simsite/frontend/node_modules/hls.js/src/utils/mp4-tools.ts

import { utf8ArrayToStr } from '@svta/common-media-library/utils/utf8ArrayToStr';
import { arrayToHex } from './hex';
import { ElementaryStreamTypes } from '../loader/fragment';
import { logger } from '../utils/logger';
import type { KeySystemIds } from './mediakeys-helper';
import type { DecryptData } from '../loader/level-key';
import type { PassthroughTrack, UserdataSample } from '../types/demuxer';
import type { ILogger } from '../utils/logger';

type BoxDataOrUndefined = Uint8Array<ArrayBuffer> | undefined;

const UINT32_MAX = Math.pow(2, 32) - 1;
const push = [].push;

// We are using fixed track IDs for driving the MP4 remuxer
// instead of following the TS PIDs.
// There is no reason not to do this and some browsers/SourceBuffer-demuxers
// may not like if there are TrackID "switches"
// See https://github.com/video-dev/hls.js/issues/1331
// Here we are mapping our internal track types to constant MP4 track IDs
// With MSE currently one can only have one track of each, and we are muxing
// whatever video/audio rendition in them.
export const RemuxerTrackIdConfig = {
  video: 1,
  audio: 2,
  id3: 3,
  text: 4,
};

export function bin2str(data: Uint8Array): string {
  return String.fromCharCode.apply(null, data);
}

export function readUint16(buffer: Uint8Array, offset: number): number {
  const val = (buffer[offset] << 8) | buffer[offset + 1];
  return val < 0 ? 65536 + val : val;
}

export function readUint32(buffer: Uint8Array, offset: number): number {
  const val = readSint32(buffer, offset);
  return val < 0 ? 4294967296 + val : val;
}

export function readUint64(buffer: Uint8Array, offset: number) {
  let result = readUint32(buffer, offset);
  result *= Math.pow(2, 32);
  result += readUint32(buffer, offset + 4);
  return result;
}

export function readSint32(buffer: Uint8Array, offset: number): number {
  return (
    (buffer[offset] << 24) |
    (buffer[offset + 1] << 16) |
    (buffer[offset + 2] << 8) |
    buffer[offset + 3]
  );
}

export function writeUint32(buffer: Uint8Array, offset: number, value: number) {
  buffer[offset] = value >> 24;
  buffer[offset + 1] = (value >> 16) & 0xff;
  buffer[offset + 2] = (value >> 8) & 0xff;
  buffer[offset + 3] = value & 0xff;
}

// Find "moof" box
export function hasMoofData(data: Uint8Array): boolean {
  const end = data.byteLength;
  for (let i = 0; i < end; ) {
    const size = readUint32(data, i);
    if (
      size > 8 &&
      data[i + 4] === 0x6d &&
      data[i + 5] === 0x6f &&
      data[i + 6] === 0x6f &&
      data[i + 7] === 0x66
    ) {
      return true;
    }
    i = size > 1 ? i + size : end;
  }
  return false;
}

// Find the data for a box specified by its path
export function findBox(data: Uint8Array, path: string[]): Uint8Array[] {
  const results = [] as Uint8Array[];
  if (!path.length) {
    // short-circuit the search for empty paths
    return results;
  }
  const end = data.byteLength;

  for (let i = 0; i < end; ) {
    const size = readUint32(data, i);
    const type = bin2str(data.subarray(i + 4, i + 8));
    const endbox = size > 1 ? i + size : end;
    if (type === path[0]) {
      if (path.length === 1) {
        // this is the end of the path and we've found the box we were
        // looking for
        results.push(data.subarray(i + 8, endbox));
      } else {
        // recursively search for the next box along the path
        const subresults = findBox(data.subarray(i + 8, endbox), path.slice(1));
        if (subresults.length) {
          push.apply(results, subresults);
        }
      }
    }
    i = endbox;
  }

  // we've finished searching all of data
  return results;
}

type SidxInfo = {
  earliestPresentationTime: number;
  timescale: number;
  version: number;
  referencesCount: number;
  references: any[];
};

function parseSegmentIndex(sidx: Uint8Array): SidxInfo | null {
  const references: any[] = [];

  const version = sidx[0];

  // set initial offset, we skip the reference ID (not needed)
  let index = 8;

  const timescale = readUint32(sidx, index);
  index += 4;

  let earliestPresentationTime = 0;
  let firstOffset = 0;

  if (version === 0) {
    earliestPresentationTime = readUint32(sidx, index);
    firstOffset = readUint32(sidx, index + 4);
    index += 8;
  } else {
    earliestPresentationTime = readUint64(sidx, index);
    firstOffset = readUint64(sidx, index + 8);
    index += 16;
  }

  // skip reserved
  index += 2;

  let startByte = sidx.length + firstOffset;

  const referencesCount = readUint16(sidx, index);
  index += 2;

  for (let i = 0; i < referencesCount; i++) {
    let referenceIndex = index;

    const referenceInfo = readUint32(sidx, referenceIndex);
    referenceIndex += 4;

    const referenceSize = referenceInfo & 0x7fffffff;
    const referenceType = (referenceInfo & 0x80000000) >>> 31;

    if (referenceType === 1) {
      logger.warn('SIDX has hierarchical references (not supported)');
      return null;
    }

    const subsegmentDuration = readUint32(sidx, referenceIndex);
    referenceIndex += 4;

    references.push({
      referenceSize,
      subsegmentDuration, // unscaled
      info: {
        duration: subsegmentDuration / timescale,
        start: startByte,
        end: startByte + referenceSize - 1,
      },
    });

    startByte += referenceSize;

    // Skipping 1 bit for |startsWithSap|, 3 bits for |sapType|, and 28 bits
    // for |sapDelta|.
    referenceIndex += 4;

    // skip to next ref
    index = referenceIndex;
  }

  return {
    earliestPresentationTime,
    timescale,
    version,
    referencesCount,
    references,
  };
}

