media/mp4/Index.cpp

/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "Index.h"

#include <algorithm>
#include <limits>

#include "BufferReader.h"
#include "mozilla/RefPtr.h"
#include "MP4Interval.h"
#include "MP4Metadata.h"
#include "SinfParser.h"

using namespace mozilla::media;

namespace mozilla {

class MOZ_STACK_CLASS RangeFinder {
 public:
  // Given that we're processing this in order we don't use a binary search
  // to find the apropriate time range. Instead we search linearly from the
  // last used point.
  explicit RangeFinder(const MediaByteRangeSet& ranges)
      : mRanges(ranges), mIndex(0) {
    // Ranges must be normalised for this to work
  }

  bool Contains(MediaByteRange aByteRange);

 private:
  const MediaByteRangeSet& mRanges;
  size_t mIndex;
};

bool RangeFinder::Contains(MediaByteRange aByteRange) {
  if (mRanges.IsEmpty()) {
    return false;
  }

  if (mRanges[mIndex].ContainsStrict(aByteRange)) {
    return true;
  }

  if (aByteRange.mStart < mRanges[mIndex].mStart) {
    // Search backwards
    do {
      if (!mIndex) {
        return false;
      }
      --mIndex;
      if (mRanges[mIndex].ContainsStrict(aByteRange)) {
        return true;
      }
    } while (aByteRange.mStart < mRanges[mIndex].mStart);

    return false;
  }

  while (aByteRange.mEnd > mRanges[mIndex].mEnd) {
    if (mIndex == mRanges.Length() - 1) {
      return false;
    }
    ++mIndex;
    if (mRanges[mIndex].ContainsStrict(aByteRange)) {
      return true;
    }
  }

  return false;
}

SampleIterator::SampleIterator(Index* aIndex)
    : mIndex(aIndex), mCurrentMoof(0), mCurrentSample(0) {
  mIndex->RegisterIterator(this);
}

SampleIterator::~SampleIterator() { mIndex->UnregisterIterator(this); }

already_AddRefed<MediaRawData> SampleIterator::GetNext() {
  Sample* s(Get());
  if (!s) {
    return nullptr;
  }

  int64_t length = std::numeric_limits<int64_t>::max();
  mIndex->mSource->Length(&length);
  if (s->mByteRange.mEnd > length) {
    // We don't have this complete sample.
    return nullptr;
  }

  RefPtr<MediaRawData> sample = new MediaRawData();
  sample->mTimecode = TimeUnit::FromMicroseconds(s->mDecodeTime);
  sample->mTime = TimeUnit::FromMicroseconds(s->mCompositionRange.start);
  sample->mDuration = TimeUnit::FromMicroseconds(s->mCompositionRange.Length());
  sample->mOffset = s->mByteRange.mStart;
  sample->mKeyframe = s->mSync;

  UniquePtr<MediaRawDataWriter> writer(sample->CreateWriter());
  // Do the blocking read
  if (!writer->SetSize(s->mByteRange.Length())) {
    return nullptr;
  }

  size_t bytesRead;
  if (!mIndex->mSource->ReadAt(sample->mOffset, writer->Data(), sample->Size(),
                               &bytesRead) ||
      bytesRead != sample->Size()) {
    return nullptr;
  }

  MoofParser* moofParser = mIndex->mMoofParser.get();
  if (!moofParser) {
    // File is not fragmented, we can't have crypto, just early return.
    Next();
    return sample.forget();
  }

