AURACAST TOOL

The "auracast" tool implements commands that implement broadcasting, receiving and controlling LE Audio broadcasts.

Running as an installed packageRunning from source

$ bumble-auracast

$ python3 apps/auracast.py <args>

Python Dependencies

Try installing the optional [auracast] dependencies:

From sourceFrom PyPI

$ python3 -m pip install ".[auracast]"

$ python3 -m pip install "bumble[auracast]"

LC3

The auracast app depends on the lc3 python module, which is available either as PyPI module (currently only available for Linux x86_64). When installing Bumble with the optional auracast dependency, the lc3 module will be installed from the lc3py PyPI package if available. If not, you will need to install it separately. This can be done with:

$ python3 -m pip install "git+https://github.com/google/liblc3.git"

SoundDevice

The sounddevice module is required for audio output to the host's sound output device(s) and/or input from the host's input device(s). If not installed, the auracast app is still functional, but will be limited to non-device inputs and output (files, external processes, ...)

On macOS and Windows, the sounddevice module gets installed with the native PortAudio libraries included.

For Linux, however, PortAudio must be installed separately. This is typically done with a command like:

$ sudo apt install libportaudio2

Visit the sounddevice documentation for details.

General Usage

Usage: bumble-auracast [OPTIONS] COMMAND [ARGS]...

Options:
  --help  Show this message and exit.

Commands:
  assist    Scan for broadcasts on behalf of an audio server
  pair      Pair with an audio server
  receive   Receive a broadcast source
  scan      Scan for public broadcasts
  transmit  Transmit a broadcast source

Use bumble-auracast <command> --help to get more detailed usage information for a specific <command>.

assist

Act as a broadcast assistant.

Use bumble-auracast assist --help for details on the commands and options.

The assistant commands are:

monitor-state

Subscribe to the state characteristic and monitor changes.

add-source

Add a broadcast source. This will instruct the device to start receiving a broadcast.

modify-source

Modify a broadcast source.

remove-source

Remote a broadcast source.

pair

Pair with a device.

receive

Receive a broadcast source.

The --output option specifies where to send the decoded audio samples. The following outputs are supported:

Sound Device

The --output argument is either device, to send the audio to the hosts's default sound device, or device:<DEVICE_ID> where <DEVICE_ID> is the integer ID of one of the available sound devices. When invoked with --output "device:?", a list of available devices and their IDs is printed out.

Standard Output

With --output stdout, the decoded audio samples are written to the standard output (currently always as float32 PCM samples)

FFPlay

With --output ffplay, the decoded audio samples are piped to ffplay in a child process. This option is only available if ffplay is a command that is available on the host.

File

With --output <filename> or --output file:<filename>, the decoded audio samples are written to a file (currently always as float32 PCM)

transmit

Broadcast an audio source as a transmitter.

The --input and --input-format options specify what audio input source to transmit. The following inputs are supported:

Sound Device

The --input argument is either device, to use the host's default sound device (typically a builtin microphone), or device:<DEVICE_ID> where <DEVICE_ID> is the integer ID of one of the available sound devices. When invoked with --input "device:?", a list of available devices and their IDs is printed out.

Standard Input

With --input stdout, the audio samples are read from the standard input. (currently always as int16 PCM).

File

With --input <filename> or --input file:<filename>, the audio samples are read from a .wav or raw PCM file.

Use the --input-format <FORMAT> option to specify the format of the audio samples in raw PCM files. <FORMAT> is expressed as: <sample-type>,<sample-rate>,<channels> (the only supported currently is 'int16le' for 16 bit signed integers with little-endian byte order)

scan

Scan for public broadcasts.

A live display of the available broadcasts is displayed continuously.

Compatibility With Some Products

The auracast app has been tested for compatibility with a few products. The list is still very limited. Please let us know if there are products that are not working well, or if there are specific instructions that should be shared to allow better compatibiity with certain products.

Transmitters

The receive command has been tested to successfully receive broadcasts from the following transmitters:

• JBL GO 4
• Flairmesh FlooGoo FMA120
• Eppfun AK3040Pro Max
• HIGHGAZE BA-25T
• Nexum Audio VOCE and USB dongle

Receivers

Pixel Buds Pro 2

The Pixel Buds Pro 2 can be used as a broadcast receiver, controlled by the auracast assist command, instructing the buds to receive a broadcast.

Use the assist --command add-source command to tell the buds to receive a broadcast.

Use the assist --command monitor-state command to monitor the current sync/receive state of the buds.

JBL

The JBL GO 4 and other JBL products that support the Auracast feature can be used as transmitters or receivers.

When running in receiver mode (pressing the Auracast button while not already playing), the JBL speaker will scan for broadcast advertisements with a specific manufacturer data. Use the --manufacturer-data option of the transmit command in order to include data that will let the speaker recognize the broadcast as a compatible source.

The manufacturer ID for JBL is 87. Using an option like --manufacturer-data 87:00000000000000000000000000000000dffd should work (tested on the JBL GO 4. The dffd value at the end of the payload may be different on other models?).

Others

• Nexum Audio VOCE and USB dongle