gizhw:audio

PCM sound on any platform. devices lists each sound device by an id the platform gives and a name; open takes the id, the direction and the wanted rate, channels and sample format. Linux plays and captures through ALSA (gizhw:alsa). A platform without a backend fails each call with the class and the platform named.

import * as Audio from "gizhw:audio";

Types

Info

type Info = { id: string; name: string; }

A sound device: id opens it (an ALSA PCM name on Linux, "default" first), name is the card's own name.

• id: string
• name: string

Wanted

type Wanted = { rate: i64; channels: i64; format: string; }

What open asks for: a rate in Hz, a channel count and a sample format; "s16le" (16-bit little-endian, the channels interleaved) is the one every backend gives.

• rate: i64
• channels: i64
• format: string

Stream

type Stream

An open stream: its direction and the rate, channels and format of its frames.

• capture: bool
• rate: i64
• channels: i64
• format: string

Functions

devices

function devices(sys: System): Vec<Info> throws string

The sound devices of this machine: the platform's default device first, then one for each card.

Effects: fail, io.

open

function open(sys: System, id: string, capture: bool, wanted: Wanted): Stream throws string

The sound device id (from devices), open for capture or for playback.

Effects: fail, io.

Methods

Stream.frameBytes

function Stream.frameBytes(self: Stream): i64

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

Effects: fail.

Stream.play

function Stream.play(self: Stream, samples: bytes): i64 throws string

Plays samples (whole frames); gives the frames played.

Effects: fail, io.

Stream.capture

function Stream.capture(self: Stream, frames: i64): bytes throws string

Captures frames frames; gives their bytes.

Effects: fail, io.

Stream.close

function Stream.close(self: Stream): void

Closes the stream.

Effects: fail, io.