gizhw:alsa

the Linux backend of gizhw:audio. PCM audio through ALSA (libasound.so.2, loaded at run time, so no build-time link): play and capture 16-bit little-endian interleaved frames on a PCM name ("default", "hw:0,0"). The library's constants are ALSA's (SND_PCM_STREAM_PLAYBACK 0, SND_PCM_STREAM_CAPTURE 1, SND_PCM_FORMAT_S16_LE 2, SND_PCM_ACCESS_RW_INTERLEAVED 3).

import * as Alsa from "gizhw:alsa";

Types

Pcm

type Pcm

An open PCM: the library's snd_pcm_t pointer, the library, the channel count and the rate.

• channels: i64
• rate: i64

Functions

frameBytes

function frameBytes(channels: i64): i64

The bytes of one frame (all channels of one instant).

Effects: fail.

open

function open(sys: System, name: string, capture: bool, rate: i64, channels: i64): Pcm throws string

Opens PCM name for capture or playback at rate Hz with channels channels.

Effects: fail, io.

play

function play(pcm: Pcm, samples: bytes): i64 throws string

Plays samples (whole frames); gives the frames played. An underrun is recovered and the write retried once.

Effects: fail, io.

capture

function capture(pcm: Pcm, frames: i64): bytes throws string

Captures frames frames; gives the bytes read (whole frames).

Effects: fail, io.

close

function close(pcm: Pcm): void

Closes the PCM.

Effects: fail, io.

cards

function cards(sys: System): Vec<Device.Device> throws IoError

The sound cards the sound class has (their devices; the PCM names are on each card).

Effects: fail, io.