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VVVV addonpack for plugins dealing with CVImageLink

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readme.md

Introduction

https://github.com/elliotwoods/VVVV.Packs.OpenCV

This pack defines a new Image type for VVVV which lets you work with images on the CPU (previously achieved with DirectShow filters and FreeFrame). CVImageLink assists automatic threading, double buffering, conversion, and simple OpenCV development

The VVVV.Nodes.OpenCV plugin defines the CVImageLink type, and introduces a base set of functionality for working with it.

The other plugins in this pack work with the CVImageLink type, generally generating, filtering or detecting something with it.

Elliot Woods (www.kimchiandchips.com)

Credits

Thanks for vux, alg and Elias. Thanks also to the other core VVVV developers and users.

Thanks to Lumacoustics of London, for their continued support in sponsoring development of the OpenCV plugins.

License

This plugin is distributed under the MIT license

Parts of this pack may reference EmguCV which is distributed under a GPL license. If you wish to use these parts without the GPL restrictions, then I suggest paying for a commercial EmguCV license for this project. Buying said license (if bought for the VVVV.Pack.OpenCV project) will also indemnify any other users of this project from the EmguCV license conditions.

Usage

Types

We are now using CVImageLink which is a polymorphic (accepts different formats of image), double threaded (handles threading, locking) and auto converting (e.g. for RGBA8 for GPU) image type.

To use this type yourself, check out examples of where we use CVImageInputSpread and CVImageInputSpreadWith

It can be used for lots of things. We can make nodes in minutes to supply video from lots of sources (e.g. CLEye, Point Grey, BlackMagic) and then use them with the full chain of CV / texture utils.

Threading

Current design is 'Highly Threaded' or 'Background' as described in the threading options list at http://vvvv.org/forum/replacing-directshow-with-managed-opencv.-video-playback-capture-cv

Each node has it's own thread, every exchange of image data between threads results in a double buffer This obviously leads to many threads + much memory usage (perhaps in the future users will be able to select the global threading model at runtime)

The node thread has an output buffer (single). When the thread is ready to send (i.e. all of its inputs are fresh) then it calls FOutputBuffer.SetImage(...) which pushes the image downstream. FOutput should not have any internal buffers, instead passing through its input directly

Links are double buffers

Memory usage

Examples of memory usage:

  • 640*480 ~= 300KB (VGA mono)
  • 640*480*3 ~= 1MB (VGA colour)
  • 640*480*16 ~= 5MB (VGA colour + alpha, 32bit float)
  • 1920*1080*3 ~= 6MB (HD colour video frame)

Generally each slice at each node = 2 * the above (double buffered)

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