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Performance: optimize AudioEngine visualization data loop #233

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Performance: optimize AudioEngine visualization data loop #233

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36 changes: 19 additions & 17 deletions src/lib/audio/AudioEngine.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -869,32 +869,34 @@ export class AudioEngine implements IAudioEngine {
: new Float32Array(outSize);
const samplesPerTarget = this.VIS_SUMMARY_SIZE / width;

// Optimized downsampling: eliminate Math.floor per iteration and the 'first' branch check
let startS = 0;

for (let i = 0; i < width; i++) {
const rangeStart = i * samplesPerTarget;
const rangeEnd = (i + 1) * samplesPerTarget;
const endS = Math.floor((i + 1) * samplesPerTarget);

let minVal = 0;
let maxVal = 0;
let first = true;

for (let s = Math.floor(rangeStart); s < Math.floor(rangeEnd); s++) {
// Use shadow buffer property to read linearly without modulo
const idx = (this.visualizationSummaryPosition + s) * 2;
const vMin = this.visualizationSummary[idx];
const vMax = this.visualizationSummary[idx + 1];

if (first) {
minVal = vMin;
maxVal = vMax;
first = false;
} else {

if (startS < endS) {
let idx = (this.visualizationSummaryPosition + startS) * 2;
minVal = this.visualizationSummary[idx];
maxVal = this.visualizationSummary[idx + 1];

for (let s = startS + 1; s < endS; s++) {
idx += 2;
const vMin = this.visualizationSummary[idx];
const vMax = this.visualizationSummary[idx + 1];
if (vMin < minVal) minVal = vMin;
if (vMax > maxVal) maxVal = vMax;
}
Comment on lines +886 to 892
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@gemini-code-assist gemini-code-assist bot Mar 28, 2026

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medium

For conciseness and potentially better performance by avoiding explicit branching, you could use Math.min() and Math.max() to update minVal and maxVal.

                for (let s = startS + 1; s < endS; s++) {
                    idx += 2;
                    minVal = Math.min(minVal, this.visualizationSummary[idx]);
                    maxVal = Math.max(maxVal, this.visualizationSummary[idx + 1]);
                }

}

subsampledBuffer[i * 2] = minVal;
subsampledBuffer[i * 2 + 1] = maxVal;
const outIdx = i * 2;
subsampledBuffer[outIdx] = minVal;
subsampledBuffer[outIdx + 1] = maxVal;

startS = endS;
}
return subsampledBuffer;
}
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