fix(rtc-node): return no frames from AudioResampler.flush() when nothing is buffered

.changeset/resampler-flush-empty.md

@@ -0,0 +1,5 @@
+---
+'@livekit/rtc-node': patch
+---
+
+Return no frames from `AudioResampler.flush()` when nothing is buffered, instead of one empty frame.

packages/livekit-rtc/src/audio_resampler.test.ts

@@ -0,0 +1,18 @@
+// SPDX-FileCopyrightText: 2026 LiveKit, Inc.
+//
+// SPDX-License-Identifier: Apache-2.0
+import { describe, expect, it } from 'vitest';
+import { AudioFrame } from './audio_frame.js';
+import { AudioResampler } from './audio_resampler.js';
+
+describe('AudioResampler', () => {
+  it('flush returns no frames when nothing is buffered', () => {
+    const resampler = new AudioResampler(48000, 16000);
+    expect(resampler.flush()).toEqual([]);
+
+    resampler.push(new AudioFrame(new Int16Array(4800), 48000, 1, 4800));
+    const tail = resampler.flush();
+    expect(tail.reduce((n, f) => n + f.samplesPerChannel, 0)).toBeGreaterThan(0);
+    expect(resampler.flush()).toEqual([]);
+  });
+});

packages/livekit-rtc/src/audio_resampler.ts

@@ -174,7 +174,7 @@ export class AudioResampler {
       throw new Error(res.error);
     }
 
-    if (!res.outputPtr) {
+    if (!res.outputPtr || !res.size) {
       return [];
     }