SND_HDSP(4)            FreeBSD Kernel Interfaces Manual            SND_HDSP(4)

NAME

     snd_hdsp - RME HDSP bridge device driver

SYNOPSIS

     To compile this driver into the kernel, place the following lines in your
     kernel configuration file:

           device sound
           device snd_hdsp

     Alternatively, to load the driver as a module at boot time, place the
     following line in loader.conf(5):

           snd_hdsp_load="YES"

DESCRIPTION

     The snd_hdsp bridge driver allows the generic audio driver sound(4) to
     attach to RME HDSP audio devices.

HARDWARE

     The snd_hdsp driver supports the following audio devices:

     o   RME HDSP 9632 (optional AO4S-192 and AIS-192 extension boards)
     o   RME HDSP 9652

     By default, each pcm(4) device corresponds to a physical port on the
     sound card.  For ADAT ports, 8 channel, 4 channel and 2 channel formats
     are supported.  The effective number of ADAT channels is 8 channels at
     single speed (32kHz-48kHz) and 4 channels at double speed (64kHz-96kHz).
     Only the HDSP 9632 can operate at quad speed (128kHz-192kHz), ADAT is
     disabled in this mode.  Depending on sample rate and channel format
     selected, not all pcm channels can be mapped to ADAT channels and vice
     versa.

LOADER TUNABLES

     These settings can be entered at the loader(8) prompt or in
     loader.conf(5).

     hw.hdsp.unified_pcm
             If set to 1, all physical ports are combined into one unified pcm
             device.  When opened in multi-channel audio software, this makes
             all ports available at the same time, and fully synchronized.
             For resulting channel numbers consult the following table:

     Sound Card    Single Speed    Double Speed    Quad Speed
                   Play | Rec      Play | Rec      Play | Rec
     HDSP 9632      16  |  16       12  |  12        8  |   8
     HDSP 9652      26  |  26       14  |  14        -  |   -

SYSCTL TUNABLES

     These settings and informational values can be accessed at runtime with
     the sysctl(8) command.  If multiple RME HDSP sound cards are installed,
     each device has a separate configuration.  To adjust the following sysctl
     identifiers for a specific sound card, insert the respective device
     number in place of `0'.

     dev.hdsp.0.sample_rate
             Set a fixed sample rate from 32000, 44100, 48000, up to 192000.
             This is usually required for digital connections (AES, S/PDIF,
             ADAT).  The default value of 0 adjusts the sample rate according
             to pcm device settings.

     dev.hdsp.0.period
             The number of samples processed per interrupt, from 32, 64, 128,
             up to 4096.  Setting a lower value here results in less latency,
             but increases system load due to frequent interrupt processing.
             Extreme values may cause audio gaps and glitches.

     dev.hdsp.0.clock_list
             Lists possible clock sources to sync with, depending on the
             hardware model.  This includes internal and external master
             clocks as well as incoming digital audio signals like AES, S/PDIF
             and ADAT.

     dev.hdsp.0.clock_preference
             Select a preferred clock source from the clock list.  HDSP cards
             will sync to this clock source when available, but fall back to
             auto-sync with any other digital clock signal they receive.  Set
             this to `internal' if the HDSP card should act as master clock.

     dev.hdsp.0.clock_source
             Shows the actual clock source in use (read only).  This differs
             from what is set as clock preference when in auto-sync mode.

     dev.hdsp.0.sync_status
             Display the current sync status of all external clock sources.
             Status indications are `none' for no signal at all, `lock' for
             when a valid signal is present, and `sync' for accurately
             synchronized signals (required for recording digital audio).

     The following tunables are applicable to HDSP 9632 devices only:

     dev.hdsp.0.input_level
             Select the sensitivity of the analog line input.  Available
             reference levels for the input signal are `LowGain', `+4dBu' and
             `-10dBV'.

     dev.hdsp.0.output_level
             Select the gain level of the analog line output.  Available
             reference levels for the output signal are `HighGain', `+4dBu'
             and `-10dBV'.

     dev.hdsp.0.phones_level
             Adjust the gain level of the phones output, separately from the
             analog line output.  The signal can be lowered by 6 or 12 dB.

     Where appropriate these sysctl values are modeled after official RME
     software on other platforms, and adopt their terminology.  Consult the
     RME user manuals for additional information.

SEE ALSO

     sound(4)

HISTORY

     The snd_hdsp device driver first appeared in FreeBSD 15.0.

AUTHORS

     Based on snd_hdspe(4) originally written by Ruslan Bukin <br@bsdpad.com>.
     All adaptation to HDSP cards by Florian Walpen <dev@submerge.ch>.

FreeBSD 15.1-STABLE-HBSD       October 28, 2024                    SND_HDSP(4)