  // We need to check if this moof has init data the CDM expects us to surface.
  // This should happen when handling the first sample, even if that sample
  // isn't encrypted (samples later in the moof may be).
  if (mCurrentSample == 0) {
    const nsTArray<Moof>& moofs = moofParser->Moofs();
    const Moof* currentMoof = &moofs[mCurrentMoof];
    if (!currentMoof->mPsshes.IsEmpty()) {
      // This Moof contained crypto init data. Report that. We only report
      // the init data on the Moof's first sample, to avoid reporting it more
      // than once per Moof.
      writer->mCrypto.mInitDatas.AppendElements(currentMoof->mPsshes);
      writer->mCrypto.mInitDataType = u"cenc"_ns;
    }
  }

  auto cryptoSchemeResult = GetEncryptionScheme();
  if (cryptoSchemeResult.isErr()) {
    // Log the error here in future.
    return nullptr;
  }
  CryptoScheme cryptoScheme = cryptoSchemeResult.unwrap();
  if (cryptoScheme == CryptoScheme::None) {
    // No crypto to handle, early return.
    Next();
    return sample.forget();
  }

  writer->mCrypto.mCryptoScheme = cryptoScheme;
  MOZ_ASSERT(writer->mCrypto.mCryptoScheme != CryptoScheme::None,
             "Should have early returned if we don't have a crypto scheme!");
  MOZ_ASSERT(writer->mCrypto.mKeyId.IsEmpty(),
             "Sample should not already have a key ID");
  MOZ_ASSERT(writer->mCrypto.mConstantIV.IsEmpty(),
             "Sample should not already have a constant IV");
  CencSampleEncryptionInfoEntry* sampleInfo = GetSampleEncryptionEntry();
  if (sampleInfo) {
    // Use sample group information if present, this supersedes track level
    // information.
    writer->mCrypto.mKeyId.AppendElements(sampleInfo->mKeyId);
    writer->mCrypto.mIVSize = sampleInfo->mIVSize;
    writer->mCrypto.mCryptByteBlock = sampleInfo->mCryptByteBlock;
    writer->mCrypto.mSkipByteBlock = sampleInfo->mSkipByteBlock;
    writer->mCrypto.mConstantIV.AppendElements(sampleInfo->mConsantIV);
  } else {
    // Use the crypto info from track metadata
    writer->mCrypto.mKeyId.AppendElements(moofParser->mSinf.mDefaultKeyID, 16);
    writer->mCrypto.mIVSize = moofParser->mSinf.mDefaultIVSize;
    writer->mCrypto.mCryptByteBlock = moofParser->mSinf.mDefaultCryptByteBlock;
    writer->mCrypto.mSkipByteBlock = moofParser->mSinf.mDefaultSkipByteBlock;
    writer->mCrypto.mConstantIV.AppendElements(
        moofParser->mSinf.mDefaultConstantIV);
  }

  if ((writer->mCrypto.mIVSize == 0 && writer->mCrypto.mConstantIV.IsEmpty()) ||
      (writer->mCrypto.mIVSize != 0 && s->mCencRange.IsEmpty())) {
    // If mIVSize == 0, this indicates that a constant IV is in use, thus we
    // should have a non empty constant IV. Alternatively if IV size is non
    // zero, we should have an IV for this sample, which we need to look up
    // in mCencRange (which must then be non empty). If neither of these are
    // true we have bad crypto data, so bail.
    return nullptr;
  }
  // Parse auxiliary information if present
  if (!s->mCencRange.IsEmpty()) {
    // The size comes from an 8 bit field
    AutoTArray<uint8_t, 256> cencAuxInfo;
    cencAuxInfo.SetLength(s->mCencRange.Length());
    if (!mIndex->mSource->ReadAt(s->mCencRange.mStart, cencAuxInfo.Elements(),
                                 cencAuxInfo.Length(), &bytesRead) ||
        bytesRead != cencAuxInfo.Length()) {
      return nullptr;
    }
    BufferReader reader(cencAuxInfo);
    if (!reader.ReadArray(writer->mCrypto.mIV, writer->mCrypto.mIVSize)) {
      return nullptr;
    }

