Implement EncryptingFragmenter from Fragmenter

Extract encryption related handlings from Fragmenter and move into new
class EncrpytingFragmenter.

Change-Id: Id42493cd321fd7e306f8ce522c7ff04990965256

media/formats/mp4/encrypting_fragmenter.cc

@@ -0,0 +1,164 @@
+// Copyright 2014 Google Inc. All rights reserved.
+//
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file or at
+// https://developers.google.com/open-source/licenses/bsd
+
+#include "media/formats/mp4/encrypting_fragmenter.h"
+
+#include "media/base/aes_encryptor.h"
+#include "media/base/buffer_reader.h"
+#include "media/base/encryption_key_source.h"
+#include "media/base/media_sample.h"
+#include "media/formats/mp4/box_definitions.h"
+#include "media/formats/mp4/cenc.h"
+
+namespace {
+// Generate 64bit IV by default.
+const size_t kDefaultIvSize = 8u;
+}  // namespace
+
+namespace media {
+namespace mp4 {
+
+EncryptingFragmenter::EncryptingFragmenter(
+    TrackFragment* traf,
+    bool normalize_presentation_timestamp,
+    scoped_ptr<EncryptionKey> encryption_key,
+    int64 clear_time,
+    uint8 nalu_length_size)
+    : Fragmenter(traf, normalize_presentation_timestamp),
+      encryption_key_(encryption_key.Pass()),
+      nalu_length_size_(nalu_length_size),
+      clear_time_(clear_time) {
+  DCHECK(encryption_key_);
+}
+EncryptingFragmenter::~EncryptingFragmenter() {}
+
+
+Status EncryptingFragmenter::AddSample(scoped_refptr<MediaSample> sample) {
+  DCHECK(sample);
+  if (encryptor_) {
+    Status status = EncryptSample(sample);
+    if (!status.ok())
+      return status;
+  }
+  return Fragmenter::AddSample(sample);
+}
+
+Status EncryptingFragmenter::InitializeFragment() {
+  Status status = Fragmenter::InitializeFragment();
+  if (!status.ok())
+    return status;
+
+  // Enable encryption for this fragment if |clear_time_| becomes non-positive.
+  if (clear_time_ <= 0)
+    return PrepareFragmentForEncryption();
+
+  // Otherwise, this fragment should be in clear text.
+  // At most two sample description entries, an encrypted entry and a clear
+  // entry, are generated. The 1-based clear entry index is always 2.
+  const uint32 kClearSampleDescriptionIndex = 2;
+
+  traf()->header.flags |=
+      TrackFragmentHeader::kSampleDescriptionIndexPresentMask;
+  traf()->header.sample_description_index = kClearSampleDescriptionIndex;
+
+  return Status::OK;
+}
+
+void EncryptingFragmenter::FinalizeFragment() {
+  if (encryptor_) {
+    DCHECK_LE(clear_time_, 0);
+    FinalizeFragmentForEncryption();
+  } else {
+    DCHECK_GT(clear_time_, 0);
+    clear_time_ -= fragment_duration();
+  }
+  Fragmenter::FinalizeFragment();
+}
+
+Status EncryptingFragmenter::PrepareFragmentForEncryption() {
+  traf()->auxiliary_size.sample_info_sizes.clear();
+  traf()->auxiliary_offset.offsets.clear();
+  return encryptor_ ? Status::OK : CreateEncryptor();
+}
+
+void EncryptingFragmenter::FinalizeFragmentForEncryption() {
+  // The offset will be adjusted in Segmenter after knowing moof size.
+  traf()->auxiliary_offset.offsets.push_back(0);
+
+  // Optimize saiz box.
+  SampleAuxiliaryInformationSize& saiz = traf()->auxiliary_size;
+  saiz.sample_count = traf()->runs[0].sample_sizes.size();
+  if (!saiz.sample_info_sizes.empty()) {
+    if (!OptimizeSampleEntries(&saiz.sample_info_sizes,
+                               &saiz.default_sample_info_size)) {
+      saiz.default_sample_info_size = 0;
+    }
+  } else {
+    // |sample_info_sizes| table is filled in only for subsample encryption,
+    // otherwise |sample_info_size| is just the IV size.
+    DCHECK(!IsSubsampleEncryptionRequired());
+    saiz.default_sample_info_size = encryptor_->iv().size();
+  }
+}
+
+Status EncryptingFragmenter::CreateEncryptor() {
+  DCHECK(encryption_key_);
+
+  scoped_ptr<AesCtrEncryptor> encryptor(new AesCtrEncryptor());
+  const bool initialized = encryption_key_->iv.empty()
+                               ? encryptor->InitializeWithRandomIv(
+                                     encryption_key_->key, kDefaultIvSize)
+                               : encryptor->InitializeWithIv(
+                                     encryption_key_->key, encryption_key_->iv);
+  if (!initialized)
+    return Status(error::MUXER_FAILURE, "Failed to create the encryptor.");
+  encryptor_ = encryptor.Pass();
+  return Status::OK;
+}
+
+void EncryptingFragmenter::EncryptBytes(uint8* data, uint32 size) {
+  DCHECK(encryptor_);
+  CHECK(encryptor_->Encrypt(data, size, data));
+}
+
+Status EncryptingFragmenter::EncryptSample(scoped_refptr<MediaSample> sample) {
+  DCHECK(encryptor_);
+
+  FrameCENCInfo cenc_info(encryptor_->iv());
+  uint8* data = sample->writable_data();
+  if (!IsSubsampleEncryptionRequired()) {
+    EncryptBytes(data, sample->data_size());
+  } else {
+    BufferReader reader(data, sample->data_size());
+    while (reader.HasBytes(1)) {
+      uint64 nalu_length;
+      if (!reader.ReadNBytesInto8(&nalu_length, nalu_length_size_))
+        return Status(error::MUXER_FAILURE, "Fail to read nalu_length.");
+
+      SubsampleEntry subsample;
+      subsample.clear_bytes = nalu_length_size_ + 1;
+      subsample.cypher_bytes = nalu_length - 1;
+      if (!reader.SkipBytes(nalu_length)) {
+        return Status(error::MUXER_FAILURE,
+                      "Sample size does not match nalu_length.");
+      }
+
+      EncryptBytes(data + subsample.clear_bytes, subsample.cypher_bytes);
+      cenc_info.AddSubsample(subsample);
+      data += nalu_length_size_ + nalu_length;
+    }
+
+    // The length of per-sample auxiliary datum, defined in CENC ch. 7.
+    traf()->auxiliary_size.sample_info_sizes.push_back(cenc_info.ComputeSize());
+  }
+
+  cenc_info.Write(aux_data());
+  encryptor_->UpdateIv();
+  return Status::OK;
+}
+
+}  // namespace mp4
+}  // namespace media

