A tool to easily maintain a smaller-size copy of your music library, and keep it in sync with your main library. Useful for keeping a compact version of your music library on a mobile device.

Features

• Transcodes files to a smaller format
• Handles many music filetypes:
  • MP3
  • FLAC
  • ogg
  • m4a
  • opus (be sure your ffmpeg is compiled with --enable-libopus, or this won't work)
• Output encoding can be selected from the above
• Plays well with mixed-encoding music libraries as input (MP3 + FLAC, etc)
• Directly copies files that are already of lower quality than the required quality instead of transcoding them.
• Multi-threaded querying and encoding
• Only re-encodes files that have been changed. Leaves unchanged files untouched.
• Select how to handle album art
• Dry run for if you want to try it out first.
• Maintains existing folder structure
• Filters out excess files. Does not copy over .cue, extra images, etc.

How to use

It should be pretty simple! syncbops /path/to/source/library /path/to/target/library <encoding>

syncbops takes two main arguments: First is a source library, which is the folder where you keep all your music (e.g. ~/Music/ on linux, or C:/Users/<username>/Music on windows). This folder will not be touched, it will just be read. Then the target library, which is where you want to synchronise to (another folder on your computer, a folder on your phone).

Finally, you should pass the encoding you want to transcode to. see the list above for supported formats.

There are several other things you can tweak about the behaviour of the program by passing flags and optional arguments. Check them at syncbops --help.

Examples

I have a music library at ~/Music. Inside this directory, songs are organised AlbumArtistName/AlbumName/01. Song Title. Most of the music here is in FLAC, but there are some MP3s, some m4a, and some ogg files too. I have mounted my phone's storage with a usb cable at /mnt/phone. It is an android phone, so music is stored at /mnt/phone/music. I have not synchronised my collection yet on this device. I want to encode everything in MP3 VBR with quality factor 3. I would use:

syncbops ~/Music /mnt/phone/music/ mp3-vbr -q 3

%% add example for art strategy %%

Installation

Easiest way is to install through cargo! This will build the program from source, so it should work on any platform.

cargo install syncbops

Alternatively, you can download precompiled binaries on the releases page, and put it on your PATH. %% TODO: Add a simple download command that automatically puts it in ~/.local/bin and chmod+x's it

Dependencies

This program uses ffmpeg under the hood. It has been tested with version 4.4.2, but it should run with newer too.

Advanced usage

Usage guide on advanced usage flags.

Output formats

You can further customise the target encoding, e.g. to set a specific target bitrate. Check these out with for example syncbops <source_lib> <target_lib> mp3-vbr --help. Think of values like bitrates for fixed bitrate formats, quality factors for variable bitrate formats, and compression for FLAC. If you don't supply these explicitly, (sane) default values will be used.

Art Strategy

The album art can be supplied in two different ways:

• Embedded into the file
• External

You can choose how you want to have album art in the synchronised library.

• none: Remove all embedded album art, and don't copy album art files
• embed-all: Embeds album art in all files. Carries over album art that was already in source files, and embeds external album art. Might take up more space!
• prefer-file: If there is both embedded and external, prefer external. E.g. If there is a cover.jpg (or similar), use that. If there is no dedicated file, use embedded art
• file-only: Do not embed any cover art: Discard all existing embedded art, only keep cover.jpg if it exists

Records

Checking if a file has changed requires a lot of reading from disk and comparing two files, which is not very fast. Saving the state of the first file at the time of synchronising to a little file can help speed this up. By default, such a file is written to the target directory and used in consecutive synchronisation runs (and updated). If the records are not present, either because you explicitly told the program not to write records, or because you deleted them manually, the fallback method is used instead.

Do note that if you turn off writing records, but there are already records present, the next run might not accurately represent the state of synchronisation of the library.

Roadmap

• Allow setting maximum resolution for cover art, and automatically make it smaller if it is larger.
• Handle centralised album art directories (AlbumName.jpg)
• Handle deleting songs, not just adding.
• Option to force re-encoding of specific filetypes, even if they are of lower bitrate (useful if an encoding is not supported on yoir target device)
• Sync playlist files (.m3u etc)