|BLUEALSA(8)||System Manager’s Manual||BLUEALSA(8)|
bluealsa - Bluetooth Audio ALSA Backend
bluealsa is a Linux daemon to give applications access to Bluetooth audio streams using the Bluetooth A2DP, HFP and/or HSP profiles. It provides a D-Bus API to applications, and can be used by ALSA applications via libasound plugins.
- -h, --help
- Output a usage message and exit.
- -V, --version
- Output the version number and exit.
- -B, --dbus=NAME
- BlueALSA D-Bus service name suffix. Without this option, bluealsa registers itself as an “org.bluealsa” D-Bus service. For more information see the EXAMPLE below.
- -S, --syslog
- Send output to system logger (syslogd(8)). By default, system output is sent to stderr.
- -i, --device=hciX
- HCI device to use. Can be specified multiple times to select more than one HCI. Because HCI numbering can change after a system reboot, this option also accepts HCI MAC address for the hciX value, e.g: --device=00:11:22:33:44:55.
- -p, --profile=NAME
- Enable NAME Bluetooth profile. Without this option, bluealsa enables a2dp-source, hfp-ag and hsp-ag. For the list of supported profiles see the PROFILES section below.
- Force monophonic sound for A2DP profile.
- Force 44.1 kHz sampling frequency for A2DP profile. Some bluetooth devices can handle streams sampled at either 48kHz or 44.1kHz, in which case they normally default to using 48kHz. With this option, bluealsa will request such a device uses only 44.1 kHz sample rate.
- Keep A2DP transport alive for SEC number of seconds after streaming was closed. This option can be useful when playing short audio files in quick succession. It will reduce the gap between playbacks caused by Bluetooth audio transport acquisition.
- Enable native A2DP volume control. By default bluealsa will use its own internal scaling algorithm to attenuate the volume. This option disables that internal scaling and instead passes the volume change request to the A2DP device. This feature can also be controlled during runtime via BlueALSA D-Bus API. Note that this feature might not work with all Bluetooth headsets.
- Set SBC encoder quality, where NB can be one of:
- 0 - low audio quality (mono: 114 kbps, stereo: 213 kbps)
- 1 - medium audio quality (mono: 132 kbps, stereo: 237 kbps)
- 2 - high audio quality (mono: 198 kbps, stereo: 345 kbps) (default)
- 3 - SBC Dual Channel HD (SBC XQ) (452 kbps)
- Selects LAME encoder internal algorithm. The NB can be in the range from 0 to 9, where 0 is the best quality but requires a lot of CPU power. Default value is 5.
- Specifies variable bit rate (VBR) quality, where NB can be in the range from 0 to 9. For best VBR quality use 0. Default value is 2 (hight quality VBR mode).
- Enables Fraunhofer AAC afterburner feature, which is a type of analysis by synthesis algorithm. This feature increases the audio quality at the cost of increased processing power and overall memory consumption.
- Select LATM syntax version used for AAC audio transport. Default value is 1.
The NB can be one of:
- 0 - LATM syntax specified by ISO-IEC 14496-3 (2001), should work with all older BT devices
- 1 - LATM syntax specified by ISO-IEC 14496-3 (2005), should work with newer BT devices
- Specifies AAC encoder variable bit rate (VBR) quality, or disables it. The NB can be one of:
- 0 - disables variable bit rate mode and uses constant bit rate specified by the A2DP AAC configuration
- 1 - lowest quality VBR mode (mono: 32 kbps, stereo: 40 kbps)
- 2 - low quality VBR mode (mono: 40 kbps, stereo: 64 kbps)
- 3 - medium quality VBR mode (mono: 56 kbps, stereo: 96 kbps)
- 4 - high quality VBR mode (mono: 72 kbps, stereo: 128 kbps) (default)
- 5 - highest quality VBR mode (mono: 112 kbps, 192 kbps)
- Enables LDAC adaptive bit rate, which will dynamically adjust encoder quality based on the connection stability.
- Specifies LDAC encoder quality, where NB can be one of:
- 0 - high quality (44.1 kHz: 909 kbps, 48 kHz: 990 kbps)
- 1 - standard quality (44.1 kHz: 606 kbps, 48 kHz: 660 kbps) (default)
- 2 - mobile quality (44.1 kHz: 303 kbps, 48 kHz: 330 kbps)
BlueALSA provides support for Bluetooth Advanced Audio Distribution Profile (A2DP), Hands-Free Profile (HFP) and Headset Profile (HFP). A2DP profile is dedicated for streaming music (i.e. stereo, 48 kHz or more sampling frequency), while HFP and HSP for two-way voice transmission (mono, 8 kHz or 16 kHz sampling frequency). With A2DP, BlueALSA includes mandatory SBC codec and various optional codecs like AAC, aptX, and other. The full list of available optional codecs, which depends on selected compilation options, will be shown with bluealsa command-line help message.
The list of profile NAMEs accepted by the --profile=NAME option:
- a2dp-source - Advanced Audio Source (streaming audio to connected device)
- a2dp-sink - Advanced Audio Sink (receiving audio from connected device)
- hfp-ofono - Hands-Free handled by oFono
- hfp-hf - Hands-Free
- hfp-ag - Hands-Free Audio Gateway
- hsp-hs - Headset
- hsp-ag Headset Audio Gateway
The hfp-ofono is available only when bluealsa was compiled with oFono support. Enabling HFP over oFono will automatically disable hfp-hf and hfp-ag.
- BlueALSA service D-Bus policy file.
Emulate Bluetooth headset with A2DP and HFP support:
bluealsa -p a2dp-sink -p hsp-hs
On systems with more than one HCI device, it is possible to expose different profiles on different HCI devices. A system with three HCI devices might (for example) use hci0 for an A2DP sink service named “org.bluealsa.sink” and both hci1 and hci2 for an A2DP source service named “org.bluealsa.source”. Such a setup might be created as follows:
bluealsa -B sink -i hci0 -p a2dp-sink & bluealsa -B source -i hci1 -i hci2 -p a2dp-source &
Setup like this will also require a change to the BlueALSA D-Bus configuration file in order to allow connection with BlueALSA services with suffixed names. Please add following lines to the BlueALSA D-Bus policy:
... <allow send_destination="org.bluealsa.sink" /> <allow send_destination="org.bluealsa.source" /> ...
Project web site at https://github.com/Arkq/bluez-alsa
Copyright (c) 2016-2020 Arkadiusz Bokowy.
The bluez-alsa project is licensed under the terms of the MIT license.
|August 2020||BlueALSA v3.0.0|