Introduce DecodeTimestamp class to make it easier to distiguish presentation and decode timestamps.

media/base/stream_parser_buffer.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef MEDIA_BASE_STREAM_PARSER_BUFFER_H_
 #define MEDIA_BASE_STREAM_PARSER_BUFFER_H_
 
 #include <deque>
 
 #include "media/base/decoder_buffer.h"
 #include "media/base/demuxer_stream.h"
 #include "media/base/media_export.h"
 #include "media/base/stream_parser.h"
 
 namespace media {
 
+// Simple wrapper around base::TimeDelta that represents a decode timestamp.
+// Making DecodeTimestamp a different type makes it easier to determine whether
+// code is operating on presentation or decode timestamps and makes conversions
+// between the two types explicit and easy to spot.
+class DecodeTimestamp {
+ public:
+  DecodeTimestamp() {}
+  DecodeTimestamp(const DecodeTimestamp& rhs) : ts_(rhs.ts_) { }
+  DecodeTimestamp& operator=(const DecodeTimestamp& rhs) {
+    if (&rhs != this)
+      ts_ = rhs.ts_;
+    return *this;
+  }
+
+  // Only operators that are actually used by the code have been defined.
+  // Reviewers should pay close attention to the addition of new operators.
+  bool operator<(const DecodeTimestamp& rhs) const { return ts_ < rhs.ts_; }
+  bool operator>(const DecodeTimestamp& rhs) const  { return ts_ > rhs.ts_; }
+  bool operator==(const DecodeTimestamp& rhs) const  { return ts_ == rhs.ts_; }
+  bool operator!=(const DecodeTimestamp& rhs) const  { return ts_ != rhs.ts_; }
+  bool operator>=(const DecodeTimestamp& rhs) const  { return ts_ >= rhs.ts_; }
+  bool operator<=(const DecodeTimestamp& rhs) const  { return ts_ <= rhs.ts_; }
+
+  base::TimeDelta operator-(const DecodeTimestamp& rhs) const {
+    return ts_ - rhs.ts_;
+  }
+
+  DecodeTimestamp& operator+=(const base::TimeDelta& rhs) {
+    ts_ += rhs;
+    return *this;
+  }
+
+  DecodeTimestamp& operator-=(const base::TimeDelta& rhs)  {
+    ts_ -= rhs;
+    return *this;
+  }
+
+  DecodeTimestamp operator+(const base::TimeDelta& rhs) const {
+    return DecodeTimestamp(ts_ + rhs);
+  }
+
+  DecodeTimestamp operator-(const base::TimeDelta& rhs) const {
+    return DecodeTimestamp(ts_ - rhs);
+  }
+
+  int64 operator/(const base::TimeDelta& rhs) const {
+    return ts_ / rhs;
+  }
+
+  static DecodeTimestamp FromSecondsD(double seconds) {
+    return DecodeTimestamp(base::TimeDelta::FromSecondsD(seconds));
+  }
+
+  static DecodeTimestamp FromMilliseconds(int64 milliseconds) {
+    return DecodeTimestamp(base::TimeDelta::FromMilliseconds(milliseconds));
+  }
+
+  static DecodeTimestamp FromMicroseconds(int64 microseconds) {
+    return DecodeTimestamp(base::TimeDelta::FromMicroseconds(microseconds));
+  }
+
+  // This method is used to explicitly call out when presentation timestamps
+  // are being converted to a decode timestamp.
+  static DecodeTimestamp FromPresentationTime(base::TimeDelta timestamp) {
+    return DecodeTimestamp(timestamp);
+  }
+
+  double InSecondsF() const { return ts_.InSecondsF(); }
+  int64 InMilliseconds() const { return ts_.InMilliseconds(); }
+  int64 InMicroseconds() const { return ts_.InMicroseconds(); }
+
+  // TODO(acolwell): Remove once all the hacks are gone. This method is called
+  // by hacks where a decode time is being used as a presentation time.
+  base::TimeDelta ToPresentationTime() const { return ts_; }
+
+ private:
+  explicit DecodeTimestamp(base::TimeDelta timestamp) : ts_(timestamp) { }
+
+  base::TimeDelta ts_;
+};
+
+MEDIA_EXPORT extern inline DecodeTimestamp kNoDecodeTimestamp() {
+  return DecodeTimestamp::FromPresentationTime(kNoTimestamp());
+}
+
 class MEDIA_EXPORT StreamParserBuffer : public DecoderBuffer {
  public:
   // Value used to signal an invalid decoder config ID.
   enum { kInvalidConfigId = -1 };
 
   typedef DemuxerStream::Type Type;
   typedef StreamParser::TrackId TrackId;
 
   static scoped_refptr<StreamParserBuffer> CreateEOSBuffer();
 
   static scoped_refptr<StreamParserBuffer> CopyFrom(
       const uint8* data, int data_size, bool is_keyframe, Type type,
       TrackId track_id);
   static scoped_refptr<StreamParserBuffer> CopyFrom(
       const uint8* data, int data_size,
       const uint8* side_data, int side_data_size, bool is_keyframe, Type type,
       TrackId track_id);
   bool IsKeyframe() const { return is_keyframe_; }
 
   // Decode timestamp. If not explicitly set, or set to kNoTimestamp(), the
   // value will be taken from the normal timestamp.
-  base::TimeDelta GetDecodeTimestamp() const;
-  void SetDecodeTimestamp(base::TimeDelta timestamp);
+  DecodeTimestamp GetDecodeTimestamp() const;
+  void SetDecodeTimestamp(DecodeTimestamp timestamp);
 
   // Gets/sets the ID of the decoder config associated with this buffer.
   int GetConfigId() const;
   void SetConfigId(int config_id);
 
   // Gets the parser's media type associated with this buffer. Value is
   // meaningless for EOS buffers.
   Type type() const { return type_; }
 
   // Gets the parser's track ID associated with this buffer. Value is
@@ skipping 32 matching lines @@
   virtual void set_timestamp(base::TimeDelta timestamp) OVERRIDE;
 
  private:
   StreamParserBuffer(const uint8* data, int data_size,
                      const uint8* side_data, int side_data_size,
                      bool is_keyframe, Type type,
                      TrackId track_id);
   virtual ~StreamParserBuffer();
 
   bool is_keyframe_;
-  base::TimeDelta decode_timestamp_;
+  DecodeTimestamp decode_timestamp_;
   int config_id_;
   Type type_;
   TrackId track_id_;
   BufferQueue splice_buffers_;
   scoped_refptr<StreamParserBuffer> preroll_buffer_;
 
   DISALLOW_COPY_AND_ASSIGN(StreamParserBuffer);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_BASE_STREAM_PARSER_BUFFER_H_