[Bf-committers] Speeding up sequencer scopes drawing

Xavier Thomas xavier.thomas.1980 at gmail.com
Mon Jan 26 17:21:45 CET 2009

Proxies are for input strips, the scopes are drawn based on the render
result (at preview size, if preview is enabled).
But each space area displaying a scope will analyse all pixel of this render
result to draw the scope. Drawing a scope by analysing only a part of the
pixels will speed things up.

Note that from what I read the subsampled image is 16 lines with the same x
resolution (for example if your project is 1920x1080 pixels, then the
subsampled image used for drawing the scopes is 1920x16 pixels) but I
suppose other kind of sumbsamplig (or quick scale) can do the work too.


2009/1/26 Roger Wickes <rogerwickes at yahoo.com>

> proxies come to mind, which are say 25%, but perhaps another proxy could be
> computed. 1/16 is like 4%
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>  ------------------------------
> *From:* Xavier Thomas <xavier.thomas.1980 at gmail.com>
> *To:* bf-blender developers <bf-committers at blender.org>
> *Sent:* Monday, January 26, 2009 5:36:17 AM
> *Subject:* [Bf-committers] Speeding up sequencer scopes drawing
> Hello,
> I use a lot the scope views in the sequencer, and having 4 of them opened
> at the same time (histogram, vectorscope, waveform and separated channels
> waveform) really slow down "time navigation". (each time we change the
> current frame the scopes need a lot of time to actualize)
> I read somewhere (don't remember where) that some commercial NLE programs
> use a subsampled version of the image (16 entire lines evenly distributed of
> the original image) to create the scopes. The trick in blender would be to
> make each scope view use the same subsampled image (if each view recalculate
> his own subsampled image the preformance gain won't be the same). Maybe
> adding a scope view that show all the scopes in the same view is a simpler
> solution.
> Further, maybe the subsample fct (or an other fct) can convert all float
> image to int so the scope drawing functions for float image can be dropped
> to keep the code base smaller.
> I will make fiew tests to investigate this, but please (Peter) tell me what
> you think.
> Xavier
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