media/formats/mp4/encrypting_fragmenter.h

@@ -0,0 +1,85 @@
+// Copyright 2014 Google Inc. All rights reserved.
+//
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file or at
+// https://developers.google.com/open-source/licenses/bsd
+
+#ifndef MEDIA_FORMATS_MP4_ENCRYPTING_FRAGMENTER_H_
+#define MEDIA_FORMATS_MP4_ENCRYPTING_FRAGMENTER_H_
+
+#include "media/formats/mp4/fragmenter.h"
+
+namespace media {
+
+class AesCtrEncryptor;
+struct EncryptionKey;
+
+namespace mp4 {
+
+/// EncryptingFragmenter generates MP4 fragments with sample encrypted.
+class EncryptingFragmenter : public Fragmenter {
+ public:
+  /// @param traf points to a TrackFragment box.
+  /// @param normalize_presentation_timestamp defines whether PTS should be
+  ///        normalized to start from zero.
+  /// @param encryption_key contains the encryption parameters.
+  /// @param clear_time specifies clear lead duration in units of the current
+  ///        track's timescale.
+  /// @param nalu_length_size specifies the size of NAL unit length, in bytes,
+  ///        for subsample encryption.
+  EncryptingFragmenter(TrackFragment* traf,
+                       bool normalize_presentation_timestamp,
+                       scoped_ptr<EncryptionKey> encryption_key,
+                       int64 clear_time,
+                       uint8 nalu_length_size);
+
+  virtual ~EncryptingFragmenter();
+
+  /// @name Fragmenter implementation overrides.
+  /// @{
+  virtual Status AddSample(scoped_refptr<MediaSample> sample) OVERRIDE;
+  virtual Status InitializeFragment() OVERRIDE;
+  virtual void FinalizeFragment() OVERRIDE;
+  /// @}
+
+ protected:
+  /// Prepare current fragment for encryption.
+  /// @return OK on success, an error status otherwise.
+  virtual Status PrepareFragmentForEncryption();
+  /// Finalize current fragment for encryption.
+  virtual void FinalizeFragmentForEncryption();
+
+  /// Create the encryptor for the internal encryption key. The existing
+  /// encryptor will be reset if it is not NULL.
+  /// @return OK on success, an error status otherwise.
+  Status CreateEncryptor();
+
+  EncryptionKey* encryption_key() { return encryption_key_.get(); }
+  AesCtrEncryptor* encryptor() { return encryptor_.get(); }
+
+  void set_encryption_key(scoped_ptr<EncryptionKey> encryption_key) {
+    encryption_key_ = encryption_key.Pass();
+  }
+
+ private:
+  void EncryptBytes(uint8* data, uint32 size);
+  Status EncryptSample(scoped_refptr<MediaSample> sample);
+
+  // Should we enable subsample encryption?
+  bool IsSubsampleEncryptionRequired() { return nalu_length_size_ != 0; }
+
+  scoped_ptr<EncryptionKey> encryption_key_;
+  scoped_ptr<AesCtrEncryptor> encryptor_;
+  // If this stream contains AVC, subsample encryption specifies that the size
+  // and type of NAL units remain unencrypted. This field specifies the size of
+  // the size field. Can be 1, 2 or 4 bytes.
+  const uint8 nalu_length_size_;
+  int64 clear_time_;
+
+  DISALLOW_COPY_AND_ASSIGN(EncryptingFragmenter);
+};
+
+}  // namespace mp4
+}  // namespace media
+
+#endif  // MEDIA_FORMATS_MP4_ENCRYPTING_FRAGMENTER_H_

