BackgroundMusic/README.md

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![](Images/README/FermataIcon.png)

# Background Music
##### macOS audio utility

<img src="Images/README/Screenshot.png" width="340" height="443" />

[Overview](#overview)<br/>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[Auto-pause music](#auto-pause-music)<br/>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[Application volume](#application-volume)<br/>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[Recording system audio](#recording-system-audio)<br/> 
[Download](#download)<br/> 
[Build and Install](#installing-from-source-code)</br>
[Uninstall](#uninstall)<br/>
[Troubleshooting](#troubleshooting)<br/> 
[Related Projects](#related-projects)<br/> 
[License](#license)<br/>  

# Overview

+ Automatically pause/unpause your music player when other audio sources are playing/stopped
+ Per-application volume control
+ Record system audio
+ No restart required to install

##### *Note: Background Music is still in alpha.*

## Auto-pause music

**Background Music** automatically pauses your music player when a second audio source is playing and unpauses the player when the second source has stopped.

The auto-pause feature currently supports following music players:

+ [iTunes](https://www.apple.com/itunes/)
+ [Spotify](https://www.spotify.com)
+ [VLC](https://www.videolan.org/vlc/)
+ [VOX](https://vox.rocks/mac-music-player)
+ [Decibel](https://sbooth.org/Decibel/)
+ [Hermes](http://hermesapp.org/)
+ [Swinsian](https://swinsian.com/)
+ [GPMDP](https://www.googleplaymusicdesktopplayer.com/) 

Adding support for a new music player is usually straightforward.<sup id="a1">[1](#f1)</sup> If you don't know how to program, or just don't feel
like it, feel free to [create an issue](https://github.com/kyleneideck/BackgroundMusic/issues/new). Otherwise, see
[BGMMusicPlayer.h](BGMApp/BGMApp/Music%20Players/BGMMusicPlayer.h). 

## Application volume

**Background Music** provides a volume slider for each application running your system. You can boost quiet applications above their maximum volume.

## Recording system audio

You can record system audio with **Background Music**. With **Background Music** running, launch **QuickTime Player** and select **File > New Audio Recording** (or **New Screen Recording**, **New Movie Recording**). Then click the dropdown menu (`⌄`) next to the record button and select **Background Music** as the input device.

You can record system audio and a microphone together by creating an [aggregate
device](https://support.apple.com/en-us/HT202000) that combines your input device (usually Built-in Input) with
the **Background Music** device. You can create the aggregate device using the **Audio MIDI Setup** utility under
***/Applications/Utilities***.

# Download

**Requires macOS 10.10+**.

You can download the current version of **Background Music** using the following options. We also have [snapshot builds](https://github.com/kyleneideck/BackgroundMusic/releases).

| ⚠️ Version 0.3.2 doesn't work on macOS Big Sur. Try this snapshot version: [0.4.0-SNAPSHOT-b38f6dd](https://github.com/kyleneideck/BackgroundMusic/releases/tag/0.4.0-SNAPSHOT-b38f6dd) |
|-------------  |

### Option 1

Download **version 0.3.2**: 

<a href="https://github.com/kyleneideck/BackgroundMusic/releases/download/v0.3.2/BackgroundMusic-0.3.2.pkg"><img 
src="Images/README/pkg-icon.png" width="32" height="32" align="absmiddle" />
BackgroundMusic-0.3.2.pkg</a> (571 KB)

> <sub>MD5: 7f34d9e6595566f3ba14e7afc89c86a2</sub><br/>
> <sub>SHA256: 0cd7b488b5ab97a1ecb496e484a6c209c29f35ab503e6f73b45e56719a7aba18</sub><br/>
> <sub>PGP:
> [sig](https://github.com/kyleneideck/BackgroundMusic/releases/download/v0.3.2/BackgroundMusic-0.3.2.pkg.asc),
> [key (0595DF814E41A6F69334C5E2CAA8D9B8E39EC18C)](https://bearisdriving.com/kyle-neideck.gpg)</sub>

### Option 2

Install using [Homebrew](https://brew.sh/) by running the following command in **Terminal**:

```bash
brew install --cask background-music
```

If you want the snapshot version, run:

```bash
brew tap homebrew/cask-versions
brew install --cask background-music-pre
```

# Installing from Source Code

**Background Music** usually takes less than a minute to build. You need [Xcode](https://developer.apple.com/xcode/download/) version 
8 or higher.