/**
 * Parses an MP4 initialization segment and extracts stream type and
 * timescale values for any declared tracks. Timescale values indicate the
 * number of clock ticks per second to assume for time-based values
 * elsewhere in the MP4.
 *
 * To determine the start time of an MP4, you need two pieces of
 * information: the timescale unit and the earliest base media decode
 * time. Multiple timescales can be specified within an MP4 but the
 * base media decode time is always expressed in the timescale from
 * the media header box for the track:
 * ```
 * moov > trak > mdia > mdhd.timescale
 * moov > trak > mdia > hdlr
 * ```
 * @param initSegment the bytes of the init segment
 * @returns a hash of track type to timescale values or null if
 * the init segment is malformed.
 */

export interface InitDataTrack {
  timescale: number;
  id: number;
  codec: string;
  encrypted: boolean;
  supplemental: string | undefined;
}

type HdlrMetadata = 'meta';
type HdlrType =
  | ElementaryStreamTypes.AUDIO
  | ElementaryStreamTypes.VIDEO
  | HdlrMetadata;

type StsdData = {
  codec: string;
  encrypted: boolean;
  supplemental: string | undefined;
};

export interface InitData extends Array<any> {
  [index: number]:
    | {
        timescale: number;
        type: HdlrType;
        stsd: StsdData;
        default?: {
          duration: number;
          flags: number;
        };
      }
    | undefined;
  audio?: InitDataTrack;
  video?: InitDataTrack;
  caption?: InitDataTrack;
}

export function parseInitSegment(initSegment: Uint8Array): InitData {
  const result: InitData = [];
  const traks = findBox(initSegment, ['moov', 'trak']);
  for (let i = 0; i < traks.length; i++) {
    const trak = traks[i];
    const tkhd = findBox(trak, ['tkhd'])[0];
    if (tkhd as any) {
      let version = tkhd[0];
      const trackId = readUint32(tkhd, version === 0 ? 12 : 20);
      const mdhd = findBox(trak, ['mdia', 'mdhd'])[0];
      if (mdhd as any) {
        version = mdhd[0];
        const timescale = readUint32(mdhd, version === 0 ? 12 : 20);
        const hdlr = findBox(trak, ['mdia', 'hdlr'])[0];
        if (hdlr as any) {
          const hdlrType = bin2str(hdlr.subarray(8, 12));
          const type: HdlrType | undefined = {
            soun: ElementaryStreamTypes.AUDIO as const,
            vide: ElementaryStreamTypes.VIDEO as const,
          }[hdlrType];
          // Parse codec details
          const stsdBox = findBox(trak, ['mdia', 'minf', 'stbl', 'stsd'])[0];
          const stsd = parseStsd(stsdBox);
          if (type) {
            // Add 'audio', 'video', and 'audiovideo' track records that will map to SourceBuffers
            result[trackId] = { timescale, type, stsd };
            result[type] = { timescale, id: trackId, ...stsd };
          } else {
            // Add 'meta' and other track records
            result[trackId] = {
              timescale,
              type: hdlrType as HdlrType,
              stsd,
            };
          }
        }
      }
    }
  }

  const trex = findBox(initSegment, ['moov', 'mvex', 'trex']);
  trex.forEach((trex) => {
    const trackId = readUint32(trex, 4);
    const track = result[trackId];
    if (track) {
      track.default = {
        duration: readUint32(trex, 12),
        flags: readUint32(trex, 20),
      };
    }
  });

