deepdrft/DeepDrftPublic/Interop/audio/OpusStreamDecoder.test.ts

/**
 * Opus WebCodecs decode-path tests — the browser-independent pieces.
 *
 * The WebCodecs decode/playback/seek itself can only run in a real browser (verified by Daniel), so
 * these tests cover the pure logic that surrounds it and that determines correctness:
 *   - OggSidecar parse: byte-for-byte round-trip against the C# wire format.
 *   - resolveOpusByteOffset: the seek transfer function (binary search over the precomputed index).
 *   - OggDemuxer: Ogg page -> Opus packet extraction (segment-table lacing, packets spanning pages,
 *     granule tracking, OpusHead/OpusTags setup-packet skipping, continuation reset).
 *   - extractOpusHead / opusHeadChannelCount: pulling the WebCodecs `description` out of the sidecar.
 *
 * There is no TS test runner configured in this repo (no package.json, no jest/vitest). This is a
 * self-contained, zero-dependency test: a tiny inline assert harness, no `node:` imports beyond Buffer
 * (Node global). It is EXCLUDED from the production tsc build (tsconfig `exclude: Interop/**\/*.test.ts`)
 * so it never ships in wwwroot/js. To run it (Node 22+ strips TS types natively — no tsc, no deps), the
 * `.js` import specifiers must resolve to the COMPILED modules, so run a copy from the compiled output:
 *
 *   # 1. produce the compiled modules (the normal build already does this):
 *   dotnet build DeepDrftPublic/DeepDrftPublic.csproj
 *   # 2. run this test next to the compiled .js siblings (Node strips the types at load):
 *   cp DeepDrftPublic/Interop/audio/OpusStreamDecoder.test.ts DeepDrftPublic/wwwroot/js/audio/
 *   node DeepDrftPublic/wwwroot/js/audio/OpusStreamDecoder.test.ts
 *
 * A thrown error / non-zero exit signals failure; "ALL <n> TESTS PASSED" signals success.
 *
 * The sidecar bytes built in `makeSidecar` reproduce the C# wire format byte-for-byte
 * (DeepDrftContent.Processors.Opus.OpusSidecar.ToBytes / OggOpusSeekIndex.ToBytes):
 *   [uint32 setupHeaderLength][setup bytes]
 *   [uint64 totalByteLength][double totalDuration][uint32 count][uint16 preSkip][uint16 reserved]
 *   count x [uint64 granulePosition][uint64 byteOffset]    — all little-endian.
 */

import { parseSidecar, presentationTimeSeconds, resolveOpusByteOffset, OPUS_SAMPLE_RATE } from './OpusSidecar.js';
import type { OpusSeekData } from './OpusSidecar.js';
import { OggDemuxer, extractOpusHead, opusHeadChannelCount } from './OggDemuxer.js';

// --- tiny inline harness (no dependencies) ---------------------------------------------------
let passed = 0;
const failures: string[] = [];
function test(name: string, fn: () => void): void {
    try {
        fn();
        passed++;
    } catch (e) {
        failures.push(`FAIL: ${name}\n    ${(e as Error).message}`);
    }
}
function assertEqual(actual: unknown, expected: unknown, msg?: string): void {
    if (actual !== expected) {
        throw new Error(`${msg ?? 'assertEqual'}: expected ${String(expected)}, got ${String(actual)}`);
    }
}
function assertArray(actual: ArrayLike<number>, expected: number[], msg?: string): void {
    const a = Array.from(actual);
    if (a.length !== expected.length || a.some((v, i) => v !== expected[i])) {
        throw new Error(`${msg ?? 'assertArray'}: expected [${expected}], got [${a}]`);
    }
}
function assertNull(actual: unknown, msg?: string): void {
    if (actual !== null) throw new Error(`${msg ?? 'assertNull'}: expected null, got ${String(actual)}`);
}
function assertNotNull<T>(actual: T | null, msg?: string): T {
    if (actual === null) throw new Error(`${msg ?? 'assertNotNull'}: got null`);
    return actual;
}

interface SidecarSpec {
    setupHeader: number[];
    totalByteLength: number;
    totalDuration: number;
    preSkip: number;
    points: Array<{ granule: number; byteOffset: number }>;
}

