357 lines
14 KiB
Plaintext
357 lines
14 KiB
Plaintext
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Sound Blaster Live mixer / default DSP code
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===========================================
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The EMU10K1 chips have a DSP part which can be programmed to support
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various ways of sample processing, which is described here.
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(This article does not deal with the overall functionality of the
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EMU10K1 chips. See the manuals section for further details.)
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The ALSA driver programs this portion of chip by default code
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(can be altered later) which offers the following functionality:
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1) IEC958 (S/PDIF) raw PCM
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--------------------------
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This PCM device (it's the 4th PCM device (index 3!) and first subdevice
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(index 0) for a given card) allows to forward 48kHz, stereo, 16-bit
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little endian streams without any modifications to the digital output
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(coaxial or optical). The universal interface allows the creation of up
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to 8 raw PCM devices operating at 48kHz, 16-bit little endian. It would
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be easy to add support for multichannel devices to the current code,
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but the conversion routines exist only for stereo (2-channel streams)
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at the time.
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Look to tram_poke routines in lowlevel/emu10k1/emufx.c for more details.
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2) Digital mixer controls
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-------------------------
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These controls are built using the DSP instructions. They offer extended
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functionality. Only the default build-in code in the ALSA driver is described
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here. Note that the controls work as attenuators: the maximum value is the
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neutral position leaving the signal unchanged. Note that if the same destination
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is mentioned in multiple controls, the signal is accumulated and can be wrapped
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(set to maximal or minimal value without checking of overflow).
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Explanation of used abbreviations:
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DAC - digital to analog converter
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ADC - analog to digital converter
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I2S - one-way three wire serial bus for digital sound by Philips Semiconductors
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(this standard is used for connecting standalone DAC and ADC converters)
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LFE - low frequency effects (subwoofer signal)
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AC97 - a chip containing an analog mixer, DAC and ADC converters
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IEC958 - S/PDIF
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FX-bus - the EMU10K1 chip has an effect bus containing 16 accumulators.
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Each of the synthesizer voices can feed its output to these accumulators
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and the DSP microcontroller can operate with the resulting sum.
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name='Wave Playback Volume',index=0
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This control is used to attenuate samples for left and right PCM FX-bus
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accumulators. ALSA uses accumulators 0 and 1 for left and right PCM samples.
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The result samples are forwarded to the front DAC PCM slots of the AC97 codec.
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name='Wave Surround Playback Volume',index=0
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This control is used to attenuate samples for left and right PCM FX-bus
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accumulators. ALSA uses accumulators 0 and 1 for left and right PCM samples.
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The result samples are forwarded to the rear I2S DACs. These DACs operates
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separately (they are not inside the AC97 codec).
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name='Wave Center Playback Volume',index=0
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This control is used to attenuate samples for left and right PCM FX-bus
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accumulators. ALSA uses accumulators 0 and 1 for left and right PCM samples.
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The result is mixed to mono signal (single channel) and forwarded to
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the ??rear?? right DAC PCM slot of the AC97 codec.
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name='Wave LFE Playback Volume',index=0
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This control is used to attenuate samples for left and right PCM FX-bus
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accumulators. ALSA uses accumulators 0 and 1 for left and right PCM.
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The result is mixed to mono signal (single channel) and forwarded to
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the ??rear?? left DAC PCM slot of the AC97 codec.
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name='Wave Capture Volume',index=0
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name='Wave Capture Switch',index=0
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These controls are used to attenuate samples for left and right PCM FX-bus
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accumulator. ALSA uses accumulators 0 and 1 for left and right PCM.
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The result is forwarded to the ADC capture FIFO (thus to the standard capture
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PCM device).
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name='Synth Playback Volume',index=0
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This control is used to attenuate samples for left and right MIDI FX-bus
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accumulators. ALSA uses accumulators 4 and 5 for left and right MIDI samples.
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The result samples are forwarded to the front DAC PCM slots of the AC97 codec.
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name='Synth Capture Volume',index=0
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name='Synth Capture Switch',index=0
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These controls are used to attenuate samples for left and right MIDI FX-bus
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accumulator. ALSA uses accumulators 4 and 5 for left and right PCM.
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The result is forwarded to the ADC capture FIFO (thus to the standard capture
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PCM device).
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name='Surround Playback Volume',index=0
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This control is used to attenuate samples for left and right rear PCM FX-bus
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accumulators. ALSA uses accumulators 2 and 3 for left and right rear PCM samples.
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The result samples are forwarded to the rear I2S DACs. These DACs operate
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separately (they are not inside the AC97 codec).
