Decode a clip from a file of its own, not its whole sound (#349)

A clip was cut from its sound's file, so a game decoded the whole file
for it and held it for as long as the page was open. A long recording
played through a few short clips cost the recording. Every clip now has
a copy of its cut as Opus, with Stream on or off, and a game decodes
that instead.

- StreamKeeper makes the copy of each clip whether its sound streams
  or not. Stream only decides whether a sound gets a copy of its own.
- clipCopyTable says which cut decodes from which copy. The sound
  library loads the copy for a clip unless the whole file is decoded
  already. Then the clip is cut from that as before.
- projectFiles decodes the whole file ahead only where something may
  play the sound itself: no clips, a clip without a fitting copy, or
  the sound's id anywhere in an asset that can name one. That last
  test walks the data, not the fields, so no place is missed.
- A copy that cannot be had falls back to the whole file. A library
  that bakes keeps to the whole files, as the bake's fingerprint does.

Tests:
- Gate: CHECK EXIT 0, 280 files, 4319 tests (7 new: streams +4,
  sound-library +3).
- e2e 34: ALL PASSED, 108 checks (2 new). With Stream off a fresh
  library decodes the ten-second reversed clip's copy and not the
  five-minute file. It is the cut made from the original to within
  0.0091 a sample and 0.013 dB in any 20 ms. Once a node plays the
  sound itself, the whole file is decoded ahead again.
- e2e 65: all passed with this change.
- Counter-checks red as they should be: the library ignoring copies,
  the whole file always decoded ahead, clip copies only with Stream.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/core/model/projectFiles.ts

@@ -1,9 +1,12 @@
 import { validBake } from '../music/bake';
-import { streamsOf } from '../properties/sounds';
+import { clipCopyTable } from '../music/streams';
+import { cutOf, streamsOf } from '../properties/sounds';
+import type { AssetType } from './AssetTypes';
+import type { SoundAsset } from './Asset';
 import { isFontFile } from './font';
 import { celFilesOf } from './pixelart';
 import type { Project } from './Project';
-import { isSoundFile } from './sound';
+import { clipsOf, cutName, isSoundFile } from './sound';
 import { isTextureFile } from './texture';
 
 /** The stored files a project draws and plays, per library – what is loaded before anything asks. */
@@ -20,17 +23,57 @@ export interface ProjectFiles {
  * an upload that failed – is left out, as the libraries would never get it anyway. So is a bake that
  * no longer holds (#340): it would never be played. So is a sound that streams (#349): the sound
  * library fetches the start of its copy instead, and decoded ahead it would weigh what streaming saves.
+ * A sound only played through its clips has their copies loaded rather than its whole file.
  */
 export function projectFiles(project: Project): ProjectFiles {
   const files: ProjectFiles = { textures: [], fonts: [], cels: [], sounds: [] };
+  const copies = clipCopyTable(project);
+  let named: ReadonlySet<string> | null = null;
+  const namedWhole = (asset: SoundAsset) => (named ??= namedStrings(project)).has(asset.id);
   for (const asset of project.assets) {
     if (asset.type === 'texture' && isTextureFile(asset.file)) files.textures.push(asset.file);
     else if (asset.type === 'font' && isFontFile(asset.file)) files.fonts.push(asset.file);
     else if (asset.type === 'pixelart') files.cels.push(...celFilesOf(asset));
     else if (asset.type === 'sound' && isSoundFile(asset.file) && !streamsOf(asset.props))
-      files.sounds.push(asset.file);
+      files.sounds.push(...decodedAhead(asset, copies, namedWhole));
     else if ((asset.type === 'pattern' || asset.type === 'song') && validBake(project, asset))
       files.sounds.push(asset.bake!.file);
   }
   return files;
 }
+
+/**
+ * What of a sound is decoded ahead: its file where something may play it whole – a sound without
+ * clips, one the project names itself, one with a clip whose copy is not there yet – else the cut of
+ * each clip, which the sound library plays from its copy.
+ */
+function decodedAhead(
+  asset: SoundAsset,
+  copies: ReadonlyMap<string, string>,
+  namedWhole: (asset: SoundAsset) => boolean,
+): string[] {
+  const cuts = clipsOf(asset).map((clip) => cutName(asset.file, cutOf(clip.props)));
+  const whole = cuts.length === 0 || cuts.some((cut) => !copies.has(cut)) || namedWhole(asset);
+  return whole ? [asset.file] : [...new Set(cuts)];
+}
+
+/** What holds no reference to a sound, and holds a lot: not walked for one. */
+const UNNAMING: ReadonlySet<AssetType> = new Set(['sound', 'texture', 'pixelart', 'tilemap', 'font']);
+
+/**
+ * Every text the project holds outside the assets that cannot name a sound. Where a sound is played
+ * whole – a sound field, an item of a song, a Sample, a Reverb's impulse – its id is one of them; a
+ * clip has an id of its own. Looked at as data, not field by field, so no place is missed: one that
+ * only looks like a reference loads the file as before.
+ */
+function namedStrings(project: Project): Set<string> {
+  const seen = new Set<string>();
+  const walk = (value: unknown): void => {
+    if (typeof value === 'string') seen.add(value);
+    else if (Array.isArray(value)) value.forEach(walk);
+    else if (typeof value === 'object' && value !== null && !ArrayBuffer.isView(value))
+      Object.values(value).forEach(walk);
+  };
+  for (const asset of project.assets) if (!UNNAMING.has(asset.type)) walk(asset);
+  return seen;
+}

