fwisound4

Usage

Overview

The fwisound driver provides audio capture from Apple FireWire devices that use a proprietary isochronous audio protocol (not IEC 61883/AMDTP).

The driver attaches to unit directories in the device CSR configuration ROM with Apple OUI (0x000a27) and decodes the "sght" packet signature to deliver stereo PCM audio to the sound(4) framework.

The device attaches as a standard sound(4) capture device accessible at /dev/dspX. The fixed audio format is 48000 Hz, 2-channel, signed 16-bit big-endian (S16BE).

Hardware

The fwisound driver supports Apple FireWire devices with the following unit directory:

unit_spec_ID

0x000a27 (Apple OUI)

unit_sw_version

0x000010

Known compatible hardware:

• Apple iSight (FireWire cylinder)

Sysctls

hw.firewire.fwisound.iso_channel

Isochronous receive channel (default 1). Can be set as a tunable in loader.conf(5). Must not conflict with hw.firewire.fwcam.iso_channel (default 0).

Files

/dev/dspX

PCM capture device created by sound(4).

Examples

Record five seconds of audio:

rec -r 48000 -c 2 -e signed-integer -b 16 -B /tmp/out.wav trim 5

If multiple sound devices are present, address the device explicitly:

sox -t ossdsp /dev/dsp4 -r 48000 -c 2 -e signed-integer -b 16 \
    /tmp/out.wav trim 5