Soundcard
From the ALSA wiki
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A Soundcard is a device which is attached to the computer and which is able to produce sound. In ALSA a soundcard can have several capabilities
- It can be used as a pcm-playback/capture device (see pcm-device)
- It might have midi hardware
- And it might have a ctl-device (a mixer).
Different soundcards will have different hardware features. A basic soundcard might have the I/O ports shown in the figure. More sophisticated cards will support more channels, S/PDIF I/O, MIDI ports, or more analog speaker outputs for surround sound or woofers.
In the figure:
- Line In - analog input from external device
- Mic In - low-level, mono microphone input
- PCM playback - digital stream from software
- Synthesizer - stream generated from wavetable
- PCM Capture - digital stream output to software
- Line Out - analog output to external device
- Speaker - amplified analog output to external speakers