  return result;
}

function parseStsd(stsd: Uint8Array): StsdData {
  const sampleEntries = stsd.subarray(8);
  const sampleEntriesEnd = sampleEntries.subarray(8 + 78);
  const fourCC = bin2str(sampleEntries.subarray(4, 8));
  let codec = fourCC;
  let supplemental;
  const encrypted = fourCC === 'enca' || fourCC === 'encv';
  if (encrypted) {
    const encBox = findBox(sampleEntries, [fourCC])[0];
    const encBoxChildren = encBox.subarray(fourCC === 'enca' ? 28 : 78);
    const sinfs = findBox(encBoxChildren, ['sinf']);
    sinfs.forEach((sinf) => {
      const schm = findBox(sinf, ['schm'])[0];
      if (schm as any) {
        const scheme = bin2str(schm.subarray(4, 8));
        if (scheme === 'cbcs' || scheme === 'cenc') {
          const frma = findBox(sinf, ['frma'])[0];
          if (frma as any) {
            // for encrypted content codec fourCC will be in frma
            codec = bin2str(frma);
          }
        }
      }
    });
  }
  const codecFourCC = codec;
  switch (codec) {
    case 'avc1':
    case 'avc2':
    case 'avc3':
    case 'avc4': {
      // extract profile + compatibility + level out of avcC box
      const avcCBox = findBox(sampleEntriesEnd, ['avcC'])[0];
      if ((avcCBox as any) && avcCBox.length > 3) {
        codec +=
          '.' + toHex(avcCBox[1]) + toHex(avcCBox[2]) + toHex(avcCBox[3]);
        supplemental = parseSupplementalDoViCodec(
          codecFourCC === 'avc1' ? 'dva1' : 'dvav',
          sampleEntriesEnd,
        );
      }
      break;
    }
    case 'mp4a': {
      const codecBox = findBox(sampleEntries, [fourCC])[0];
      const esdsBox = findBox(codecBox.subarray(28), ['esds'])[0];
      if ((esdsBox as any) && esdsBox.length > 7) {
        let i = 4;
        // ES Descriptor tag
        if (esdsBox[i++] !== 0x03) {
          break;
        }
        i = skipBERInteger(esdsBox, i);
        i += 2; // skip es_id;
        const flags = esdsBox[i++];
        if (flags & 0x80) {
          i += 2; // skip dependency es_id
        }
        if (flags & 0x40) {
          i += esdsBox[i++]; // skip URL
        }
        // Decoder config descriptor
        if (esdsBox[i++] !== 0x04) {
          break;
        }
        i = skipBERInteger(esdsBox, i);
        const objectType = esdsBox[i++];
        if (objectType === 0x40) {
          codec += '.' + toHex(objectType);
        } else {
          break;
        }
        i += 12;
        // Decoder specific info
        if (esdsBox[i++] !== 0x05) {
          break;
        }
        i = skipBERInteger(esdsBox, i);
        const firstByte = esdsBox[i++];
        let audioObjectType = (firstByte & 0xf8) >> 3;
        if (audioObjectType === 31) {
          audioObjectType +=
            1 + ((firstByte & 0x7) << 3) + ((esdsBox[i] & 0xe0) >> 5);
        }
        codec += '.' + audioObjectType;
      }
      break;
    }
    case 'hvc1':
    case 'hev1': {
      const hvcCBox = findBox(sampleEntriesEnd, ['hvcC'])[0];
      if ((hvcCBox as any) && hvcCBox.length > 12) {
        const profileByte = hvcCBox[1];
        const profileSpace = ['', 'A', 'B', 'C'][profileByte >> 6];
        const generalProfileIdc = profileByte & 0x1f;
        const profileCompat = readUint32(hvcCBox, 2);
        const tierFlag = (profileByte & 0x20) >> 5 ? 'H' : 'L';
        const levelIDC = hvcCBox[12];
        const constraintIndicator = hvcCBox.subarray(6, 12);
        codec += '.' + profileSpace + generalProfileIdc;
        codec +=
          '.' + reverse32BitInt(profileCompat).toString(16).toUpperCase();
        codec += '.' + tierFlag + levelIDC;
        let constraintString = '';
        for (let i = constraintIndicator.length; i--; ) {
          const byte = constraintIndicator[i];
          if (byte || constraintString) {
            const encodedByte = byte.toString(16).toUpperCase();
            constraintString = '.' + encodedByte + constraintString;
          }
        }
        codec += constraintString;
      }
      supplemental = parseSupplementalDoViCodec(
        codecFourCC == 'hev1' ? 'dvhe' : 'dvh1',
        sampleEntriesEnd,
      );
      break;
    }
    case 'dvh1':
    case 'dvhe':
    case 'dvav':
    case 'dva1':
    case 'dav1': {
      codec = parseSupplementalDoViCodec(codec, sampleEntriesEnd) || codec;
      break;
    }
    case 'vp09': {
      const vpcCBox = findBox(sampleEntriesEnd, ['vpcC'])[0];
      if ((vpcCBox as any) && vpcCBox.length > 6) {
        const profile = vpcCBox[4];
        const level = vpcCBox[5];
        const bitDepth = (vpcCBox[6] >> 4) & 0x0f;
        codec +=
          '.' +
          addLeadingZero(profile) +
          '.' +
          addLeadingZero(level) +
          '.' +
          addLeadingZero(bitDepth);
      }
      break;
    }
    case 'av01': {
      const av1CBox = findBox(sampleEntriesEnd, ['av1C'])[0];
      if ((av1CBox as any) && av1CBox.length > 2) {
        const profile = av1CBox[1] >>> 5;
        const level = av1CBox[1] & 0x1f;
        const tierFlag = av1CBox[2] >>> 7 ? 'H' : 'M';
        const highBitDepth = (av1CBox[2] & 0x40) >> 6;
        const twelveBit = (av1CBox[2] & 0x20) >> 5;
        const bitDepth =
          profile === 2 && highBitDepth
            ? twelveBit
              ? 12
              : 10
            : highBitDepth
              ? 10
              : 8;
        const monochrome = (av1CBox[2] & 0x10) >> 4;
        const chromaSubsamplingX = (av1CBox[2] & 0x08) >> 3;
        const chromaSubsamplingY = (av1CBox[2] & 0x04) >> 2;
        const chromaSamplePosition = av1CBox[2] & 0x03;
        // TODO: parse color_description_present_flag
        // default it to BT.709/limited range for now
        // more info https://aomediacodec.github.io/av1-isobmff/#av1codecconfigurationbox-syntax
        const colorPrimaries = 1;
        const transferCharacteristics = 1;
        const matrixCoefficients = 1;
        const videoFullRangeFlag = 0;
        codec +=
          '.' +
          profile +
          '.' +
          addLeadingZero(level) +
          tierFlag +
          '.' +
          addLeadingZero(bitDepth) +
          '.' +
          monochrome +
          '.' +
          chromaSubsamplingX +
          chromaSubsamplingY +
          chromaSamplePosition +
          '.' +
          addLeadingZero(colorPrimaries) +
          '.' +
          addLeadingZero(transferCharacteristics) +
          '.' +
          addLeadingZero(matrixCoefficients) +
          '.' +
          videoFullRangeFlag;
        supplemental = parseSupplementalDoViCodec('dav1', sampleEntriesEnd);
      }
      break;
    }
    case 'ac-3':
    case 'ec-3':
    case 'alac':
    case 'fLaC':
    case 'Opus':
    default:
      break;
  }
  return { codec, encrypted, supplemental };
}

function parseSupplementalDoViCodec(
  fourCC: string,
  sampleEntriesEnd: Uint8Array,
): string | undefined {
  const dvvCResult = findBox(sampleEntriesEnd, ['dvvC']); // used by DoVi Profile 8 to 10
  const dvXCBox = dvvCResult.length
    ? dvvCResult[0]
    : findBox(sampleEntriesEnd, ['dvcC'])[0]; // used by DoVi Profiles up to 7 and 20
  if (dvXCBox as any) {
    const doViProfile = (dvXCBox[2] >> 1) & 0x7f;
    const doViLevel = ((dvXCBox[2] << 5) & 0x20) | ((dvXCBox[3] >> 3) & 0x1f);
    return (
      fourCC +
      '.' +
      addLeadingZero(doViProfile) +
      '.' +
      addLeadingZero(doViLevel)
    );
  }
}