    // Parse the auxiliary information for subsample information
    auto res = reader.ReadU16();
    if (res.isOk() && res.unwrap() > 0) {
      uint16_t count = res.unwrap();

      if (reader.Remaining() < count * 6) {
        return nullptr;
      }

      for (size_t i = 0; i < count; i++) {
        auto res_16 = reader.ReadU16();
        auto res_32 = reader.ReadU32();
        if (res_16.isErr() || res_32.isErr()) {
          return nullptr;
        }
        writer->mCrypto.mPlainSizes.AppendElement(res_16.unwrap());
        writer->mCrypto.mEncryptedSizes.AppendElement(res_32.unwrap());
      }
    } else {
      // No subsample information means the entire sample is encrypted.
      writer->mCrypto.mPlainSizes.AppendElement(0);
      writer->mCrypto.mEncryptedSizes.AppendElement(sample->Size());
    }
  }

  Next();

  return sample.forget();
}

SampleDescriptionEntry* SampleIterator::GetSampleDescriptionEntry() {
  nsTArray<Moof>& moofs = mIndex->mMoofParser->Moofs();
  Moof& currentMoof = moofs[mCurrentMoof];
  uint32_t sampleDescriptionIndex =
      currentMoof.mTfhd.mDefaultSampleDescriptionIndex;
  // Mp4 indices start at 1, shift down 1 so we index our array correctly.
  sampleDescriptionIndex--;
  FallibleTArray<SampleDescriptionEntry>& sampleDescriptions =
      mIndex->mMoofParser->mSampleDescriptions;
  if (sampleDescriptionIndex >= sampleDescriptions.Length()) {
    // The sample description index is invalid, the mp4 is malformed. Bail out.
    return nullptr;
  }
  return &sampleDescriptions[sampleDescriptionIndex];
}

CencSampleEncryptionInfoEntry* SampleIterator::GetSampleEncryptionEntry() {
  nsTArray<Moof>& moofs = mIndex->mMoofParser->Moofs();
  Moof* currentMoof = &moofs[mCurrentMoof];
  SampleToGroupEntry* sampleToGroupEntry = nullptr;

  // Default to using the sample to group entries for the fragment, otherwise
  // fall back to the sample to group entries for the track.
  FallibleTArray<SampleToGroupEntry>* sampleToGroupEntries =
      currentMoof->mFragmentSampleToGroupEntries.Length() != 0
          ? &currentMoof->mFragmentSampleToGroupEntries
          : &mIndex->mMoofParser->mTrackSampleToGroupEntries;

  uint32_t seen = 0;

  for (SampleToGroupEntry& entry : *sampleToGroupEntries) {
    if (seen + entry.mSampleCount > mCurrentSample) {
      sampleToGroupEntry = &entry;
      break;
    }
    seen += entry.mSampleCount;
  }

  // ISO-14496-12 Section 8.9.2.3 and 8.9.4 : group description index
  // (1) ranges from 1 to the number of sample group entries in the track
  // level SampleGroupDescription Box, or (2) takes the value 0 to
  // indicate that this sample is a member of no group, in this case, the
  // sample is associated with the default values specified in
  // TrackEncryption Box, or (3) starts at 0x10001, i.e. the index value
  // 1, with the value 1 in the top 16 bits, to reference fragment-local
  // SampleGroupDescription Box.

  // According to the spec, ISO-14496-12, the sum of the sample counts in this
  // box should be equal to the total number of samples, and, if less, the
  // reader should behave as if an extra SampleToGroupEntry existed, with
  // groupDescriptionIndex 0.

  if (!sampleToGroupEntry || sampleToGroupEntry->mGroupDescriptionIndex == 0) {
    return nullptr;
  }

  FallibleTArray<CencSampleEncryptionInfoEntry>* entries =
      &mIndex->mMoofParser->mTrackSampleEncryptionInfoEntries;

  uint32_t groupIndex = sampleToGroupEntry->mGroupDescriptionIndex;

