fix(recording): normalize native Windows mic loudness



electron/ipc/ffmpeg/filters.test.ts

@@ -69,6 +69,32 @@ describe("getAudioSyncAdjustment", () => {
 			"[1:a]apad=pad_dur=120.000,aresample=async=1:first_pts=0,asetpts=PTS-STARTPTS[aout]",
 		]);
 	});
+
+	it("can add a small gain boost before resampling", () => {
+		const filterParts: string[] = [];
+		appendSyncedAudioFilter(
+			filterParts,
+			"[1:a]",
+			"aout",
+			getAudioSyncAdjustment(120, 120),
+			1.4,
+		);
+
+		expect(filterParts).toEqual([
+			"[1:a]volume=1.400,aresample=async=1:first_pts=0,asetpts=PTS-STARTPTS[aout]",
+		]);
+	});
+
+	it("can prepend mic normalization filters before sync handling", () => {
+		const filterParts: string[] = [];
+		appendSyncedAudioFilter(filterParts, "[1:a]", "aout", getAudioSyncAdjustment(120, 120), {
+			preFilters: ["loudnorm=I=-16:TP=-1.5:LRA=11"],
+		});
+
+		expect(filterParts).toEqual([
+			"[1:a]loudnorm=I=-16:TP=-1.5:LRA=11,aresample=async=1:first_pts=0,asetpts=PTS-STARTPTS[aout]",
+		]);
+	});
 });
 
 describe("applyRecordedAudioStartDelay", () => {

electron/ipc/ffmpeg/filters.ts

@@ -102,8 +102,12 @@ export function appendSyncedAudioFilter(
 	inputLabel: string,
 	outputLabel: string,
 	adjustment: AudioSyncAdjustment,
+	options: number | { volumeMultiplier?: number; preFilters?: string[] } = 1,
 ) {
-	const filters: string[] = [];
+	const volumeMultiplier =
+		typeof options === "number" ? options : (options.volumeMultiplier ?? 1);
+	const preFilters = typeof options === "number" ? [] : (options.preFilters ?? []);
+	const filters: string[] = [...preFilters];
 
 	if (adjustment.mode === "delay" && adjustment.delayMs > 0) {
 		filters.push(`adelay=${adjustment.delayMs}|${adjustment.delayMs}`);
@@ -117,6 +121,14 @@ export function appendSyncedAudioFilter(
 		filters.push(`apad=pad_dur=${formatFfmpegSeconds(adjustment.durationDeltaMs)}`);
 	}
 
+	if (
+		Number.isFinite(volumeMultiplier) &&
+		volumeMultiplier > 0 &&
+		Math.abs(volumeMultiplier - 1) > 0.0005
+	) {
+		filters.push(`volume=${volumeMultiplier.toFixed(3)}`);
+	}
+
 	filters.push("aresample=async=1:first_pts=0", "asetpts=PTS-STARTPTS");
 	filterParts.push(`${inputLabel}${filters.join(",")}[${outputLabel}]`);
 }

electron/ipc/recording/windows.ts

@@ -33,6 +33,9 @@ import {
 import { emitRecordingInterrupted } from "./events";
 
 const execFileAsync = promisify(execFile);
+// Match the browser path's "usable speech level" intent with a standard
+// loudness pass on native Windows mic audio instead of a fixed tiny boost.
+const WINDOWS_NATIVE_MIC_PRE_FILTERS = ["loudnorm=I=-16:TP=-1.5:LRA=11"];
 
 export async function isNativeWindowsCaptureAvailable(): Promise<boolean> {
 	if (process.platform !== "win32") return false;
@@ -266,7 +269,9 @@ export async function muxNativeWindowsVideoWithAudio(
 			const micLabel = micPauseFilter ? "[mic_trimmed]" : "[2:a]";
 
 			appendSyncedAudioFilter(filterParts, systemLabel, "s", systemAdjustment);
-			appendSyncedAudioFilter(filterParts, micLabel, "m", micAdjustment);
+			appendSyncedAudioFilter(filterParts, micLabel, "m", micAdjustment, {
+				preFilters: WINDOWS_NATIVE_MIC_PRE_FILTERS,
+			});
 			filterParts.push("[s][m]amix=inputs=2:duration=longest:normalize=0[aout]");
 
 			await execFileAsync(
@@ -312,7 +317,13 @@ export async function muxNativeWindowsVideoWithAudio(
 				filterParts.push(pauseFilter);
 			}
 			const srcLabel = pauseFilter ? "[trimmed_audio]" : "[1:a]";
-			appendSyncedAudioFilter(filterParts, srcLabel, "aout", singleAdjustment);
+			appendSyncedAudioFilter(
+				filterParts,
+				srcLabel,
+				"aout",
+				singleAdjustment,
+				audioInputs[0] === "mic" ? { preFilters: WINDOWS_NATIVE_MIC_PRE_FILTERS } : 1,
+			);
 
 			await execFileAsync(
 				ffmpegPath,