roboflex.audio_alsa

Support for reading audio data on linux from the Advanced Linux Sound Architecture (ALSA).

System dependencies

Requires ALSA to be installed. More than likely, it already is installed in your distro. But if not:

apt-get install libasound2 alsa-utils alsa-oss

Import

import numpy
import roboflex.audio_alsa as raa

Nodes

There is only one: AudioSensor

# all parameters optional: below are the defaults
audio_sensor = raa.AudioSensor(
    name = "WebcamSensor",
    channels = 1,
    sampling_rate = 48000,
    capture_frames = 512,
    produce_frames = 1024,
    bit_depth = raa.BitDepth.S16LE,
    device_name = "default",
)

# must be started (like all sensors)!
audio_sensor.start()

Messages

from roboflex.audio_alsa import AudioData, AudioData32

API:

# the timestamp just before reading from device
message.t0 -> Float

# the timestamp just after reading from device
message.t1 -> Float

# the audio data read from the device
message.data -> np.array
    shape = [C, P] where C is channels, P is produce_frames
    dtype = np.int16

DYNOFLEX:

# the timestamp just before reading from device
message["t0"] -> Double

# the timestamp just after reading from device
message["t1"] -> Double

# the audio data read from the device
message.data -> np.array
    shape = [C, P] where C is channels, P is produce_frames
    dtype = np.int32

Other

Available BitDepths:

enum raa.BitDepth:
    S16LE,
    S24LE,
    S32LE,
    S24_3LE