參數(shù)資料
型號(hào)： AD1818
廠商： Analog Devices, Inc.
英文描述： PCI SoundComm DC97 Digital Controller(PCI SoundComm DC97型數(shù)字控制器)
中文描述： 的PCI SoundComm DC97數(shù)字控制器（的PCI SoundComm DC97型數(shù)字控制器）
文件頁(yè)數(shù)： 8/29頁(yè)
文件大?。?/td> 364K
代理商： AD1818
AD1818
–8–
REV. 0
Given the high resolution of the SRCs, the mixer can be used to
accelerate the pitch shifting operation for digital effect or music
TECHNCAL
DATA
DirectSound Mixer
One of the principal features of DirectSound is mixing. Most
games open between three to eight sound buffers and mix
them simultaneously. A buffer contains either a mono or a
stereo source. When multiple sounds are mixed in software,
CPU utilization increases and system latency may cause sounds
and visual cues to become unsynchronized. In order to allow
games to run faster and more smoothly, the AD1818 has a built-
in hardware mixer capable of mixing and sample rate converting
up to 64 digital streams. The stereo output of the mixer may be
sent the analog interface, the DSP for digital processing as in
DirectSound 3D and effects, or returned to the host via the PCI
Bus.
The AD1818’s 32-channel PCI DMA Controller interface
transfers either 32 stereo channels (64 streams) or 32 mono
streams into the hardware mixer. The DMA controller directs
the playing or stopping of a sample buffer and is capable of
automatically looping to the start of a buffer. The DMA
controller counts the number of bytes transferred and can stop
playing a sample after a specified number of bytes have been
transferred. If the number of bytes is greater than the length of
the buffer, the buffer automatically loops back to the beginning.
After initiating a DMA transfer, the sample data enters the
AD1818 mixer. Attenuation blocks (A) control the volume of
a sample from 0 dB to –94.5 dB in 1.5 dB steps for the left and
right channel of each stream, or the stream can be completely
muted (M). Panning is supported by a combination of the left
and right attenuation blocks, making the sound move across a
sound field.
The streams are then summed together in blocks of four. Every
four streams of left channel data (must be at the same sample
rate) are summed together as well as every four streams of right
channel data (same sample rate) producing eight separate
samples of left and right data. The eight stereo samples then
enter the sample rate converter block (SRC). Eight independent
programmable SRC blocks convert the summed samples from a
user-specified sample rate to the AC ’97 standard sample rate of
48 kHz. The input sample rate ranges from 1 Hz to 48 kHz in
1 Hz increments. The resulting left data may be returned to the
Mixer Data Bus or summed to produce one left output stream.
Right digital data may be returned to the Mixer Data Bus or
summed to produce one right output stream completing the
stereo sample pair of the Primary Summer. The stereo output of
the Primary Summer may be sent to either the Mixer Data
Bus or the Analog Interface. The Secondary Summer provides an
additional stereo output for the Mixer Data Bus, which may be
sent to the DSP for effects processing or routed back to the
PCI bus.
Extended DirectSound Mixer
In addition to the AD1818’s Basic DirectSound Mixer, an
Extended Mixer and SRC stage handles streams sent to the Mixer
Data Bus from the DSP and the internal Music Synthesizer.
The Extended Mixer allows for further processing and remixing
of data. For example, data handled by the Basic Mixer may be
sent to the DSP for effects processing and then mixed with the
AD1818’s output to generate effects such as echo and rever-
beration or DirectSound3D.
Sample Rate Converter
The sample rate converter (SRC) blocks attached to the basic and
extended DirectSound audio streams are variable interpolating
SRCs. Each converter accepts samples at the rate of 1 Hz to
48 kHz and interpolates the samples to a common rate of
48 kHz. In addition, a variable decimation SRC is included to
accept a single stereo channel of audio data at 48 kHz and
Utilizing Analog Devices’ variable sample rate technology, each
SRC employs a scalable anti-aliasing or anti-imaging filter to
properly filter the rate converted data. The result is a high
A
P
S
L
R
SRC
SRC
SRC
MIXER DATA BUS
MUSIC SYNTHESIZER
DSP TRANSMIT FIFO
DSP TRANSMIT FIFO
BASIC DIRECT SOUND MIXER OUTPUT
Figure 5. Extended DirectSound Digital Mixer and Sample Rate Converters
相關(guān)PDF資料
PDF描述
AD1819A AC97 SoundPort Codec(AC97型聲音端口信號(hào)編解碼器)
AD1819BJST AC’97 SoundPort Codec
AD1819 ECONOLINE: RD & RC - Dual Output from a Single Input Rail- 1kVDC & 2kVDC Isolation- Power Sharing on Output- Custom Solutions Available- UL94V-0 Package Material- Efficiency to 86%
AD1819B AC’97 SoundPort Codec
AD1833A 24-Bit, 192 kHz, DAC
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
AD18-182 制造商:Thomas & Betts 功能描述:Terminal; 22 to 18 AWG; Brass; Non-Insulated; Tin Plated; UL 94V-2 制造商:Thomas & Betts 功能描述:DISCONNECTFEMALE 制造商:Thomas & Betts 功能描述:Quick Disconnect Terminal 18-22AWG F 21.08mm 5.84mm Tin
AD18-183 制造商:Thomas & Betts 功能描述:Terminal; 22 to 18 AWG; Brass; Nylon; Tin Plated; UL 94V-2 制造商:Thomas & Betts 功能描述:NON-INS FEM-187 DISC, 22-18 LEN .64 制造商:Thomas & Betts 功能描述:Quick Disconnect Terminal 18-22AWG F 16.26mm 5.84mm Tin
AD1819 制造商:AD 制造商全稱(chēng):Analog Devices 功能描述:AC’97 SoundPort Codec
AD1819AJST 制造商:Rochester Electronics LLC 功能描述:
AD1819B 制造商:AD 制造商全稱(chēng):Analog Devices 功能描述:AC’97 SoundPort Codec
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