media/formats/mp4/fragmenter.cc

@@ -6,50 +6,20 @@
 
 #include "media/formats/mp4/fragmenter.h"
 
-#include "media/base/aes_encryptor.h"
-#include "media/base/buffer_reader.h"
 #include "media/base/buffer_writer.h"
-#include "media/base/encryption_key_source.h"
 #include "media/base/media_sample.h"
 #include "media/formats/mp4/box_definitions.h"
-#include "media/formats/mp4/cenc.h"
 
 namespace media {
 namespace mp4 {
 
 namespace {
-// Generate 64bit IV by default.
-const size_t kDefaultIvSize = 8u;
 const int64 kInvalidTime = kint64max;
-
-// Optimize sample entries table. If all values in |entries| are identical,
-// then |entries| is cleared and the value is assigned to |default_value|;
-// otherwise it is a NOP. Return true if the table is optimized.
-template <typename T>
-bool OptimizeSampleEntries(std::vector<T>* entries, T* default_value) {
-  DCHECK(entries);
-  DCHECK(default_value);
-  DCHECK(!entries->empty());
-
-  typename std::vector<T>::const_iterator it = entries->begin();
-  T value = *it;
-  for (; it < entries->end(); ++it)
-    if (value != *it)
-      return false;
-
-  // Clear |entries| if it contains only one value.
-  entries->clear();
-  *default_value = value;
-  return true;
-}
-
 }  // namespace
 
 Fragmenter::Fragmenter(TrackFragment* traf,
                        bool normalize_presentation_timestamp)
     : traf_(traf),
-      nalu_length_size_(0),
-      clear_time_(0),
       fragment_finalized_(false),
       fragment_duration_(0),
       normalize_presentation_timestamp_(normalize_presentation_timestamp),
@@ -59,47 +29,21 @@ Fragmenter::Fragmenter(TrackFragment* traf,
   DCHECK(traf);
 }
 
-Fragmenter::Fragmenter(TrackFragment* traf,
-                       bool normalize_presentation_timestamp,
-                       scoped_ptr<EncryptionKey> encryption_key,
-                       int64 clear_time,
-                       uint8 nalu_length_size)
-    : traf_(traf),
-      encryption_key_(encryption_key.Pass()),
-      nalu_length_size_(nalu_length_size),
-      clear_time_(clear_time),
-      fragment_finalized_(false),
-      fragment_duration_(0),
-      normalize_presentation_timestamp_(normalize_presentation_timestamp),
-      presentation_start_time_(kInvalidTime),
-      earliest_presentation_time_(kInvalidTime),
-      first_sap_time_(kInvalidTime) {
-  DCHECK(traf);
-  DCHECK(encryption_key_);
-}
-
 Fragmenter::~Fragmenter() {}
 