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name='Surround Capture Volume',index=0
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name='Surround Capture Switch',index=0
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These controls are used to attenuate samples for left and right rear PCM FX-bus
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accumulators. ALSA uses accumulators 2 and 3 for left and right rear PCM samples.
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The result is forwarded to the ADC capture FIFO (thus to the standard capture
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PCM device).
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name='Center Playback Volume',index=0
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This control is used to attenuate sample for center PCM FX-bus accumulator.
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ALSA uses accumulator 6 for center PCM sample. The result sample is forwarded
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to the ??rear?? right DAC PCM slot of the AC97 codec.
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name='LFE Playback Volume',index=0
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This control is used to attenuate sample for center PCM FX-bus accumulator.
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ALSA uses accumulator 6 for center PCM sample. The result sample is forwarded
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to the ??rear?? left DAC PCM slot of the AC97 codec.
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name='AC97 Playback Volume',index=0
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This control is used to attenuate samples for left and right front ADC PCM slots
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of the AC97 codec. The result samples are forwarded to the front DAC PCM
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slots of the AC97 codec.
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********************************************************************************
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*** Note: This control should be zero for the standard operations, otherwise ***
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*** a digital loopback is activated. ***
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********************************************************************************
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name='AC97 Capture Volume',index=0
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This control is used to attenuate samples for left and right front ADC PCM slots
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of the AC97 codec. The result is forwarded to the ADC capture FIFO (thus to
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the standard capture PCM device).
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********************************************************************************
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*** Note: This control should be 100 (maximal value), otherwise no analog ***
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*** inputs of the AC97 codec can be captured (recorded). ***
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********************************************************************************
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name='IEC958 TTL Playback Volume',index=0
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This control is used to attenuate samples from left and right IEC958 TTL
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digital inputs (usually used by a CDROM drive). The result samples are
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forwarded to the front DAC PCM slots of the AC97 codec.
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name='IEC958 TTL Capture Volume',index=0
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This control is used to attenuate samples from left and right IEC958 TTL
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digital inputs (usually used by a CDROM drive). The result samples are
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forwarded to the ADC capture FIFO (thus to the standard capture PCM device).
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name='Zoom Video Playback Volume',index=0
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This control is used to attenuate samples from left and right zoom video
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digital inputs (usually used by a CDROM drive). The result samples are
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forwarded to the front DAC PCM slots of the AC97 codec.
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name='Zoom Video Capture Volume',index=0
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This control is used to attenuate samples from left and right zoom video
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digital inputs (usually used by a CDROM drive). The result samples are
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forwarded to the ADC capture FIFO (thus to the standard capture PCM device).
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name='IEC958 LiveDrive Playback Volume',index=0
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This control is used to attenuate samples from left and right IEC958 optical
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digital input. The result samples are forwarded to the front DAC PCM slots
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of the AC97 codec.
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name='IEC958 LiveDrive Capture Volume',index=0
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This control is used to attenuate samples from left and right IEC958 optical
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digital inputs. The result samples are forwarded to the ADC capture FIFO
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(thus to the standard capture PCM device).
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name='IEC958 Coaxial Playback Volume',index=0
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This control is used to attenuate samples from left and right IEC958 coaxial
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digital inputs. The result samples are forwarded to the front DAC PCM slots
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of the AC97 codec.
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name='IEC958 Coaxial Capture Volume',index=0
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This control is used to attenuate samples from left and right IEC958 coaxial
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digital inputs. The result samples are forwarded to the ADC capture FIFO
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(thus to the standard capture PCM device).
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name='Line LiveDrive Playback Volume',index=0
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name='Line LiveDrive Playback Volume',index=1
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This control is used to attenuate samples from left and right I2S ADC
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inputs (on the LiveDrive). The result samples are forwarded to the front
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DAC PCM slots of the AC97 codec.
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name='Line LiveDrive Capture Volume',index=1
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name='Line LiveDrive Capture Volume',index=1
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This control is used to attenuate samples from left and right I2S ADC
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inputs (on the LiveDrive). The result samples are forwarded to the ADC
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capture FIFO (thus to the standard capture PCM device).
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name='Tone Control - Switch',index=0
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This control turns the tone control on or off. The samples for front, rear
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and center / LFE outputs are affected.
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name='Tone Control - Bass',index=0
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This control sets the bass intensity. There is no neutral value!!
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When the tone control code is activated, the samples are always modified.
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The closest value to pure signal is 20.
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name='Tone Control - Treble',index=0
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This control sets the treble intensity. There is no neutral value!!
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When the tone control code is activated, the samples are always modified.
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The closest value to pure signal is 20.
