101 lines
3.5 KiB
C++
101 lines
3.5 KiB
C++
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// 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/formats/mp4/key_rotation_fragmenter.h"
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#include "media/base/aes_encryptor.h"
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#include "media/formats/mp4/box_definitions.h"
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namespace media {
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namespace mp4 {
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KeyRotationFragmenter::KeyRotationFragmenter(
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MovieFragment* moof,
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TrackFragment* traf,
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bool normalize_presentation_timestamp,
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EncryptionKeySource* encryption_key_source,
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EncryptionKeySource::TrackType track_type,
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int64 crypto_period_duration,
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int64 clear_time,
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uint8 nalu_length_size)
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: Fragmenter(traf,
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normalize_presentation_timestamp,
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scoped_ptr<EncryptionKey>(new EncryptionKey()),
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clear_time,
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nalu_length_size),
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moof_(moof),
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encryption_key_source_(encryption_key_source),
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track_type_(track_type),
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crypto_period_duration_(crypto_period_duration),
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prev_crypto_period_index_(-1) {
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DCHECK(moof);
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DCHECK(encryption_key_source);
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}
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KeyRotationFragmenter::~KeyRotationFragmenter() {}
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Status KeyRotationFragmenter::PrepareFragmentForEncryption() {
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traf()->auxiliary_size.sample_info_sizes.clear();
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traf()->auxiliary_offset.offsets.clear();
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size_t current_crypto_period_index =
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traf()->decode_time.decode_time / crypto_period_duration_;
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if (current_crypto_period_index != prev_crypto_period_index_) {
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scoped_ptr<EncryptionKey> encryption_key(new EncryptionKey());
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Status status = encryption_key_source_->GetCryptoPeriodKey(
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current_crypto_period_index, track_type_, encryption_key.get());
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if (!status.ok())
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return status;
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set_encryption_key(encryption_key.Pass());
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status = CreateEncryptor();
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if (!status.ok())
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return status;
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prev_crypto_period_index_ = current_crypto_period_index;
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}
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EncryptionKey* encryption_key = Fragmenter::encryption_key();
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DCHECK(encryption_key);
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AesCtrEncryptor* encryptor = Fragmenter::encryptor();
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DCHECK(encryptor);
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// We support key rotation in fragment boundary only, i.e. there is at most
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// one key for a single fragment. So we should have only one entry in
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// Sample Group Description box and one entry in Sample to Group box.
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// Fill in Sample Group Description box information.
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traf()->sample_group_description.grouping_type = FOURCC_SEIG;
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traf()->sample_group_description.entries.resize(1);
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traf()->sample_group_description.entries[0].is_encrypted = true;
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traf()->sample_group_description.entries[0].iv_size = encryptor->iv().size();
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traf()->sample_group_description.entries[0].key_id = encryption_key->key_id;
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// Fill in Sample to Group box information.
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traf()->sample_to_group.grouping_type = FOURCC_SEIG;
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traf()->sample_to_group.entries.resize(1);
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// sample_count is adjusted in |FinalizeFragment| later.
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traf()->sample_to_group.entries[0].group_description_index =
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SampleToGroupEntry::kTrackFragmentGroupDescriptionIndexBase + 1;
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// We need one and only one pssh box.
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if (moof_->pssh.empty())
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moof_->pssh.resize(1);
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moof_->pssh[0].raw_box = encryption_key->pssh;
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return Status::OK;
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}
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void KeyRotationFragmenter::FinalizeFragmentForEncryption() {
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Fragmenter::FinalizeFragmentForEncryption();
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DCHECK_EQ(1u, traf()->sample_to_group.entries.size());
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traf()->sample_to_group.entries[0].sample_count =
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traf()->auxiliary_size.sample_count;
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}
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} // namespace media
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} // namespace mp4
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