1 files changed, 143 insertions, 0 deletions
diff --git a/apps/web/src/timeline/audio-separation/index.ts b/apps/web/src/timeline/audio-separation/index.ts
new file mode 100644
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+++ b/apps/web/src/timeline/audio-separation/index.ts
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+import { cloneAnimations } from "@/animation";
+import type { ElementAnimations } from "@/animation/types";
+import type { MediaAsset } from "@/media/types";
+import { DEFAULTS } from "@/timeline/defaults";
+import type {
+	CreateUploadAudioElement,
+	TimelineElement,
+	AudioElement,
+	VideoElement,
+} from "../types";
+
+type MediaAudioState = Pick<MediaAsset, "hasAudio">;
+
+export function isSourceAudioEnabled({
+	element,
+}: {
+	element: VideoElement;
+}): boolean {
+	return element.isSourceAudioEnabled !== false;
+}
+
+export function isSourceAudioSeparated({
+	element,
+}: {
+	element: VideoElement;
+}): boolean {
+	return !isSourceAudioEnabled({ element });
+}
+
+export function canExtractSourceAudio(
+	element: TimelineElement,
+	mediaAsset: MediaAudioState | null | undefined,
+): element is VideoElement {
+	return (
+		element.type === "video" &&
+		isSourceAudioEnabled({ element }) &&
+		!!mediaAsset &&
+		mediaAsset.hasAudio !== false
+	);
+}
+
+export function canRecoverSourceAudio(
+	element: TimelineElement,
+): element is VideoElement {
+	return element.type === "video" && isSourceAudioSeparated({ element });
+}
+
+export function canToggleSourceAudio(
+	element: TimelineElement,
+	mediaAsset: MediaAudioState | null | undefined,
+): element is VideoElement {
+	return (
+		canRecoverSourceAudio(element) || canExtractSourceAudio(element, mediaAsset)
+	);
+}
+
+export function doesElementHaveEnabledAudio({
+	element,
+	mediaAsset,
+}: {
+	element: AudioElement | VideoElement;
+	mediaAsset?: MediaAudioState | null;
+}): boolean {
+	if (element.type === "audio") {
+		return true;
+	}
+
+	return (
+		!!mediaAsset &&
+		mediaAsset.hasAudio !== false &&
+		isSourceAudioEnabled({ element })
+	);
+}
+
+export function buildSeparatedAudioElement({
+	sourceElement,
+}: {
+	sourceElement: VideoElement;
+}): CreateUploadAudioElement {
+	return {
+		type: "audio",
+		sourceType: "upload",
+		mediaId: sourceElement.mediaId,
+		name: sourceElement.name,
+		duration: sourceElement.duration,
+		startTime: sourceElement.startTime,
+		trimStart: sourceElement.trimStart,
+		trimEnd: sourceElement.trimEnd,
+		sourceDuration: sourceElement.sourceDuration,
+		volume: sourceElement.volume ?? DEFAULTS.element.volume,
+		muted: sourceElement.muted ?? false,
+		retime: sourceElement.retime
+			? {
+					rate: sourceElement.retime.rate,
+					maintainPitch: sourceElement.retime.maintainPitch,
+				}
+			: undefined,
+		animations: cloneVolumeAnimations({
+			animations: sourceElement.animations,
+		}),
+	};
+}
+
+export function getSourceAudioActionLabel({
+	element,
+}: {
+	element: VideoElement;
+}): "Extract audio" | "Recover audio" {
+	return isSourceAudioSeparated({ element })
+		? "Recover audio"
+		: "Extract audio";
+}
+
+function cloneVolumeAnimations({
+	animations,
+}: {
+	animations: ElementAnimations | undefined;
+}): ElementAnimations | undefined {
+	const volumeBinding = animations?.bindings.volume;
+	if (!volumeBinding) {
+		return undefined;
+	}
+
+	const subsetChannels = Object.fromEntries(
+		volumeBinding.components.flatMap((component) => {
+			const channel = animations?.channels[component.channelId];
+			return channel ? [[component.channelId, channel] as const] : [];
+		}),
+	);
+	if (Object.keys(subsetChannels).length === 0) {
+		return undefined;
+	}
+
+	return cloneAnimations({
+		animations: {
+			bindings: {
+				volume: volumeBinding,
+			},
+			channels: subsetChannels,
+		},
+		shouldRegenerateKeyframeIds: true,
+	});
+}