/** Serialize a sidecar blob exactly as the C# OpusSidecar/OggOpusSeekIndex writers do. */
function makeSidecar(spec: SidecarSpec): Uint8Array {
    const SEEK_INDEX_HEADER_SIZE = 24;
    const SEEK_POINT_SIZE = 16;
    const setupLen = spec.setupHeader.length;
    const total = 4 + setupLen + SEEK_INDEX_HEADER_SIZE + spec.points.length * SEEK_POINT_SIZE;

    const bytes = new Uint8Array(total);
    const view = new DataView(bytes.buffer);

    view.setUint32(0, setupLen, true);
    bytes.set(spec.setupHeader, 4);

    let p = 4 + setupLen;
    writeUint64(view, p, spec.totalByteLength);
    view.setFloat64(p + 8, spec.totalDuration, true);
    view.setUint32(p + 16, spec.points.length, true);
    view.setUint16(p + 20, spec.preSkip, true);
    // bytes 22-23 reserved (zero)

    p += SEEK_INDEX_HEADER_SIZE;
    for (const pt of spec.points) {
        writeUint64(view, p, pt.granule);
        writeUint64(view, p + 8, pt.byteOffset);
        p += SEEK_POINT_SIZE;
    }
    return bytes;
}

function writeUint64(view: DataView, offset: number, value: number): void {
    view.setUint32(offset, value >>> 0, true);
    view.setUint32(offset + 4, Math.floor(value / 0x100000000), true);
}

// --- parseSidecar: byte-for-byte round-trip against the C# layout -----------------------------

test('parseSidecar round-trips the C# binary layout exactly', () => {
    const setup = [0x4f, 0x70, 0x75, 0x73, 0x48, 0x65, 0x61, 0x64]; // "OpusHead" stand-in
    const spec: SidecarSpec = {
        setupHeader: setup,
        totalByteLength: 1_234_567,
        totalDuration: 212.5,
        preSkip: 312,
        points: [
            { granule: 312, byteOffset: 4096 },          // first point: granule == preSkip -> t=0
            { granule: 312 + 24000, byteOffset: 9000 },  // +0.5 s
            { granule: 312 + 48000, byteOffset: 14000 }, // +1.0 s
        ],
    };

    const parsed: OpusSeekData = assertNotNull(parseSidecar(makeSidecar(spec)));
    assertEqual(parsed.kind, 'opus-sidecar', 'kind');
    assertArray(parsed.setupHeaderBytes, setup, 'setup header bytes');
    assertEqual(parsed.totalByteLength, spec.totalByteLength, 'totalByteLength');
    assertEqual(parsed.totalDurationSeconds, spec.totalDuration, 'totalDuration');
    assertEqual(parsed.preSkip, spec.preSkip, 'preSkip');
    assertEqual(parsed.points.length, 3, 'point count');
    assertEqual(parsed.points[1].granulePosition, 312 + 24000, 'point[1].granule');
    assertEqual(parsed.points[1].byteOffset, 9000, 'point[1].byteOffset');
});

test('parseSidecar honours a borrowed view byteOffset (sidecar not at buffer start)', () => {
    const blob = makeSidecar({
        setupHeader: [1, 2, 3, 4],
        totalByteLength: 100,
        totalDuration: 1.0,
        preSkip: 0,
        points: [{ granule: 0, byteOffset: 8 }],
    });
    const padded = new Uint8Array(blob.length + 7);
    padded.set(blob, 7);
    const parsed = assertNotNull(parseSidecar(padded.subarray(7)));
    assertArray(parsed.setupHeaderBytes, [1, 2, 3, 4], 'borrowed setup bytes');
    assertEqual(parsed.points[0].byteOffset, 8, 'borrowed point offset');
});

