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BTA2DPD(8)                  System Manager's Manual                 BTA2DPD(8)

     bta2dpd - Bluetooth Advanced Audio Distribution Profile daemon

     bta2dpd [-Dnv] [-A bitpool_allocation] [-B bitpool] [-b blocks]
             [-d device] [-e encoding_bands] [-f channel_mode] [-M mtu]
             [-m mode] [-r rate] [-V volume] -a address files ...
     bta2dpd -K [-DIv] [-A bitpool_allocation] [-B bitpool] [-b blocks]
             [-d device] [-e encoding_bands] [-f channel_mode] [-m mode]
             [-p psm] [-r rate] [a address] file
     bta2dpd -t [-A bitpool_allocation] [-B bitpool] [-b blocks]
             [-e encoding_bands] [-f channel_mode] [-M mtu] [-r rate]
             [-V volume] files ...
     bta2dpd -t -K file

     The bta2dpd daemon is used to transmit/receive audio to/from Bluetooth
     devices such as speakers or headphones, using the Advanced Audio
     Distribution Profile (A2DP).

     -a address
             Remote device address.  The address may be given as BDADDR or a

             If a name was specified, bta2dpd attempts to resolve the name via

     -B bitpool
             Allows setting the maximum bitpool value for your device.  This
             may have to be lowered if audio is distorted.

             Use bta2dpd with only the -v option and the maximum bitpool for
             your device will be printed to stdout.

     -D      Run in the background.

     -n      Do not close connection on end of file (EOF).  Useful for pad(4).

     -d device
             Local device address.  May be given as BDADDR or device name.

     -I      Initiate a Discover command.
              Useful when used as an audio sink as some devices need this to

     -K      Allows registering as an audio sink receiving an incoming

     -M mtu  Allows setting the Maximum Transmission Unit (MTU) for the
             streaming connections.

             For most devices this would be 672 but if audio is broken or has
             gaps lowering this value may help.

     -m mode
             Set L2CAP connection link mode.  Supported modes are:

             auth     Require devices to be paired.
             encrypt  Auth, plus enable encryption.
             secure   Encryption, plus change of link key.

     -p psm  Allows changing the l2cap psm for an audio sink the default is
             25.  Most all devices will use 25.

     -t      Test mode can be used with -K to decode and receive encoded music
             from stdout/stdin to file.

     -V volume
             Allows shifting the volume of the music by 1 or 2 bits prior to
             encoding for increased volume.

             USE WITH CARE as this may mean the output is quite loud.

     -v      Be verbose.

     files ...
             Files to stream.  These can be WAV files or CD-Audio Red Book
             data or output from a pad(4) device.  If not specified, the
             default is stdin or stdout if -K applied and bta2dpd is used as
             an audio sink.

             When writing to a file or stdout it is raw 16-bit little endian
             (pulse coded modulation) PCM data.  So a utility must be used to
             convert the file to add a header or use the audioplay(1) command
             as stated in EXAMPLES.

   Channel Modes
     -f channel_mode

             0   This specifies that all possible input formats are accepted
                 and then one is chosen starting with joint stereo then stereo
                 then 2 channel then mono.

             m   This specifies that the input is monophonic.

             2   This specifies that the input is dual-channel.

             j   This specifies that the input is joint-stereo.

             s   This specifies that the input is stereo.  This is the

             Specifying joint stereo as opposed to stereo would allow for a
             slightly higher quality of playback as bta2dpd will only encode
             stereo and monophonic streams.

     -r rate
             The frequency of the input.  Where rate is one of 0, 16000,
             32000, 44100, 48000.  This defaults to 44.1 kHz.

             A value of 0 will arbitrate from the highest to lowest frequency.

   Sub Band Codec (SBC) Encoding Options
     -A bitpool_allocation

             0   Bit Allocation is negotiated starting with Loudness then SNR.

             S   Audio is encoded with SNR (Signal to Noise Ratio) bit

             L   Audio is encoded with Loudness bit allocation.  This is the

     -b blocks
             Number of blocks to use for encoding.  Where blocks is one of 0,
             4, 8, 12, 16.  This defaults to 16 blocks.

             In the case of 0 the number of blocks is negotiated starting from
             16 down to 4.

     -e bands

             0   Number of SBC bands is negotiated 8 then 4.

             4   Audio is encoded with 4 SBC bands.

             8   Audio is encoded with 8 SBC bands.  This is the default.

     It may be necessary to use btconfig(8) to set the class of your Bluetooth
     adapter to that of headphones when using bta2dpd as an audio sink.  I.e.,
           btconfig ubt0 class 0x200418
     Then start bta2dpd with -K before pairing.

     This is necessary as some devices only perform an sdpquery(1) just after
     pairing and cache the result.

     It is possible to specify multiples of -r -e -b -f.  This will mean that
     the specified combinations are reported as being accepted by the

     When used as a sink (-K), all modes, bands, blocks and allocation modes
     will be accepted unless specified as options.  I.e., -r 44100 will only
     accept a connection with a rate of 44.1kHz.

           bta2dpd -a spkr my.wav
     Encode and send audio my.wav to address `spkr'.

           bta2dpd -a spkr /dev/pad
     Encode and send audio from pad(4) to address `spkr'.

           bta2dpd -K out.pcm
     Decode stream from any connected address and write it to out.pcm.

           bta2dpd -K -a phone | audioplay -f -e linear -P 16 -s 44100 -c 2 --
     Decode stream from address `phone' and send to speakers.

     audioplay(1), sdpquery(1), pad(4), btconfig(8)

     Nathanial Sloss

NetBSD 9.99                      July 27, 2019                     NetBSD 9.99