function reverse32BitInt(val: number) {
  let result = 0;
  for (let i = 0; i < 32; i++) {
    result |= ((val >> i) & 1) << (32 - 1 - i);
  }
  return result >>> 0;
}

function skipBERInteger(bytes: Uint8Array, i: number): number {
  const limit = i + 5;
  while (bytes[i++] & 0x80 && i < limit) {
    /* do nothing */
  }
  return i;
}

function toHex(x: number): string {
  return ('0' + x.toString(16).toUpperCase()).slice(-2);
}

function addLeadingZero(num: number): string {
  return (num < 10 ? '0' : '') + num;
}

export function patchEncyptionData(
  initSegment: Uint8Array<ArrayBuffer> | undefined,
  decryptdata: DecryptData | null,
) {
  if (!initSegment || !decryptdata) {
    return;
  }
  const keyId = decryptdata.keyId;
  if (keyId && decryptdata.isCommonEncryption) {
    applyToTencBoxes(initSegment, (tenc, isAudio) => {
      // Look for default key id (keyID offset is always 8 within the tenc box):
      const tencKeyId = tenc.subarray(8, 24);
      if (!tencKeyId.some((b) => b !== 0)) {
        logger.log(
          `[eme] Patching keyId in 'enc${
            isAudio ? 'a' : 'v'
          }>sinf>>tenc' box: ${arrayToHex(tencKeyId)} -> ${arrayToHex(keyId)}`,
        );
        tenc.set(keyId, 8);
      }
    });
  }
}

export function parseKeyIdsFromTenc(
  initSegment: Uint8Array<ArrayBuffer>,
): Uint8Array<ArrayBuffer>[] {
  const keyIds: Uint8Array<ArrayBuffer>[] = [];
  applyToTencBoxes(initSegment, (tenc) => keyIds.push(tenc.subarray(8, 24)));
  return keyIds;
}

function applyToTencBoxes(
  initSegment: Uint8Array<ArrayBuffer>,
  predicate: (tenc: Uint8Array<ArrayBuffer>, isAudio: boolean) => void,
) {
  const traks = findBox(initSegment, ['moov', 'trak']);
  traks.forEach((trak) => {
    const stsd = findBox(trak, [
      'mdia',
      'minf',
      'stbl',
      'stsd',
    ])[0] as BoxDataOrUndefined;
    if (!stsd) return;
    const sampleEntries = stsd.subarray(8);
    let encBoxes = findBox(sampleEntries, ['enca']);
    const isAudio = encBoxes.length > 0;
    if (!isAudio) {
      encBoxes = findBox(sampleEntries, ['encv']);
    }
    encBoxes.forEach((enc) => {
      const encBoxChildren = isAudio ? enc.subarray(28) : enc.subarray(78);
      const sinfBoxes = findBox(encBoxChildren, ['sinf']);
      sinfBoxes.forEach((sinf) => {
        const tenc = parseSinf(sinf);
        if (tenc) {
          predicate(tenc, isAudio);
        }
      });
    });
  });
}

export function parseSinf(sinf: Uint8Array): BoxDataOrUndefined {
  const schm = findBox(sinf, ['schm'])[0] as BoxDataOrUndefined;
  if (schm) {
    const scheme = bin2str(schm.subarray(4, 8));
    if (scheme === 'cbcs' || scheme === 'cenc') {
      const tenc = findBox(sinf, ['schi', 'tenc'])[0] as BoxDataOrUndefined;
      if (tenc) {
        return tenc;
      }
    } else if (scheme === 'cbc2') {
      /* no-op */
    }
  }
}

/*
  For Reference:
  aligned(8) class TrackFragmentHeaderBox
           extends FullBox(‘tfhd’, 0, tf_flags){
     unsigned int(32)  track_ID;
     // all the following are optional fields
     unsigned int(64)  base_data_offset;
     unsigned int(32)  sample_description_index;
     unsigned int(32)  default_sample_duration;
     unsigned int(32)  default_sample_size;
     unsigned int(32)  default_sample_flags
  }
 */
export type TrackTimes = {
  duration: number;
  keyFrameIndex?: number;
  keyFrameStart?: number;
  start: number;
  sampleCount: number;
  timescale: number;
  type: HdlrType;
};

export function getSampleData(
  data: Uint8Array,
  initData: InitData,
  logger: ILogger,
): Record<number, TrackTimes> {
  const tracks: Record<number, TrackTimes> = {};
  const trafs = findBox(data, ['moof', 'traf']);
  for (let i = 0; i < trafs.length; i++) {
    const traf = trafs[i];
    // There is only one tfhd & trun per traf
    // This is true for CMAF style content, and we should perhaps check the ftyp
    // and only look for a single trun then, but for ISOBMFF we should check
    // for multiple track runs.
    const tfhd = findBox(traf, ['tfhd'])[0];
    // get the track id from the tfhd
    const id = readUint32(tfhd, 4);
    const track = initData[id];
    if (!track) {
      continue;
    }
    (tracks[id] as any) ||= {
      start: NaN,
      duration: 0,
      sampleCount: 0,
      timescale: track.timescale,
      type: track.type,
    };
    const trackTimes: TrackTimes = tracks[id];
    // get start DTS
    const tfdt = findBox(traf, ['tfdt'])[0];

    if (tfdt as any) {
      const version = tfdt[0];
      let baseTime = readUint32(tfdt, 4);
      if (version === 1) {
        // If value is too large, assume signed 64-bit. Negative track fragment decode times are invalid, but they exist in the wild.
        // This prevents large values from being used for initPTS, which can cause playlist sync issues.
        // https://github.com/video-dev/hls.js/issues/5303
        if (baseTime === UINT32_MAX) {
          logger.warn(
            `[mp4-demuxer]: Ignoring assumed invalid signed 64-bit track fragment decode time`,
          );
        } else {
          baseTime *= UINT32_MAX + 1;
          baseTime += readUint32(tfdt, 8);
        }
      }
      if (
        Number.isFinite(baseTime) &&
        (!Number.isFinite(trackTimes.start) || baseTime < trackTimes.start)
      ) {
        trackTimes.start = baseTime;
      }
    }