test('parseSidecar returns null on a truncated blob', () => {
    const blob = makeSidecar({
        setupHeader: [0],
        totalByteLength: 1,
        totalDuration: 0,
        preSkip: 0,
        points: [{ granule: 0, byteOffset: 0 }],
    });
    assertNull(parseSidecar(blob.subarray(0, 3)), 'short of length prefix');
    assertNull(parseSidecar(blob.subarray(0, blob.length - 4)), 'declared count overruns');
});

test('presentationTimeSeconds applies preSkip and clamps at zero (RFC 7845)', () => {
    assertEqual(presentationTimeSeconds(312, 312), 0, 'granule == preSkip');
    assertEqual(presentationTimeSeconds(0, 312), 0, 'below preSkip clamps');
    assertEqual(presentationTimeSeconds(312 + OPUS_SAMPLE_RATE, 312), 1.0, '+48000 -> 1 s');
});

// --- resolveOpusByteOffset: binary search over the precomputed index (exact, not interpolation) -

function sidecarFrom(spec: SidecarSpec): OpusSeekData {
    return assertNotNull(parseSidecar(makeSidecar(spec)), 'sidecar should parse');
}

test('resolveOpusByteOffset returns the page-start of the largest entry with time <= t', () => {
    const points = [0, 1, 2, 3].map(i => ({
        granule: 1000 + i * (OPUS_SAMPLE_RATE / 2),
        byteOffset: 4096 + i * 5000,
    }));
    const sc = sidecarFrom({
        setupHeader: [9, 9, 9, 9], totalByteLength: 999_999, totalDuration: 1.5, preSkip: 1000, points,
    });
    assertEqual(resolveOpusByteOffset(sc, 0.0), 4096, 't=0 -> first point');
    assertEqual(resolveOpusByteOffset(sc, 0.4), 4096, 'just before bucket 1');
    assertEqual(resolveOpusByteOffset(sc, 0.5), 9096, 'exactly bucket 1');
    assertEqual(resolveOpusByteOffset(sc, 0.9), 9096, 'within bucket 1');
    assertEqual(resolveOpusByteOffset(sc, 1.0), 14096, 'exactly bucket 2');
    assertEqual(resolveOpusByteOffset(sc, 99), 19096, 'past end -> last point');
});

test('resolveOpusByteOffset never interpolates between points', () => {
    const sc = sidecarFrom({
        setupHeader: [0], totalByteLength: 10_000, totalDuration: 1.0, preSkip: 0,
        points: [{ granule: 0, byteOffset: 100 }, { granule: OPUS_SAMPLE_RATE, byteOffset: 9000 }],
    });
    assertEqual(resolveOpusByteOffset(sc, 0.5), 100, 'midpoint snaps to lower page start');
});

test('resolveOpusByteOffset degrades to start of audio with an empty index', () => {
    const sc = sidecarFrom({
        setupHeader: [1, 2, 3, 4, 5], totalByteLength: 0, totalDuration: 0, preSkip: 0, points: [],
    });
    // start of audio == setup header length (server emits [setup pages][audio pages]).
    assertEqual(resolveOpusByteOffset(sc, 10), 5, 'empty index degrades to audio start');
});

// --- OggDemuxer: page -> packet extraction ----------------------------------------------------
//
// Builds minimal Ogg pages by hand (no codec) so the lacing logic is exercised deterministically.

