10 files changed, 1977 insertions, 0 deletions
diff --git a/apps/web/src/media/audio-mastering.ts b/apps/web/src/media/audio-mastering.ts
new file mode 100644
index 00000000..f901c3bf
--- /dev/null
+++ b/apps/web/src/media/audio-mastering.ts
@@ -0,0 +1,103 @@
+const MASTER_LIMITER_THRESHOLD_DB = -1;
+const MASTER_LIMITER_KNEE_DB = 0;
+const MASTER_LIMITER_RATIO = 20;
+const MASTER_LIMITER_ATTACK_SECONDS = 0.001;
+const MASTER_LIMITER_RELEASE_SECONDS = 0.12;
+const MASTER_OUTPUT_HEADROOM = 0.98;
+
+export function getAudioBufferPeak({
+	audioBuffer,
+}: {
+	audioBuffer: AudioBuffer;
+}): number {
+	let peak = 0;
+
+	for (let channel = 0; channel < audioBuffer.numberOfChannels; channel++) {
+		const channelData = audioBuffer.getChannelData(channel);
+		for (let index = 0; index < channelData.length; index++) {
+			const magnitude = Math.abs(channelData[index]);
+			if (magnitude > peak) {
+				peak = magnitude;
+			}
+		}
+	}
+
+	return peak;
+}
+
+export function createAudioMasteringChain({
+	audioContext,
+	destination,
+}: {
+	audioContext: AudioContext | OfflineAudioContext;
+	destination: AudioNode;
+}): {
+	input: GainNode;
+} {
+	const input = audioContext.createGain();
+	const limiter = audioContext.createDynamicsCompressor();
+	const outputGain = audioContext.createGain();
+
+	limiter.threshold.value = MASTER_LIMITER_THRESHOLD_DB;
+	limiter.knee.value = MASTER_LIMITER_KNEE_DB;
+	limiter.ratio.value = MASTER_LIMITER_RATIO;
+	limiter.attack.value = MASTER_LIMITER_ATTACK_SECONDS;
+	limiter.release.value = MASTER_LIMITER_RELEASE_SECONDS;
+	outputGain.gain.value = MASTER_OUTPUT_HEADROOM;
+
+	input.connect(limiter);
+	limiter.connect(outputGain);
+	outputGain.connect(destination);
+
+	return { input };
+}
+
+export async function applyAudioMasteringToBuffer({
+	audioBuffer,
+}: {
+	audioBuffer: AudioBuffer;
+}): Promise<AudioBuffer> {
+	if (getAudioBufferPeak({ audioBuffer }) <= MASTER_OUTPUT_HEADROOM) {
+		return audioBuffer;
+	}
+
+	const offlineContext = new OfflineAudioContext(
+		audioBuffer.numberOfChannels,
+		Math.max(1, audioBuffer.length),
+		audioBuffer.sampleRate,
+	);
+	const source = offlineContext.createBufferSource();
+	source.buffer = audioBuffer;
+
+	const { input } = createAudioMasteringChain({
+		audioContext: offlineContext,
+		destination: offlineContext.destination,
+	});
+	source.connect(input);
+	source.start(0);
+
+	const renderedBuffer = await offlineContext.startRendering();
+	clampAudioBufferPeak({
+		audioBuffer: renderedBuffer,
+		maxPeak: MASTER_OUTPUT_HEADROOM,
+	});
+	return renderedBuffer;
+}
+
+function clampAudioBufferPeak({
+	audioBuffer,
+	maxPeak,
+}: {
+	audioBuffer: AudioBuffer;
+	maxPeak: number;
+}): void {
+	for (let channel = 0; channel < audioBuffer.numberOfChannels; channel++) {
+		const channelData = audioBuffer.getChannelData(channel);
+		for (let index = 0; index < channelData.length; index++) {
+			channelData[index] = Math.max(
+				-maxPeak,
+				Math.min(maxPeak, channelData[index]),
+			);
+		}
+	}
+}
diff --git a/apps/web/src/media/audio.ts b/apps/web/src/media/audio.ts
new file mode 100644
index 00000000..42756d49
--- /dev/null
+++ b/apps/web/src/media/audio.ts
@@ -0,0 +1,868 @@
+import type {
+	AudioElement,
+	VideoElement,
+	LibraryAudioElement,
+	RetimeConfig,
+	SceneTracks,
+} from "@/timeline";
+import { shouldMaintainPitch } from "@/retime/rate";
+import type { MediaAsset } from "@/media/types";
+import { applyAudioMasteringToBuffer } from "@/media/audio-mastering";
+import type { AudioCapableElement } from "@/timeline/audio-state";
+import {
+	hasAnimatedVolume,
+	resolveEffectiveAudioGain,
+} from "@/timeline/audio-state";
+import { doesElementHaveEnabledAudio } from "@/timeline/audio-separation";
+import { canElementHaveAudio, hasMediaId } from "@/timeline/element-utils";
+import { canTrackHaveAudio } from "@/timeline";
+import { mediaSupportsAudio } from "@/media/media-utils";
+import { getSourceTimeAtClipTime, renderRetimedBuffer } from "@/retime";
+import { Input, ALL_FORMATS, BlobSource, AudioBufferSink } from "mediabunny";
+import { TICKS_PER_SECOND } from "@/wasm";
+import {
+	computeRmsBuckets,
+	type SampleBucket,
+} from "@/media/waveform-summary";
+
+const MAX_AUDIO_CHANNELS = 2;
+const EXPORT_SAMPLE_RATE = 44100;
+
+export interface CollectedAudioElement {
+	timelineElement: AudioCapableElement;
+	buffer: AudioBuffer;
+	startTime: number;
+	duration: number;
+	trimStart: number;
+	trimEnd: number;
+	volume: number;
+	muted: boolean;
+	retime?: RetimeConfig;
+}
+
+export function createAudioContext({
+	sampleRate,
+}: {
+	sampleRate?: number;
+} = {}): AudioContext {
+	const AudioContextConstructor =
+		window.AudioContext ||
+		(window as typeof window & { webkitAudioContext?: typeof AudioContext })
+			.webkitAudioContext;
+
+	return new AudioContextConstructor(sampleRate ? { sampleRate } : undefined);
+}
+
+export interface DecodedAudio {
+	samples: Float32Array;
+	sampleRate: number;
+}
+
+export async function decodeAudioToFloat32({
+	audioBlob,
+	sampleRate,
+}: {
+	audioBlob: Blob;
+	sampleRate?: number;
+}): Promise<DecodedAudio> {
+	const audioContext = createAudioContext({ sampleRate });
+	const arrayBuffer = await audioBlob.arrayBuffer();
+	const audioBuffer = await audioContext.decodeAudioData(arrayBuffer);
+
+	// mix down to mono
+	const numChannels = audioBuffer.numberOfChannels;
+	const length = audioBuffer.length;
+	const samples = new Float32Array(length);
+
+	for (let i = 0; i < length; i++) {
+		let sum = 0;
+		for (let channel = 0; channel < numChannels; channel++) {
+			sum += audioBuffer.getChannelData(channel)[i];
+		}
+		samples[i] = sum / numChannels;
+	}
+
+	return { samples, sampleRate: audioBuffer.sampleRate };
+}
+
+export interface AudibleElementCandidate {
+	element: AudioElement | VideoElement;
+	mediaAsset: MediaAsset | null;
+}
+
+export function collectAudibleCandidates({
+	tracks,
+	mediaAssets,
+}: {
+	tracks: SceneTracks;
+	mediaAssets: MediaAsset[];
+}): AudibleElementCandidate[] {
+	const allTracks = [...tracks.overlay, tracks.main, ...tracks.audio];
+	const mediaMap = new Map(mediaAssets.map((a) => [a.id, a]));
+	const candidates: AudibleElementCandidate[] = [];
+
+	for (const track of allTracks) {
+		if (canTrackHaveAudio(track) && track.muted) continue;
+
+		for (const element of track.elements) {
+			if (!canElementHaveAudio(element)) continue;
+			if (element.duration <= 0) continue;
+
+			const mediaAsset = hasMediaId(element)
+				? (mediaMap.get(element.mediaId) ?? null)
+				: null;
+			if (!doesElementHaveEnabledAudio({ element, mediaAsset })) continue;
+
+			candidates.push({ element, mediaAsset });
+		}
+	}
+