src/core/music/streams.ts

@@ -1,9 +1,9 @@
 /**
  * Sounds streamed rather than decoded whole (#349). A sound with `stream` on is played from a copy as
- * Opus in Ogg, made in the browser, and each of its clips from a copy of its own cut, so no clip needs
- * the whole file either. A bake (#340) is Opus already and always streams. What a game plays is still
- * named as before – the file, or the cut a clip is – and the table here says which of those names to
- * stream from which copy.
+ * Opus in Ogg, made in the browser. Every clip of every sound has a copy of its own cut, so no clip
+ * needs the whole file: streamed where its sound streams, decoded where it does not. A bake (#340) is
+ * Opus already and always streams. What a game plays is still named as before – the file, or the cut
+ * a clip is – and the tables here say which of those names to play from which copy.
  */
 import type { SoundAsset, SoundClip, SoundStream } from '../model/Asset';
 import type { Project } from '../model/Project';
@@ -97,6 +97,23 @@ function heldCopy(stream: SoundStream | undefined, played: string): StreamedFile
   return stream && stream.from === played ? { file: stream.file, frames: stream.frames } : null;
 }
 
+/**
+ * The cut each clip plays, with the copy it is decoded from instead of its sound's whole file – of a
+ * sound that streams too, for where a stream cannot be had. A clip whose copy does not fit is left out.
+ */
+export function clipCopyTable(project: Project): Map<string, string> {
+  const table = new Map<string, string>();
+  for (const asset of project.assets) {
+    if (asset.type !== 'sound' || !asset.file) continue;
+    for (const clip of clipsOf(asset)) {
+      const played = cutName(asset.file, cutOf(clip.props));
+      const copy = played === asset.file ? null : heldCopy(clip.stream, played);
+      if (copy) table.set(played, copy.file);
+    }
+  }
+  return table;
+}
+
 /** A copy to make: of a sound, or of one of its clips, from what it plays now. */
 export interface StreamJob {
   assetId: string;
@@ -104,7 +121,7 @@ export interface StreamJob {
   from: string;
 }
 
-/** A copy that is to go: its sound no longer streams, or a clip of it has become the whole file. */
+/** A copy that is to go: its sound no longer streams or has no file, or a clip is the whole file. */
 export interface StreamDrop {
   assetId: string;
   clipId: string | null;
@@ -116,16 +133,16 @@ export function streamWork(project: Project): { jobs: StreamJob[]; drops: Stream
   const drops: StreamDrop[] = [];
   for (const asset of project.assets) {
     if (asset.type !== 'sound') continue;
-    const on = streamsOf(asset.props) && asset.file !== '';
     const keep = (owner: SoundAsset | SoundClip, clipId: string | null, from: string | null) => {
       if (from === null) {
         if (owner.stream) drops.push({ assetId: asset.id, clipId });
       } else if (owner.stream?.from !== from) jobs.push({ assetId: asset.id, clipId, from });
     };
-    keep(asset, null, on ? asset.file : null);
+    keep(asset, null, streamsOf(asset.props) && asset.file !== '' ? asset.file : null);
+    // A clip has its copy whether its sound streams or not.
     for (const clip of clipsOf(asset)) {
       const played = cutName(asset.file, cutOf(clip.props));
-      keep(clip, clip.id, on && played !== asset.file ? played : null);
+      keep(clip, clip.id, asset.file !== '' && played !== asset.file ? played : null);
     }
   }
   return { jobs, drops };