  // If the first bit is set to a one, then we should use the sample group
  // descriptions from the fragment.
  if (groupIndex > SampleToGroupEntry::kFragmentGroupDescriptionIndexBase) {
    groupIndex -= SampleToGroupEntry::kFragmentGroupDescriptionIndexBase;
    entries = &currentMoof->mFragmentSampleEncryptionInfoEntries;
  }

  // The group_index is one based.
  return groupIndex > entries->Length() ? nullptr
                                        : &entries->ElementAt(groupIndex - 1);
}

Result<CryptoScheme, nsCString> SampleIterator::GetEncryptionScheme() {
  // See ISO/IEC 23001-7 for information on the metadata being checked.
  MoofParser* moofParser = mIndex->mMoofParser.get();
  if (!moofParser) {
    // This mp4 isn't fragmented so it can't be encrypted.
    return CryptoScheme::None;
  }

  SampleDescriptionEntry* sampleDescriptionEntry = GetSampleDescriptionEntry();
  if (!sampleDescriptionEntry) {
    // For the file to be valid the tfhd must reference a sample description
    // entry.
    // If we encounter this error often, we may consider using the first
    // sample description entry if the index is out of bounds.
    return mozilla::Err(nsLiteralCString(
        "Could not determine encryption scheme due to bad index for sample "
        "description entry."));
  }

  if (!sampleDescriptionEntry->mIsEncryptedEntry) {
    return CryptoScheme::None;
  }

  if (!moofParser->mSinf.IsValid()) {
    // The sample description entry says this sample is encrypted, but we
    // don't have a valid sinf box. This shouldn't happen as the sinf box is
    // part of the sample description entry. Suggests a malformed file, bail.
    return mozilla::Err(nsLiteralCString(
        "Could not determine encryption scheme. Sample description entry "
        "indicates encryption, but could not find associated sinf box."));
  }

  CencSampleEncryptionInfoEntry* sampleInfo = GetSampleEncryptionEntry();
  if (sampleInfo && !sampleInfo->mIsEncrypted) {
    // May not have sample encryption info, but if we do, it should match other
    // metadata.
    return mozilla::Err(nsLiteralCString(
        "Could not determine encryption scheme. Sample description entry "
        "indicates encryption, but sample encryption entry indicates sample is "
        "not encrypted. These should be consistent."));
  }

  if (moofParser->mSinf.mDefaultEncryptionType == AtomType("cenc")) {
    return CryptoScheme::Cenc;
  } else if (moofParser->mSinf.mDefaultEncryptionType == AtomType("cbcs")) {
    return CryptoScheme::Cbcs;
  }
  return mozilla::Err(nsLiteralCString(
      "Could not determine encryption scheme. Sample description entry "
      "reports sample is encrypted, but no scheme, or an unsupported scheme "
      "is in use."));
}

Sample* SampleIterator::Get() {
  if (!mIndex->mMoofParser) {
    MOZ_ASSERT(!mCurrentMoof);
    return mCurrentSample < mIndex->mIndex.Length()
               ? &mIndex->mIndex[mCurrentSample]
               : nullptr;
  }

  nsTArray<Moof>& moofs = mIndex->mMoofParser->Moofs();
  while (true) {
    if (mCurrentMoof == moofs.Length()) {
      if (!mIndex->mMoofParser->BlockingReadNextMoof()) {
        return nullptr;
      }
      MOZ_ASSERT(mCurrentMoof < moofs.Length());
    }
    if (mCurrentSample < moofs[mCurrentMoof].mIndex.Length()) {
      break;
    }
    mCurrentSample = 0;
    ++mCurrentMoof;
  }
  return &moofs[mCurrentMoof].mIndex[mCurrentSample];
}

void SampleIterator::Next() { ++mCurrentSample; }

void SampleIterator::Seek(Microseconds aTime) {
  size_t syncMoof = 0;
  size_t syncSample = 0;
  mCurrentMoof = 0;
  mCurrentSample = 0;
  Sample* sample;
  while (!!(sample = Get())) {
    if (sample->mCompositionRange.start > aTime) {
      break;
    }
    if (sample->mSync) {
      syncMoof = mCurrentMoof;
      syncSample = mCurrentSample;
    }
    if (sample->mCompositionRange.start == aTime) {
      break;
    }
    Next();
  }
  mCurrentMoof = syncMoof;
  mCurrentSample = syncSample;
}