+	return candidates;
+}
+
+export function timelineHasAudio({
+	tracks,
+	mediaAssets,
+}: {
+	tracks: SceneTracks;
+	mediaAssets: MediaAsset[];
+}): boolean {
+	return collectAudibleCandidates({ tracks, mediaAssets }).some(
+		({ element }) => element.muted !== true,
+	);
+}
+
+export async function collectAudioElements({
+	tracks,
+	mediaAssets,
+	audioContext,
+}: {
+	tracks: SceneTracks;
+	mediaAssets: MediaAsset[];
+	audioContext: AudioContext;
+}): Promise<CollectedAudioElement[]> {
+	const candidates = collectAudibleCandidates({ tracks, mediaAssets });
+	const mediaMap = new Map<string, MediaAsset>(
+		mediaAssets.map((media) => [media.id, media]),
+	);
+	const pendingElements: Array<Promise<CollectedAudioElement | null>> = [];
+
+	for (const { element, mediaAsset } of candidates) {
+		if (element.type === "audio") {
+			pendingElements.push(
+				resolveAudioBufferForElement({
+					element,
+					mediaMap,
+					audioContext,
+				}).then((audioBuffer) => {
+					if (!audioBuffer) return null;
+					return {
+						timelineElement: element,
+						buffer: audioBuffer,
+						startTime: element.startTime / TICKS_PER_SECOND,
+						duration: element.duration / TICKS_PER_SECOND,
+						trimStart: element.trimStart / TICKS_PER_SECOND,
+						trimEnd: element.trimEnd / TICKS_PER_SECOND,
+						volume: resolveEffectiveAudioGain({
+							element,
+							trackMuted: false,
+							localTime: 0,
+						}),
+						muted: element.muted === true,
+						retime: element.retime,
+					};
+				}),
+			);
+			continue;
+		}
+
+		if (element.type === "video") {
+			if (!mediaAsset || !mediaSupportsAudio({ media: mediaAsset })) continue;
+
+			pendingElements.push(
+				resolveAudioBufferForAsset({
+					asset: mediaAsset,
+					audioContext,
+				}).then((audioBuffer) => {
+					if (!audioBuffer) return null;
+					return {
+						timelineElement: element,
+						buffer: audioBuffer,
+						startTime: element.startTime / TICKS_PER_SECOND,
+						duration: element.duration / TICKS_PER_SECOND,
+						trimStart: element.trimStart / TICKS_PER_SECOND,
+						trimEnd: element.trimEnd / TICKS_PER_SECOND,
+						volume: resolveEffectiveAudioGain({
+							element,
+							trackMuted: false,
+							localTime: 0,
+						}),
+						muted: element.muted ?? false,
+						retime: element.retime,
+					};
+				}),
+			);
+		}
+	}
+
+	const resolvedElements = await Promise.all(pendingElements);
+	const audioElements: CollectedAudioElement[] = [];
+	for (const element of resolvedElements) {
+		if (element) audioElements.push(element);
+	}
+	return audioElements;
+}
+
+async function resolveAudioBufferForElement({
+	element,
+	mediaMap,
+	audioContext,
+}: {
+	element: AudioElement;
+	mediaMap: Map<string, MediaAsset>;
+	audioContext: AudioContext;
+}): Promise<AudioBuffer | null> {
+	try {
+		if (element.sourceType === "upload") {
+			const asset = mediaMap.get(element.mediaId);
+			if (!asset) return null;
+			return await resolveAudioBufferForAsset({ asset, audioContext });
+		}
+
+		if (element.buffer) return element.buffer;
+
+		const response = await fetch(element.sourceUrl);
+		if (!response.ok) {
+			throw new Error(`Library audio fetch failed: ${response.status}`);
+		}
+
+		const arrayBuffer = await response.arrayBuffer();
+		return await audioContext.decodeAudioData(arrayBuffer.slice(0));
+	} catch (error) {
+		console.warn("Failed to decode audio:", error);
+		return null;
+	}
+}
+
+async function resolveAudioBufferForAsset({
+	asset,
+	audioContext,
+}: {
+	asset: MediaAsset;
+	audioContext: AudioContext;
+}): Promise<AudioBuffer | null> {
+	if (asset.type === "audio") {
+		try {
+			const arrayBuffer = await asset.file.arrayBuffer();
+			return await audioContext.decodeAudioData(arrayBuffer.slice(0));
+		} catch (error) {
+			console.warn("Failed to decode audio asset:", error);
+			return null;
+		}
+	}
+
+	const input = new Input({
+		source: new BlobSource(asset.file),
+		formats: ALL_FORMATS,
+	});
+
+	try {
+		const audioTrack = await input.getPrimaryAudioTrack();
+		if (!audioTrack) return null;
+
+		const sink = new AudioBufferSink(audioTrack);
+		const targetSampleRate = audioContext.sampleRate;
+
+		const chunks: AudioBuffer[] = [];
+		let totalSamples = 0;
+
+		for await (const { buffer } of sink.buffers(0)) {
+			chunks.push(buffer);
+			totalSamples += buffer.length;
+		}
+
+		if (chunks.length === 0) return null;
+
+		const nativeSampleRate = chunks[0].sampleRate;
+		const numChannels = Math.min(
+			MAX_AUDIO_CHANNELS,
+			chunks[0].numberOfChannels,
+		);
+
+		const nativeChannels = Array.from(
+			{ length: numChannels },
+			() => new Float32Array(totalSamples),
+		);
+		let offset = 0;
+		for (const chunk of chunks) {
+			for (let channel = 0; channel < numChannels; channel++) {
+				const sourceData = chunk.getChannelData(
+					Math.min(channel, chunk.numberOfChannels - 1),
+				);
+				nativeChannels[channel].set(sourceData, offset);
+			}
+			offset += chunk.length;
+		}
+
+		// use OfflineAudioContext for high-quality resampling to target rate
+		const outputSamples = Math.ceil(
+			totalSamples * (targetSampleRate / nativeSampleRate),
+		);
+		const offlineContext = new OfflineAudioContext(
+			numChannels,
+			outputSamples,
+			targetSampleRate,
+		);
+
+		const nativeBuffer = audioContext.createBuffer(
+			numChannels,
+			totalSamples,
+			nativeSampleRate,
+		);
+		for (let ch = 0; ch < numChannels; ch++) {
+			nativeBuffer.copyToChannel(nativeChannels[ch], ch);
+		}
+
+		const sourceNode = offlineContext.createBufferSource();
+		sourceNode.buffer = nativeBuffer;
+		sourceNode.connect(offlineContext.destination);
+		sourceNode.start(0);
+
+		return await offlineContext.startRendering();
+	} catch (error) {
+		console.warn("Failed to decode asset audio:", error);
+		return null;
+	} finally {
+		input.dispose();
+	}
+}
+
+interface AudioMixSource {
+	timelineElement: AudioCapableElement;
+	file: File;
+	startTime: number;
+	duration: number;
+	trimStart: number;
+	trimEnd: number;
+	volume: number;
+	retime?: RetimeConfig;
+}
+
+export interface AudioClipSource {
+	timelineElement: AudioCapableElement;
+	id: string;
+	sourceKey: string;
+	file: File;
+	startTime: number;
+	duration: number;
+	trimStart: number;
+	trimEnd: number;
+	volume: number;
+	muted: boolean;
+	retime?: RetimeConfig;
+}
+
+async function fetchLibraryAudioSource({
+	element,
+	volume,
+}: {
+	element: LibraryAudioElement;
+	volume: number;
+}): Promise<AudioMixSource | null> {
+	try {
+		const response = await fetch(element.sourceUrl);
+		if (!response.ok) {
+			throw new Error(`Library audio fetch failed: ${response.status}`);
+		}
+
+		const blob = await response.blob();