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name='IEC958 Optical Raw Playback Switch',index=0
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If this switch is on, then the samples for the IEC958 (S/PDIF) digital
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output are taken only from the raw FX8010 PCM, otherwise standard front
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PCM samples are taken.
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name='Headphone Playback Volume',index=1
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This control attenuates the samples for the headphone output.
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name='Headphone Center Playback Switch',index=1
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If this switch is on, then the sample for the center PCM is put to the
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left headphone output (useful for SB Live cards without separate center/LFE
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output).
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name='Headphone LFE Playback Switch',index=1
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If this switch is on, then the sample for the center PCM is put to the
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right headphone output (useful for SB Live cards without separate center/LFE
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output).
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3) PCM stream related controls
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------------------------------
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name='EMU10K1 PCM Volume',index 0-31
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Channel volume attenuation in range 0-0xffff. The maximum value (no
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attenuation) is default. The channel mapping for three values is
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as follows:
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0 - mono, default 0xffff (no attenuation)
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1 - left, default 0xffff (no attenuation)
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2 - right, default 0xffff (no attenuation)
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name='EMU10K1 PCM Send Routing',index 0-31
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This control specifies the destination - FX-bus accumulators. There are
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twelve values with this mapping:
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0 - mono, A destination (FX-bus 0-15), default 0
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1 - mono, B destination (FX-bus 0-15), default 1
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2 - mono, C destination (FX-bus 0-15), default 2
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3 - mono, D destination (FX-bus 0-15), default 3
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4 - left, A destination (FX-bus 0-15), default 0
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5 - left, B destination (FX-bus 0-15), default 1
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6 - left, C destination (FX-bus 0-15), default 2
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7 - left, D destination (FX-bus 0-15), default 3
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8 - right, A destination (FX-bus 0-15), default 0
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9 - right, B destination (FX-bus 0-15), default 1
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10 - right, C destination (FX-bus 0-15), default 2
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11 - right, D destination (FX-bus 0-15), default 3
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Don't forget that it's illegal to assign a channel to the same FX-bus accumulator
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more than once (it means 0=0 && 1=0 is an invalid combination).
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name='EMU10K1 PCM Send Volume',index 0-31
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It specifies the attenuation (amount) for given destination in range 0-255.
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The channel mapping is following:
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0 - mono, A destination attn, default 255 (no attenuation)
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1 - mono, B destination attn, default 255 (no attenuation)
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2 - mono, C destination attn, default 0 (mute)
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3 - mono, D destination attn, default 0 (mute)
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4 - left, A destination attn, default 255 (no attenuation)
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5 - left, B destination attn, default 0 (mute)
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6 - left, C destination attn, default 0 (mute)
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7 - left, D destination attn, default 0 (mute)
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8 - right, A destination attn, default 0 (mute)
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9 - right, B destination attn, default 255 (no attenuation)
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10 - right, C destination attn, default 0 (mute)
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11 - right, D destination attn, default 0 (mute)
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4) MANUALS/PATENTS:
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-------------------
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ftp://opensource.creative.com/pub/doc
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-------------------------------------
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Files:
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LM4545.pdf AC97 Codec
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m2049.pdf The EMU10K1 Digital Audio Processor
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hog63.ps FX8010 - A DSP Chip Architecture for Audio Effects
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WIPO Patents
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------------
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Patent numbers:
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WO 9901813 (A1) Audio Effects Processor with multiple asynchronous (Jan. 14, 1999)
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streams
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WO 9901814 (A1) Processor with Instruction Set for Audio Effects (Jan. 14, 1999)
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WO 9901953 (A1) Audio Effects Processor having Decoupled Instruction
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Execution and Audio Data Sequencing (Jan. 14, 1999)
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US Patents (http://www.uspto.gov/)
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----------------------------------
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US 5925841 Digital Sampling Instrument employing cache memory (Jul. 20, 1999)
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US 5928342 Audio Effects Processor integrated on a single chip (Jul. 27, 1999)
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with a multiport memory onto which multiple asynchronous
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digital sound samples can be concurrently loaded
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US 5930158 Processor with Instruction Set for Audio Effects (Jul. 27, 1999)
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US 6032235 Memory initialization circuit (Tram) (Feb. 29, 2000)
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US 6138207 Interpolation looping of audio samples in cache connected to (Oct. 24, 2000)
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system bus with prioritization and modification of bus transfers
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in accordance with loop ends and minimum block sizes
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US 6151670 Method for conserving memory storage using a (Nov. 21, 2000)
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pool of short term memory registers
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US 6195715 Interrupt control for multiple programs communicating with (Feb. 27, 2001)
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a common interrupt by associating programs to GP registers,
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defining interrupt register, polling GP registers, and invoking
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callback routine associated with defined interrupt register
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