Spotify Connect devices get listed.

If that didn't work, double-check that you've set up your Spotify developer account properly (as discussed under the spotify_creds section below).

Volume Sync - Remote Server

You'll want to set music-transfer audio-server to auto-launch at startup.

Windows

• Create a shortcut to the music-transfer.exe
• Open the shortcut's Properties, and modify the "target" to include the following CLI params: audio-server --port 12345
• Open Run (Win + R), and run shell:startup
• Drag the shortcut into that folder

The music-transfer audio server will now launch automatically at startup.

Configuration

Depending on what features you're using, you'll need to fill out different/all parts of the configuration file. It's pretty obvious what features correspond to what settings, and if something isn't right, you should get a helpful error message telling you what you're missing.

Notably, volume-server does not require any config options to be set, as it is entirely configured via the CLI.

{
    "spotify_creds": {
        "spotify_client_id": "00000000000000000000000000000000",
        "spotify_client_secret": "00000000000000000000000000000000",
        "spotify_redirect_uri": "https://example.com/whatever"
    },
    "spotify_transfer": {
        "spotify_name_remote": "REMOTE_COMUTER_NAME",
        "spotify_name_local": "LOCAL_COMPUTER_NAME"
    },
    "volume_sync": {
        "remote_host": "REMOTE_COMUTER_NAME.local",
        "remote_port": "12345"
    }
}

spotify_creds

In order to connect to the Spotify API, you'll need to register for a Spotify developer account and provide music-transfer with a few bits of information.

See https://docs.rs/rspotify/0.11.3/rspotify/#authorization for details.

spotify_transfer

• spotify_name_remote: friendly Spotify name for the remote computer
• spotify_name_local: friendly Spotify name for the local computer

Note: you can use music-transfer list-spotify-devices to list available spotify connect devices.

volume_sync

In order to sync volume across computers, the remote computer needs to be running an instance of music-transfer audio-server.

• remote_host: Hostname of remote computer (e.g: IP address, .local addr)
• remote_port: Port to connect to on the remote computer