This chapter includes information about QNX Sound Architecture (QSA), sounds cards and
devices, sound card control devices, mixers, and pulse code modulation (PCM).
QNX Sound Architecture
In order for an application to produce sound, the system must include several components.
QSA with QNX Acoustics Management Platform
QNX Acoustics Management Platform (AMP) enables an audio pathway from capture to playback that is optimized for low-latency, high frame-rate, small frame size, real-time acoustic signal processing applications.
Cards and devices
The basic piece of hardware needed to produce or capture (i.e., record) sound is an audio chip or sound card, referred to simply as a card. QSA can support more than one card at a time, and can even mount and unmount cards “on the fly” (more about this later). All the sound devices are attached to a card, so in order to reach a device, you must first know what card it's attached to.
Control device
There's one control device for each sound card in the system.
Mixer devices
Mixer devices are responsible for combining or mixing the various analog signals on the sound card.
Pulse Code Modulation (PCM) devices
PCM devices are responsible for converting digital sound sequences to analog waveforms, or analog waveforms to digital sound sequences.