UPIS Interface Description

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Preface

The socket interface provided by UPIS can be backwards-compatible with the original ImageSrv application. Currently, it can produce 24-bit raw and JPEG-compressed pictures. If backwards-compatibility is desired, make sure to enable the legacy mode ( -l) command-line option.

Workflow

1. Wait for connection from a client
2. For each client:
   1. If legacy mode is enabled, transmit a full frame.
   2. Wait for a request from the client.
   3. Send out the requested picture
   4. Go to step 2.

Command-line options

Flag	Name	Default	Description
-l	Legacy mode	off	Server will transmit a full frame when new clients connect.
-f FORMAT	Frame format	GOOD	Sets the compression format to one of the following case-sensitive tags: {RAW, SUPER, GOOD, NORMAL, FAIR, BAD}.
-s	Frame skip	6	Sets the minimum number of frames to skip between captures.

Requests

OK	Send out a full frame image
U[x][y][width][height]	Send out a rectangular region of the full image (x, y, width, and height are unsigned 32-bit ints)

Data format

The server supports both raw pictures and jpeg pictures. The image data format is:

0	1	2	3	4	...
1 byte	4 bytes				n bytes
Image Type	Image Size				Image Data

Image Type is the format of the image. It can be:

0	raw data
1	jpeg - super quality
2	jpeg - good quality
3	jpeg - normal quality
4	jpeg - fair quality
5	jpeg - bad quality

Image Size is the total length of Image Data in bytes, represented as an unsigned int.

Image Data is the actual data of the image. The length of the data in bytes is specified by Image Size.

Raw data

Image Data is in the form:

0	1	2	3	4	5	6	...
2 bytes		2 bytes		1 byte	1 byte	1 byte
width		height		R	G	B

Data is packed from left to right, from top to bottom.

JPEG Data

Image Data is in the form of pure jpeg data. It can be decompressed directly by any jpeg decoder.