src/editor/debug/soundHooks.ts

@@ -1,7 +1,8 @@
 import { findAssetOf } from '../../core/model/Project';
-import { clipsOf, findSound } from '../../core/model/sound';
+import { projectFiles } from '../../core/model/projectFiles';
+import { clipsOf, cutChannels, cutRange, findSound, parseCutName } from '../../core/model/sound';
 import { STREAM_RATE } from '../../core/music/streamQueue';
-import { playedPlan, streamTable } from '../../core/music/streams';
+import { clipCopyTable, playedPlan, streamTable } from '../../core/music/streams';
 import { playedSoundOf } from '../../core/properties/playedSound';
 import { soundLibrary } from '../../viewport/SoundLibrary';
 import { centreOf, type HookContext } from './hookHelpers';
@@ -121,6 +122,49 @@ export function soundHooks({ state, editor }: HookContext) {
           skipped: played.skipped,
         };
       },
+      /**
+       * What a game decodes that has just opened the project, in a library of its own so nothing this
+       * page holds counts: the names it decodes ahead, whether that decoded the whole file of a name's
+       * sound, and what the name then plays held against its cut made from that file – samples, rate,
+       * the loudest difference of a sample and of the level of any 20 ms.
+       */
+      fresh: async (name: string) => {
+        const library = soundLibrary.aside();
+        library.setStreams(streamTable(state.project));
+        library.setCopies(clipCopyTable(state.project));
+        const ahead = projectFiles(state.project).sounds;
+        await Promise.all(ahead.map((file) => library.load(file)));
+        const { file, cut } = parseCutName(name);
+        const whole = library.decoded(file) !== null;
+        const played = await library.load(name);
+        const original = await soundLibrary.decodeApart(file, STREAM_RATE);
+        if (!played || !cut || played.sampleRate !== STREAM_RATE) return { ahead, whole, played: null };
+        const [reference] = cutChannels(
+          [original.getChannelData(0)],
+          cutRange(original.length, STREAM_RATE, cut),
+        );
+        const heard = played.getChannelData(0);
+        let worst = 0;
+        let level = 0;
+        const span = Math.round(0.02 * STREAM_RATE);
+        for (let from = 0; from + span <= heard.length; from += span) {
+          let own = 0;
+          let wanted = 0;
+          for (let i = from; i < from + span; i++) {
+            worst = Math.max(worst, Math.abs(heard[i]! - (reference![i] ?? 0)));
+            own += heard[i]! ** 2;
+            wanted += (reference![i] ?? 0) ** 2;
+          }
+          // Only where it is heard: the fades start from silence.
+          if (wanted / span > 1e-6) level = Math.max(level, Math.abs(10 * Math.log10(own / wanted)));
+        }
+        return {
+          ahead,
+          whole,
+          played: { length: played.length, wanted: reference!.length, worst, level },
+          decoded: library.stats().decoded,
+        };
+      },
       /** What a sound and each of its clips keep of their copies. */
       copies: (id: string) => {
         const asset = findAssetOf(state.project, id, 'sound');

src/editor/sound/StreamKeeper.ts

@@ -14,10 +14,10 @@ import type { EditorState } from '../state';
 const SETTLE_MS = 600;
 
