Minimize sample waveform rendering time #7210
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Eliminates vector allocation. Reduces the number of frames to process per pixel index from 512 down to 16. Restructure the 2 loops and move some math out of the loops.
khoidauminh
changed the title
Veratil
reviewed
Apr 21, 2024
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Sacrifices too much quality in exchange for performance. |
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I've been noticing that LMMS was lagging under a big project with long samples. Zooming in and out causes notable frame rate drop.
This pull request makes the following changes to
SampleWaveform::visualize(in order of performance improvement):Change
maxFramesPerPixelfrom 512 to 24. Often, processing this many frames are redundant and can cause lag when working on a sample heavy project.Remove 3 vector allocation by nesting the loops. The
min,maxandsquaredvalues are computed on the spot for each newpixelIndex, which means they no longer need to be stored in vectors.Calculate
halfHeight,parameters.amplificationandframe.size()outside of the loops intoscalingFactor.The refactoring tries to minimize the performance cost while retaining the look of the waveform. Compared to the original code, when zoomed all the way out, some sample tracks may appear to be quieter. However they look almost identical when zoomed in.
comparison:
Master branch:
lmms-sample-original-code.mp4
Pull request:
lmms-sample-new-code.mp4