+		const file = new File([blob], `${element.name}.mp3`, {
+			type: "audio/mpeg",
+		});
+
+		return {
+			timelineElement: element,
+			file,
+			startTime: element.startTime / TICKS_PER_SECOND,
+			duration: element.duration / TICKS_PER_SECOND,
+			trimStart: element.trimStart / TICKS_PER_SECOND,
+			trimEnd: element.trimEnd / TICKS_PER_SECOND,
+			volume,
+			retime: element.retime,
+		};
+	} catch (error) {
+		console.warn("Failed to fetch library audio:", error);
+		return null;
+	}
+}
+
+async function fetchLibraryAudioClip({
+	element,
+	muted,
+	volume,
+}: {
+	element: LibraryAudioElement;
+	muted: boolean;
+	volume: number;
+}): Promise<AudioClipSource | null> {
+	try {
+		const response = await fetch(element.sourceUrl);
+		if (!response.ok) {
+			throw new Error(`Library audio fetch failed: ${response.status}`);
+		}
+
+		const blob = await response.blob();
+		const file = new File([blob], `${element.name}.mp3`, {
+			type: "audio/mpeg",
+		});
+
+		return {
+			timelineElement: element,
+			id: element.id,
+			sourceKey: element.id,
+			file,
+			startTime: element.startTime,
+			duration: element.duration,
+			trimStart: element.trimStart,
+			trimEnd: element.trimEnd,
+			volume,
+			muted,
+			retime: element.retime,
+		};
+	} catch (error) {
+		console.warn("Failed to fetch library audio:", error);
+		return null;
+	}
+}
+
+function collectMediaAudioSource({
+	element,
+	mediaAsset,
+	volume,
+}: {
+	element: AudioCapableElement;
+	mediaAsset: MediaAsset;
+	volume: number;
+}): AudioMixSource {
+	return {
+		timelineElement: element,
+		file: mediaAsset.file,
+		startTime: element.startTime / TICKS_PER_SECOND,
+		duration: element.duration / TICKS_PER_SECOND,
+		trimStart: element.trimStart / TICKS_PER_SECOND,
+		trimEnd: element.trimEnd / TICKS_PER_SECOND,
+		volume,
+		retime: element.retime,
+	};
+}
+
+function collectMediaAudioClip({
+	element,
+	mediaAsset,
+	muted,
+	volume,
+}: {
+	element: AudioCapableElement;
+	mediaAsset: MediaAsset;
+	muted: boolean;
+	volume: number;
+}): AudioClipSource {
+	return {
+		timelineElement: element,
+		id: element.id,
+		sourceKey: mediaAsset.id,
+		file: mediaAsset.file,
+		startTime: element.startTime / TICKS_PER_SECOND,
+		duration: element.duration / TICKS_PER_SECOND,
+		trimStart: element.trimStart / TICKS_PER_SECOND,
+		trimEnd: element.trimEnd / TICKS_PER_SECOND,
+		volume,
+		muted,
+		retime: element.retime,
+	};
+}
+
+export async function collectAudioMixSources({
+	tracks,
+	mediaAssets,
+}: {
+	tracks: SceneTracks;
+	mediaAssets: MediaAsset[];
+}): Promise<AudioMixSource[]> {
+	const orderedTracks = [...tracks.overlay, tracks.main, ...tracks.audio];
+	const audioMixSources: AudioMixSource[] = [];
+	const mediaMap = new Map<string, MediaAsset>(
+		mediaAssets.map((asset) => [asset.id, asset]),
+	);
+	const pendingLibrarySources: Array<Promise<AudioMixSource | null>> = [];
+
+	for (const track of orderedTracks) {
+		if (canTrackHaveAudio(track) && track.muted) continue;
+
+		for (const element of track.elements) {
+			if (!canElementHaveAudio(element)) continue;
+			if (element.muted === true) continue;
+			const mediaAsset = hasMediaId(element)
+				? (mediaMap.get(element.mediaId) ?? null)
+				: null;
+			if (!doesElementHaveEnabledAudio({ element, mediaAsset })) continue;
+			const volume = resolveEffectiveAudioGain({
+				element,
+				localTime: 0,
+			});
+
+			if (element.type === "audio") {
+				if (element.sourceType === "upload") {
+					const mediaAsset = mediaMap.get(element.mediaId);
+					if (!mediaAsset) continue;
+
+					audioMixSources.push(
+						collectMediaAudioSource({ element, mediaAsset, volume }),
+					);
+				} else {
+					pendingLibrarySources.push(
+						fetchLibraryAudioSource({ element, volume }),
+					);
+				}
+				continue;
+			}
+
+			if (element.type === "video") {
+				if (mediaAsset && mediaSupportsAudio({ media: mediaAsset })) {
+					audioMixSources.push(
+						collectMediaAudioSource({ element, mediaAsset, volume }),
+					);
+				}
+			}
+		}
+	}
+
+	const resolvedLibrarySources = await Promise.all(pendingLibrarySources);
+	for (const source of resolvedLibrarySources) {
+		if (source) audioMixSources.push(source);
+	}
+
+	return audioMixSources;
+}
+
+export async function collectAudioClips({
+	tracks,
+	mediaAssets,
+}: {
+	tracks: SceneTracks;
+	mediaAssets: MediaAsset[];
+}): Promise<AudioClipSource[]> {
+	const orderedTracks = [...tracks.overlay, tracks.main, ...tracks.audio];
+	const clips: AudioClipSource[] = [];
+	const mediaMap = new Map<string, MediaAsset>(
+		mediaAssets.map((asset) => [asset.id, asset]),
+	);
+	const pendingLibraryClips: Array<Promise<AudioClipSource | null>> = [];
+
+	for (const track of orderedTracks) {
+		const isTrackMuted = canTrackHaveAudio(track) && track.muted;
+
+		for (const element of track.elements) {
+			if (!canElementHaveAudio(element)) continue;
+
+			const mediaAsset = hasMediaId(element)
+				? (mediaMap.get(element.mediaId) ?? null)
+				: null;
+			if (!doesElementHaveEnabledAudio({ element, mediaAsset })) continue;
+
+			const isElementMuted =
+				"muted" in element ? (element.muted ?? false) : false;
+			const muted = isTrackMuted || isElementMuted;
+			const volume = resolveEffectiveAudioGain({
+				element,
+				trackMuted: isTrackMuted,
+				localTime: 0,
+			});
+
+			if (element.type === "audio") {
+				if (element.sourceType === "upload") {
+					const mediaAsset = mediaMap.get(element.mediaId);
+					if (!mediaAsset) continue;
+
+					clips.push(
+						collectMediaAudioClip({
+							element,
+							mediaAsset,
+							muted,
+							volume,
+						}),
+					);
+				} else {
+					pendingLibraryClips.push(
+						fetchLibraryAudioClip({ element, muted, volume }),
+					);
+				}
+				continue;
+			}
+
+			if (element.type === "video") {
+				if (mediaAsset && mediaSupportsAudio({ media: mediaAsset })) {
+					clips.push(
+						collectMediaAudioClip({
+							element,
+							mediaAsset,
+							muted,
+							volume,
+						}),
+					);
+				}
+			}
+		}
+	}
+
+	const resolvedLibraryClips = await Promise.all(pendingLibraryClips);
+	for (const clip of resolvedLibraryClips) {
+		if (clip) clips.push(clip);
+	}
+
+	return clips;
+}
+
+export async function createTimelineAudioBuffer({
+	tracks,
+	mediaAssets,
+	duration,
+	sampleRate = EXPORT_SAMPLE_RATE,
+	audioContext,
+}: {
+	tracks: SceneTracks;
+	mediaAssets: MediaAsset[];
+	duration: number;
+	sampleRate?: number;
+	audioContext?: AudioContext;
+}): Promise<AudioBuffer | null> {
+	const context = audioContext ?? createAudioContext({ sampleRate });
+
+	const audioElements = await collectAudioElements({
