Ubuntu Manpage: bluealsa-aplay - a simple bluealsa player

Provided by: bluez-alsa-utils_4.0.0-2_amd64

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

-h, --help
Output a usage message and exit.

-V, --version
Output the version number and exit.

-v, --verbose
Make the output more verbose.

-l, --list-devices
List connected Bluetooth audio devices.

-L, --list-pcms
List available Bluetooth audio PCMs on connected devices.

-B NAME, --dbus=NAME
BlueALSA service name suffix. For more information see --dbus=NAME option of
bluealsa(8) service daemon.

-D NAME, --pcm=NAME
Select ALSA playback PCM device to use for audio output. The default is default.

bluealsa-aplay does not perform any mixing of streams. If multiple devices are
connected it opens a new connection to the ALSA PCM device for each stream.
Therefore the PCM NAME must itself allow multiple open connections and mix the
streams together. See option --single-audio to change this behavior. Similarly,
bluealsa-aplay does not apply any transformations to the stream. For this reason it
is often necessary to use the ALSA dmix and plug plugins in the NAME PCM.

--pcm-buffer-time=INT
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.

--pcm-period-time=INT
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 section below for more information on rate calculation rounding
errors.

-M NAME, --mixer-device=NAME
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.

--mixer-name=NAME
Set the name of the mixer element. The default is Master.

--mixer-index=NUM
Set the index of the mixer channel. The default is 0.

--profile-a2dp
Use A2DP profile (default).

--profile-sco
Use SCO profile.

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

--single-audio
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).

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
                  }
              }
          }

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