 Status Fragmenter::AddSample(scoped_refptr<MediaSample> sample) {
+  DCHECK(sample);
   CHECK_GT(sample->duration(), 0);
 
-  if (encryptor_) {
-    Status status = EncryptSample(sample);
-    if (!status.ok())
-      return status;
-  }
-
   // Fill in sample parameters. It will be optimized later.
   traf_->runs[0].sample_sizes.push_back(sample->data_size());
   traf_->runs[0].sample_durations.push_back(sample->duration());
   traf_->runs[0].sample_flags.push_back(
       sample->is_key_frame() ? 0 : TrackFragmentHeader::kNonKeySampleMask);
-  traf_->runs[0]
+  traf_->runs[0].sample_composition_time_offsets.push_back(sample->pts() -
-      .sample_composition_time_offsets.push_back(sample->pts() - sample->dts());
+                                                           sample->dts());
-  if (sample->pts() != sample->dts()) {
+  if (sample->pts() != sample->dts())
-    traf_->runs[0].flags |=
+    traf_->runs[0].flags |= TrackFragmentRun::kSampleCompTimeOffsetsPresentMask;
-        TrackFragmentRun::kSampleCompTimeOffsetsPresentMask;
-  }
 
   data_->AppendArray(sample->data(), sample->data_size());
   fragment_duration_ += sample->duration();
@@ -114,7 +58,7 @@ Status Fragmenter::AddSample(scoped_refptr<MediaSample> sample) {
       presentation_start_time_ = pts;
       pts = 0;
     } else {
-      // Can we safely assume the first sample in the media has the earliest
+      // Is it safe to assume the first sample in the media has the earliest
       // presentation timestamp?
       DCHECK_GE(pts, presentation_start_time_);
       pts -= presentation_start_time_;
@@ -145,30 +89,10 @@ Status Fragmenter::InitializeFragment() {
   first_sap_time_ = kInvalidTime;
   data_.reset(new BufferWriter());
   aux_data_.reset(new BufferWriter());
-
-  if (!encryption_key_)
-    return Status::OK;
-
-  // Enable encryption for this fragment if decode time passes clear lead.
-  if (static_cast<int64>(traf_->decode_time.decode_time) >= clear_time_)
-    return PrepareFragmentForEncryption();
-
-  // Otherwise, this fragment should be in clear text.
-  // We generate at most two sample description entries, encrypted entry and
-  // clear entry. The 1-based clear entry index is always 2.
-  const uint32 kClearSampleDescriptionIndex = 2;
-
-  traf_->header.flags |=
-      TrackFragmentHeader::kSampleDescriptionIndexPresentMask;
-  traf_->header.sample_description_index = kClearSampleDescriptionIndex;
-
   return Status::OK;
 }
 
 void Fragmenter::FinalizeFragment() {
-  if (encryptor_)
-    FinalizeFragmentForEncryption();
-
   // Optimize trun box.
   traf_->runs[0].sample_count = traf_->runs[0].sample_sizes.size();
   if (OptimizeSampleEntries(&traf_->runs[0].sample_durations,
@@ -209,88 +133,6 @@ void Fragmenter::GenerateSegmentReference(SegmentReference* reference) {
   reference->earliest_presentation_time = earliest_presentation_time_;
 }
 