+		tracks,
+		mediaAssets,
+		audioContext: context,
+	});
+
+	if (audioElements.length === 0) return null;
+
+	const outputChannels = 2;
+	const durationSeconds = duration / TICKS_PER_SECOND;
+	const outputLength = Math.ceil(durationSeconds * sampleRate);
+	const outputBuffer = context.createBuffer(
+		outputChannels,
+		outputLength,
+		sampleRate,
+	);
+
+	for (const element of audioElements) {
+		if (element.muted) continue;
+
+		const renderedBuffer = shouldMaintainPitch({
+			rate: element.retime?.rate ?? 1,
+			maintainPitch: element.retime?.maintainPitch,
+		})
+			? await renderRetimedBuffer({
+					audioContext: context,
+					sourceBuffer: element.buffer,
+					trimStart: element.trimStart,
+					clipDuration: element.duration,
+					retime: element.retime,
+					maintainPitch: true,
+				})
+			: undefined;
+
+		mixAudioChannels({
+			element,
+			buffer: renderedBuffer ?? element.buffer,
+			trimStart: renderedBuffer ? 0 : element.trimStart,
+			retime: renderedBuffer ? undefined : element.retime,
+			outputBuffer,
+			outputLength,
+			sampleRate,
+		});
+	}
+
+	return await applyAudioMasteringToBuffer({ audioBuffer: outputBuffer });
+}
+
+function collectPeakRange({
+	buffer,
+	count,
+	startSample,
+	endSample,
+}: {
+	buffer: AudioBuffer;
+	count: number;
+	startSample: number;
+	endSample: number;
+}): Float32Array {
+	const channels = buffer.numberOfChannels;
+	const peaks = new Float32Array(count);
+
+	for (let c = 0; c < channels; c++) {
+		const data = buffer.getChannelData(c);
+		for (let i = 0; i < count; i++) {
+			const { bucketStart: start, bucketEnd: end } = getSampleBucketRange({
+				startSample,
+				endSample,
+				bucketIndex: i,
+				bucketCount: count,
+			});
+			for (let j = start; j < end; j++) {
+				const abs = Math.abs(data[j]);
+				if (abs > peaks[i]) peaks[i] = abs;
+			}
+		}
+	}
+
+	return peaks;
+}
+
+export function extractPeakRange({
+	buffer,
+	count,
+	startSample,
+	endSample,
+}: {
+	buffer: AudioBuffer;
+	count: number;
+	startSample: number;
+	endSample: number;
+}): number[] {
+	return Array.from(
+		collectPeakRange({
+			buffer,
+			count,
+			startSample,
+			endSample,
+		}),
+	);
+}
+
+export function getSampleBucketRange({
+	startSample,
+	endSample,
+	bucketIndex,
+	bucketCount,
+}: {
+	startSample: number;
+	endSample: number;
+	bucketIndex: number;
+	bucketCount: number;
+}): {
+	bucketStart: number;
+	bucketEnd: number;
+} {
+	const rangeLength = Math.max(0, endSample - startSample);
+	const bucketStart =
+		startSample + Math.floor((bucketIndex * rangeLength) / bucketCount);
+	const bucketEnd =
+		startSample + Math.floor(((bucketIndex + 1) * rangeLength) / bucketCount);
+	return {
+		bucketStart,
+		bucketEnd: Math.max(bucketStart, bucketEnd),
+	};
+}
+
+export function extractRmsBuckets({
+	buffer,
+	buckets,
+}: {
+	buffer: AudioBuffer;
+	buckets: SampleBucket[];
+}): number[] {
+	return computeRmsBuckets({ buffer, buckets });
+}
+
+/**
+ * Computes per-bucket waveform amplitude using the maximum RMS over a short
+ * analysis window inside each bucket.
+ *
+ * A naive mean-RMS over a whole bucket averages silence together with nearby
+ * sound, which smears transitions (e.g. the onset of speech) across the
+ * bucket and makes the waveform respond late. Taking the max over fixed
+ * short windows (~20 ms) preserves the smooth, non-jittery RMS character
+ * while making transitions land where they actually happen in the audio.
+ *
+ * Channels are combined per-window before taking the max, so the measure
+ * reflects total energy regardless of stereo layout.
+ */
+export function extractRmsRange({
+	buffer,
+	count,
+	startSample,
+	endSample,
+}: {
+	buffer: AudioBuffer;
+	count: number;
+	startSample: number;
+	endSample: number;
+}): number[] {
+	return extractRmsBuckets({
+		buffer,
+		buckets: Array.from({ length: count }, (_, bucketIndex) =>
+			getSampleBucketRange({
+				startSample,
+				endSample,
+				bucketIndex,
+				bucketCount: count,
+			}),
+		),
+	});
+}
+
+function mixAudioChannels({
+	element,
+	buffer,
+	trimStart,
+	retime,
+	outputBuffer,
+	outputLength,
+	sampleRate,
+}: {
+	element: CollectedAudioElement;
+	buffer: AudioBuffer;
+	trimStart: number;
+	retime?: RetimeConfig;
+	outputBuffer: AudioBuffer;
+	outputLength: number;
+	sampleRate: number;
+}): void {
+	const { startTime, duration: elementDuration } = element;
+
+	const outputStartSample = Math.floor(startTime * sampleRate);
+	const renderedLength = Math.ceil(elementDuration * sampleRate);
+
+	const outputChannels = 2;
+	for (let channel = 0; channel < outputChannels; channel++) {
+		const outputData = outputBuffer.getChannelData(channel);
+		const sourceChannel = Math.min(channel, buffer.numberOfChannels - 1);
+		const sourceData = buffer.getChannelData(sourceChannel);
+
+		for (let i = 0; i < renderedLength; i++) {
+			const outputIndex = outputStartSample + i;
+			if (outputIndex >= outputLength) break;
+
+			const clipTime = i / sampleRate;
+			const sourceTime =
+				trimStart + getSourceTimeAtClipTime({ clipTime, retime });
+			const sourceIndex = sourceTime * buffer.sampleRate;
+			if (sourceIndex >= sourceData.length) break;
+
+			const lowerIndex = Math.floor(sourceIndex);
+			const upperIndex = Math.min(sourceData.length - 1, lowerIndex + 1);
+			const fraction = sourceIndex - lowerIndex;
+			const gain = hasAnimatedVolume({ element: element.timelineElement })
+				? resolveEffectiveAudioGain({
+						element: element.timelineElement,
+						localTime: clipTime,
+					})
+				: element.volume;
+			outputData[outputIndex] +=
+				(sourceData[lowerIndex] * (1 - fraction) +
+					sourceData[upperIndex] * fraction) *
+				gain;
+		}
+	}
+}
diff --git a/apps/web/src/media/media-utils.ts b/apps/web/src/media/media-utils.ts
new file mode 100644
index 00000000..dd59bf31
--- /dev/null
+++ b/apps/web/src/media/media-utils.ts
@@ -0,0 +1,32 @@
+import type { MediaAsset, MediaType } from "@/media/types";
+
+export const SUPPORTS_AUDIO: readonly MediaType[] = ["audio", "video"];
+
+export function mediaSupportsAudio({
+	media,
+}: {
+	media: MediaAsset | null | undefined;
+}): boolean {
+	if (!media) return false;
+	return SUPPORTS_AUDIO.includes(media.type);
+}
+
+export const getMediaTypeFromFile = ({
+	file,
+}: {
+	file: File;
+}): MediaType | null => {
+	const { type } = file;
+
+	if (type.startsWith("image/")) {
+		return "image";
+	}
+	if (type.startsWith("video/")) {
+		return "video";
+	}
+	if (type.startsWith("audio/")) {
+		return "audio";
+	}
+
+	return null;
+};
diff --git a/apps/web/src/media/mediabunny.ts b/apps/web/src/media/mediabunny.ts
new file mode 100644
index 00000000..47ffaeb1
