From 25f684eb589c6f368f66e957e1f4215556fe56f9 Mon Sep 17 00:00:00 2001
From: ValueOn AG <p.motsch@valueon.ch>
Date: Sat, 28 Feb 2026 00:49:11 +0100
Subject: [PATCH] AudioCapture: adaptive chunks (8s max, flush after 1s
 silence)

Made-with: Cursor
---
 src/bot/audioCaptureProcedure.ts | 40 +++++++++++++++++++++++++-------
 1 file changed, 32 insertions(+), 8 deletions(-)

diff --git a/src/bot/audioCaptureProcedure.ts b/src/bot/audioCaptureProcedure.ts
index 008be26..8866c39 100644
--- a/src/bot/audioCaptureProcedure.ts
+++ b/src/bot/audioCaptureProcedure.ts
@@ -124,18 +124,20 @@ export class AudioCaptureProcedure {
             let callbackCount = 0;
             let totalNonZeroSamples = 0;
             const minRmsThreshold = 0.0003;
-            const samplesPerChunk = nativeRate * 4;
+            const maxSamplesPerChunk = nativeRate * 8;
             const targetRate = 16000;
-            // Pre-roll: keep last 500ms of discarded silent chunks so that
-            // speech onsets at the tail of a silent window are preserved.
             const preRollSamples = Math.ceil(nativeRate * 0.5);
+            const minFlushSamples = Math.ceil(nativeRate * 0.5);
+            // Adaptive flush: after ~1s silence following voiced content
+            const silenceFlushCallbacks = 6;
+            let hasVoicedContent = false;
+            let consecutiveSilentCallbacks = 0;
 
             processor.onaudioprocess = (e: AudioProcessingEvent) => {
               const input = e.inputBuffer.getChannelData(0);
               callbackCount++;
 
               // #region agent log
-              // Count non-zero samples on EVERY callback for accurate diagnostics
               let nonZeroThisCallback = 0;
               for (let i = 0; i < input.length; i++) {
                 if (input[i] !== 0) nonZeroThisCallback++;
@@ -154,10 +156,32 @@ export class AudioCaptureProcedure {
               }
               // #endregion
 
+              // Per-callback voice activity detection
+              let cbPower = 0;
+              for (let i = 0; i < input.length; i++) {
+                cbPower += input[i] * input[i];
+              }
+              const cbRms = Math.sqrt(cbPower / Math.max(input.length, 1));
+
+              if (cbRms >= minRmsThreshold) {
+                hasVoicedContent = true;
+                consecutiveSilentCallbacks = 0;
+              } else {
+                consecutiveSilentCallbacks++;
+              }
+
               chunkBuffer.push(new Float32Array(input));
               samplesCollected += input.length;
 
-              if (samplesCollected >= samplesPerChunk) {
+              // Flush: max duration reached OR voiced content followed by ~1s silence
+              const shouldFlush = (
+                samplesCollected >= maxSamplesPerChunk
+                || (hasVoicedContent
+                    && consecutiveSilentCallbacks >= silenceFlushCallbacks
+                    && samplesCollected > minFlushSamples)
+              );
+
+              if (shouldFlush) {
                 const merged = new Float32Array(samplesCollected);
                 let offset = 0;
                 for (const buf of chunkBuffer) {
@@ -171,6 +195,9 @@ export class AudioCaptureProcedure {
                 }
                 const rms = Math.sqrt(powerSum / Math.max(merged.length, 1));
 
+                hasVoicedContent = false;
+                consecutiveSilentCallbacks = 0;
+
                 if (rms < minRmsThreshold) {
                   skippedSilentChunks++;
                   if (skippedSilentChunks % 10 === 0) {
@@ -178,9 +205,6 @@ export class AudioCaptureProcedure {
                       `[AudioCapture] silent chunk skipped: track=${trackId}, readyState=${event.track.readyState}, muted=${event.track.muted}, enabled=${event.track.enabled}, rms=${rms.toFixed(6)}, callbacks=${callbackCount}, totalNonZero=${totalNonZeroSamples}`
                     );
                   }
-                  // Pre-roll: retain the tail of the silent chunk so the next
-                  // voiced chunk includes the speech onset that may have started
-                  // in the last few hundred ms of this window.
                   const keep = Math.min(preRollSamples, merged.length);
                   const preRoll = merged.slice(merged.length - keep);
                   chunkBuffer = [preRoll];