 /**
- * Makes the copies streamed sounds are played from (#349). A moment after the project last changed,
- * each sound with `stream` on gets a copy of its file as Opus, and each of its clips one of its cut,
- * one at a time, from the file decoded for it and let go again. A copy no longer wanted is taken off
- * its sound and deleted once the project has been saved without it. Not while the game runs.
+ * Makes the copies sounds and clips are played from (#349). A moment after the project last changed,
+ * each sound with `stream` on gets a copy of its file as Opus, and each clip of any sound one of its
+ * cut, one at a time, from the file decoded for it and let go again. A copy no longer wanted is taken
+ * off its sound and deleted once the project has been saved without it. Not while the game runs.
  */
 export class StreamKeeper {
   private job: { job: StreamJob; share: number } | null = null;
@@ -77,7 +77,7 @@ export class StreamKeeper {
       if (error instanceof BakeCancelled) return this.later(0);
       this.failed.add(keyOf(next));
       this.state.setNotice(
-        `No stream copy of ${this.label(next)}: ${error instanceof Error ? error.message : String(error)}`,
+        `No copy of ${this.label(next)}: ${error instanceof Error ? error.message : String(error)}`,
         'error',
       );
     } finally {
@@ -100,7 +100,7 @@ export class StreamKeeper {
         const before = Math.round(running.share * 100);
         running.share = share;
         const now = Math.round(share * 100);
-        if (now !== before) this.state.setNotice(`Making a stream copy of ${label}: ${now}%`, 'quiet');
+        if (now !== before) this.state.setNotice(`Making a copy of ${label}: ${now}%`, 'quiet');
       },
       cancelled: () => !this.stillWanted(job),
     });
@@ -119,14 +119,14 @@ export class StreamKeeper {
       bytes: uploaded.bytes,
     });
     if (old && old !== uploaded.file && !this.named(old)) dropWhenSaved(this.state, this.sounds, old);
-    this.state.setNotice(`Made a stream copy of ${label}`, 'quiet');
+    this.state.setNotice(`Made a copy of ${label}`, 'quiet');
   }
 
-  /** Whether the sound still streams and still plays what the copy is being made of. */
+  /** Whether the sound, or its clip, still plays what the copy is being made of – a sound still streams. */
   private stillWanted(job: StreamJob): boolean {
     const asset = this.sound(job.assetId);
-    if (!asset || !streamsOf(asset.props)) return false;
-    if (job.clipId === null) return asset.file === job.from;
+    if (!asset) return false;
+    if (job.clipId === null) return streamsOf(asset.props) && asset.file === job.from;
     const clip = clipsOf(asset).find((c) => c.id === job.clipId);
     return clip !== undefined && cutName(asset.file, cutOf(clip.props)) === job.from;
   }

src/viewport/SoundLibrary.ts

@@ -378,6 +378,8 @@ export class SoundLibrary implements AudioSink {
   private readonly mixVolumes = new Map<string, number>();
   /** The names streamed (#349) and the copies they stream from, by name and by copy. */
   private streams: ReadonlyMap<string, StreamedFile> = new Map();
+  /** The cut of each clip, with the copy it is decoded from rather than its whole file (#349). */
+  private copies: ReadonlyMap<string, string> = new Map();
   private readonly streamFiles = new Map<string, StreamFile>();
   private readonly feeds = new Set<StreamFeed>();
   /** Every sample streamed so far that came too late to be heard, of the feeds gone (test hook). */
@@ -398,6 +400,21 @@ export class SoundLibrary implements AudioSink {
     for (const name of table.keys()) void this.streamed(name)?.ready();
   }
 
+  /**
+   * The copies clips are decoded from (#349), each under the cut it plays (`clipCopyTable`). A clip
+   * whose sound's whole file is decoded anyway is cut from that as before. One that bakes keeps to the
+   * whole files, as the fingerprint of a bake does.
+   */
+  setCopies(table: ReadonlyMap<string, string>): void {
+    this.copies = table;
+  }
+
+  /** The copy a clip is decoded from, while it has one that has not failed. */
+  private copyOf(name: string): string | null {
+    const copy = this.render ? undefined : this.copies.get(name);
+    return copy && !this.failed.has(copy) ? copy : null;
+  }
+
   /** The copy a name streams from, while it streams and the copy has not failed. */
   private streamed(name: string): StreamFile | null {
     const entry = this.streams.get(name);
@@ -1755,10 +1772,14 @@ export class SoundLibrary implements AudioSink {
 
