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NAME
     audioamd - telephone quality audio device

DESCRIPTION
     The audioamd device uses  the  AM79C30A  Digital  Subscriber
     Controller  chip  to  implement  the audio device interface.
     This interface is described fully in  the  audio(7I)  manual
     page.

     Applications that open /dev/audio may use  the  AUDIO_GETDEV
     ioctl  to  determine  which  audio device is being used. The
     audioamd driver will return "SUNW,am79c30" in the name field
     of  the  audio_device structure. The version field will con-
     tain "a" and the config field will be set to "onboard1" .

     The AUDIO_SETINFO ioctl controls device configuration param-
     eters.  When  an application modifies the record.buffer_size
     field using the AUDIO_SETINFO ioctl, the  driver  will  con-
     strain  it to be greater than zero and less than or equal to
     8000 bytes or one second of  audio  data.  Applications  are
     warned that setting this field too low or too high may cause
     system performance problems and should  therefore  set  this
     field with caution.

  Audio Data Formats
     The audioamd device supports the audio formats listed in the
     following  table.  When  the device is open for simultaneous
     play and record, the input  and  output  data  formats  must
     match.

     Supported Audio Data Formats

     __________________________________________________________________
    | Sample Rate|         Encoding         | Precision |   Channels  |
    |____________|__________________________|___________|_____________|
    |   8000 Hz  |          mu-law          |     8     |       1     |
    |____________|__________________________|___________|_____________|
    |   8000 Hz  |           A-law          |     8     |       1     |
    |____________|__________________________|___________|_____________|


     Since  audioamd  supports  only  single-channel   (monaural)
     audio,  the  play.balance  and  record.balance fields of the
     audio_info structure are ignored.

  Audio Ports
     The record.avail_ports and play.avail_ports  fields  of  the
     audio_info  structure  report the available input and output
     ports.   The  audioamd  device  supports  one  input   port,
     selected    by    setting    the    record.port   field   to
     AUDIO_MICROPHONE. The play.port field may be set  to  either
     AUDIO_SPEAKER  or AUDIO_HEADPHONE, to direct audio output to
     the built-in speaker or headphone jack, respectively.   Note
     that AUDIO_SPEAKER cannot be enabled for systems that do not
     include a built-in speaker.

  Sample Granularity
     Since the audioamd  device  manipulates  single  samples  of
     audio data, the reported input and output sample counts will
     be very close to the actual  sample  count.   However,  some
     other  audio  devices report sample counts that are approxi-
     mate, due to buffering constraints. Programs should, in gen-
     eral,  not  rely  on  absolute  accuracy of the sample count
     fields.

FILES
     /dev/audio

     /dev/audioctl

     /dev/sound

     /usr/demo/SOUND

ATTRIBUTES
     See attributes(5) for descriptions of the  following  attri-
     butes:

     ____________________________________________________________
    |   ATTRIBUTE TYPE   |            ATTRIBUTE VALUE           |
    |____________________|______________________________________|
    | Architecture       | SPARC: SPARCstation  1  and  2,  IPC,|
    |                    | IPX,  SLC,  ELC,  LC, and SPARCserver|
    |                    | 6xx system                           |
    |____________________|______________________________________|


     Desktop SPARCsystems include a built-in  speaker  for  audio
     output. The audio cable provides connectors for a microphone
     and external headset. The headset output level  is  adequate
     to power most headphones, but may be too low for some exter-
     nal speakers. Powered speakers or an external amplifier  may
     be  used.  SPARCserver  6xx  systems do not have an internal
     speaker, but support an external microphone and speaker con-
     nected through the audio cable.

     The Sun Microphone is recommended for normal  desktop  audio
     recording. It contains a battery that must be replaced after
     210 hours of use. Other microphones may be used, but a  pre-
     amplifier  circuit  may  be required to achieve a sufficient
     input signal. Other audio sources may be  recorded  by  con-
     necting  one  channel  of the line output to the audio cable
     microphone input. If the input signal is distorted, external
     attenuation  may  be  required  (audio  sources  may also be
     connected from their headphone output with the volume turned
     down).

SEE ALSO
     ioctl(2), attributes(5), audio(7I), streamio(7I)

     AMD data sheet for  the  AM79C30A  Digital  Subscriber  Con-
     troller, Publication number 09893.

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