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13890a6a87
- Clarify the data flows. For SB Live! I fixed only the most obvious
point ("from" vs. "for").
- Mention 7.1 side channels on Audigy.
- Be unspecific about the output DACs on Audigy, as lots of variants
actually exist (see emu_chip_details table).
Signed-off-by: Oswald Buddenhagen <oswald.buddenhagen@gmx.de>
Link: https://lore.kernel.org/r/20230825222157.170978-2-oswald.buddenhagen@gmx.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
307 lines
13 KiB
ReStructuredText
307 lines
13 KiB
ReStructuredText
=============================================
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Sound Blaster Audigy mixer / default DSP code
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=============================================
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This is based on sb-live-mixer.rst.
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The EMU10K2 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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EMU10K2 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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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 built-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 clipped
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(set to maximal or minimal value without checking for overflow).
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Explanation of used abbreviations:
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DAC
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digital to analog converter
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ADC
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analog to digital converter
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I2S
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one-way three wire serial bus for digital sound by Philips Semiconductors
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(this standard is used for connecting standalone D/A and A/D converters)
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LFE
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low frequency effects (used as subwoofer signal)
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AC97
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a chip containing an analog mixer, D/A and A/D converters
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IEC958
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S/PDIF
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FX-bus
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the EMU10K2 chip has an effect bus containing 64 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='PCM Front Playback Volume',index=0
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----------------------------------------
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This control is used to attenuate samples from left and right front PCM FX-bus
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accumulators. ALSA uses accumulators 8 and 9 for left and right front PCM
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samples for 5.1 playback. The result samples are forwarded to the front speakers.
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name='PCM Surround Playback Volume',index=0
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-------------------------------------------
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This control is used to attenuate samples from left and right surround PCM FX-bus
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accumulators. ALSA uses accumulators 2 and 3 for left and right surround PCM
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samples for 5.1 playback. The result samples are forwarded to the surround (rear)
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speakers.
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name='PCM Side Playback Volume',index=0
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---------------------------------------
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This control is used to attenuate samples from left and right side PCM FX-bus
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accumulators. ALSA uses accumulators 14 and 15 for left and right side PCM
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samples for 7.1 playback. The result samples are forwarded to the side speakers.
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name='PCM Center Playback Volume',index=0
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-----------------------------------------
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This control is used to attenuate samples from center PCM FX-bus accumulator.
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ALSA uses accumulator 6 for center PCM samples for 5.1 playback. The result
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samples are forwarded to the center speaker.
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name='PCM LFE Playback Volume',index=0
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--------------------------------------
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This control is used to attenuate sample for LFE PCM FX-bus accumulator.
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ALSA uses accumulator 7 for LFE PCM samples for 5.1 playback. The result
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samples are forwarded to the subwoofer.
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name='PCM Playback Volume',index=0
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----------------------------------
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This control is used to attenuate samples from left and right PCM FX-bus
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accumulators. ALSA uses accumulators 0 and 1 for left and right PCM samples for
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stereo playback. The result samples are forwarded to the front speakers.
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name='PCM Capture Volume',index=0
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---------------------------------
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This control is used to attenuate samples from left and right PCM FX-bus
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accumulators. ALSA uses accumulators 0 and 1 for left and right PCM samples for
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stereo playback. The result is forwarded to the standard capture PCM device.
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name='Music Playback Volume',index=0
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------------------------------------
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This control is used to attenuate samples from 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 virtual stereo mixer.
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name='Music Capture Volume',index=0
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-----------------------------------
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These controls are used to attenuate samples from left and right MIDI FX-bus
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accumulator. ALSA uses accumulators 4 and 5 for left and right MIDI samples.
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The result is forwarded to the standard capture PCM device.
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name='Mic Playback Volume',index=0
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----------------------------------
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This control is used to attenuate samples from left and right Mic input of
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the AC97 codec. The result samples are forwarded to the virtual stereo mixer.
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name='Mic Capture Volume',index=0
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---------------------------------
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This control is used to attenuate samples from left and right Mic input of
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the AC97 codec. The result is forwarded to the standard capture PCM device.
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The original samples are also forwarded to the Mic capture PCM device (device 1;
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16bit/8KHz mono) without volume control.
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name='Audigy CD Playback Volume',index=0
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----------------------------------------
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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 virtual stereo mixer.
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name='Audigy CD Capture Volume',index=0
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---------------------------------------
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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 is forwarded
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to the standard capture PCM device.
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name='IEC958 Optical Playback Volume',index=0
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---------------------------------------------
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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 virtual stereo mixer.
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name='IEC958 Optical Capture Volume',index=0
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--------------------------------------------
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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 is forwarded to the standard capture PCM device.
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name='Line2 Playback Volume',index=0
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------------------------------------
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This control is used to attenuate samples from left and right I2S ADC
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inputs (on the AudigyDrive). The result samples are forwarded to the virtual
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stereo mixer.
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name='Line2 Capture Volume',index=1
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-----------------------------------
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This control is used to attenuate samples from left and right I2S ADC
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inputs (on the AudigyDrive). The result is forwarded to the standard capture
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PCM device.
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name='Analog Mix Playback Volume',index=0
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-----------------------------------------
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This control is used to attenuate samples from left and right I2S ADC
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inputs from Philips ADC. The result samples are forwarded to the virtual
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stereo mixer. This contains mix from analog sources like CD, Line In, Aux, ....
