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NAME
     utadem -  Sun Ray audio driver emulator

DESCRIPTION
     utadem is an audio interface that provides a generic virtual
     audio  interface to Sun Ray appliances. The actual interface
     to the appliance is by network interconnect through a daemon
     that  is  session-aware.  The  daemon is connected to utadem
     through a master port, and is responsible for  creating  the
     slave  device  nodes  which connect to normal audio applica-
     tions.

APPLICATION PROGRAM INTERFACE
     Applications that normally open /dev/audio may use utadem as
     long  as  they  have some way of selecting the audio device,
     such as through the -d  <device>  switch,  or  the  AUDIODEV
     environment  variable.  The  exact capabilities of the audio
     device emulated depend on  the  daemon.  Compliance  to  the
     standard  audio(7I)  interface  is  handled in the following
     manner:

     Audio Data Formats
           The Data  formats  supported  depend  on  the  daemon.
           Please refer to the daemon documentation for its capa-
           bilities.

     Audio Ports
           Input and output audio ports are directly dependent on
           the  Sun Ray appliance and not on the daemon. The dae-
           mon is capable of discovering the type and quantity of
           input   ports   available   and  report  them  in  the
           record.avail_ports and play.avail_ports fields of  the
           audio_info  structure.  Although the ports can be con-
           trolled directly, the actual audio output is generally
           a  mix  of multiple services, so the play.gain setting
           is the contribution of this audio device to the  total
           experience.  Since  recording is exclusive of a single
           service, the record.gain and  record.balance  controls
           directly affect the hardware gain.

     Sample Granularity
           Since the utadem driver is working  through  a  daemon
           that  .is  then  transferring  the  audio data over an
           interconnect, there is likely to be larger  granulari-
           ties  than normal, and some jitter in the reporting of
           sample counts. At any given time, the  reported  input
           and  output  sample  counts  will vary from the actual
           sample count by no more than the size of  the  buffers
           it  is  transferring. Programs should, in general, not
           rely on absolute  accuracy  of  the  play.samples  and
           record.samples fields of the audio_info structure.

     Audio Status Change Notification
           As described in audio(7I), it is possible  to  request
           asynchronous  notification  of changes in the state of
           an audio device.

ERRORS
     utadem errors are defined in the audio(7I), man pages. Addi-
     tionally, if the daemon has exited, further audio operations
     will no longer be possible on the slave  ports.  Audio  pro-
     grams must exit in order to clear this error. New opens will
     return ENODEV,  ioctl  operations  and  writes  will  return
     ENXIO.  Data  reads will complete normally, then return end-
     of-file.

FILES
     The following file is used:

          /dev/utadem
                master port for daemons


     The logical device name of the slave  port  depends  on  the
     daemon.

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

     ____________________________________________________________
    |       ATTRIBUTE TYPE        |       ATTRIBUTE VALUE       |
    | Architecture                | SPARC                       |
    | Availability                | SUNWutu                     |
    | MT-Level                    | Safe                        |
    |_____________________________|_____________________________|


SEE ALSO
     utaudio(1), ioctl(2), attributes(5), audio(7I), streamio(7I)

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