    const trackDefault = track.default;
    const tfhdFlags = readUint32(tfhd, 0) | trackDefault?.flags!;
    let defaultSampleDuration: number = trackDefault?.duration || 0;
    if (tfhdFlags & 0x000008) {
      // 0x000008 indicates the presence of the default_sample_duration field
      if (tfhdFlags & 0x000002) {
        // 0x000002 indicates the presence of the sample_description_index field, which precedes default_sample_duration
        // If present, the default_sample_duration exists at byte offset 12
        defaultSampleDuration = readUint32(tfhd, 12);
      } else {
        // Otherwise, the duration is at byte offset 8
        defaultSampleDuration = readUint32(tfhd, 8);
      }
    }
    const truns = findBox(traf, ['trun']);
    let sampleDTS = trackTimes.start || 0;
    let rawDuration = 0;
    let sampleDuration = defaultSampleDuration;
    for (let j = 0; j < truns.length; j++) {
      const trun = truns[j];
      const sampleCount = readUint32(trun, 4);
      const sampleIndex = trackTimes.sampleCount;
      trackTimes.sampleCount += sampleCount;
      // Get duration from samples
      const dataOffsetPresent = trun[3] & 0x01;
      const firstSampleFlagsPresent = trun[3] & 0x04;
      const sampleDurationPresent = trun[2] & 0x01;
      const sampleSizePresent = trun[2] & 0x02;
      const sampleFlagsPresent = trun[2] & 0x04;
      const sampleCompositionTimeOffsetPresent = trun[2] & 0x08;
      let offset = 8;
      let remaining = sampleCount;
      if (dataOffsetPresent) {
        offset += 4;
      }
      if (firstSampleFlagsPresent && sampleCount) {
        const isNonSyncSample = trun[offset + 1] & 0x01;
        if (!isNonSyncSample && trackTimes.keyFrameIndex === undefined) {
          trackTimes.keyFrameIndex = sampleIndex;
        }
        offset += 4;
        if (sampleDurationPresent) {
          sampleDuration = readUint32(trun, offset);
          offset += 4;
        } else {
          sampleDuration = defaultSampleDuration;
        }
        if (sampleSizePresent) {
          offset += 4;
        }
        if (sampleCompositionTimeOffsetPresent) {
          offset += 4;
        }
        sampleDTS += sampleDuration;
        rawDuration += sampleDuration;
        remaining--;
      }
      while (remaining--) {
        if (sampleDurationPresent) {
          sampleDuration = readUint32(trun, offset);
          offset += 4;
        } else {
          sampleDuration = defaultSampleDuration;
        }
        if (sampleSizePresent) {
          offset += 4;
        }
        if (sampleFlagsPresent) {
          const isNonSyncSample = trun[offset + 1] & 0x01;
          if (!isNonSyncSample) {
            if (trackTimes.keyFrameIndex === undefined) {
              trackTimes.keyFrameIndex =
                trackTimes.sampleCount - (remaining + 1);
              trackTimes.keyFrameStart = sampleDTS;
            }
          }
          offset += 4;
        }
        if (sampleCompositionTimeOffsetPresent) {
          offset += 4;
        }
        sampleDTS += sampleDuration;
        rawDuration += sampleDuration;
      }
      if (!rawDuration && defaultSampleDuration) {
        rawDuration += defaultSampleDuration * sampleCount;
      }
    }
    trackTimes.duration += rawDuration;
  }
  if (!Object.keys(tracks).some((trackId) => tracks[trackId].duration)) {
    // If duration samples are not available in the traf use sidx subsegment_duration
    let sidxMinStart = Infinity;
    let sidxMaxEnd = 0;
    const sidxs = findBox(data, ['sidx']);
    for (let i = 0; i < sidxs.length; i++) {
      const sidx = parseSegmentIndex(sidxs[i]);
      if (sidx?.references) {
        sidxMinStart = Math.min(
          sidxMinStart,
          sidx.earliestPresentationTime / sidx.timescale,
        );
        const subSegmentDuration = sidx.references.reduce(
          (dur, ref) => dur + ref.info.duration || 0,
          0,
        );
        sidxMaxEnd = Math.max(
          sidxMaxEnd,
          subSegmentDuration + sidx.earliestPresentationTime / sidx.timescale,
        );
      }
    }
    if (sidxMaxEnd && Number.isFinite(sidxMaxEnd)) {
      Object.keys(tracks).forEach((trackId) => {
        if (!tracks[trackId].duration) {
          tracks[trackId].duration =
            sidxMaxEnd * tracks[trackId].timescale - tracks[trackId].start;
        }
      });
    }
  }
  return tracks;
}

