opencv csc module

[totaam]

Issue migrated from trac ticket # 1108

component: encodings | priority: trivial | resolution: fixed

2016-02-01 20:00:51: antoine created the issue

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Related to #1030: [http://opencv.org/] provides simple utility csc functions, including [http: opencv.org ] provides simple utility csc functions, including [CSC](http:--opencv.org-] provides simple utility csc functions, including [../wiki/CSC) via cvtcolor: rgb = cv2.cvtColor(bgr, cv2.COLOR_BGR2RGB)

I'm not sure how we can deal with rowstride, but I think the underlying numpy buffers it uses can help us with that.

It should be quite easy to make a csc module, then we can see what performance we get, how it compares to the leading contenders (#973), how portable it is (builds on win32, not yet on osx), etc.

[totaam]

2016-02-01 23:47:24: antoine changed status from new to assigned

[totaam]

2016-02-01 23:47:24: antoine commented

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Added a csc_opencv csc module in r11811, minor fixes in r11819.

Notes / limitations / TODO:

• it's disappointing: just not very fast, even my crappy Cython csc module is faster
• performance data needs to be added to CSC Performance
• the code only handles RGB modes to YUV420P at present - not sure we care
• we claim to be handling odd dimensions and resize the pixel buffers on the fly (looks like a bug in the csc / codec interface, which should be able to handle width and height masks better?) - this step is using numpy copy line-by-line, but it is actually quite fast
• the code is quite small which is nice, and it should be portable
• it could handle scaling using cvResize: it even supports different interpolation types (linear, nearest, etc..)

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Can easily be tested by forcing CSC with h264:

XPRA_FORCE_CSC_MODE=YUV420P \
XPRA_ENCODING_STRICT_MODE=1 \
xpra --start-child=xterm start :10 -d opencv --csc-modules=opencv

[totaam]

2016-02-17 14:37:38: antoine changed status from assigned to closed

[totaam]

2016-02-17 14:37:38: antoine set resolution to fixed

[totaam]

2016-02-17 14:37:38: antoine edited the issue description

[totaam]

2016-02-17 14:37:38: antoine commented

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This will do for now.