Scroll to navigation

BLUEALSA-APLAY(1) General Commands Manual BLUEALSA-APLAY(1)

NAME

bluealsa-aplay - a simple bluealsa player

SYNOPSIS

bluealsa-aplay [OPTION]... [BT-ADDR]...

DESCRIPTION

Capture audio streams from Bluetooth devices (via bluealsa(8)) and play them to an ALSA playback device.

By default bluealsa-aplay captures audio from all connected Bluetooth devices. It is possible to select specific Bluetooth devices by providing a list of BT-ADDR MAC addresses. Using the special MAC address 00:00:00:00:00:00 will disable device filtering - the same as the default behavior.

OPTIONS

Output a usage message and exit.
Output the version number and exit.
Send output to system logger (syslogd(8)). By default, log output is sent to stderr.
Make the output more verbose.
List connected Bluetooth audio devices.
List available Bluetooth audio PCMs on connected devices.
BlueALSA service name suffix. For more information see --dbus=NAME option of bluealsa(8) service daemon.
Select ALSA playback PCM device to use for audio output. The default is default.

Internally, bluealsa-aplay does not perform any audio transformations nor streams mixing. If multiple Bluetooth devices are connected it simply opens a new connection to the ALSA PCM device for each stream. Selected hardware parameters like sampling frequency and number of channels are taken from the audio profile of a particular Bluetooth connection. Note, that each connection can have a different setup.

If playing multiple streams at the same time is not desired, it is possible to change that behavior by using the --single-audio option.

For more information see the EXAMPLES section below.

Set the playback PCM buffer duration time to INT microseconds. The default is 500000. It is recommended to choose a buffer time that is an exact multiple of the period time to avoid potential issues with some ALSA plugins (see --pcm-period-time option below). ALSA may choose the nearest available alternative if the requested value is not supported.

If you experience underruns on the ALSA device then a larger buffer may help. However, a larger buffer will also increase the latency. For reliable performance the buffer time should be at least 3 times the period time.

Set the playback PCM period duration time to INT microseconds. The default is 100000. ALSA may choose the nearest available alternative if the requested value is not supported.

The ALSA rate plugin, which may be invoked by plug, does not always produce the exact required effective sample rate because of rounding errors in the conversion between period time and period size. This can have a significant impact on synchronization "drift", especially with small period sizes, and can also result in stream underruns (if the effective rate is too fast) or dropped A2DP frames in the bluealsa(8) server (if the effective rate is too slow). This effect is avoided if the selected period time results in an exact integer number of frames for both the source rate (Bluetooth) and sink rate (hardware card). For example, in the case of Bluetooth stream sampled at 44100Hz playing to a hardware device that supports only 48000Hz, choosing a period time that is a multiple of 10000 microseconds will result in zero rounding error. (10000 µs at 44100Hz is 441 frames, and at 48000Hz is 480 frames).

See also dmix in the NOTES section below for more information on rate calculation rounding errors.

Select ALSA mixer device to use for controlling audio output mute state and volume level. In order to use this feature, BlueALSA PCM can not use software volume. The default is default.

See Volume control in the NOTES section below for more information on volume control.

Set the name of the ALSA simple mixer control to use. The default is Master.

To work with bluealsa-aplay this simple control must provide decibel scaling information for the volume control. Most, but not all, modern sound cards do provide this information.

Set the index of the ALSA simple mixer control. The default is 0.

This is required only if the simple mixer control name applies to multiple simple controls on the same card. This is most common with HDMI devices which may have many playback ports.

Use A2DP profile (default).
Use SCO profile.

Note: Only one of A2DP or SCO can be used. If both are specified, the last one given will be selected.

Allow only one Bluetooth device to play audio at a time. If multiple devices are connected, only the first to start will play, the others will be paused. When that first device stops, then the next to send audio will be played.

Without this option, bluealsa-aplay plays audio from all selected Bluetooth devices. Please note that playing from all Bluetooth devices at a time requires used PCM to be able to mix audio from multiple sources (i.e., it can be opened more than once; for example the ALSA dmix plugin).


NOTES

Volume control

If the BlueALSA PCM is using native Bluetooth volume control, then bluealsa-aplay operates its given ALSA mixer control to implement volume change requests received from the remote Bluetooth device.

If the Bluetooth PCM is using soft-volume volume control, then volume adjustment will have been applied to the PCM stream within the bluealsa daemon; so bluealsa-aplay does not operate the mixer control in this case.

Native Bluetooth volume control for A2DP relies on AVRCP volume control in BlueZ, which has not always been reliably implemented. It is recommended to use BlueZ release 5.65 or later to be certain that native A2DP volume control will always be available with those devices which provide it.

See bluealsa(8) for more information on native and soft-volume volume control.

dmix

The ALSA dmix plugin will ignore the period and buffer times selected by the application (because it has to allow connections from multiple applications). Instead it will choose its own values, which can lead to rounding errors in the period size calculation when used with the ALSA rate plugin. To avoid this, it is recommended to explicitly define the hardware period size and buffer size for dmix in your ALSA configuration. For example, suppose we want a period time of 100000 µs and a buffer holding 5 periods with an Intel 'PCH' card:

defaults.dmix.PCH.period_time 100000
defaults.dmix.PCH.periods 5


Alternatively we can define a PCM with the required setting:

pcm.dmix_rate_fix {


    type plug


    slave.pcm {


        type dmix


        ipc_key 12345


        slave {


            pcm "hw:0,0"


            period_time 100000


            periods 5


        }


    }
}


EXAMPLES

The simplest usage of bluealsa-aplay is to run it with no arguments. It will play audio from all connected Bluetooth devices to the default ALSA playback PCM.

bluealsa-aplay


If there is more than one sound card attached one can create a setup where the audio of a particular Bluetooth device is played to a specific sound card. The setup below shows how to do this using the --pcm=NAME option and known Bluetooth device addresses.

Please note that in the following example we assume that the second card is named "USB" and the appropriate mixer control is named "Speaker". Real names of attached sound cards can be obtained by running aplay -l. A list of control names for a card called "USB" can be obtained by running amixer -c USB scontrols.

bluealsa-aplay --pcm=default 94:B8:6D:AF:CD:EF F8:87:F1:B8:30:85 &
bluealsa-aplay --pcm=default:USB C8:F7:33:66:F0:DE &


Also, it might be desired to specify ALSA mixer device and/or control element for each ALSA playback PCM device. This will be mostly useful when BlueALSA PCM does not use software volume (for more information see --a2dp-volume option of bluealsa(8) service daemon).

bluealsa-aplay --pcm=default 94:B8:6D:AF:CD:EF F8:87:F1:B8:30:85 &
bluealsa-aplay --pcm=default:USB --mixer-device=hw:USB --mixer-name=Speaker C8:F7:33:66:F0:DE &


Such setup will route 94:B8:6D:AF:CD:EF and F8:87:F1:B8:30:85 Bluetooth devices to the default ALSA playback PCM device and C8:F7:33:66:F0:DE device to the USB sound card. For the USB sound card the Speaker control element will be used as a hardware volume control knob.

COPYRIGHT

Copyright (c) 2016-2023 Arkadiusz Bokowy.

The bluez-alsa project is licensed under the terms of the MIT license.

SEE ALSO

amixer(1), aplay(1), bluealsa-rfcomm(1), bluealsa(8)

https://github.com/arkq/bluez-alsa

January 2023 BlueALSA v4.1.1