interface PageSpec {
    granule: number;       // -1 (0xFFFF...) means "no granule"
    continued?: boolean;   // header-type bit 0x01
    eos?: boolean;         // header-type bit 0x04
    /** Packet payloads to lace into this page (each split into 255-byte segments per Ogg rules). */
    packets?: Uint8Array[];
    /** Raw segment lengths + payload, for hand-crafting page-spanning packets. */
    rawSegments?: number[];
    rawPayload?: Uint8Array;
}

function buildPage(spec: PageSpec): Uint8Array {
    let segTable: number[];
    let payload: Uint8Array;

    if (spec.rawSegments && spec.rawPayload) {
        segTable = spec.rawSegments;
        payload = spec.rawPayload;
    } else {
        segTable = [];
        const chunks: number[] = [];
        for (const pkt of spec.packets ?? []) {
            let remaining = pkt.length;
            let o = 0;
            // Lace: emit 255-byte segments until the final (< 255) segment terminates the packet.
            for (;;) {
                const seg = Math.min(255, remaining);
                segTable.push(seg);
                for (let i = 0; i < seg; i++) chunks.push(pkt[o + i]);
                o += seg;
                remaining -= seg;
                if (seg < 255) break; // terminating segment
            }
        }
        payload = new Uint8Array(chunks);
    }

    const header = new Uint8Array(OGG_HDR + segTable.length + payload.length);
    header.set([0x4f, 0x67, 0x67, 0x53], 0); // "OggS"
    header[4] = 0; // version
    header[5] = (spec.continued ? 0x01 : 0) | (spec.eos ? 0x04 : 0);
    // granule (LE uint64)
    if (spec.granule < 0) {
        for (let i = 0; i < 8; i++) header[6 + i] = 0xff;
    } else {
        let g = spec.granule;
        for (let i = 0; i < 8; i++) { header[6 + i] = g & 0xff; g = Math.floor(g / 256); }
    }
    header[26] = segTable.length;
    header.set(segTable, OGG_HDR);
    header.set(payload, OGG_HDR + segTable.length);
    return header;
}
const OGG_HDR = 27;

function opusHeadPacket(channels: number, preSkip: number): Uint8Array {
    // "OpusHead"(8) version(1) channels(1) preSkip(2 LE) inputRate(4) gain(2) mapping(1) = 19 bytes
    const p = new Uint8Array(19);
    p.set([0x4f, 0x70, 0x75, 0x73, 0x48, 0x65, 0x61, 0x64], 0);
    p[8] = 1;
    p[9] = channels;
    p[10] = preSkip & 0xff;
    p[11] = (preSkip >> 8) & 0xff;
    return p;
}
function opusTagsPacket(): Uint8Array {
    const p = new Uint8Array(16);
    p.set([0x4f, 0x70, 0x75, 0x73, 0x54, 0x61, 0x67, 0x73], 0); // "OpusTags"
    return p;
}

test('OggDemuxer skips OpusHead/OpusTags and returns audio packets with the page granule', () => {
    const head = buildPage({ granule: 0, packets: [opusHeadPacket(2, 312)] });
    const tags = buildPage({ granule: 0, packets: [opusTagsPacket()] });
    const audio = buildPage({ granule: 24000, packets: [new Uint8Array([0xaa, 0xbb]), new Uint8Array([0xcc])] });

    const d = new OggDemuxer();
    const packets = d.push(concat([head, tags, audio]));
    assertEqual(packets.length, 2, 'two audio packets, setup skipped');
    assertArray(packets[0].data, [0xaa, 0xbb], 'first audio packet bytes');
    assertEqual(packets[0].pageGranule, null, 'non-final packet carries no granule');
    assertArray(packets[1].data, [0xcc], 'second audio packet bytes');
    assertEqual(packets[1].pageGranule, 24000, 'final completing packet carries the page granule');
    assertEqual(packets[1].isLastPage, false, 'not EOS');
});

test('OggDemuxer flags the EOS page', () => {
    const head = buildPage({ granule: 0, packets: [opusHeadPacket(1, 100)] });
    const tags = buildPage({ granule: 0, packets: [opusTagsPacket()] });
    const audio = buildPage({ granule: 48000, eos: true, packets: [new Uint8Array([0x01])] });
    const d = new OggDemuxer();
    const packets = d.push(concat([head, tags, audio]));
    assertEqual(packets.length, 1, 'one audio packet');
    assertEqual(packets[0].isLastPage, true, 'EOS flagged');
});