   /**
    * Fetches and decodes once per file; a second play while it is in flight waits on the first. A cut
-   * (#343) loads its file and is made from it.
+   * (#343) loads its file and is made from it – the cut of a clip with a copy (#349) loads that
+   * instead, unless the whole file is there already.
    */
   async load(file: string): Promise<AudioBuffer | null> {
     if (parseCutName(file).cut) {
+      const copy = this.copyOf(file);
+      if (copy && !this.buffers.has(parseCutName(file).file) && (await this.load(copy)))
+        return this.buffer(file);
       const whole = await this.load(parseCutName(file).file);
       return whole ? this.buffer(file) : null;
     }
@@ -2331,6 +2352,13 @@ export class SoundLibrary implements AudioSink {
     };
   }
 
+  /** A library of its own, served from where this one is, that has decoded nothing yet (test hook). */
+  aside(): SoundLibrary {
+    const library = new SoundLibrary(this.guarded);
+    library.configure(this.base);
+    return library;
+  }
+
   /** All of the copy a name streams from, decoded as the feed decodes it (test hook). */
   async streamedWhole(name: string): Promise<Float32Array[] | null> {
     const file = this.streamed(name);
@@ -2446,10 +2474,16 @@ export class SoundLibrary implements AudioSink {
     });
   }
 
-  /** What a name plays, a cut made from its file the first time; null while the file is not loaded. */
+  /**
+   * What a name plays: the copy of a clip (#349) once it is decoded, else a cut made from its file the
+   * first time; null while neither is loaded.
+   */
   private buffer(name: string): AudioBuffer | null {
     const whole = this.buffers.get(name);
     if (whole) return whole;
+    const copy = this.copyOf(name);
+    const copied = copy ? this.buffers.get(copy) : undefined;
+    if (copied) return copied;
     const held = this.cuts.get(name);
     if (held) {
       this.cuts.delete(name);
@@ -2476,12 +2510,17 @@ export class SoundLibrary implements AudioSink {
     return made;
   }
 
-  /** The samples of its loaded file a name plays: all of them, or the stretch a cut keeps. */
+  /**
+   * The samples of its loaded file a name plays: all of them, or the stretch a cut keeps – all of a
+   * clip's copy (#349), which is that stretch already.
+   */
   private rangeOf(name: string): (CutRange & { whole: AudioBuffer }) | null {
     const { file, cut } = parseCutName(name);
-    const whole = this.buffers.get(file);
+    const copy = this.copyOf(name);
+    const copied = copy ? this.buffers.get(copy) : undefined;
+    const whole = copied ?? this.buffers.get(file);
     if (!whole) return null;
-    if (!cut)
+    if (!cut || copied)
       return {
         whole,
         from: 0,
@@ -2498,9 +2537,9 @@ export class SoundLibrary implements AudioSink {
   /** How long a sound a Reverb takes as its impulse response rings (#328): all it may, while unknown. */
   private readonly soundLength = (file: string): number => this.duration(file) ?? REVERB_MAX_DECAY;
 
-  /** Whether the file of a name could not be had: a cut of it cannot either. */
+  /** Whether the file of a name could not be had: a cut of it cannot either, unless it has a copy. */
   private hasFailed(name: string): boolean {
-    return this.failed.has(parseCutName(name).file);
+    return this.copyOf(name) === null && this.failed.has(parseCutName(name).file);
   }
 
   /** Loads the FX worklet (Pitch, Bitcrusher, Chip, Phaser, Flanger) into the context once; says whether it is there. */

src/viewport/projectFiles.ts

@@ -1,7 +1,7 @@
 import type { Renderer } from 'pixi.js';
 import type { Project } from '../core/model/Project';
 import { projectFiles } from '../core/model/projectFiles';
-import { streamTable } from '../core/music/streams';
+import { clipCopyTable, streamTable } from '../core/music/streams';
 import { requestRender } from '../ui';
 import { fontLibrary } from './FontLibrary';
 import { installPixelArtPictures } from './pixelArtPicture';
@@ -47,7 +47,9 @@ export function preloadProjectFiles(project: Project): void {
   textureLibrary.preload(files.textures);
   fontLibrary.preload(files.fonts);
   pixelCels.preload(files.cels);
-  // Which of them stream (#349) first, so their copies are fetched rather than they decoded.
+  // Which of them stream (#349) first, so their copies are fetched rather than they decoded, and
+  // which clips decode from a copy of their own rather than from their sound's whole file.
   soundLibrary.setStreams(streamTable(project));
+  soundLibrary.setCopies(clipCopyTable(project));
   soundLibrary.preload(files.sounds);
 }