feat: add transitions, track mixing, and voiceover controls

1 files changed, 38 insertions, 2 deletions

diff --git a/apps/web/src/voiceover/recorder.ts b/apps/web/src/voiceover/recorder.ts
index b71ca74f..48322898 100644
--- a/apps/web/src/voiceover/recorder.ts
+++ b/apps/web/src/voiceover/recorder.ts
@@ -5,6 +5,8 @@
  * actual microphone stream.
  */
 
+import { buildVoiceOverAudioConstraints } from "@/voiceover/devices";
+
 export const PREFERRED_MIME_TYPES = [
 	"audio/webm;codecs=opus",
 	"audio/webm",
@@ -95,6 +97,11 @@ interface ActiveRecording {
 	startedAtMs: number;
 }
 
+export interface VoiceOverRecordingSession {
+	stream: MediaStream;
+	mimeType: string;
+}
+
 let activeRecording: ActiveRecording | null = null;
 
 function stopStreamTracks({ stream }: { stream: MediaStream }): void {
@@ -103,7 +110,15 @@ function stopStreamTracks({ stream }: { stream: MediaStream }): void {
 	}
 }
 
-export async function startVoiceOverRecording(): Promise<void> {
+export function getActiveVoiceOverRecordingStream(): MediaStream | null {
+	return activeRecording?.stream ?? null;
+}
+
+export async function startVoiceOverRecording({
+	deviceId,
+}: {
+	deviceId?: string | null;
+} = {}): Promise<VoiceOverRecordingSession> {
 	if (activeRecording) {
 		throw new Error("A voice-over recording is already in progress");
 	}
@@ -113,7 +128,24 @@ export async function startVoiceOverRecording(): Promise<void> {
 		throw new Error("Voice-over recording is not supported in this browser");
 	}
 
-	const stream = await mediaDevices.getUserMedia({ audio: true });
+	let stream: MediaStream;
+	try {
+		stream = await mediaDevices.getUserMedia(
+			buildVoiceOverAudioConstraints({ deviceId }),
+		);
+	} catch (error) {
+		if (
+			deviceId &&
+			error instanceof DOMException &&
+			(error.name === "NotFoundError" || error.name === "OverconstrainedError")
+		) {
+			stream = await mediaDevices.getUserMedia(
+				buildVoiceOverAudioConstraints({ deviceId: null }),
+			);
+		} else {
+			throw error;
+		}
+	}
 	try {
 		const mimeType = pickSupportedMimeType({
 			isTypeSupported: (candidate) => MediaRecorder.isTypeSupported(candidate),
@@ -135,6 +167,10 @@ export async function startVoiceOverRecording(): Promise<void> {
 			mimeType: recorder.mimeType || mimeType || "audio/webm",
 			startedAtMs: performance.now(),
 		};
+		return {
+			stream,
+			mimeType: activeRecording.mimeType,
+		};
 	} catch (error) {
 		stopStreamTracks({ stream });
 		throw error;