COP Image Capture

Image capture is a mechanism which allows you to capture individual frames from a VIRGO feed. Image capture is by default turned off. It may be turned on for a feed at any time but only one capture session can be active at any given time. A “capture lease” is required to turn image capture on or to restart an already active capture session. A “capture lease” is represented by its “capture lease date” which you must send to VIRGO. VIRGO does not interpret the lease date value - it only cares about a change in the lease date value.

You turn image capturing on by sending a “capture.max-frames” with a value > 0, a valid “capture.deposite-base-url” and a unique “capture.lease-date”. The “maximum-frames” value defines how many frames should be captured before image capturing is automatically turned off again. This mechanism ensures that image capturing can not be accidentally left turned on by, for example, forgetting to send a new image capture state. You turn image capture off by sending “maximum-frames” with a value of 0 or by sending “capture.deposite-base-url” with an empty string value.

VIRGO sends a HTTP POST request with the JPEG compressed image in its body to the final per-image deposits URL. The final deposit URL is formed by adding the image file name to the “capture.deposite-base-url”. The image file name is computed as follows:

<feed name>_<yyyy>-<mm>-<dd>_<pts>.jpg

Where “yyyy-mm-dd” is referring to the current year, month and day and “pts” refers to the presentation time stamp of the captured frame. The presentation time stamp is in terms of microseconds from the start of the stream.

The following HTTP custom headers are included with every capture POST request:

Header Description
X-CLIENT-ID The client id of the virgod instance. This is immutable, factory configured, unique and descriptive VIRGO instance identifier.
For example:
VRGO-LNX-TRPR-16-123
X-CLIENT-TYPE The type of the client. This is a combination of the client name and the platform name.
For example:
Virgo-Linux
X-FEED-ID The ID of the feed from which the image was captured.
For example:
VRGO-LNX-TRPR-16-123-camera_1

See Also