--- /dev/null
+++ b/apps/web/src/media/mediabunny.ts
@@ -0,0 +1,168 @@
+import { Input, ALL_FORMATS, BlobSource } from "mediabunny";
+import { createTimelineAudioBuffer } from "@/media/audio";
+import type { SceneTracks } from "@/timeline";
+import type { MediaAsset } from "@/media/types";
+import { TICKS_PER_SECOND } from "@/wasm";
+
+export async function getVideoInfo({
+	videoFile,
+}: {
+	videoFile: File;
+}): Promise<{
+	duration: number;
+	width: number;
+	height: number;
+	fps: number;
+	hasAudio: boolean;
+}> {
+	const input = new Input({
+		source: new BlobSource(videoFile),
+		formats: ALL_FORMATS,
+	});
+
+	const duration = await input.computeDuration();
+	const videoTrack = await input.getPrimaryVideoTrack();
+
+	if (!videoTrack) {
+		throw new Error("No video track found in the file");
+	}
+
+	const packetStats = await videoTrack.computePacketStats(100);
+	const fps = packetStats.averagePacketRate;
+	const audioTrack = await input.getPrimaryAudioTrack();
+
+	return {
+		duration,
+		width: videoTrack.displayWidth,
+		height: videoTrack.displayHeight,
+		fps,
+		hasAudio: audioTrack !== null,
+	};
+}
+
+const SAMPLE_RATE = 44100;
+const NUM_CHANNELS = 2;
+const EMPTY_TIMELINE_SILENT_DURATION_SECONDS = 0.1;
+const MIN_SILENT_DURATION_SECONDS = 0.001;
+
+export const extractTimelineAudio = async ({
+	tracks,
+	mediaAssets,
+	totalDuration,
+	onProgress,
+}: {
+	tracks: SceneTracks;
+	mediaAssets: MediaAsset[];
+	totalDuration: number;
+	onProgress?: (progress: number) => void;
+}): Promise<Blob> => {
+	if (totalDuration === 0) {
+		return createWavBlob({
+			samples: new Float32Array(
+				SAMPLE_RATE * EMPTY_TIMELINE_SILENT_DURATION_SECONDS,
+			),
+		});
+	}
+
+	onProgress?.(10);
+
+	const audioBuffer = await createTimelineAudioBuffer({
+		tracks,
+		mediaAssets,
+		duration: totalDuration,
+		sampleRate: SAMPLE_RATE,
+	});
+
+	if (!audioBuffer) {
+		const silentDurationSeconds = Math.max(
+			MIN_SILENT_DURATION_SECONDS,
+			totalDuration / TICKS_PER_SECOND,
+		);
+		const silentSamples = new Float32Array(
+			Math.ceil(silentDurationSeconds * SAMPLE_RATE) * NUM_CHANNELS,
+		);
+		return createWavBlob({ samples: silentSamples });
+	}
+
+	onProgress?.(90);
+
+	const interleavedSamples = interleaveAudioBuffer({ audioBuffer });
+	onProgress?.(100);
+
+	return createWavBlob({ samples: interleavedSamples });
+};
+
+function interleaveAudioBuffer({
+	audioBuffer,
+}: {
+	audioBuffer: AudioBuffer;
+}): Float32Array {
+	const numChannels = Math.min(NUM_CHANNELS, audioBuffer.numberOfChannels);
+	const interleavedSamples = new Float32Array(
+		audioBuffer.length * NUM_CHANNELS,
+	);
+
+	for (let sampleIndex = 0; sampleIndex < audioBuffer.length; sampleIndex++) {
+		for (let channel = 0; channel < NUM_CHANNELS; channel++) {
+			const sourceChannel = Math.min(channel, Math.max(0, numChannels - 1));
+			interleavedSamples[sampleIndex * NUM_CHANNELS + channel] =
+				audioBuffer.getChannelData(sourceChannel)[sampleIndex] ?? 0;
+		}
+	}
+
+	return interleavedSamples;
+}
+
+function createWavBlob({ samples }: { samples: Float32Array }): Blob {
+	const numChannels = NUM_CHANNELS;
+	const bitsPerSample = 16;
+	const bytesPerSample = bitsPerSample / 8;
+	const numSamples = samples.length / numChannels;
+	const dataSize = numSamples * numChannels * bytesPerSample;
+	const buffer = new ArrayBuffer(44 + dataSize);
+	const view = new DataView(buffer);
+
+	// riff header
+	writeString({ view, offset: 0, str: "RIFF" });
+	view.setUint32(4, 36 + dataSize, true);
+	writeString({ view, offset: 8, str: "WAVE" });
+
+	// fmt chunk
+	writeString({ view, offset: 12, str: "fmt " });
+	view.setUint32(16, 16, true);
+	view.setUint16(20, 1, true);
+	view.setUint16(22, numChannels, true);
+	view.setUint32(24, SAMPLE_RATE, true);
+	view.setUint32(28, SAMPLE_RATE * numChannels * bytesPerSample, true);
+	view.setUint16(32, numChannels * bytesPerSample, true);
+	view.setUint16(34, bitsPerSample, true);
+
+	// data chunk
+	writeString({ view, offset: 36, str: "data" });
+	view.setUint32(40, dataSize, true);
+
+	// convert float32 to int16 and write
+	let offset = 44;
+	for (let i = 0; i < samples.length; i++) {
+		const sample = Math.max(-1, Math.min(1, samples[i]));
+		const int16 = sample < 0 ? sample * 0x8000 : sample * 0x7fff;
+		view.setInt16(offset, int16, true);
+		offset += 2;
+	}
+
+	return new Blob([buffer], { type: "audio/wav" });
+}
+
+function writeString({
+	view,
+	offset,
+	str,
+}: {
+	view: DataView;
+	offset: number;
+	str: string;
+}): void {
+	for (let i = 0; i < str.length; i++) {
+		view.setUint8(offset + i, str.charCodeAt(i));
+	}
+}
diff --git a/apps/web/src/media/processing.ts b/apps/web/src/media/processing.ts
new file mode 100644
index 00000000..d8d483f8
--- /dev/null
+++ b/apps/web/src/media/processing.ts
@@ -0,0 +1,296 @@
+import { Input, ALL_FORMATS, BlobSource, VideoSampleSink } from "mediabunny";
+import { toast } from "sonner";
+import { getMediaTypeFromFile } from "@/media/media-utils";
+import { formatStorageBytes } from "@/services/storage/quota";
+import { storageService } from "@/services/storage/service";
+import type { MediaAsset } from "@/media/types";
+import { getVideoInfo } from "./mediabunny";
+
+export interface ProcessedMediaAsset extends Omit<MediaAsset, "id"> {}
+
+const THUMBNAIL_MAX_WIDTH = 1280;
+const THUMBNAIL_MAX_HEIGHT = 720;
+
+const getStorageLimitDescription = ({
+	fileSize,
+	availableBytes,
+}: {
+	fileSize: number;
+	availableBytes: number | null;
+}): string => {
+	const fileSizeLabel = formatStorageBytes({ bytes: fileSize });
+
+	if (availableBytes === null) {
+		return `File size is ${fileSizeLabel}.`;
+	}
+
+	return `File size is ${fileSizeLabel}, but only ${formatStorageBytes({
+		bytes: availableBytes,
+	})} is safely available in browser storage.`;
+};
+
+const getThumbnailSize = ({
+	width,
+	height,
+}: {
+	width: number;
+	height: number;
+}): { width: number; height: number } => {
+	const aspectRatio = width / height;
+	let targetWidth = width;
+	let targetHeight = height;
+
+	if (targetWidth > THUMBNAIL_MAX_WIDTH) {
+		targetWidth = THUMBNAIL_MAX_WIDTH;
+		targetHeight = Math.round(targetWidth / aspectRatio);
+	}
+	if (targetHeight > THUMBNAIL_MAX_HEIGHT) {
+		targetHeight = THUMBNAIL_MAX_HEIGHT;
+		targetWidth = Math.round(targetHeight * aspectRatio);
+	}
+
+	return { width: targetWidth, height: targetHeight };
+};
+
+const renderToThumbnailDataUrl = ({
+	width,
+	height,
+	draw,
+}: {
+	width: number;
+	height: number;
+	draw: ({
+		context,
+		width,
+		height,
+	}: {
+		context: CanvasRenderingContext2D;
+		width: number;
+		height: number;
+	}) => void;
+}): string => {