test('OggDemuxer reassembles a packet that spans two pages (255 last segment + continuation)', () => {
    const head = buildPage({ granule: 0, packets: [opusHeadPacket(2, 0)] });
    const tags = buildPage({ granule: 0, packets: [opusTagsPacket()] });
    // First audio page: one 255-byte segment that does NOT terminate (packet continues).
    const part1 = new Uint8Array(255).fill(0x11);
    const pageA = buildPage({ granule: -1, rawSegments: [255], rawPayload: part1 });
    // Second page (continued): a 10-byte terminating segment completes the packet.
    const part2 = new Uint8Array(10).fill(0x22);
    const pageB = buildPage({ granule: 24000, continued: true, rawSegments: [10], rawPayload: part2 });

    const d = new OggDemuxer();
    const packets = d.push(concat([head, tags, pageA, pageB]));
    assertEqual(packets.length, 1, 'one reassembled packet');
    assertEqual(packets[0].data.length, 265, 'packet is 255 + 10 bytes');
    assertEqual(packets[0].data[0], 0x11, 'first byte from page A');
    assertEqual(packets[0].data[264], 0x22, 'last byte from page B');
    assertEqual(packets[0].pageGranule, 24000, 'granule from the completing page');
});

test('OggDemuxer handles bytes split across push() calls (page straddles a network chunk)', () => {
    const head = buildPage({ granule: 0, packets: [opusHeadPacket(2, 0)] });
    const tags = buildPage({ granule: 0, packets: [opusTagsPacket()] });
    const audio = buildPage({ granule: 960, packets: [new Uint8Array([0x07, 0x08, 0x09])] });
    const full = concat([head, tags, audio]);

    const d = new OggDemuxer();
    const cut = full.length - 2; // split mid-audio-page
    const first = d.push(full.subarray(0, cut));
    assertEqual(first.length, 0, 'no whole audio packet yet');
    const second = d.push(full.subarray(cut));
    assertEqual(second.length, 1, 'audio packet completes on the second push');
    assertArray(second[0].data, [0x07, 0x08, 0x09], 'reassembled across pushes');
});

test('OggDemuxer.reset(continuation) treats the first page as audio (no setup expected)', () => {
    const audio = buildPage({ granule: 96000, packets: [new Uint8Array([0x42])] });
    const d = new OggDemuxer();
    d.reset(true);
    const packets = d.push(audio);
    assertEqual(packets.length, 1, 'continuation: first page is audio');
    assertArray(packets[0].data, [0x42], 'audio packet bytes');
});

// --- extractOpusHead / opusHeadChannelCount: WebCodecs description from the sidecar -----------

test('extractOpusHead returns the OpusHead packet from the setup pages', () => {
    const head = buildPage({ granule: 0, packets: [opusHeadPacket(2, 312)] });
    const tags = buildPage({ granule: 0, packets: [opusTagsPacket()] });
    const setup = concat([head, tags]);
    const opusHead = assertNotNull(extractOpusHead(setup), 'OpusHead extracted');
    assertArray(opusHead.subarray(0, 8), [0x4f, 0x70, 0x75, 0x73, 0x48, 0x65, 0x61, 0x64], 'OpusHead magic');
    assertEqual(opusHeadChannelCount(opusHead), 2, 'channel count');
});

test('extractOpusHead returns null when no OpusHead page is present', () => {
    const tags = buildPage({ granule: 0, packets: [opusTagsPacket()] });
    assertNull(extractOpusHead(tags), 'no OpusHead');
});

function concat(arrs: Uint8Array[]): Uint8Array {
    let len = 0;
    for (const a of arrs) len += a.length;
    const out = new Uint8Array(len);
    let o = 0;
    for (const a of arrs) { out.set(a, o); o += a.length; }
    return out;
}

// --- report ----------------------------------------------------------------------------------
if (failures.length > 0) {
    console.error(failures.join('\n'));
    throw new Error(`${failures.length} test(s) failed, ${passed} passed`);
}
console.log(`ALL ${passed} TESTS PASSED`);