112 lines
4.0 KiB
C++
112 lines
4.0 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/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 edash_packager {
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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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KeySource* encryption_key_source,
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KeySource::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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: EncryptingFragmenter(traf,
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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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bool enable_encryption) {
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bool need_to_refresh_encryptor = !encryptor();
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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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prev_crypto_period_index_ = current_crypto_period_index;
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need_to_refresh_encryptor = true;
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}
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// One and only one 'pssh' box is needed.
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if (moof_->pssh.empty())
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moof_->pssh.resize(1);
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DCHECK(encryption_key());
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moof_->pssh[0].raw_box = encryption_key()->pssh;
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// Skip the following steps if the current fragment is not going to be
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// encrypted. 'pssh' box needs to be included in the fragment, which is
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// performed above, regardless of whether the fragment is encrypted. This is
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// necessary for two reasons: 1) Requesting keys before reaching encrypted
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// content avoids playback delay due to license requests; 2) In Chrome, CDM
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// must be initialized before starting the playback and CDM can only be
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// initialized with a valid 'pssh'.
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if (!enable_encryption) {
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DCHECK(!encryptor());
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return Status::OK;
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}
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if (need_to_refresh_encryptor) {
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Status status = CreateEncryptor();
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if (!status.ok())
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return status;
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}
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DCHECK(encryptor());
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// Key rotation happens in fragment boundary only in this implementation,
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// i.e. there is at most one key for the fragment. So there should be only
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// one entry in SampleGroupDescription box and one entry in SampleToGroup box.
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// Fill in SampleGroupDescription 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 =
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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 SampleToGroup 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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return Status::OK;
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}
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void KeyRotationFragmenter::FinalizeFragmentForEncryption() {
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EncryptingFragmenter::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 mp4
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} // namespace media
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} // namespace edash_packager
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