+	const size = getThumbnailSize({ width, height });
+	const canvas = document.createElement("canvas");
+	canvas.width = size.width;
+	canvas.height = size.height;
+	const context = canvas.getContext("2d");
+
+	if (!context) {
+		throw new Error("Could not get canvas context");
+	}
+
+	draw({ context, width: size.width, height: size.height });
+	return canvas.toDataURL("image/jpeg", 0.8);
+};
+
+async function generateThumbnail({
+	videoFile,
+	timeInSeconds,
+}: {
+	videoFile: File;
+	timeInSeconds: number;
+}): Promise<string> {
+	const input = new Input({
+		source: new BlobSource(videoFile),
+		formats: ALL_FORMATS,
+	});
+
+	const videoTrack = await input.getPrimaryVideoTrack();
+	if (!videoTrack) {
+		throw new Error("No video track found in the file");
+	}
+
+	const canDecode = await videoTrack.canDecode();
+	if (!canDecode) {
+		throw new Error("Video codec not supported for decoding");
+	}
+
+	const sink = new VideoSampleSink(videoTrack);
+
+	const frame = await sink.getSample(timeInSeconds);
+
+	if (!frame) {
+		throw new Error("Could not get frame at specified time");
+	}
+
+	try {
+		return renderToThumbnailDataUrl({
+			width: videoTrack.displayWidth,
+			height: videoTrack.displayHeight,
+			draw: ({ context, width, height }) => {
+				frame.draw(context, 0, 0, width, height);
+			},
+		});
+	} finally {
+		frame.close();
+	}
+}
+
+async function generateImageThumbnail({
+	imageFile,
+}: {
+	imageFile: File;
+}): Promise<{ thumbnailUrl: string; width: number; height: number }> {
+	return new Promise((resolve, reject) => {
+		const image = new window.Image();
+		const objectUrl = URL.createObjectURL(imageFile);
+
+		image.addEventListener("load", () => {
+			try {
+				const thumbnailUrl = renderToThumbnailDataUrl({
+					width: image.naturalWidth,
+					height: image.naturalHeight,
+					draw: ({ context, width, height }) => {
+						context.drawImage(image, 0, 0, width, height);
+					},
+				});
+				resolve({
+					thumbnailUrl,
+					width: image.naturalWidth,
+					height: image.naturalHeight,
+				});
+			} catch (error) {
+				reject(
+					error instanceof Error ? error : new Error("Could not render image"),
+				);
+			} finally {
+				URL.revokeObjectURL(objectUrl);
+				image.remove();
+			}
+		});
+
+		image.addEventListener("error", () => {
+			URL.revokeObjectURL(objectUrl);
+			image.remove();
+			reject(new Error("Could not load image"));
+		});
+
+		image.src = objectUrl;
+	});
+}
+
+export async function processMediaAssets({
+	files,
+	onProgress,
+}: {
+	files: FileList | File[];
+	onProgress?: ({ progress }: { progress: number }) => void;
+}): Promise<ProcessedMediaAsset[]> {
+	const fileArray = Array.from(files);
+	const processedAssets: ProcessedMediaAsset[] = [];
+
+	const total = fileArray.length;
+	let completed = 0;
+
+	for (const file of fileArray) {
+		const fileType = getMediaTypeFromFile({ file });
+
+		if (!fileType) {
+			toast.error(`Unsupported file type: ${file.name}`);
+			continue;
+		}
+
+		const storageCheck = await storageService.canStoreFile({
+			size: file.size,
+		});
+
+		if (!storageCheck.canStore) {
+			toast.error(`Not enough browser storage for ${file.name}`, {
+				description: getStorageLimitDescription({
+					fileSize: file.size,
+					availableBytes: storageCheck.availableBytes,
+				}),
+			});
+			continue;
+		}
+
+		const url = URL.createObjectURL(file);
+		let thumbnailUrl: string | undefined;
+		let duration: number | undefined;
+		let width: number | undefined;
+		let height: number | undefined;
+		let fps: number | undefined;
+		let hasAudio: boolean | undefined;
+
+		try {
+			if (fileType === "image") {
+				const result = await generateImageThumbnail({ imageFile: file });
+				thumbnailUrl = result.thumbnailUrl;
+				width = result.width;
+				height = result.height;
+			} else if (fileType === "video") {
+				try {
+					const videoInfo = await getVideoInfo({ videoFile: file });
+					duration = videoInfo.duration;
+					width = videoInfo.width;
+					height = videoInfo.height;
+					fps = Number.isFinite(videoInfo.fps)
+						? Math.round(videoInfo.fps)
+						: undefined;
+					hasAudio = videoInfo.hasAudio;
+
+					thumbnailUrl = await generateThumbnail({
+						videoFile: file,
+						timeInSeconds: 1,
+					});
+				} catch (error) {
+					console.warn("Video processing failed", error);
+				}
+			} else if (fileType === "audio") {
+				// For audio, we don't set width/height/fps (they'll be undefined)
+				duration = await getMediaDuration({ file });
+			}
+
+			processedAssets.push({
+				name: file.name,
+				type: fileType,
+				file,
+				url,
+				thumbnailUrl,
+				duration,
+				width,
+				height,
+				fps,
+				hasAudio,
+			});
+
+			await new Promise((resolve) => setTimeout(resolve, 0));
+
+			completed += 1;
+			if (onProgress) {
+				const percent = Math.round((completed / total) * 100);
+				onProgress({ progress: percent });
+			}
+		} catch (error) {
+			console.error("Error processing file:", file.name, error);
+			toast.error(`Failed to process ${file.name}`);
+			URL.revokeObjectURL(url); // Clean up on error
+		}
+	}
+
+	return processedAssets;
+}
+
+const getMediaDuration = ({ file }: { file: File }): Promise<number> => {
+	return new Promise((resolve, reject) => {
+		const element = document.createElement(
+			file.type.startsWith("video/") ? "video" : "audio",
+		) as HTMLVideoElement;
+		const objectUrl = URL.createObjectURL(file);
+
+		element.addEventListener("loadedmetadata", () => {
+			resolve(element.duration);
+			URL.revokeObjectURL(objectUrl);
+			element.remove();
+		});
+
+		element.addEventListener("error", () => {
+			reject(new Error("Could not load media"));
+			URL.revokeObjectURL(objectUrl);
+			element.remove();
+		});
+
+		element.src = objectUrl;
+		element.load();
+	});
+};
diff --git a/apps/web/src/media/types.ts b/apps/web/src/media/types.ts
new file mode 100644
index 00000000..4d3e4106
--- /dev/null
+++ b/apps/web/src/media/types.ts
@@ -0,0 +1,9 @@
+import type { MediaAssetData } from "@/services/storage/types";
+
+export type MediaType = "image" | "video" | "audio";
+
+export interface MediaAsset
+	extends Omit<MediaAssetData, "size" | "lastModified"> {
+	file: File;
+	url?: string;
+}
diff --git a/apps/web/src/media/upload-toast.ts b/apps/web/src/media/upload-toast.ts
new file mode 100644
index 00000000..45846206
--- /dev/null
+++ b/apps/web/src/media/upload-toast.ts
@@ -0,0 +1,51 @@
+import { toast } from "sonner";
+
+export interface MediaUploadToastResult {
+	uploadedCount: number;
+	assetNames?: string[];
+}
+
+function getAssetLabel({ count }: { count: number }): string {
+	return count === 1 ? "media asset" : "media assets";
