Cleanup OPUS decoder. Remove extraneous transforms and copies.

media/filters/audio_renderer_impl.cc

 // 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.
 
 #include "media/filters/audio_renderer_impl.h"
 
 #include <math.h>
 
 #include <algorithm>
 
@@ skipping 381 matching lines @@
 bool AudioRendererImpl::HandleSplicerBuffer(
     const scoped_refptr<AudioBuffer>& buffer) {
   if (buffer->end_of_stream()) {
     received_end_of_stream_ = true;
 
     // Transition to kPlaying if we are currently handling an underflow since
     // no more data will be arriving.
     if (state_ == kUnderflow || state_ == kRebuffering)
       ChangeState_Locked(kPlaying);
   } else {
-    if (state_ == kPrerolling && IsBeforePrerollTime(buffer))
-      return true;
+    if (state_ == kPrerolling) {
+      if (IsBeforePrerollTime(buffer))
+        return true;
+
+      // Trim off any additional time before the preroll timestamp.
+      const base::TimeDelta trim_time =
+          preroll_timestamp_ - buffer->timestamp();
+      if (trim_time > base::TimeDelta()) {
+        buffer->TrimStart(buffer->frame_count() *
+                          (static_cast<double>(trim_time.InMicroseconds()) /
+                           buffer->duration().InMicroseconds()));
+      }
+      // If the entire buffer was trimmed, request a new one.
+      if (!buffer->frame_count())
+        return true;
+    }
 
     if (state_ != kUninitialized && state_ != kStopped)
       algorithm_->EnqueueBuffer(buffer);
   }
 
   switch (state_) {
     case kUninitialized:
     case kFlushing:
       NOTREACHED();
       return false;
@@ skipping 268 matching lines @@
   }
 }
 
 void AudioRendererImpl::ChangeState_Locked(State new_state) {
   DVLOG(1) << __FUNCTION__ << " : " << state_ << " -> " << new_state;
   lock_.AssertAcquired();
   state_ = new_state;
 }
 
 }  // namespace media