gizhw:camera

video capture on any platform. cameras lists each camera by an id the platform gives and a name; open takes the id with the wanted size and pixel format, and the frames come in that format. Linux captures through V4L2 (gizhw:v4l2). A platform without a backend fails each call with the class and the platform named.

import * as Camera from "gizhw:camera";

Types

Info

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

A camera: id opens it (its /dev/video node on Linux), name is the device's own name.

• id: string
• name: string

Wanted

type Wanted = { width: i64; height: i64; format: string; }

What open asks for: a size in pixels and a pixel format, "nv12", "yuyv" or "mjpeg". The device can give another size; the camera and each frame say which.

• width: i64
• height: i64
• format: string

Frame

type Frame = { data: bytes; width: i64; height: i64; format: string; }

One captured frame: its bytes in format, width x height pixels.

• data: bytes
• width: i64
• height: i64
• format: string

Camera

type Camera

An open camera: the size and format its frames have.

• width: i64
• height: i64
• format: string

Functions

cameras

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

The cameras of this machine, in the order the platform lists them.

Effects: fail, io.

open

function open(sys: System, id: string, wanted: Wanted): Camera throws string

The camera id (from cameras), streaming at the wanted size and format.

Effects: fail, io.

Methods

Camera.frame

function Camera.frame(self: Camera): Frame throws string

The next frame, waiting for it.

Effects: fail, io.

Camera.close

function Camera.close(self: Camera): void

Stops the stream and releases the device.

Effects: fail, io.