+}
+
+function waitForNextPaint(): Promise<void> {
+	return new Promise((resolve) => {
+		requestAnimationFrame(() => {
+			requestAnimationFrame(() => resolve());
+		});
+	});
+}
+
+export async function showMediaUploadToast<T extends MediaUploadToastResult>({
+	filesCount,
+	promise,
+}: {
+	filesCount: number;
+	promise: Promise<T> | (() => Promise<T>);
+}) {
+	const run = typeof promise === "function" ? promise : () => promise;
+	const toastPromise = toast.promise(async () => {
+		await waitForNextPaint();
+		return run();
+	}, {
+		loading: `Uploading ${getAssetLabel({ count: filesCount })}...`,
+		success: ({ uploadedCount, assetNames }) => {
+			if (uploadedCount === 1) {
+				const assetName = assetNames?.[0];
+				return assetName
+					? `${assetName} has been uploaded`
+					: "1 media asset has been uploaded";
+			}
+
+			if (uploadedCount > 1) {
+				return `${uploadedCount} media assets have been uploaded`;
+			}
+
+			return "No media assets were uploaded";
+		},
+		error: `Failed to upload ${getAssetLabel({ count: filesCount })}`,
+	});
+
+	return toastPromise.unwrap();
+}
diff --git a/apps/web/src/media/use-file-upload.ts b/apps/web/src/media/use-file-upload.ts
new file mode 100644
index 00000000..1ee30ad9
--- /dev/null
+++ b/apps/web/src/media/use-file-upload.ts
@@ -0,0 +1,101 @@
+import { useState, useRef } from "react";
+import { hasDragData } from "@/timeline/drag-data";
+
+interface UseFileUploadOptions {
+	accept?: string;
+	multiple?: boolean;
+	onFilesSelected?: (files: File[]) => void;
+}
+
+function containsFiles(dataTransfer: DataTransfer): boolean {
+	return !hasDragData({ dataTransfer }) && dataTransfer.types.includes("Files");
+}
+
+export function useFileUpload({
+	accept,
+	multiple,
+	onFilesSelected,
+}: UseFileUploadOptions = {}) {
+	const [isDragOver, setIsDragOver] = useState(false);
+	const dragCounterRef = useRef(0);
+	const inputRef = useRef<HTMLInputElement>(null);
+
+	function openFilePicker() {
+		if (!inputRef.current) return;
+
+		inputRef.current.accept = accept || "*";
+		inputRef.current.multiple = multiple || false;
+		inputRef.current.click();
+	}
+
+	function handleFileChange(event: React.ChangeEvent<HTMLInputElement>) {
+		const files = Array.from(event.target.files ?? []);
+		if (files.length > 0 && onFilesSelected) {
+			onFilesSelected(files);
+		}
+
+		if (event.target) {
+			event.target.value = "";
+		}
+	}
+
+	function handleDragEnter(e: React.DragEvent) {
+		e.preventDefault();
+
+		if (!containsFiles(e.dataTransfer)) return;
+
+		dragCounterRef.current += 1;
+		setIsDragOver(true);
+	}
+
+	function handleDragOver(e: React.DragEvent) {
+		e.preventDefault();
+
+		if (!containsFiles(e.dataTransfer)) return;
+	}
+
+	function handleDragLeave(e: React.DragEvent) {
+		e.preventDefault();
+
+		if (!containsFiles(e.dataTransfer)) return;
+
+		dragCounterRef.current -= 1;
+		if (dragCounterRef.current === 0) {
+			setIsDragOver(false);
+		}
+	}
+
+	function handleDrop(e: React.DragEvent) {
+		e.preventDefault();
+		setIsDragOver(false);
+		dragCounterRef.current = 0;
+
+		if (onFilesSelected && containsFiles(e.dataTransfer)) {
+			const files = Array.from(e.dataTransfer.files);
+			const shouldUseMultiple = multiple ?? false;
+
+			if (shouldUseMultiple) {
+				onFilesSelected(files);
+			} else if (files.length > 0) {
+				onFilesSelected([files[0]]);
+			}
+		}
+	}
+
+	return {
+		isDragOver,
+		openFilePicker,
+		fileInputProps: {
+			ref: inputRef,
+			type: "file",
+			style: { display: "none" },
+			onChange: handleFileChange,
+		},
+		dragProps: {
+			onDragEnter: handleDragEnter,
+			onDragOver: handleDragOver,
+			onDragLeave: handleDragLeave,
+			onDrop: handleDrop,
+		},
+	};
+}
diff --git a/apps/web/src/media/use-paste-media.ts b/apps/web/src/media/use-paste-media.ts
new file mode 100644
index 00000000..3055920e
--- /dev/null
+++ b/apps/web/src/media/use-paste-media.ts
@@ -0,0 +1,116 @@
+import { useEffect } from "react";
+import { useEditor } from "@/editor/use-editor";
+import { processMediaAssets } from "@/media/processing";
+import { showMediaUploadToast } from "@/media/upload-toast";
+import { buildElementFromMedia } from "@/timeline/element-utils";
+import { AddMediaAssetCommand } from "@/commands/media";
+import { InsertElementCommand } from "@/commands/timeline";
+import { BatchCommand } from "@/commands";
+import { DEFAULT_NEW_ELEMENT_DURATION } from "@/timeline/creation";
+import { TICKS_PER_SECOND } from "@/wasm";
+import { isTypableDOMElement } from "@/utils/browser";
+import type { MediaType } from "@/media/types";
+
+const MEDIA_MIME_PREFIXES: MediaType[] = ["image", "video", "audio"];
+
+function isMediaMimeType({ type }: { type: string }): boolean {
+	return MEDIA_MIME_PREFIXES.some((prefix) => type.startsWith(`${prefix}/`));
+}
+
+function extractMediaFilesFromClipboard({
+	clipboardData,
+}: {
+	clipboardData: DataTransfer | null;
+}): File[] {
+	if (!clipboardData?.items) return [];
+
+	const files: File[] = [];
+	for (const item of clipboardData.items) {
+		if (item.kind !== "file") continue;
+		if (!isMediaMimeType({ type: item.type })) continue;
+
+		const file = item.getAsFile();
+		if (file) files.push(file);
+	}
+	return files;
+}
+
+export function usePasteMedia() {
+	const editor = useEditor();
+
+	useEffect(() => {
+		const handlePaste = async (event: ClipboardEvent) => {
+			const activeElement = document.activeElement as HTMLElement;
+
+			if (activeElement && isTypableDOMElement({ element: activeElement })) {
+				return;
+			}
+
+			const files = extractMediaFilesFromClipboard({
+				clipboardData: event.clipboardData,
+			});
+			if (files.length === 0) {
+				event.preventDefault();
+				editor.clipboard.paste();
+				return;
+			}
+
+			event.preventDefault();
+
+			const activeProject = editor.project.getActive();
+			if (!activeProject) return;
+
+			try {
+				await showMediaUploadToast({
+					filesCount: files.length,
+					promise: async () => {
+						const processedAssets = await processMediaAssets({ files });
+						const startTime = editor.playback.getCurrentTime();
+
+						for (const asset of processedAssets) {
+							const addMediaCmd = new AddMediaAssetCommand(
+								activeProject.metadata.id,
+								asset,
+							);
+							const assetId = addMediaCmd.getAssetId();
+							const duration =
+								asset.duration != null
+									? Math.round(asset.duration * TICKS_PER_SECOND)
+									: DEFAULT_NEW_ELEMENT_DURATION;
+							const trackType = asset.type === "audio" ? "audio" : "video";
+
+							const element = buildElementFromMedia({
+								mediaId: assetId,
+								mediaType: asset.type,
+								name: asset.name,