// TODO: Check if the last moof+mdat pair is part of the valid range
export function segmentValidRange(
  data: Uint8Array<ArrayBuffer>,
): SegmentedRange {
  const segmentedRange: SegmentedRange = {
    valid: null,
    remainder: null,
  };

  const moofs = findBox(data, ['moof']);
  if (moofs.length < 2) {
    segmentedRange.remainder = data;
    return segmentedRange;
  }
  const last = moofs[moofs.length - 1];
  // Offset by 8 bytes; findBox offsets the start by as much
  segmentedRange.valid = data.slice(0, last.byteOffset - 8);
  segmentedRange.remainder = data.slice(last.byteOffset - 8);
  return segmentedRange;
}

export interface SegmentedRange {
  valid: Uint8Array<ArrayBuffer> | null;
  remainder: Uint8Array<ArrayBuffer> | null;
}

export function appendUint8Array(data1: Uint8Array, data2: Uint8Array) {
  const temp = new Uint8Array(data1.length + data2.length);
  temp.set(data1);
  temp.set(data2, data1.length);
  return temp;
}

export interface IEmsgParsingData {
  schemeIdUri: string;
  value: string;
  timeScale: number;
  presentationTimeDelta?: number;
  presentationTime?: number;
  eventDuration: number;
  id: number;
  payload: Uint8Array;
}

export function parseSamples(
  timeOffset: number,
  track: PassthroughTrack,
): UserdataSample[] {
  const seiSamples = [] as UserdataSample[];
  const videoData = track.samples;
  const timescale = track.timescale;
  const trackId = track.id;
  let isHEVCFlavor = false;

  const moofs = findBox(videoData, ['moof']);
  moofs.map((moof) => {
    const moofOffset = moof.byteOffset - 8;
    const trafs = findBox(moof, ['traf']);
    trafs.map((traf) => {
      // get the base media decode time from the tfdt
      const baseTime = findBox(traf, ['tfdt']).map((tfdt) => {
        const version = tfdt[0];
        let result = readUint32(tfdt, 4);
        if (version === 1) {
          result *= Math.pow(2, 32);
          result += readUint32(tfdt, 8);
        }
        return result / timescale;
      })[0];

      if ((baseTime as any) !== undefined) {
        timeOffset = baseTime;
      }

      return findBox(traf, ['tfhd']).map((tfhd) => {
        const id = readUint32(tfhd, 4);
        const tfhdFlags = readUint32(tfhd, 0) & 0xffffff;
        const baseDataOffsetPresent = (tfhdFlags & 0x000001) !== 0;
        const sampleDescriptionIndexPresent = (tfhdFlags & 0x000002) !== 0;
        const defaultSampleDurationPresent = (tfhdFlags & 0x000008) !== 0;
        let defaultSampleDuration = 0;
        const defaultSampleSizePresent = (tfhdFlags & 0x000010) !== 0;
        let defaultSampleSize = 0;
        const defaultSampleFlagsPresent = (tfhdFlags & 0x000020) !== 0;
        let tfhdOffset = 8;

        if (id === trackId) {
          if (baseDataOffsetPresent) {
            tfhdOffset += 8;
          }
          if (sampleDescriptionIndexPresent) {
            tfhdOffset += 4;
          }
          if (defaultSampleDurationPresent) {
            defaultSampleDuration = readUint32(tfhd, tfhdOffset);
            tfhdOffset += 4;
          }
          if (defaultSampleSizePresent) {
            defaultSampleSize = readUint32(tfhd, tfhdOffset);
            tfhdOffset += 4;
          }
          if (defaultSampleFlagsPresent) {
            tfhdOffset += 4;
          }
          if (track.type === 'video') {
            isHEVCFlavor = isHEVC(track.codec);
          }

          findBox(traf, ['trun']).map((trun) => {
            const version = trun[0];
            const flags = readUint32(trun, 0) & 0xffffff;
            const dataOffsetPresent = (flags & 0x000001) !== 0;
            let dataOffset = 0;
            const firstSampleFlagsPresent = (flags & 0x000004) !== 0;
            const sampleDurationPresent = (flags & 0x000100) !== 0;
            let sampleDuration = 0;
            const sampleSizePresent = (flags & 0x000200) !== 0;
            let sampleSize = 0;
            const sampleFlagsPresent = (flags & 0x000400) !== 0;
            const sampleCompositionOffsetsPresent = (flags & 0x000800) !== 0;
            let compositionOffset = 0;
            const sampleCount = readUint32(trun, 4);
            let trunOffset = 8; // past version, flags, and sample count

            if (dataOffsetPresent) {
              dataOffset = readUint32(trun, trunOffset);
              trunOffset += 4;
            }
            if (firstSampleFlagsPresent) {
              trunOffset += 4;
            }

            let sampleOffset = dataOffset + moofOffset;

            for (let ix = 0; ix < sampleCount; ix++) {
              if (sampleDurationPresent) {
                sampleDuration = readUint32(trun, trunOffset);
                trunOffset += 4;
              } else {
                sampleDuration = defaultSampleDuration;
              }
              if (sampleSizePresent) {
                sampleSize = readUint32(trun, trunOffset);
                trunOffset += 4;
              } else {
                sampleSize = defaultSampleSize;
              }
              if (sampleFlagsPresent) {
                trunOffset += 4;
              }
              if (sampleCompositionOffsetsPresent) {
                if (version === 0) {
                  compositionOffset = readUint32(trun, trunOffset);
                } else {
                  compositionOffset = readSint32(trun, trunOffset);
                }
                trunOffset += 4;
              }
              if (track.type === ElementaryStreamTypes.VIDEO) {
                let naluTotalSize = 0;
                while (naluTotalSize < sampleSize) {
                  const naluSize = readUint32(videoData, sampleOffset);
                  sampleOffset += 4;
                  if (isSEIMessage(isHEVCFlavor, videoData[sampleOffset])) {
                    const data = videoData.subarray(
                      sampleOffset,
                      sampleOffset + naluSize,
                    );
                    parseSEIMessageFromNALu(
                      data,
                      isHEVCFlavor ? 2 : 1,
                      timeOffset + compositionOffset / timescale,
                      seiSamples,
                    );
                  }
                  sampleOffset += naluSize;
                  naluTotalSize += naluSize + 4;
                }
              }

              timeOffset += sampleDuration / timescale;
            }
          });
        }
      });
    });
  });
  return seiSamples;
}

export function isHEVC(codec: string | undefined) {
  if (!codec) {
    return false;
  }
  const baseCodec = codec.substring(0, 4);
  return (
    baseCodec === 'hvc1' ||
    baseCodec === 'hev1' ||
    // Dolby Vision
    baseCodec === 'dvh1' ||
    baseCodec === 'dvhe'
  );
}