### Option 1

1. Open **Terminal**.
2. Copy and paste the following command into **Terminal**:

```shell
(set -eo pipefail; URL='https://github.com/kyleneideck/BackgroundMusic/archive/master.tar.gz'; \
    cd $(mktemp -d); echo Downloading $URL to $(pwd); curl -qfL# $URL | gzcat - | tar x && \
    /bin/bash BackgroundMusic-master/build_and_install.sh -w && rm -rf BackgroundMusic-master)
```

<details><summary>More info...</summary>

This command uses `/bin/bash` instead of `bash` in case someone has a nonstandard Bash in their `$PATH`. However, it doesn't do this for `tar` or `curl`. In addition, `build_and_install.sh` doesn't call programs by absolute paths. This command also uses `gzcat - | tar x` instead of `tar xz` because `gzcat` will also check the file's integrity (gzip files
include a checksum), and will ensure that a half-downloaded copy of `build_and_install.sh` doesn't run.

</details>

### Option 2

1. Clone or [download](https://github.com/kyleneideck/BackgroundMusic/archive/master.zip) the project.
2. If the project is in a zip, unzip it.
3. Open **Terminal** and [change the directory](https://github.com/0nn0/terminal-mac-cheatsheet#core-commands) to the
   directory containing the project.
4. Run: `/bin/bash build_and_install.sh`.

The script restarts the system audio process (coreaudiod) at the end of the installation, so pause any applications
playing audio if you can.

To manually build and install, see [MANUAL_INSTALL.md](https://github.com/kyleneideck/BackgroundMusic/blob/master/MANUAL-INSTALL.md).

# Uninstall

To uninstall **Background Music** from your system, follow these steps:

1. Open **Terminal**.
2. To locate `uninstall.sh`, run: `cd /Applications/Background\ Music.app/Contents/Resources/`.
3. Run: `bash uninstall.sh`.

If you cannot locate `uninstall.sh`, you can [download the project](https://github.com/kyleneideck/BackgroundMusic/archive/master.zip) again.

To manually uninstall, see [MANUAL_UNINSTALL.md](https://github.com/kyleneideck/BackgroundMusic/blob/master/MANUAL-UNINSTALL.md).

# Troubleshooting

If Background Music crashes and your audio stops working, open `System Preferences > Sound` and change your
system's default output device to something other than the **Background Music device**. If it already is, then
change the default device and then change it back again.

Make sure you allow "microphone access" when you first run Background Music. If you denied it, go to
`System Preferences > Security & Privacy > Privacy > Microphone`, find Background Music in the list
and check the box next to it. Background Music doesn't actually listen to your microphone. It needs
the permission because it gets your system audio from its virtual input device, which macOS counts
as a microphone. (We're working on it in [#177](/../../issues/177).)

If the volume slider for an app isn't working, try looking in `More Apps` for entries like `Some
App (Helper)`. For some meeting or video chat apps, you may need to do this to change the current
meeting volume.

## Known issues and solutions

- **Setting an application's volume above 50% can cause [clipping](https://en.wikipedia.org/wiki/Clipping_(audio)).**

    - Set your volume to its maximum level and lower the volumes of other applications.

- **Only 2-channel (stereo) audio devices are currently supported for output.**

- **VLC pauses iTunes or Spotify when playing, and stops Background Music from unpausing your music afterward.** 

    - Under VLC's preferences, select **Show All**. Navigate to **Interface > Main interfaces > macosx** and change *Control external music players* to either *Do nothing* or *Pause and resume iTunes/Spotify*. 

- **Skype pauses iTunes during calls.** 

    - To disable this, uncheck *Pause iTunes during calls* on the **General** tab of **Skype**'s preferences.

- **Plugging in or unplugging headphones when Background Music isn't running causes silence in the system audio.** 
    - Navigate to **System Preferences > Sound**. Click the **Output** tab and change your default output device to something other than the **Background Music** device. Alternatively, press **Option + Click** on the sound icon within the menu bar to select a different output device. This happens when macOS remembers that the **Background Music** device was your default audio device the last time you used (or didn't use) headphones.