Microseconds SampleIterator::GetNextKeyframeTime() {
  SampleIterator itr(*this);
  Sample* sample;
  while (!!(sample = itr.Get())) {
    if (sample->mSync) {
      return sample->mCompositionRange.start;
    }
    itr.Next();
  }
  return -1;
}

Index::Index(const IndiceWrapper& aIndices, ByteStream* aSource,
             uint32_t aTrackId, bool aIsAudio)
    : mSource(aSource), mIsAudio(aIsAudio) {
  if (!aIndices.Length()) {
    mMoofParser =
        MakeUnique<MoofParser>(aSource, AsVariant(aTrackId), aIsAudio);
  } else {
    if (!mIndex.SetCapacity(aIndices.Length(), fallible)) {
      // OOM.
      return;
    }
    media::IntervalSet<int64_t> intervalTime;
    MediaByteRange intervalRange;
    bool haveSync = false;
    bool progressive = true;
    int64_t lastOffset = 0;
    for (size_t i = 0; i < aIndices.Length(); i++) {
      Indice indice;
      if (!aIndices.GetIndice(i, indice)) {
        // Out of index?
        return;
      }
      if (indice.sync || mIsAudio) {
        haveSync = true;
      }
      if (!haveSync) {
        continue;
      }
      Sample sample;
      sample.mByteRange =
          MediaByteRange(indice.start_offset, indice.end_offset);
      sample.mCompositionRange = MP4Interval<Microseconds>(
          indice.start_composition, indice.end_composition);
      sample.mDecodeTime = indice.start_decode;
      sample.mSync = indice.sync || mIsAudio;
      // FIXME: Make this infallible after bug 968520 is done.
      MOZ_ALWAYS_TRUE(mIndex.AppendElement(sample, fallible));
      if (indice.start_offset < lastOffset) {
        NS_WARNING("Chunks in MP4 out of order, expect slow down");
        progressive = false;
      }
      lastOffset = indice.end_offset;

      // Pack audio samples in group of 128.
      if (sample.mSync && progressive && (!mIsAudio || !(i % 128))) {
        if (mDataOffset.Length()) {
          auto& last = mDataOffset.LastElement();
          last.mEndOffset = intervalRange.mEnd;
          NS_ASSERTION(intervalTime.Length() == 1,
                       "Discontinuous samples between keyframes");
          last.mTime.start = intervalTime.GetStart();
          last.mTime.end = intervalTime.GetEnd();
        }
        if (!mDataOffset.AppendElement(
                MP4DataOffset(mIndex.Length() - 1, indice.start_offset),
                fallible)) {
          // OOM.
          return;
        }
        intervalTime = media::IntervalSet<int64_t>();
        intervalRange = MediaByteRange();
      }
      intervalTime += media::Interval<int64_t>(sample.mCompositionRange.start,
                                               sample.mCompositionRange.end);
      intervalRange = intervalRange.Span(sample.mByteRange);
    }

    if (mDataOffset.Length() && progressive) {
      Indice indice;
      if (!aIndices.GetIndice(aIndices.Length() - 1, indice)) {
        return;
      }
      auto& last = mDataOffset.LastElement();
      last.mEndOffset = indice.end_offset;
      last.mTime =
          MP4Interval<int64_t>(intervalTime.GetStart(), intervalTime.GetEnd());
    } else {
      mDataOffset.Clear();
    }
  }
}