function isSEIMessage(isHEVCFlavor: boolean, naluHeader: number) {
  if (isHEVCFlavor) {
    const naluType = (naluHeader >> 1) & 0x3f;
    return naluType === 39 || naluType === 40;
  } else {
    const naluType = naluHeader & 0x1f;
    return naluType === 6;
  }
}

export function parseSEIMessageFromNALu(
  unescapedData: Uint8Array,
  headerSize: number,
  pts: number,
  samples: UserdataSample[],
) {
  const data = discardEPB(unescapedData);
  let seiPtr = 0;
  // skip nal header
  seiPtr += headerSize;
  let payloadType = 0;
  let payloadSize = 0;
  let b = 0;

  while (seiPtr < data.length) {
    payloadType = 0;
    do {
      if (seiPtr >= data.length) {
        break;
      }
      b = data[seiPtr++];
      payloadType += b;
    } while (b === 0xff);

    // Parse payload size.
    payloadSize = 0;
    do {
      if (seiPtr >= data.length) {
        break;
      }
      b = data[seiPtr++];
      payloadSize += b;
    } while (b === 0xff);

    const leftOver = data.length - seiPtr;
    // Create a variable to process the payload
    let payPtr = seiPtr;

    // Increment the seiPtr to the end of the payload
    if (payloadSize < leftOver) {
      seiPtr += payloadSize;
    } else if (payloadSize > leftOver) {
      // Some type of corruption has happened?
      logger.error(
        `Malformed SEI payload. ${payloadSize} is too small, only ${leftOver} bytes left to parse.`,
      );
      // We might be able to parse some data, but let's be safe and ignore it.
      break;
    }

    if (payloadType === 4) {
      const countryCode = data[payPtr++];
      if (countryCode === 181) {
        const providerCode = readUint16(data, payPtr);
        payPtr += 2;

        if (providerCode === 49) {
          const userStructure = readUint32(data, payPtr);
          payPtr += 4;

          if (userStructure === 0x47413934) {
            const userDataType = data[payPtr++];

            // Raw CEA-608 bytes wrapped in CEA-708 packet
            if (userDataType === 3) {
              const firstByte = data[payPtr++];
              const totalCCs = 0x1f & firstByte;
              const enabled = 0x40 & firstByte;
              const totalBytes = enabled ? 2 + totalCCs * 3 : 0;
              const byteArray = new Uint8Array(totalBytes);
              if (enabled) {
                byteArray[0] = firstByte;
                for (let i = 1; i < totalBytes; i++) {
                  byteArray[i] = data[payPtr++];
                }
              }

              samples.push({
                type: userDataType,
                payloadType,
                pts,
                bytes: byteArray,
              });
            }
          }
        }
      }
    } else if (payloadType === 5) {
      if (payloadSize > 16) {
        const uuidStrArray: Array<string> = [];
        for (let i = 0; i < 16; i++) {
          const b = data[payPtr++].toString(16);
          uuidStrArray.push(b.length == 1 ? '0' + b : b);

          if (i === 3 || i === 5 || i === 7 || i === 9) {
            uuidStrArray.push('-');
          }
        }
        const length = payloadSize - 16;
        const userDataBytes = new Uint8Array(length);
        for (let i = 0; i < length; i++) {
          userDataBytes[i] = data[payPtr++];
        }

        samples.push({
          payloadType,
          pts,
          uuid: uuidStrArray.join(''),
          userData: utf8ArrayToStr(userDataBytes),
          userDataBytes,
        });
      }
    }
  }
}

/**
 * remove Emulation Prevention bytes from a RBSP
 */
export function discardEPB(data: Uint8Array): Uint8Array {
  const length = data.byteLength;
  const EPBPositions = [] as Array<number>;
  let i = 1;

  // Find all `Emulation Prevention Bytes`
  while (i < length - 2) {
    if (data[i] === 0 && data[i + 1] === 0 && data[i + 2] === 0x03) {
      EPBPositions.push(i + 2);
      i += 2;
    } else {
      i++;
    }
  }

  // If no Emulation Prevention Bytes were found just return the original
  // array
  if (EPBPositions.length === 0) {
    return data;
  }

  // Create a new array to hold the NAL unit data
  const newLength = length - EPBPositions.length;
  const newData = new Uint8Array(newLength);
  let sourceIndex = 0;

  for (i = 0; i < newLength; sourceIndex++, i++) {
    if (sourceIndex === EPBPositions[0]) {
      // Skip this byte
      sourceIndex++;
      // Remove this position index
      EPBPositions.shift();
    }
    newData[i] = data[sourceIndex];
  }
  return newData;
}

export function parseEmsg(data: Uint8Array): IEmsgParsingData {
  const version = data[0];
  let schemeIdUri: string = '';
  let value: string = '';
  let timeScale: number = 0;
  let presentationTimeDelta: number = 0;
  let presentationTime: number = 0;
  let eventDuration: number = 0;
  let id: number = 0;
  let offset: number = 0;

  if (version === 0) {
    while (bin2str(data.subarray(offset, offset + 1)) !== '\0') {
      schemeIdUri += bin2str(data.subarray(offset, offset + 1));
      offset += 1;
    }

    schemeIdUri += bin2str(data.subarray(offset, offset + 1));
    offset += 1;

    while (bin2str(data.subarray(offset, offset + 1)) !== '\0') {
      value += bin2str(data.subarray(offset, offset + 1));
      offset += 1;
    }

    value += bin2str(data.subarray(offset, offset + 1));
    offset += 1;