- **[A Chrome bug](https://bugs.chromium.org/p/chromium/issues/detail?id=557620) stops Chrome from switching to the Background Music device after you open Background Music.**
    - Chrome's audio will still play, but **Background Music** won't be aware of it.

- **Some applications play notification sounds that are only just long enough to trigger an auto-pause.**
    - Increase the `kPauseDelayNSec` constant in [BGMAutoPauseMusic.mm](/BGMApp/BGMApp/BGMAutoPauseMusic.mm). It will increase your music's overlap time over other audio, so don't increase it too much. See [#5](https://github.com/kyleneideck/BackgroundMusic/issues/5) for details.

Many other issues are listed in [TODO.md](/TODO.md) and in [GitHub
Issues](https://github.com/kyleneideck/BackgroundMusic/issues).

# Related projects

- [Core Audio User-Space Driver
  Examples](https://developer.apple.com/library/mac/samplecode/AudioDriverExamples/Introduction/Intro.html)
  The sample code from Apple that BGMDriver is based on.
- [Soundflower](https://github.com/mattingalls/Soundflower) - "MacOS system extension that allows applications to pass
  audio to other applications."
- [WavTap](https://github.com/pje/WavTap) - "globally capture whatever your mac is playing—-as simply as a screenshot"
- [eqMac](http://www.bitgapp.com/eqmac/), [GitHub](https://github.com/nodeful/eqMac2) - "System-wide Audio Equalizer for the Mac"
- [llaudio](https://github.com/mountainstorm/llaudio) - "An old piece of work to reverse engineer the Mac OSX
  user/kernel audio interface. Shows how to read audio straight out of the kernel as you would on Darwin (where most the
  OSX goodness is missing)"
- [mute.fm](http://www.mutefm.com), [GitHub](https://github.com/jaredsohn/mutefm) (Windows) - Auto-pause music
- [Jack OS X](http://www.jackosx.com) - "A Jack audio connection kit implementation for Mac OS X"
- [PulseAudio OS X](https://github.com/zonque/PulseAudioOSX) - "PulseAudio for Mac OS X"
- [Sound Pusher](https://github.com/q-p/SoundPusher) - "Virtual audio device, real-time encoder and SPDIF forwarder for
  Mac OS X"
- [Zirkonium](https://code.google.com/archive/p/zirkonium) - "An infrastructure and application for multi-channel sound
  spatialization on MacOS X."
- [BlackHole](https://github.com/ExistentialAudio/BlackHole) - "a modern macOS virtual audio driver that allows applications to pass audio to other applications with zero additional latency."

### Non-free

- [Audio Hijack](https://rogueamoeba.com/audiohijack/), [SoundSource](https://rogueamoeba.com/soundsource/) - "Capture
  Audio From Anywhere on Your Mac", "Get truly powerful control over all the audio on your Mac!"
- [Sound Siphon](https://staticz.com/soundsiphon/), [Sound Control](https://staticz.com/soundcontrol/) - System/app audio recording, per-app volumes, system audio equaliser
- [SoundBunny](https://www.prosofteng.com/soundbunny-mac-volume-control/) - "Control application volume independently."
- [Boom 2](https://www.globaldelight.com/boom/) - "The Best Volume Booster & Equalizer For Mac"

## License

Copyright © 2016-2021 [Background Music contributors](https://github.com/kyleneideck/BackgroundMusic/graphs/contributors).
Licensed under [GPLv2](https://www.gnu.org/licenses/gpl-2.0.html), or any later version.

**Background Music** includes code from:

- [Core Audio User-Space Driver
  Examples](https://developer.apple.com/library/mac/samplecode/AudioDriverExamples/Introduction/Intro.html), [original
  license](LICENSE-Apple-Sample-Code), Copyright (C) 2013 Apple Inc. All Rights Reserved.
- [Core Audio Utility
  Classes](https://developer.apple.com/library/content/samplecode/CoreAudioUtilityClasses/Introduction/Intro.html),
  [original license](LICENSE-Apple-Sample-Code), Copyright (C) 2014 Apple Inc. All Rights Reserved.

----

<b id="f1">[1]</b> However, if the music player doesn't support AppleScript, or doesn't support the events Background
Music needs (`isPlaying`, `isPaused`, `play` and `pause`), it can take significantly more effort to add. (And in some
cases would require changes to the music player itself.) [↩](#a1)