Index::~Index() = default;

void Index::UpdateMoofIndex(const MediaByteRangeSet& aByteRanges) {
  UpdateMoofIndex(aByteRanges, false);
}

void Index::UpdateMoofIndex(const MediaByteRangeSet& aByteRanges,
                            bool aCanEvict) {
  if (!mMoofParser) {
    return;
  }
  size_t moofs = mMoofParser->Moofs().Length();
  bool canEvict = aCanEvict && moofs > 1;
  if (canEvict) {
    // Check that we can trim the mMoofParser. We can only do so if all
    // iterators have demuxed all possible samples.
    for (const SampleIterator* iterator : mIterators) {
      if ((iterator->mCurrentSample == 0 && iterator->mCurrentMoof == moofs) ||
          iterator->mCurrentMoof == moofs - 1) {
        continue;
      }
      canEvict = false;
      break;
    }
  }
  mMoofParser->RebuildFragmentedIndex(aByteRanges, &canEvict);
  if (canEvict) {
    // The moofparser got trimmed. Adjust all registered iterators.
    for (SampleIterator* iterator : mIterators) {
      iterator->mCurrentMoof -= moofs - 1;
    }
  }
}

Microseconds Index::GetEndCompositionIfBuffered(
    const MediaByteRangeSet& aByteRanges) {
  FallibleTArray<Sample>* index;
  if (mMoofParser) {
    if (!mMoofParser->ReachedEnd() || mMoofParser->Moofs().IsEmpty()) {
      return 0;
    }
    index = &mMoofParser->Moofs().LastElement().mIndex;
  } else {
    index = &mIndex;
  }

  Microseconds lastComposition = 0;
  RangeFinder rangeFinder(aByteRanges);
  for (size_t i = index->Length(); i--;) {
    const Sample& sample = (*index)[i];
    if (!rangeFinder.Contains(sample.mByteRange)) {
      return 0;
    }
    lastComposition = std::max(lastComposition, sample.mCompositionRange.end);
    if (sample.mSync) {
      return lastComposition;
    }
  }
  return 0;
}

TimeIntervals Index::ConvertByteRangesToTimeRanges(
    const MediaByteRangeSet& aByteRanges) {
  if (aByteRanges == mLastCachedRanges) {
    return mLastBufferedRanges;
  }
  mLastCachedRanges = aByteRanges;

  if (mDataOffset.Length()) {
    TimeIntervals timeRanges;
    for (const auto& range : aByteRanges) {
      uint32_t start = mDataOffset.IndexOfFirstElementGt(range.mStart - 1);
      if (!mIsAudio && start == mDataOffset.Length()) {
        continue;
      }
      uint32_t end = mDataOffset.IndexOfFirstElementGt(
          range.mEnd, MP4DataOffset::EndOffsetComparator());
      if (!mIsAudio && end < start) {
        continue;
      }
      if (mIsAudio && start &&
          range.Intersects(MediaByteRange(mDataOffset[start - 1].mStartOffset,
                                          mDataOffset[start - 1].mEndOffset))) {
        // Check if previous audio data block contains some available samples.
        for (size_t i = mDataOffset[start - 1].mIndex; i < mIndex.Length();
             i++) {
          if (range.ContainsStrict(mIndex[i].mByteRange)) {
            timeRanges += TimeInterval(
                TimeUnit::FromMicroseconds(mIndex[i].mCompositionRange.start),
                TimeUnit::FromMicroseconds(mIndex[i].mCompositionRange.end));
          }
        }
      }
      if (end > start) {
        for (uint32_t i = start; i < end; i++) {
          timeRanges += TimeInterval(
              TimeUnit::FromMicroseconds(mDataOffset[i].mTime.start),
              TimeUnit::FromMicroseconds(mDataOffset[i].mTime.end));
        }
      }
      if (end < mDataOffset.Length()) {
        // Find samples in partial block contained in the byte range.
        for (size_t i = mDataOffset[end].mIndex;
             i < mIndex.Length() && range.ContainsStrict(mIndex[i].mByteRange);
             i++) {
          timeRanges += TimeInterval(
              TimeUnit::FromMicroseconds(mIndex[i].mCompositionRange.start),
              TimeUnit::FromMicroseconds(mIndex[i].mCompositionRange.end));
        }
      }
    }
    mLastBufferedRanges = timeRanges;
    return timeRanges;
  }