+								duration,
+								startTime,
+								buffer:
+									asset.type === "audio"
+										? new AudioBuffer({ length: 1, sampleRate: 44100 })
+										: undefined,
+							});
+
+							const insertCmd = new InsertElementCommand({
+								element,
+								placement: { mode: "auto", trackType },
+							});
+							const batchCmd = new BatchCommand([addMediaCmd, insertCmd]);
+							editor.command.execute({ command: batchCmd });
+						}
+
+						return {
+							uploadedCount: processedAssets.length,
+							assetNames: processedAssets.map((asset) => asset.name),
+						};
+					},
+				});
+			} catch (error) {
+				console.error("Failed to paste media:", error);
+			}
+		};
+
+		window.addEventListener("paste", handlePaste);
+		return () => window.removeEventListener("paste", handlePaste);
+	}, [editor]);
+}
diff --git a/apps/web/src/media/waveform-summary.ts b/apps/web/src/media/waveform-summary.ts
new file mode 100644
index 00000000..03a0059c
--- /dev/null
+++ b/apps/web/src/media/waveform-summary.ts
@@ -0,0 +1,233 @@
+"use client";
+
+import { getSourceTimeAtClipTime } from "@/retime";
+import type { RetimeConfig } from "@/timeline";
+
+const RMS_ANALYSIS_WINDOW_SECONDS = 0.02;
+const DEFAULT_SOURCE_WAVEFORM_BUCKET_SIZE = 128;
+
+function computePeakBuckets({
+	buffer,
+	buckets,
+}: {
+	buffer: AudioBuffer;
+	buckets: SampleBucket[];
+}): number[] {
+	const channels = buffer.numberOfChannels;
+	const channelData: Float32Array[] = Array.from({ length: channels }, (_, c) =>
+		buffer.getChannelData(c),
+	);
+
+	return buckets.map(({ bucketStart, bucketEnd }) => {
+		let peak = 0;
+		for (let c = 0; c < channels; c++) {
+			const data = channelData[c];
+			for (let j = bucketStart; j < bucketEnd; j++) {
+				const abs = Math.abs(data[j] ?? 0);
+				if (abs > peak) {
+					peak = abs;
+				}
+			}
+		}
+		return peak;
+	});
+}
+
+export interface SampleBucket {
+	bucketStart: number;
+	bucketEnd: number;
+}
+
+export interface SourceWaveformSummary {
+	sourceKey: string;
+	sampleRate: number;
+	totalSamples: number;
+	bucketSize: number;
+	amplitudes: Float32Array;
+}
+
+export function buildWaveformSourceKey({
+	kind,
+	id,
+}: {
+	kind: "media" | "library";
+	id: string;
+}): string {
+	return `${kind}:${id}`;
+}
+
+export function buildSourceWaveformSummary({
+	sourceKey,
+	buffer,
+	bucketSize = DEFAULT_SOURCE_WAVEFORM_BUCKET_SIZE,
+}: {
+	sourceKey: string;
+	buffer: AudioBuffer;
+	bucketSize?: number;
+}): SourceWaveformSummary {
+	const safeBucketSize = Math.max(1, Math.floor(bucketSize));
+	const bucketCount = Math.max(1, Math.ceil(buffer.length / safeBucketSize));
+	const amplitudes = computePeakBuckets({
+		buffer,
+		buckets: Array.from({ length: bucketCount }, (_, bucketIndex) => {
+			const bucketStart = bucketIndex * safeBucketSize;
+			const bucketEnd = Math.min(buffer.length, bucketStart + safeBucketSize);
+			return { bucketStart, bucketEnd };
+		}),
+	});
+
+	return {
+		sourceKey,
+		sampleRate: buffer.sampleRate,
+		totalSamples: buffer.length,
+		bucketSize: safeBucketSize,
+		amplitudes: Float32Array.from(amplitudes),
+	};
+}
+
+export function buildWaveformSampleBuckets({
+	clipLeftPx,
+	clipRightPx,
+	barCount,
+	pixelsPerSecond,
+	clipDurationSec,
+	sourceStartSec,
+	retime,
+	sampleRate,
+	maxSampleExclusive,
+	barStepPx,
+}: {
+	clipLeftPx: number;
+	clipRightPx: number;
+	barCount: number;
+	pixelsPerSecond: number;
+	clipDurationSec: number;
+	sourceStartSec: number;
+	retime?: RetimeConfig;
+	sampleRate: number;
+	maxSampleExclusive: number;
+	barStepPx: number;
+}): SampleBucket[] {
+	return Array.from({ length: barCount }, (_, index) => {
+		const bucketLeftPx = clipLeftPx + index * barStepPx;
+		const bucketRightPx = Math.min(clipRightPx, bucketLeftPx + barStepPx);
+		const clipStartSec = Math.max(
+			0,
+			Math.min(clipDurationSec, bucketLeftPx / pixelsPerSecond),
+		);
+		const clipEndSec = Math.max(
+			clipStartSec,
+			Math.min(clipDurationSec, bucketRightPx / pixelsPerSecond),
+		);
+		const sourceBucketStartSec =
+			sourceStartSec +
+			getSourceTimeAtClipTime({
+				clipTime: clipStartSec,
+				retime,
+			});
+		const sourceBucketEndSec =
+			sourceStartSec +
+			getSourceTimeAtClipTime({
+				clipTime: clipEndSec,
+				retime,
+			});
+
+		return {
+			bucketStart: Math.max(0, Math.floor(sourceBucketStartSec * sampleRate)),
+			bucketEnd: Math.min(
+				maxSampleExclusive,
+				Math.max(0, Math.ceil(sourceBucketEndSec * sampleRate)),
+			),
+		};
+	});
+}
+
+export function sampleSourceWaveformSummary({
+	summary,
+	buckets,
+}: {
+	summary: SourceWaveformSummary;
+	buckets: SampleBucket[];
+}): number[] {
+	return buckets.map(({ bucketStart, bucketEnd }) => {
+		if (bucketEnd <= bucketStart) {
+			return 0;
+		}
+
+		const startIndex = Math.max(
+			0,
+			Math.floor(bucketStart / summary.bucketSize),
+		);
+		const endIndex = Math.min(
+			summary.amplitudes.length,
+			Math.max(startIndex + 1, Math.ceil(bucketEnd / summary.bucketSize)),
+		);
+
+		let maxAmplitude = 0;
+		for (let i = startIndex; i < endIndex; i++) {
+			const amplitude = summary.amplitudes[i] ?? 0;
+			if (amplitude > maxAmplitude) {
+				maxAmplitude = amplitude;
+			}
+		}
+
+		return maxAmplitude;
+	});
+}
+
+export function computeRmsBuckets({
+	buffer,
+	buckets,
+}: {
+	buffer: AudioBuffer;
+	buckets: SampleBucket[];
+}): number[] {
+	const channels = buffer.numberOfChannels;
+	const maxWindowLength = Math.max(
+		1,
+		Math.floor(buffer.sampleRate * RMS_ANALYSIS_WINDOW_SECONDS),
+	);
+
+	const channelData: Float32Array[] = new Array(channels);
+	for (let c = 0; c < channels; c++) {
+		channelData[c] = buffer.getChannelData(c);
+	}
+
+	const result = new Array<number>(buckets.length);
+
+	for (let i = 0; i < buckets.length; i++) {
+		const { bucketStart, bucketEnd } = buckets[i];
+		const bucketLength = bucketEnd - bucketStart;
+		if (bucketLength <= 0) {
+			result[i] = 0;
+			continue;
+		}
+
+		const windowLength = Math.max(1, Math.min(bucketLength, maxWindowLength));
+		let maxMeanSquare = 0;
+
+		for (let winStart = bucketStart; winStart < bucketEnd; ) {
+			const winEnd = Math.min(winStart + windowLength, bucketEnd);
+			const n = winEnd - winStart;
+			if (n > 0) {
+				let sum = 0;
+				for (let c = 0; c < channels; c++) {
+					const data = channelData[c];
+					for (let j = winStart; j < winEnd; j++) {
+						const v = data[j];
+						sum += v * v;
+					}
+				}
+				const meanSquare = sum / (n * channels);
+				if (meanSquare > maxMeanSquare) {
+					maxMeanSquare = meanSquare;
+				}
+			}
+			winStart = winEnd;
+		}
+
+		result[i] = Math.sqrt(maxMeanSquare);
+	}
+
+	return result;
+}