-Status Fragmenter::PrepareFragmentForEncryption() {
-  traf_->auxiliary_size.sample_info_sizes.clear();
-  traf_->auxiliary_offset.offsets.clear();
-  return encryptor_ ? Status::OK : CreateEncryptor();
-}
-
-void Fragmenter::FinalizeFragmentForEncryption() {
-  // The offset will be adjusted in Segmenter when we know moof size.
-  traf_->auxiliary_offset.offsets.push_back(0);
-
-  // Optimize saiz box.
-  SampleAuxiliaryInformationSize& saiz = traf_->auxiliary_size;
-  saiz.sample_count = traf_->runs[0].sample_sizes.size();
-  if (!saiz.sample_info_sizes.empty()) {
-    if (!OptimizeSampleEntries(&saiz.sample_info_sizes,
-                               &saiz.default_sample_info_size)) {
-      saiz.default_sample_info_size = 0;
-    }
-  } else {
-    // |sample_info_sizes| table is filled in only for subsample encryption,
-    // otherwise |sample_info_size| is just the IV size.
-    DCHECK(!IsSubsampleEncryptionRequired());
-    saiz.default_sample_info_size = encryptor_->iv().size();
-  }
-}
-
-Status Fragmenter::CreateEncryptor() {
-  DCHECK(encryption_key_);
-
-  scoped_ptr<AesCtrEncryptor> encryptor(new AesCtrEncryptor());
-  const bool initialized = encryption_key_->iv.empty()
-                               ? encryptor->InitializeWithRandomIv(
-                                     encryption_key_->key, kDefaultIvSize)
-                               : encryptor->InitializeWithIv(
-                                     encryption_key_->key, encryption_key_->iv);
-  if (!initialized)
-    return Status(error::MUXER_FAILURE, "Failed to create the encryptor.");
-  encryptor_ = encryptor.Pass();
-  return Status::OK;
-}
-
-void Fragmenter::EncryptBytes(uint8* data, uint32 size) {
-  DCHECK(encryptor_);
-  CHECK(encryptor_->Encrypt(data, size, data));
-}
-
-Status Fragmenter::EncryptSample(scoped_refptr<MediaSample> sample) {
-  DCHECK(encryptor_);
-
-  FrameCENCInfo cenc_info(encryptor_->iv());
-  uint8* data = sample->writable_data();
-  if (!IsSubsampleEncryptionRequired()) {
-    EncryptBytes(data, sample->data_size());
-  } else {
-    BufferReader reader(data, sample->data_size());
-    while (reader.HasBytes(1)) {
-      uint64 nalu_length;
-      if (!reader.ReadNBytesInto8(&nalu_length, nalu_length_size_))
-        return Status(error::MUXER_FAILURE, "Fail to read nalu_length.");
-
-      SubsampleEntry subsample;
-      subsample.clear_bytes = nalu_length_size_ + 1;
-      subsample.cypher_bytes = nalu_length - 1;
-      if (!reader.SkipBytes(nalu_length)) {
-        return Status(error::MUXER_FAILURE,
-                      "Sample size does not match nalu_length.");
-      }
-
-      EncryptBytes(data + subsample.clear_bytes, subsample.cypher_bytes);
-      cenc_info.AddSubsample(subsample);
-      data += nalu_length_size_ + nalu_length;
-    }
-
-    // The length of per-sample auxiliary datum, defined in CENC ch. 7.
-    traf_->auxiliary_size.sample_info_sizes.push_back(cenc_info.ComputeSize());
-  }
-
-  cenc_info.Write(aux_data_.get());
-  encryptor_->UpdateIv();
-  return Status::OK;
-}
-
 bool Fragmenter::StartsWithSAP() {
   DCHECK(!traf_->runs.empty());
   uint32 start_sample_flag;

media/formats/mp4/fragmenter.h

@@ -15,54 +15,36 @@
 
 namespace media {
 
-class AesCtrEncryptor;
 class BufferWriter;
 class MediaSample;
 
-struct EncryptionKey;
-
 namespace mp4 {
 
-struct MovieFragment;
 struct SegmentReference;
 struct TrackFragment;
 
-/// Fragmenter is responsible for the generation of MP4 fragments, i.e. traf
+/// Fragmenter is responsible for the generation of MP4 fragments, i.e. 'traf'
-/// box and corresponding mdat box. The samples are also encrypted if encryption
+/// box and corresponding 'mdat' box.
-/// is requested.
 class Fragmenter {
  public:
   /// @param traf points to a TrackFragment box.
   /// @param normalize_presentation_timestamp defines whether PTS should be
   ///        normalized to start from zero.
-  Fragmenter(TrackFragment* traf,
+  Fragmenter(TrackFragment* traf, bool normalize_presentation_timestamp);
-             bool normalize_presentation_timestamp);
-
-  /// @param traf points to a TrackFragment box.
-  /// @param normalize_presentation_timestamp defines whether PTS should be
-  ///        normalized to start from zero.
-  /// @param encryption_key contains the encryption parameters.
-  /// @param clear_time specifies clear lead duration in units of the current
-  ///        track's timescale.
-  /// @param nalu_length_size NAL unit length size, in bytes, for subsample
-  ///        encryption.
-  Fragmenter(TrackFragment* traf,
-             bool normalize_presentation_timestamp,
-             scoped_ptr<EncryptionKey> encryption_key,
-             int64 clear_time,
-             uint8 nalu_length_size);
 
   virtual ~Fragmenter();
 
   /// Add a sample to the fragmenter.
-  Status AddSample(scoped_refptr<MediaSample> sample);
+  /// @param sample points to the sample to be added.
+  /// @return OK on success, an error status otherwise.
+  virtual Status AddSample(scoped_refptr<MediaSample> sample);
 
