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2.2 Understand mixer and record audio line


A sound card mixer is the part of a sound card that can mix the sound input from different sources..

Mixing scheme

The following schematic shows how a sound card's mixer manipulates sound from different sources:



Play controls on a typical sound mixer
Control channels Controlled source
Wave* stereo Sound generated by the computer when playing MP3, WAV,...
Also the sound when playing a CD-DA in some programs (Windows Media Player, Media Player Classic) or playing a MIDI in certain programs (JetAudio)
MIDI/SW Synth stereo Sound generated from a MIDI device or synthesizer (electronic keyboard, Windows Media Player, IrfanView, Media Player Classic, ...)
CD playback stereo Sound generated when playing a CD-DA in most programs (JetAudio, IrfanView, ...)
Microphone mono Sound entering through an internal microphone, or the microphone jack
Line in/Aux stereo Sound from an external source (iPod, television, etc.)
SPDIF mono Uncommon digital interface of some devices
PC speaker mono Sound generated in the old internal PC speaker. This is the sound heard in old MS-DOS programs and on boot (on PC's)
Volume control stereo Mixed sound sent to the speakers (output)
  • TV tuner cards and other similar devices output their sound via the Wave channel.
Record controls
Control Channels Source
Stereo mix stereo Mixed sound sent to the recorder
Mono mix mono Mixed sound converted into mono, sent to the recorder
Microphone mono Sound from the microphone that is directly going to be recorded


Record streaming sound
As this sound is controlled through wave control, you have to set this volume in the play control (maybe it's convenient to mute all others, except volume control if you want to hear it meanwhile) In record play select stereo mix or mono mix.
In this way you can also record any other internal sound of your PC, i.e. voices of TTS engines, sounds of the operating system,
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