Remove muting for extreme playbackRates.

media/filters/audio_renderer_algorithm.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_algorithm.h"
 
 #include <algorithm>
 #include <cmath>
 
 #include "base/logging.h"
@@ skipping 28 matching lines @@
 //
 // 5) Overlap-and-add |optimal_block_| to the |wsola_output_|.
 //
 // 6) Update:
 //    |target_block_| = |optimal_index| + |ola_window_size_| / 2.
 //    |output_index_| = |output_index_| + |ola_window_size_| / 2,
 //    |search_block_center_offset_| = |output_index_| * |playback_rate_|, and
 //    |search_block_index_| = |search_block_center_offset_| -
 //        |search_block_center_offset_|.
 
-// Max/min supported playback rates for fast/slow audio. Audio outside of these
-// ranges are muted.
-// Audio at these speeds would sound better under a frequency domain algorithm.

[scherkus (not reviewing), 2014/03/19 19:44:27]

FYI I don't believe this comment is necessarily true anymore since turajs@
landed the new algorithm as this was added way, waaaay back in
http://src.chromium.org/viewvc/chrome?revision=22974&view=revision

(hence landing this CL)

-static const float kMinPlaybackRate = 0.5f;
-static const float kMaxPlaybackRate = 4.0f;
-
 // Overlap-and-add window size in milliseconds.
 static const int kOlaWindowSizeMs = 20;
 
 // Size of search interval in milliseconds. The search interval is
 // [-delta delta] around |output_index_| * |playback_rate_|. So the search
 // interval is 2 * delta.
 static const int kWsolaSearchIntervalMs = 30;
 
 // The maximum size in seconds for the |audio_buffer_|. Arbitrarily determined.
 static const int kMaxCapacityInSeconds = 3;
@@ skipping 128 matching lines @@
   do {
     rendered_frames += WriteCompletedFramesTo(
         requested_frames - rendered_frames, rendered_frames, dest);
   } while (rendered_frames < requested_frames && RunOneWsolaIteration());
   return rendered_frames;
 }
 
 void AudioRendererAlgorithm::SetPlaybackRate(float new_rate) {
   DCHECK_GE(new_rate, 0);
   playback_rate_ = new_rate;
-  muted_ =
-      playback_rate_ < kMinPlaybackRate || playback_rate_ > kMaxPlaybackRate;
+  muted_ = new_rate == 0.0f;

[scherkus (not reviewing), 2014/03/19 19:44:27]

dalecurtis: can we rip out all the |muted_| related code if we always intend to
run the WSOLA algorithm?

AFAIK if the rate == 0 we shouldn't be calling FillBuffer()

sandersd: can you see if that's true?

 }
 
 void AudioRendererAlgorithm::FlushBuffers() {
   // Clear the queue of decoded packets (releasing the buffers).
   audio_buffer_.Clear();
   output_time_ = 0.0;
   search_block_index_ = 0;
   target_block_index_ = 0;
   wsola_output_->Zero();
   num_complete_frames_ = 0;
@@ skipping 172 matching lines @@
     read_offset_frames = 0;
     num_frames_to_read -= num_zero_frames_appended;
     write_offset = num_zero_frames_appended;
     dest->ZeroFrames(num_zero_frames_appended);
   }
   audio_buffer_.PeekFrames(num_frames_to_read, read_offset_frames,
                            write_offset, dest);
 }
 
 }  // namespace media