New method TimestampAligner::TranslateTimestamp

webrtc/base/timestampaligner.h

 /*
  *  Copyright (c) 2016 The WebRTC Project Authors. All rights reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
 #ifndef WEBRTC_BASE_TIMESTAMPALIGNER_H_
 #define WEBRTC_BASE_TIMESTAMPALIGNER_H_
 
 #include "webrtc/base/basictypes.h"
 #include "webrtc/base/constructormagic.h"
-#include "webrtc/base/optional.h"
 
 namespace rtc {
 
 // This class is not thread safe, so all calls to it must be synchronized
 // externally.
 class TimestampAligner {

[perkj_webrtc, 2016/09/08 13:41:05]

Add comment about the purpose of this class please.

[nisse-webrtc, 2016/09/09 13:32:44]

Done.

  public:
   TimestampAligner();
   ~TimestampAligner();
 
  public:
+  // Recommended function for code outside of webrtc. |camera_time_us|

[perkj_webrtc, 2016/09/08 13:41:05]

Why only outside webrtc and what does that mean? Why not always use this?

+  // is assumed to be accurate, but with an unknown epoch and
+  // frequency drift. |system_time_us| is time according to
+  // rtc::TimeMicros(), preferably read as soon as possible when the
+  // frame is received. It may have poor accuracy due to poor

[perkj_webrtc, 2016/09/08 13:41:05]

/s frame is received -> frame is captured

[nisse-webrtc, 2016/09/09 13:32:43]

Done.

+  // resolution or scheduling delays. Returns the translated
+  // timestamp.
+  int64_t TranslateTimestamp(int64_t camera_time_us, int64_t system_time_us);
+
   // Update the estimated offset between camera time and system monotonic time.
   int64_t UpdateOffset(int64_t camera_time_us, int64_t system_time_us);

[perkj_webrtc, 2016/09/08 13:41:05]

 make private ?

[nisse-webrtc, 2016/09/09 13:32:43]

Done. (Or rather protected, to make it available for the unit tests).

 
+  // Clip timestamp, return value is larger than the previous
+  // timestamp but no larger than |system_time_us|.
   int64_t ClipTimestamp(int64_t filtered_time_us, int64_t system_time_us);

[perkj_webrtc, 2016/09/08 13:41:05]

make private ?

[nisse-webrtc, 2016/09/09 13:32:43]

Same here.

 
  private:
   // State for the timestamp translation.
   int frames_seen_;
   // Estimated offset between camera time and system monotonic time.
   int64_t offset_us_;
 
   // State for timestamp clipping, applied after the filter, to ensure
-  // that translated timestamps are monotonic and not in the future.
+  // that translated timestamps are monotonous and not in the future.
   // Subtracted from the translated timestamps.
   int64_t clip_bias_us_;
-  rtc::Optional<int64_t> prev_translated_time_us_;
+  int64_t prev_translated_time_us_;
   RTC_DISALLOW_COPY_AND_ASSIGN(TimestampAligner);
 };
 
 }  // namespace rtc
 
 #endif  // WEBRTC_BASE_TIMESTAMPALIGNER_H_