AUDIOAMD(4)

NAME
audioamd - telephone quality audio device

CONFIG
device-driver audioamd

AVAILABILITY

SPARCstation 1 and 2, IPC, IPX, SLC, SLX, and SPARCserver 6xx systems.

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 external 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 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 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).

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(4) manual page.

The AUDIO_GETDEV ioctl(2V) returns AUDIO_DEV_AMD to identify the audioamd device type. The AUDIO_SETINFO ioctl controls device configuration parameters.

  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	u-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 approximate, due to buffering constraints. Programs should, in general, not rely on absolute accuracy of the sample count fields.

FILES
/dev/audio
/dev/audioctl
/usr/demo/SOUND

SEE ALSO
ioctl(2V), audio(4), streamio(4)

AMD data sheet for the AM79C30A Digital Subscriber Controller, Publication number 09893.

BUGS
The audioamd device driver does not currently support the output_muted field of the audio_info structure.