Audio functions are constrained by the following platform limitations for AR755x, AR8652, and WP8548.

This table lists possible audio connections:

Input stream	Spkr	USB Tx	PCM Tx	I2S Tx	Mdm Tx	Rec
Mic					X(*)	X(*)
USB Rx					X
PCM Rx					X
I2S Rx						X
Mdm Rx	X(*)	X	X	X		X
Pb	X(*)	X	X	X	X

(*) AR platform only

Pb = file playback
Rec = file recording

Only 1 point to 1 point connection is possible except for Pb and Rec. Pb and Rec can be added to any active 1 point to 1 point connections or simply tied to 1 single stream.

Function \ IF	I2S	PCM	USB	Analog (Mic / Spkr)	Mdm Tx	Mdm Rx	Pb
Gain (Set / Get)				X(*)	X	X	X
Mute / Unmute				X(*)	X	X	X
NS					X
EC					X
IIR					X	X
FIR					X	X
AGC	Only Tx	Only Tx	Only Tx	Only Spkr(*)	X	X

(*) AR platform only

NS = Noise Suppressor
EC = Echo Canceller
IIR = Infinite Impulse Response filter
FIR = Finite Impulse Response filter
AGC = Automatic Gain Control

Playback and recording

File playback supports these file types:

.wav
.amr
.awb

File recording is only supported for .wav file types.

One single file playback and one single file recording can be activated simultaneously.

Continuous playback of one file doesn't work well.

PCM insertion/extraction

Only supports 16-bit sampling resolution on the AR7 platform.

Copyright (C) Sierra Wireless Inc. Use of this work is subject to license.