Mixer Device
Sound and Music
A mixer device controls mixing of sounds from miscellaneous sound sources. Mixer device is component of a sound card and can vary in different sound cards.
Image bm961.GIF mixer device
The mixer device element is a text variable. By reading it a multiline list of mixer device names in the system is returned. By setting one of device names into the element the selection of device which will be controlled is performed. Without performing a device selection a first found mixer device will be used.
Image bm962.GIF destination line
The mixer device can control several output (destination) lines. The most frequent case is one speaker output line (reproduction) and one A/D sampler output line (recording). The destination line element allows to select controlled output line of the selected mixer device. By setting one of line names into the element the selection of the destination line will be performed. Without performing a destination line selection a first found output line (usually it will be a speaker output) will be used.
Image bm963.GIF source line (none=only destination line)
Every output line can be mixed from several input (source) lines. Input lines can be controlled separately (volume level of single input lines) and in most cases an output line (global volume) can be controlled, too. The source line element returns a multiline list of source line names for the selected output line. By setting one signal name into the element the selection of the source line will be performed which will be controlled. By setting an empty text the output signal will be selected as controlled signal (it is default setting after a destination line selection).
Image bm964.GIF type of line
The type of line element is a numeric variable returning a type code of the selected source line (or destination if an empty name of the source line is entered). By setting a type code into the element the line corresponding to the entered value will be searched (and set as active). Searching is performed for all lines of the mixer device, independently on destination line selected. Here are adduced typical values:
Output (destination) lines:
0 undefined
1 digital
2 line
3 monitor
4 speakers
5 headphones
6 telephone
7 audio (Wave In)
8 voice input
Input (source) lines:
$1000 undefined
$1001 digital (SPDIF-In)
$1002 line
$1003 microphone
$1004 music (MIDI)
$1005 CD
$1006 telephone (TAD-In)
$1007 PC speaker
$1008 audio (Wave Out)
$1009 AUX
$100A analog input
Image bm965.GIF control item
Every input or output line can have one or more control items. The control item element returns a multiline list of control item names for selected input or output line. By setting a control item name into the element the control item can be selected which will be manipulated.
Image bm966.GIF type of control item
The type of control item element is a numeric variable returning a type code of the selected control item. By setting a control item type code the appropriate control item will be found (and set as active). Searching is performed among selected line items only. Item type code is composed from the following values:
Item class (mask $F0000000):
$00000000 custom class
$10000000 meter
$20000000 switch
$30000000 number
$40000000 slider
$50000000 fader
$60000000 time
$70000000 list
Item subclass (mask $0F000000):
$00000000 switch - boolean
$01000000 switch - button
$00000000 time - microseconds
$01000000 time - milliseconds
$00000000 list - single
$01000000 list - multiple
Value unit (mask $00FF0000):
$00000000 custom
$00010000 boolean
$00020000 signed
$00030000 unsigned
$00040000 decibels (in 10ths)
$00050000 percent (in 10ths)
Typical values of control item type:
$10010000 boolean meter
$10020000 signed meter
$10020001 peak meter
$10030000 unsigned meter
$20010001 "On/Off" switch
$20010002 "Mute" switch
$20010003 "Mono" switch
$20010004 "Loudness" switch
$20010005 "Stereo Enhanced" switch
$21010004 button
$30020000 signed number
$30030000 unsigned number
$30040000 decibel number
$30050000 percent number
$40020000 "Balance" slider
$40020001 "Pan" slider
$40020002 "QSound Pan" slider
$50030001 "Volume" fader
$50030002 "Bass" fader
$50030003 "Treble" fader
$50030004 "Equalizer" fader
$60030000 time in microseconds
$61030000 time in milliseconds
$70010000 single select list
$70010001 multiplexer (list)
$71010000 multiple select list
$71010001 mixer (list)
Image bm967.GIF controlled channel (-1=all)
Some of control items allow to control more channels of the line (2 channels for sterero). Number of controlled channel for the selected control item can be selected by setting the controlled channel element (value 0, 1, ...). By setting -1 value all channels of the line will be controlled. By reading the element value the number of channels which can be controlled by the element can be found out.
Image bm968.GIF selection of item value
The selection of item value element enables to select item's controlled value for list and multiple items (equalizers). By reading it a multiline text list of value names for the active control item is returned. By setting one of the name into the element the item value can be selected which will be controlled. Items with one value need not selection of a controlled value (buttons, faders).
Image bm969.GIF value of control item (0 to 1)
The value of control item numeric element enables to find out and to set the control item value. The value is in range of 0 to 1. For signed items a middle value corresponds to the 0.5 number. For switches the switch-on state corresponds to the 1 value and switch-off to the 0 value. For lists individual values of the list are handled as a switch. For a single select list to switch on a new selected item only is sufficient, the other items will be turned off automatically.
Note: In programs and games the mixer can be used simplified. In most cases it is sufficient to select control item by setting the type of line element to the line code and the type of control item element to the item code and then control the value of control item element (the mixer selection is done automatically). For example:
Volume: line=4, item=$50030001
Bass: line=4, item=$50030002
Treble: line=4, item=$50030003
Music: line=$1004, item=$50030001
Sounds: line=$1008, item=$50030001
CD: line=$1005, item=$50030001

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