Webcam Class

Namespace: GHIElectronics.TinyCLR.Devices.UsbHost · Assembly: GHIElectronics.TinyCLR.Devices.UsbHost

Allows a USB webcam (UVC class, YUY2 uncompressed) to be used.

public class Webcam : BaseDevice

Constructors

Webcam(uint id, byte interfaceIndex)

public Webcam(uint id, byte interfaceIndex) : base(id, interfaceIndex, DeviceType.Webcam)

Constructs a webcam wrapper for a connected UVC camera.

Parameter	Type	Description
id	uint	Device id from the connection event.
interfaceIndex	byte	VideoControl interface index from the connection event.

Properties

IsStreaming

public bool IsStreaming { get; }

True while the camera is streaming.

IsMjpeg

public bool IsMjpeg { get; }

True if the active stream is MJPEG (caller must JPEG-decode); false for YUY2 (use ConvertYuy2ToRgb565).

Width

public int Width { get; }

The negotiated frame width in pixels (valid while streaming).

Height

public int Height { get; }

The negotiated frame height in pixels (valid while streaming).

FrameSize

public int FrameSize { get; }

Bytes per frame, RGB565 (= Width * Height * 2). Valid while streaming.

SupportedFormats

public Format[] SupportedFormats { get; }

The camera's supported YUY2 formats (queried at construction).

Methods

StartStreaming(Format format, int fps)

public void StartStreaming(Format format, int fps = 15)

Starts streaming the chosen format. Allocates the device-side double buffer.

Parameter	Type	Description
format	Format	One of the entries from SupportedFormats.
fps	int	Requested frame rate. Default is 15 — the slowest rate that virtually every UVC camera supports, so it's the broadest-compatibility starting point. Pass 0 to use the camera's own default rate (typically 30 fps) from the frame descriptor. Any other value asks the camera for that rate; the camera rounds to its nearest supported value (visible in the PROBE GET_CUR exchange). Use this to throttle a camera that produces faster than your application can consume: cheap UVC cameras often have an internal FIFO and produce at their max rate regardless. If you can render at 10 fps but the camera produces at 30, 20 fps of frames pile up in its FIFO per second, manifesting as a several-second "playback delayed behind reality" lag. Setting fps to match your app's processing rate keeps producer and consumer aligned and eliminates the lag. When the camera refuses to go below its minimum supported rate, use Resync periodically to flush its internal FIFO instead.

Resync(bool soft)

public void Resync(bool soft = false)

Flushes any frames the camera has queued in its internal sensor->encoder FIFO.

Parameter	Type	Description
soft	bool	false (default) — hard flush via streaming alt-setting toggle. Definitive on every UVC camera but ~500-1000 ms blackout because the camera reboots its sensor pipeline. true — soft flush, replays the previously negotiated SET_CUR (Commit) only. ~20 ms blackout. Camera-dependent: some cameras flush their FIFO on commit-during-streaming, others ignore it and the call is effectively a no-op. Try once on your specific camera and fall back to false if the lag doesn't drop.

StopStreaming()

public void StopStreaming()

Stops streaming and frees device-side buffers.

IsNewFrameAvailable()

public bool IsNewFrameAvailable()

Returns true and clears the flag if a new frame is ready since the last call.

Returns bool

GetFrame(byte[] buffer)

public int GetFrame(byte[] buffer)

Copies the most recently completed frame into buffer as raw bytes.

Parameter	Type	Description
buffer	byte[]	Destination buffer. Must be at least FrameSize bytes (which is the upper bound; actual size returned).

Returns int — Actual number of bytes written. For YUY2 always Width*Height*2. For MJPEG, varies per frame.

ConvertYuy2ToRgb565(byte[] yuy2, byte[] rgb565)

public static void ConvertYuy2ToRgb565(byte[] yuy2, byte[] rgb565)

Converts a YUY2 (YUYV-packed) buffer to RGB565 in place into rgb565.

Parameter	Type	Description
yuy2	byte[]	Source buffer with YUY2-packed pixels (Y1 U Y2 V tuples).
rgb565	byte[]	Destination buffer for RGB565 pixels (2 bytes per pixel).

Dispose(bool disposing)

protected override void Dispose(bool disposing)

Disposes the webcam, stopping any active stream.

Parameter	Type	Description
disposing	bool

CheckEvents(object sender)

protected override void CheckEvents(object sender)

Polled by BaseDevice's worker; raises FrameAvailable when a new frame lands.

Parameter	Type	Description
sender	object

Events

FrameAvailable

public event FrameAvailableEventHandler FrameAvailable

Raised on the BaseDevice worker thread when a new frame is available.