263 lines
9.0 KiB
C++
263 lines
9.0 KiB
C++
// Copyright 2014 Google Inc. All rights reserved.
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//
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file or at
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// https://developers.google.com/open-source/licenses/bsd
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#include "media/mp4/fragmenter.h"
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#include "media/base/aes_encryptor.h"
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#include "media/base/buffer_reader.h"
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#include "media/base/buffer_writer.h"
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#include "media/base/media_sample.h"
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#include "media/mp4/box_definitions.h"
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#include "media/mp4/cenc.h"
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namespace {
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const int64 kInvalidTime = kint64max;
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// Optimize sample entries table. If all values in |entries| are identical,
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// then |entries| is cleared and the value is assigned to |default_value|;
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// otherwise it is a NOP. Return true if the table is optimized.
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template <typename T>
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bool OptimizeSampleEntries(std::vector<T>* entries, T* default_value) {
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DCHECK(entries);
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DCHECK(default_value);
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DCHECK(!entries->empty());
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typename std::vector<T>::const_iterator it = entries->begin();
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T value = *it;
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for (; it < entries->end(); ++it)
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if (value != *it)
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return false;
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// Clear |entries| if it contains only one value.
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entries->clear();
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*default_value = value;
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return true;
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}
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} // namespace
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namespace media {
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namespace mp4 {
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Fragmenter::Fragmenter(TrackFragment* traf,
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scoped_ptr<AesCtrEncryptor> encryptor,
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int64 clear_time,
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uint8 nalu_length_size,
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bool normalize_presentation_timestamp)
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: encryptor_(encryptor.Pass()),
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nalu_length_size_(nalu_length_size),
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traf_(traf),
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fragment_finalized_(false),
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fragment_duration_(0),
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normalize_presentation_timestamp_(normalize_presentation_timestamp),
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presentation_start_time_(kInvalidTime),
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earliest_presentation_time_(kInvalidTime),
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first_sap_time_(kInvalidTime),
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clear_time_(clear_time) {}
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Fragmenter::~Fragmenter() {}
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Status Fragmenter::AddSample(scoped_refptr<MediaSample> sample) {
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CHECK_GT(sample->duration(), 0);
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if (ShouldEncryptFragment()) {
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Status status = EncryptSample(sample);
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if (!status.ok())
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return status;
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}
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// Fill in sample parameters. It will be optimized later.
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traf_->runs[0].sample_sizes.push_back(sample->data_size());
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traf_->runs[0].sample_durations.push_back(sample->duration());
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traf_->runs[0].sample_flags.push_back(
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sample->is_key_frame() ? 0 : TrackFragmentHeader::kNonKeySampleMask);
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traf_->runs[0]
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.sample_composition_time_offsets.push_back(sample->pts() - sample->dts());
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if (sample->pts() != sample->dts()) {
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traf_->runs[0].flags |=
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TrackFragmentRun::kSampleCompTimeOffsetsPresentMask;
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}
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data_->AppendArray(sample->data(), sample->data_size());
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fragment_duration_ += sample->duration();
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int64 pts = sample->pts();
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if (normalize_presentation_timestamp_) {
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// Normalize PTS to start from 0. Some players do not like non-zero
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// presentation starting time.
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// NOTE: The timeline of the remuxed video may not be exactly the same as
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// the original video. An EditList box may be useful to solve this.
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if (presentation_start_time_ == kInvalidTime) {
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presentation_start_time_ = pts;
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pts = 0;
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} else {
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// Can we safely assume the first sample in the media has the earliest
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// presentation timestamp?
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DCHECK_GT(pts, presentation_start_time_);
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pts -= presentation_start_time_;
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}
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}
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// Set |earliest_presentation_time_| to |pts| if |pts| is smaller or if it is
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// not yet initialized (kInvalidTime > pts is always true).
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if (earliest_presentation_time_ > pts)
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earliest_presentation_time_ = pts;
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if (sample->is_key_frame()) {
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if (first_sap_time_ == kInvalidTime)
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first_sap_time_ = pts;
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}
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return Status::OK;
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}
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void Fragmenter::InitializeFragment() {
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fragment_finalized_ = false;
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traf_->decode_time.decode_time += fragment_duration_;
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traf_->auxiliary_size.sample_info_sizes.clear();
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traf_->auxiliary_offset.offsets.clear();
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traf_->runs.clear();
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traf_->runs.resize(1);
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traf_->runs[0].flags = TrackFragmentRun::kDataOffsetPresentMask;
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traf_->header.flags = TrackFragmentHeader::kDefaultBaseIsMoofMask;
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fragment_duration_ = 0;
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earliest_presentation_time_ = kInvalidTime;
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first_sap_time_ = kInvalidTime;
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data_.reset(new BufferWriter());
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aux_data_.reset(new BufferWriter());
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if (ShouldEncryptFragment()) {
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if (!IsSubsampleEncryptionRequired()) {
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DCHECK(encryptor_);
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traf_->auxiliary_size.default_sample_info_size = encryptor_->iv().size();
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}
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}
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}
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void Fragmenter::FinalizeFragment() {
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if (ShouldEncryptFragment()) {
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DCHECK(encryptor_);
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// The offset will be adjusted in Segmenter when we know moof size.