    timeScale = readUint32(data, 12);
    presentationTimeDelta = readUint32(data, 16);
    eventDuration = readUint32(data, 20);
    id = readUint32(data, 24);
    offset = 28;
  } else if (version === 1) {
    offset += 4;
    timeScale = readUint32(data, offset);
    offset += 4;
    const leftPresentationTime = readUint32(data, offset);
    offset += 4;
    const rightPresentationTime = readUint32(data, offset);
    offset += 4;
    presentationTime = 2 ** 32 * leftPresentationTime + rightPresentationTime;
    if (!Number.isSafeInteger(presentationTime)) {
      presentationTime = Number.MAX_SAFE_INTEGER;
      logger.warn(
        'Presentation time exceeds safe integer limit and wrapped to max safe integer in parsing emsg box',
      );
    }

    eventDuration = readUint32(data, offset);
    offset += 4;
    id = readUint32(data, offset);
    offset += 4;

    while (bin2str(data.subarray(offset, offset + 1)) !== '\0') {
      schemeIdUri += bin2str(data.subarray(offset, offset + 1));
      offset += 1;
    }

    schemeIdUri += bin2str(data.subarray(offset, offset + 1));
    offset += 1;

    while (bin2str(data.subarray(offset, offset + 1)) !== '\0') {
      value += bin2str(data.subarray(offset, offset + 1));
      offset += 1;
    }

    value += bin2str(data.subarray(offset, offset + 1));
    offset += 1;
  }
  const payload = data.subarray(offset, data.byteLength);

  return {
    schemeIdUri,
    value,
    timeScale,
    presentationTime,
    presentationTimeDelta,
    eventDuration,
    id,
    payload,
  };
}

export function mp4Box(type: ArrayLike<number>, ...payload: Uint8Array[]) {
  const len = payload.length;
  let size = 8;
  let i = len;
  while (i--) {
    size += payload[i].byteLength;
  }
  const result = new Uint8Array(size);
  result[0] = (size >> 24) & 0xff;
  result[1] = (size >> 16) & 0xff;
  result[2] = (size >> 8) & 0xff;
  result[3] = size & 0xff;
  result.set(type, 4);
  for (i = 0, size = 8; i < len; i++) {
    result.set(payload[i], size);
    size += payload[i].byteLength;
  }
  return result;
}

export function mp4pssh(
  systemId: Uint8Array,
  keyids: Array<Uint8Array> | null,
  data: Uint8Array,
) {
  if (systemId.byteLength !== 16) {
    throw new RangeError('Invalid system id');
  }
  let version;
  let kids;
  if (keyids) {
    version = 1;
    kids = new Uint8Array(keyids.length * 16);
    for (let ix = 0; ix < keyids.length; ix++) {
      const k = keyids[ix]; // uint8array
      if (k.byteLength !== 16) {
        throw new RangeError('Invalid key');
      }
      kids.set(k, ix * 16);
    }
  } else {
    version = 0;
    kids = new Uint8Array();
  }
  let kidCount;
  if (version > 0) {
    kidCount = new Uint8Array(4);
    if (keyids!.length > 0) {
      new DataView(kidCount.buffer).setUint32(0, keyids!.length, false);
    }
  } else {
    kidCount = new Uint8Array();
  }
  const dataSize = new Uint8Array(4);
  if (data.byteLength > 0) {
    new DataView(dataSize.buffer).setUint32(0, data.byteLength, false);
  }
  return mp4Box(
    [112, 115, 115, 104],
    new Uint8Array([
      version,
      0x00,
      0x00,
      0x00, // Flags
    ]),
    systemId, // 16 bytes
    kidCount,
    kids,
    dataSize,
    data,
  );
}

export type PsshData = {
  version: 0 | 1;
  systemId: KeySystemIds;
  kids: null | Uint8Array<ArrayBuffer>[];
  data: null | Uint8Array<ArrayBuffer>;
  offset: number;
  size: number;
};

export type PsshInvalidResult = {
  systemId?: undefined;
  kids?: undefined;
  offset: number;
  size: number;
};

export function parseMultiPssh(
  initData: ArrayBuffer,
): (PsshData | PsshInvalidResult)[] {
  const results: (PsshData | PsshInvalidResult)[] = [];
  if (initData instanceof ArrayBuffer) {
    const length = initData.byteLength;
    let offset = 0;
    while (offset + 32 < length) {
      const view = new DataView(initData, offset);
      const pssh = parsePssh(view);
      results.push(pssh);
      offset += pssh.size;
    }
  }
  return results;
}

function parsePssh(view: DataView<ArrayBuffer>): PsshData | PsshInvalidResult {
  const size = view.getUint32(0);
  const offset = view.byteOffset;
  const length = view.byteLength;
  if (length < size) {
    return {
      offset,
      size: length,
    };
  }
  const type = view.getUint32(4);
  if (type !== 0x70737368) {
    return { offset, size };
  }
  const version = view.getUint32(8) >>> 24;
  if (version !== 0 && version !== 1) {
    return { offset, size };
  }
  const buffer = view.buffer;
  const systemId = arrayToHex(
    new Uint8Array(buffer, offset + 12, 16),
  ) as KeySystemIds;

  let kids: null | Uint8Array<ArrayBuffer>[] = null;
  let data: null | Uint8Array<ArrayBuffer> = null;
  let dataSizeOffset = 0;

  if (version === 0) {
    dataSizeOffset = 28;
  } else {
    const kidCounts = view.getUint32(28);
    if (!kidCounts || length < 32 + kidCounts * 16) {
      return { offset, size };
    }
    kids = [];
    for (let i = 0; i < kidCounts; i++) {
      kids.push(new Uint8Array(buffer, offset + 32 + i * 16, 16));
    }
    dataSizeOffset = 32 + kidCounts * 16;
  }

  if (!dataSizeOffset) {
    return { offset, size };
  }

  const dataSizeOrKidCount = view.getUint32(dataSizeOffset);
  if (size - 32 < dataSizeOrKidCount) {
    return { offset, size };
  }
  data = new Uint8Array(
    buffer,
    offset + dataSizeOffset + 4,
    dataSizeOrKidCount,
  );
  return {
    version,
    systemId,
    kids,
    data,
    offset,
    size,
  };
}