   /// Initialize the fragment with default data.
   /// @return OK on success, an error status otherwise.
-  Status InitializeFragment();
+  virtual Status InitializeFragment();
 
   /// Finalize and optimize the fragment.
-  void FinalizeFragment();
+  virtual void FinalizeFragment();
 
   /// Fill @a reference with current fragment information.
   void GenerateSegmentReference(SegmentReference* reference);
@@ -77,45 +59,19 @@ class Fragmenter {
   BufferWriter* aux_data() { return aux_data_.get(); }
 
  protected:
-  /// Prepare current fragment for encryption.
-  /// @return OK on success, an error status otherwise.
-  virtual Status PrepareFragmentForEncryption();
-  /// Finalize current fragment for encryption.
-  virtual void FinalizeFragmentForEncryption();
-
-  /// Create the encryptor for the internal encryption key. The existing
-  /// encryptor will be reset if it is not NULL.
-  /// @return OK on success, an error status otherwise.
-  Status CreateEncryptor();
-
   TrackFragment* traf() { return traf_; }
-  EncryptionKey* encryption_key() { return encryption_key_.get(); }
-  AesCtrEncryptor* encryptor() { return encryptor_.get(); }
 
-  void set_encryption_key(scoped_ptr<EncryptionKey> encryption_key) {
+  /// Optimize sample entries table. If all values in @a entries are identical,
-    encryption_key_ = encryption_key.Pass();
+  /// then @a entries is cleared and the value is assigned to @a default_value;
-  }
+  /// otherwise it is a NOP. Return true if the table is optimized.
+  template <typename T>
+  bool OptimizeSampleEntries(std::vector<T>* entries, T* default_value);
 
  private:
-  void EncryptBytes(uint8* data, uint32 size);
-  Status EncryptSample(scoped_refptr<MediaSample> sample);
-
-  // Should we enable subsample encryption?
-  bool IsSubsampleEncryptionRequired() { return nalu_length_size_ != 0; }
-
   // Check if the current fragment starts with SAP.
   bool StartsWithSAP();
 
   TrackFragment* traf_;
-
-  scoped_ptr<EncryptionKey> encryption_key_;
-  scoped_ptr<AesCtrEncryptor> encryptor_;
-  // If this stream contains AVC, subsample encryption specifies that the size
-  // and type of NAL units remain unencrypted. This field specifies the size of
-  // the size field. Can be 1, 2 or 4 bytes.
-  const uint8 nalu_length_size_;
-  const int64 clear_time_;
-
   bool fragment_finalized_;
   uint64 fragment_duration_;
   bool normalize_presentation_timestamp_;
@@ -128,6 +84,25 @@ class Fragmenter {
   DISALLOW_COPY_AND_ASSIGN(Fragmenter);
 };
 
+template <typename T>
+bool Fragmenter::OptimizeSampleEntries(std::vector<T>* entries,
+                                       T* default_value) {
+  DCHECK(entries);
+  DCHECK(default_value);
+  DCHECK(!entries->empty());
+
+  typename std::vector<T>::const_iterator it = entries->begin();
+  T value = *it;
+  for (; it < entries->end(); ++it)
+    if (value != *it)
+      return false;
+
+  // Clear |entries| if it contains only one value.
+  entries->clear();
+  *default_value = value;
+  return true;
+}
+
 }  // namespace mp4
 }  // namespace media
 

media/formats/mp4/key_rotation_fragmenter.cc

@@ -21,7 +21,7 @@ KeyRotationFragmenter::KeyRotationFragmenter(
     int64 crypto_period_duration,
     int64 clear_time,
     uint8 nalu_length_size)
-    : Fragmenter(traf,
+    : EncryptingFragmenter(traf,
                            normalize_presentation_timestamp,
                            scoped_ptr<EncryptionKey>(new EncryptionKey()),
                            clear_time,
@@ -57,14 +57,14 @@ Status KeyRotationFragmenter::PrepareFragmentForEncryption() {
     prev_crypto_period_index_ = current_crypto_period_index;
   }
 
-  EncryptionKey* encryption_key = Fragmenter::encryption_key();
+  EncryptionKey* encryption_key = EncryptingFragmenter::encryption_key();
   DCHECK(encryption_key);
-  AesCtrEncryptor* encryptor = Fragmenter::encryptor();
+  AesCtrEncryptor* encryptor = EncryptingFragmenter::encryptor();
   DCHECK(encryptor);
 