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traf_->auxiliary_offset.offsets.push_back(0);
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// Optimize saiz box.
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SampleAuxiliaryInformationSize& saiz = traf_->auxiliary_size;
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saiz.sample_count = traf_->runs[0].sample_sizes.size();
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if (!saiz.sample_info_sizes.empty()) {
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if (!OptimizeSampleEntries(&saiz.sample_info_sizes,
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&saiz.default_sample_info_size)) {
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saiz.default_sample_info_size = 0;
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}
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}
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} else if (encryptor_ && clear_time_ > 0) {
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// This fragment should be in clear.
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// We generate at most two sample description entries, encrypted entry and
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// clear entry. The 1-based clear entry index is always 2.
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const uint32 kClearSampleDescriptionIndex = 2;
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traf_->header.flags |=
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TrackFragmentHeader::kSampleDescriptionIndexPresentMask;
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traf_->header.sample_description_index = kClearSampleDescriptionIndex;
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clear_time_ -= fragment_duration_;
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}
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// Optimize trun box.
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traf_->runs[0].sample_count = traf_->runs[0].sample_sizes.size();
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if (OptimizeSampleEntries(&traf_->runs[0].sample_durations,
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&traf_->header.default_sample_duration)) {
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traf_->header.flags |=
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TrackFragmentHeader::kDefaultSampleDurationPresentMask;
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} else {
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traf_->runs[0].flags |= TrackFragmentRun::kSampleDurationPresentMask;
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}
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if (OptimizeSampleEntries(&traf_->runs[0].sample_sizes,
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&traf_->header.default_sample_size)) {
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traf_->header.flags |= TrackFragmentHeader::kDefaultSampleSizePresentMask;
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} else {
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traf_->runs[0].flags |= TrackFragmentRun::kSampleSizePresentMask;
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}
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if (OptimizeSampleEntries(&traf_->runs[0].sample_flags,
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&traf_->header.default_sample_flags)) {
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traf_->header.flags |= TrackFragmentHeader::kDefaultSampleFlagsPresentMask;
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} else {
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traf_->runs[0].flags |= TrackFragmentRun::kSampleFlagsPresentMask;
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}
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fragment_finalized_ = true;
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}
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void Fragmenter::GenerateSegmentReference(SegmentReference* reference) {
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// NOTE: Daisy chain is not supported currently.
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reference->reference_type = false;
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reference->subsegment_duration = fragment_duration_;
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reference->starts_with_sap = StartsWithSAP();
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if (kInvalidTime == first_sap_time_) {
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reference->sap_type = SegmentReference::TypeUnknown;
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reference->sap_delta_time = 0;
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} else {
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reference->sap_type = SegmentReference::Type1;
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reference->sap_delta_time = first_sap_time_ - earliest_presentation_time_;
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}
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reference->earliest_presentation_time = earliest_presentation_time_;
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}
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void Fragmenter::EncryptBytes(uint8* data, uint32 size) {
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DCHECK(encryptor_);
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CHECK(encryptor_->Encrypt(data, size, data));
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}
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Status Fragmenter::EncryptSample(scoped_refptr<MediaSample> sample) {
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DCHECK(encryptor_);
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FrameCENCInfo cenc_info(encryptor_->iv());
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uint8* data = sample->writable_data();
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if (!IsSubsampleEncryptionRequired()) {
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EncryptBytes(data, sample->data_size());
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} else {
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BufferReader reader(data, sample->data_size());
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while (reader.HasBytes(1)) {
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uint64 nalu_length;
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if (!reader.ReadNBytesInto8(&nalu_length, nalu_length_size_))
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return Status(error::MUXER_FAILURE, "Fail to read nalu_length.");
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SubsampleEntry subsample;
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subsample.clear_bytes = nalu_length_size_ + 1;
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subsample.cypher_bytes = nalu_length - 1;
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if (!reader.SkipBytes(nalu_length)) {
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return Status(error::MUXER_FAILURE,
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"Sample size does not match nalu_length.");
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}
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EncryptBytes(data + subsample.clear_bytes, subsample.cypher_bytes);
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cenc_info.AddSubsample(subsample);
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data += nalu_length_size_ + nalu_length;
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}
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// The length of per-sample auxiliary datum, defined in CENC ch. 7.
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traf_->auxiliary_size.sample_info_sizes.push_back(cenc_info.ComputeSize());
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}
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cenc_info.Write(aux_data_.get());
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encryptor_->UpdateIv();
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return Status::OK;
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}
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bool Fragmenter::StartsWithSAP() {
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DCHECK(!traf_->runs.empty());
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uint32 start_sample_flag;
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if (traf_->runs[0].flags & TrackFragmentRun::kSampleFlagsPresentMask) {
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DCHECK(!traf_->runs[0].sample_flags.empty());
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start_sample_flag = traf_->runs[0].sample_flags[0];
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} else {
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DCHECK(traf_->header.flags &
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TrackFragmentHeader::kDefaultSampleFlagsPresentMask);
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start_sample_flag = traf_->header.default_sample_flags;
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}
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return (start_sample_flag & TrackFragmentHeader::kNonKeySampleMask) == 0;
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}
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} // namespace mp4
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} // namespace media
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