Technical data

SunOS 5.5 Devices audioamd(7D)
NAME audioamd − telephone quality audio device
AVAILABILITY SPARC
SPARCstation 1 and 2, IPC, IPX, SLC, ELC, LC, and SPARCserver 6xx systems.
Desktop SPARCsystems include a built-in speaker for audio output. The audio cable pro-
vides connectors for a microphone and external headset. The headset output levelis ade-
quate to power most headphones, but may be too low for some external speakers.
Powered speakers or an external amplifier may be used. SPARCserver 6xx systems do not
have an internalspeaker, but support an external microphone and speaker connected
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 connecting one channelof the line output to the audio cable
microphone input. If the input signal is distorted, external attenuationmay be required
(audio sources may also be connected from their headphone output with the volume
turned down).
DESCRIPTION The audioamd device uses theAM79C30A Digital Subscriber Controller chip to imple-
ment 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 beingused. The audioamd driver will return"SUNW,am79c30" in
the name field of the audio_device structure. The version field will contain "a" and the
config field will be set to "onboard1" .
The AUDIO_SETINFO ioctl controls device configuration parameters. When an applica-
tion modifies the record.buffer_sizefield using theAUDIO_SETINFO ioctl, the driver will
constrain 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 µ-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.
modified 18 Feb 1993 7D-33