  RangeFinder rangeFinder(aByteRanges);
  nsTArray<MP4Interval<Microseconds>> timeRanges;
  nsTArray<FallibleTArray<Sample>*> indexes;
  if (mMoofParser) {
    // We take the index out of the moof parser and move it into a local
    // variable so we don't get concurrency issues. It gets freed when we
    // exit this function.
    for (int i = 0; i < mMoofParser->Moofs().Length(); i++) {
      Moof& moof = mMoofParser->Moofs()[i];

      // We need the entire moof in order to play anything
      if (rangeFinder.Contains(moof.mRange)) {
        if (rangeFinder.Contains(moof.mMdatRange)) {
          MP4Interval<Microseconds>::SemiNormalAppend(timeRanges,
                                                      moof.mTimeRange);
        } else {
          indexes.AppendElement(&moof.mIndex);
        }
      }
    }
  } else {
    indexes.AppendElement(&mIndex);
  }

  bool hasSync = false;
  for (size_t i = 0; i < indexes.Length(); i++) {
    FallibleTArray<Sample>* index = indexes[i];
    for (size_t j = 0; j < index->Length(); j++) {
      const Sample& sample = (*index)[j];
      if (!rangeFinder.Contains(sample.mByteRange)) {
        // We process the index in decode order so we clear hasSync when we hit
        // a range that isn't buffered.
        hasSync = false;
        continue;
      }

      hasSync |= sample.mSync;
      if (!hasSync) {
        continue;
      }

      MP4Interval<Microseconds>::SemiNormalAppend(timeRanges,
                                                  sample.mCompositionRange);
    }
  }

  // This fixes up when the compositon order differs from the byte range order
  nsTArray<MP4Interval<Microseconds>> timeRangesNormalized;
  MP4Interval<Microseconds>::Normalize(timeRanges, &timeRangesNormalized);
  // convert timeRanges.
  media::TimeIntervals ranges;
  for (size_t i = 0; i < timeRangesNormalized.Length(); i++) {
    ranges += media::TimeInterval(
        media::TimeUnit::FromMicroseconds(timeRangesNormalized[i].start),
        media::TimeUnit::FromMicroseconds(timeRangesNormalized[i].end));
  }
  mLastBufferedRanges = ranges;
  return ranges;
}

uint64_t Index::GetEvictionOffset(Microseconds aTime) {
  uint64_t offset = std::numeric_limits<uint64_t>::max();
  if (mMoofParser) {
    // We need to keep the whole moof if we're keeping any of it because the
    // parser doesn't keep parsed moofs.
    for (int i = 0; i < mMoofParser->Moofs().Length(); i++) {
      Moof& moof = mMoofParser->Moofs()[i];

      if (moof.mTimeRange.Length() && moof.mTimeRange.end > aTime) {
        offset = std::min(offset, uint64_t(std::min(moof.mRange.mStart,
                                                    moof.mMdatRange.mStart)));
      }
    }
  } else {
    // We've already parsed and stored the moov so we don't need to keep it.
    // All we need to keep is the sample data itself.
    for (size_t i = 0; i < mIndex.Length(); i++) {
      const Sample& sample = mIndex[i];
      if (aTime >= sample.mCompositionRange.end) {
        offset = std::min(offset, uint64_t(sample.mByteRange.mEnd));
      }
    }
  }
  return offset;
}

void Index::RegisterIterator(SampleIterator* aIterator) {
  mIterators.AppendElement(aIterator);
}

void Index::UnregisterIterator(SampleIterator* aIterator) {
  mIterators.RemoveElement(aIterator);
}

}  // namespace mozilla