Mixers Audio mixers are an integral part of most sound card hardware used on Microsoft Windows computers. Typically, sound hardware will have one mixer driver associated with it. So if you have two sets of sound card hardware (for example, built-in hardware and a USB or FireWire sound card), you will have two mixers drivers available in your system. This does not have to be the case, however. Some specialised sound hardware does not have a mixer at all. Some other sound hardware has more than ONE Mixer Driver Associated with it. The Sound Hardware Drivers Determine The Quantity and Capability of The Mixers in a System.
Destinations Sound Hardware Provides A Number of Signal Destination Lines (I.E. Places That Audio Goes (I. Places That Audio Goes). Typically, They Provide At Least TWO:
· A Playback Destination, The Destination Used to Play Back Audio Through The Loudspeakers Or Headphones Attached to the Computer
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More complicated sound cards may have more destinations that this. For example, they may have an extra destination for sending audio to telephone lines, or they may have separate playback destinations for headphones and loudspeakers. Specialised sound hardware may have only one destination in the mixer . for example, a USB microphone may only have one destination for recording and USB speakers may only have one destination for playback. Destinations have a number of properties that can be accessed by software, including a user-friendly name, the type of each destination , and the type of hardware that they are connected to. The sound hardware driver determines the quantity and type of destinations in a mixer. Sources The audio that goes to the destinations must come from somewhere, so each destination is normally associated with one or more Source Lines. Are Typically Associated (as you might expect) with MicroPhone, Line in, Synthesizer etc. Like Destinations, Sourcees h ave a number of properties that can be accessed by software, including a user-friendly name, the type of each source, and the type of hardware that they are connected to. The sound hardware driver determines the quantity and type of sources in a mixer . Controls Sources and destinations may have controls associated with them. Usually (but not always) the controls include individual volume controls and mute switches for each source and for the destination. Sometimes extra controls are provided for tone control, gain boost, and other effects Controls Also Have A Number of Properties That Can Be Accessed by Software, Including A User-Friendly Name and The Type of Each Control. They Also Have Values (as you might expect!
) That you can read and write to alter the way the mixer operates. The sound hardware driver determines the quantity and type of the controls in a mixer. Mixer architecture for a single destination Given destinations, sources, and controls, the signal path for a SINGLE MIXER DESTINATION LOOKS SOMETHING LIKE THIS: AND THE Architecture for a Complete Mixer Looks Something Like this:
Note that the mixer sections for each destination are normally completely separate. However, some mixer drivers make the destination of one section one of the sources for another. Typically, a playback destination is linked to one of the source lines for the recording destination (Creative Sound Blaster drivers call this 'What-U-Hear';... other drivers call this 'Wave Out' or similar) However, The mixer architecture is wholly determined by the sound hardware driver Remember that It is important if you want to develop Applications That Will Work with Many Different Types of Sound Hardware.