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name='Analog Mix Capture Volume',index=1
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----------------------------------------
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This control is used to attenuate samples from left and right I2S ADC
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inputs Philips ADC. The result is forwarded to the standard capture PCM device.
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name='Aux2 Playback Volume',index=0
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-----------------------------------
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This control is used to attenuate samples from left and right I2S ADC
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inputs (on the AudigyDrive). The result samples are forwarded to the virtual
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stereo mixer.
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name='Aux2 Capture Volume',index=1
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----------------------------------
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This control is used to attenuate samples from left and right I2S ADC
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inputs (on the AudigyDrive). The result is forwarded to the standard capture
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PCM device.
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name='Front Playback Volume',index=0
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------------------------------------
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This control is used to attenuate samples from the virtual stereo mixer.
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The result samples are forwarded to the front speakers.
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name='Surround Playback Volume',index=0
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---------------------------------------
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This control is used to attenuate samples from the virtual stereo mixer.
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The result samples are forwarded to the surround (rear) speakers.
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name='Side Playback Volume',index=0
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-----------------------------------
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This control is used to attenuate samples from the virtual stereo mixer.
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The result samples are forwarded to the side speakers.
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name='Center Playback Volume',index=0
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-------------------------------------
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This control is used to attenuate samples from the virtual stereo mixer.
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The result samples are forwarded to the center speaker.
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name='LFE Playback Volume',index=0
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----------------------------------
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This control is used to attenuate samples from the virtual stereo mixer.
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The result samples are forwarded to the subwoofer.
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name='Tone Control - Switch',index=0
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------------------------------------
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This control turns the tone control on or off. The samples forwarded to
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the speaker outputs are affected.
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name='Tone Control - Bass',index=0
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----------------------------------
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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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------------------------------------
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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='Master Playback Volume',index=0
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-------------------------------------
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This control is used to attenuate samples forwarded to the speaker outputs.
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name='IEC958 Optical Raw Playback Switch',index=0
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-------------------------------------------------
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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 iec958 ALSA PCM device (which uses
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accumulators 20 and 21 for left and right PCM by default).
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PCM stream related controls
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===========================
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name='EMU10K1 PCM Volume',index 0-31
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------------------------------------
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Channel volume attenuation in range 0-0x1fffd. The middle 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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------------------------------------------
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This control specifies the destination - FX-bus accumulators. There are 24
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values in this mapping:
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* 0 - mono, A destination (FX-bus 0-63), default 0
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* 1 - mono, B destination (FX-bus 0-63), default 1
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* 2 - mono, C destination (FX-bus 0-63), default 2
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* 3 - mono, D destination (FX-bus 0-63), default 3
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* 4 - mono, E destination (FX-bus 0-63), default 4
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* 5 - mono, F destination (FX-bus 0-63), default 5
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* 6 - mono, G destination (FX-bus 0-63), default 6
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* 7 - mono, H destination (FX-bus 0-63), default 7
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* 8 - left, A destination (FX-bus 0-63), default 0
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* 9 - left, B destination (FX-bus 0-63), default 1
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* 10 - left, C destination (FX-bus 0-63), default 2
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* 11 - left, D destination (FX-bus 0-63), default 3
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* 12 - left, E destination (FX-bus 0-63), default 4
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* 13 - left, F destination (FX-bus 0-63), default 5
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* 14 - left, G destination (FX-bus 0-63), default 6
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* 15 - left, H destination (FX-bus 0-63), default 7
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* 16 - right, A destination (FX-bus 0-63), default 0
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* 17 - right, B destination (FX-bus 0-63), default 1
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* 18 - right, C destination (FX-bus 0-63), default 2
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* 19 - right, D destination (FX-bus 0-63), default 3
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* 20 - right, E destination (FX-bus 0-63), default 4
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* 21 - right, F destination (FX-bus 0-63), default 5
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* 22 - right, G destination (FX-bus 0-63), default 6
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* 23 - right, H destination (FX-bus 0-63), default 7
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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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-----------------------------------------
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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 - mono, E destination attn, default 0 (mute)
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* 5 - mono, F destination attn, default 0 (mute)
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* 6 - mono, G destination attn, default 0 (mute)
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* 7 - mono, H destination attn, default 0 (mute)
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* 8 - left, A destination attn, default 255 (no attenuation)
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* 9 - left, B destination attn, default 0 (mute)
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* 10 - left, C destination attn, default 0 (mute)
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* 11 - left, D destination attn, default 0 (mute)
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* 12 - left, E destination attn, default 0 (mute)
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* 13 - left, F destination attn, default 0 (mute)
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* 14 - left, G destination attn, default 0 (mute)
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* 15 - left, H destination attn, default 0 (mute)
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* 16 - right, A destination attn, default 0 (mute)
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* 17 - right, B destination attn, default 255 (no attenuation)
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* 18 - right, C destination attn, default 0 (mute)
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* 19 - right, D destination attn, default 0 (mute)
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* 20 - right, E destination attn, default 0 (mute)
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* 21 - right, F destination attn, default 0 (mute)
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* 22 - right, G destination attn, default 0 (mute)
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* 23 - right, H destination attn, default 0 (mute)
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MANUALS/PATENTS
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===============
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See sb-live-mixer.rst.
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