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The Creative Labs Sound Blaster family of audio cards comprises DMA -capable ISA bus plug-in cards that provide 8 and 16 bit mono and stereo digitized sound recording and playback over a wide range of sampling rates. Each card includes a digital sound processor and mixing capability. Some of the cards also support more advanced audio features such as FM synthesis, advanced signal processing, advanced wave effects, and MIDI capability; however, the sbpro driver does not currently support those advanced features. The features and interfaces supported by the Solaris sbpro driver are described here and in audio(7I) .
Some Sound Blaster cards support optional non-audio capabilities such as SCSI interfaces and CD-ROM interfaces. These interfaces are not supported by the sbpro driver. The Sound Blaster 16 optional SCSI -2 interface is supported by the aic(7D) driver.
The sbpro driver will return "SUNW,sbpro" or "SUNW,sb16" in the name field of the audio_device structure. The version field will contain the version number of the card’s DSP chip, and the config field will be set to "SBPRO" or "SB16" . The AWE32 is currently identified as an SB16 . In all the discussion below, the Sound Blaster AWE32 behaves the same as the Sound Blaster 16.
The Sound Blaster Pro handles 8-bit samples. In mono mode, audio data may be sampled at rates from 4,000 to 44,100 samples per second. In stereo mode, samples may be handled at the rates of 11,025 and 22,050 samples per second. The SB-16 can sample 8-bit or 16-bit mono or stereo data in the range of 5,000 to 44,100 Hz.
The Sound Blaster Pro hardware handles 8 bit linear samples in excess-128 format. The Sound Blaster 16 handles that format, as well as 16 bit linear samples in two’s complement format. The sbpro driver will generate and accept data in these formats if AUDIO_ENCODING_LINEAR is selected in the encoding field of the audio information structure. 16 bit precision is not available on the Sound Blaster Pro. The sbpro driver will also accept and generate u-law format data if the encoding field is set to AUDIO_ENCODING_ULAW . In this case, driver software performs the translation between linear and u-law formats. u-law encoding is designed to provide an improved signal-to-noise ratio at low amplitude levels. To achieve best results when using u-law encoding, the audio record volume should be set so that typical amplitude levels lie within approximately three-fourths of the full dynamic range.
The Sound Blaster hardware does not support multiple output devices, so the play.port field of the audio information structure only supports AUDIO_HEADPHONE . Output volume is controlled by software. There is a volume control thumbwheel on the back of the card which should be turned all the way up to maximum; otherwise no sound may be audible.
The record.port field of the audio information structure allows selection
of which audio source is used for recording, and may be set to one of AUDIO_MICROPHONE
,
AUDIO_LINE_IN
, or AUDIO_CD
. These select input from the microphone jack,
line-level input jack, or internal CD
input, respectively. The microphone
input is treated as a mono source by the hardware, although the microphone
jack is a stereo jack. If your microphone has a mono plug, you should convert
it to a stereo plug using an appropriate adapter. Line and CD
are stereo
sources. When recording in mono mode, both stereo channels are mixed before
recording.
Creative Labs, Inc. Sound Blaster Pro User Reference Manual
The current driver implementation does not support the A-law encoding mode.