-  // We support key rotation in fragment boundary only, i.e. there is at most
+  // Key rotation happens in fragment boundary only in this implementation,
-  // one key for a single fragment. So we should have only one entry in
+  // i.e. there is at most one key for the fragment. So there should be only
-  // Sample Group Description box and one entry in Sample to Group box.
+  // one entry in SampleGroupDescription box and one entry in SampleToGroup box.
   // Fill in SampleGroupDescription box information.
   traf()->sample_group_description.grouping_type = FOURCC_SEIG;
   traf()->sample_group_description.entries.resize(1);
@@ -72,14 +72,14 @@ Status KeyRotationFragmenter::PrepareFragmentForEncryption() {
   traf()->sample_group_description.entries[0].iv_size = encryptor->iv().size();
   traf()->sample_group_description.entries[0].key_id = encryption_key->key_id;
 
-  // Fill in Sample to Group box information.
+  // Fill in SampleToGroup box information.
   traf()->sample_to_group.grouping_type = FOURCC_SEIG;
   traf()->sample_to_group.entries.resize(1);
   // sample_count is adjusted in |FinalizeFragment| later.
   traf()->sample_to_group.entries[0].group_description_index =
       SampleToGroupEntry::kTrackFragmentGroupDescriptionIndexBase + 1;
 
-  // We need one and only one pssh box.
+  // One and only one 'pssh' box is needed.
   if (moof_->pssh.empty())
     moof_->pssh.resize(1);
   moof_->pssh[0].raw_box = encryption_key->pssh;
@@ -88,7 +88,7 @@ Status KeyRotationFragmenter::PrepareFragmentForEncryption() {
 }
 
 void KeyRotationFragmenter::FinalizeFragmentForEncryption() {
-  Fragmenter::FinalizeFragmentForEncryption();
+  EncryptingFragmenter::FinalizeFragmentForEncryption();
   DCHECK_EQ(1u, traf()->sample_to_group.entries.size());
   traf()->sample_to_group.entries[0].sample_count =
       traf()->auxiliary_size.sample_count;
@@ -96,5 +96,3 @@ void KeyRotationFragmenter::FinalizeFragmentForEncryption() {
 
 }  // namespace media
 }  // namespace mp4
-
-

media/formats/mp4/key_rotation_fragmenter.h

@@ -8,12 +8,16 @@
 #define MEDIA_FORMATS_MP4_KEY_ROTATION_FRAGMENTER_H_
 
 #include "media/base/encryption_key_source.h"
-#include "media/formats/mp4/fragmenter.h"
+#include "media/formats/mp4/encrypting_fragmenter.h"
 
 namespace media {
 namespace mp4 {
 
-class KeyRotationFragmenter : public Fragmenter {
+struct MovieFragment;
+
+/// KeyRotationFragmenter generates MP4 fragments with sample encrypted by
+/// rotation keys.
+class KeyRotationFragmenter : public EncryptingFragmenter {
  public:
   /// @param moof points to a MovieFragment box.
   /// @param traf points to a TrackFragment box.

media/formats/mp4/mp4.gyp

@@ -37,6 +37,8 @@
         'composition_offset_iterator.h',
         'decoding_time_iterator.cc',
         'decoding_time_iterator.h',
+        'encrypting_fragmenter.cc',
+        'encrypting_fragmenter.h',
         'es_descriptor.cc',
         'es_descriptor.h',
         'fourccs.h',

media/formats/mp4/segmenter.cc

@@ -180,14 +180,14 @@ Status Segmenter::Initialize(const std::vector<MediaStream*>& streams,
     GenerateEncryptedSampleEntry(
         *encryption_key, clear_lead_in_seconds, &description);
 
-    // We need one and only one pssh box.
+    // One and only one pssh box is needed.
     if (moov_->pssh.empty()) {
       moov_->pssh.resize(1);
       moov_->pssh[0].raw_box = encryption_key->pssh;
     }
 
-    fragmenters_[i] =
+    fragmenters_[i] = new EncryptingFragmenter(
-        new Fragmenter(&moof_->tracks[i],
+        &moof_->tracks[i],
         options_.normalize_presentation_timestamp,
         encryption_key.Pass(),
         clear_lead_in_seconds * streams[i]->info()->time_scale(),