Remove muted_ and playback_rate_ from media::AudioRendererAlgorithm.

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 24 matching lines @@
 //
 // 4) Update:
 //    |optimal_block_| = |transition_window_| * |target_block_| +
 //    (1 - |transition_window_|) * |optimal_block_|.
 //
 // 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_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.
 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
+// [-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;
 
 // The starting size in frames for |audio_buffer_|. Previous usage maintained a
 // queue of 16 AudioBuffers, each of 512 frames. This worked well, so we
 // maintain this number of frames.
 static const int kStartingBufferSizeInFrames = 16 * 512;
 
 COMPILE_ASSERT(kStartingBufferSizeInFrames <
                (kMaxCapacityInSeconds * limits::kMinSampleRate),
                max_capacity_smaller_than_starting_buffer_size);
 
 AudioRendererAlgorithm::AudioRendererAlgorithm()
     : channels_(0),
       samples_per_second_(0),
-      playback_rate_(0),
-      muted_(false),
       muted_partial_frame_(0),
       capacity_(kStartingBufferSizeInFrames),
       output_time_(0.0),
       search_block_center_offset_(0),
       search_block_index_(0),
       num_candidate_blocks_(0),
       target_block_index_(0),
       ola_window_size_(0),
       ola_hop_size_(0),
       num_complete_frames_(0) {
 }
 
 AudioRendererAlgorithm::~AudioRendererAlgorithm() {}
 
-void AudioRendererAlgorithm::Initialize(float initial_playback_rate,
-                                        const AudioParameters& params) {
+void AudioRendererAlgorithm::Initialize(const AudioParameters& params) {
   CHECK(params.IsValid());
 
   channels_ = params.channels();
   samples_per_second_ = params.sample_rate();
-  SetPlaybackRate(initial_playback_rate);
   num_candidate_blocks_ = (kWsolaSearchIntervalMs * samples_per_second_) / 1000;
   ola_window_size_ = kOlaWindowSizeMs * samples_per_second_ / 1000;
 
   // Make sure window size in an even number.
   ola_window_size_ += ola_window_size_ & 1;
   ola_hop_size_ = ola_window_size_ / 2;
 
   // |num_candidate_blocks_| / 2 is the offset of the center of the search
   // block to the center of the first (left most) candidate block. The offset
   // of the center of a candidate block to its left most point is
@@ skipping 27 matching lines @@
   wsola_output_ = AudioBus::Create(channels_, ola_window_size_ + ola_hop_size_);
   wsola_output_->Zero();  // Initialize for overlap-and-add of the first block.
 
   // Auxiliary containers.
   optimal_block_ = AudioBus::Create(channels_, ola_window_size_);
   search_block_ = AudioBus::Create(
       channels_, num_candidate_blocks_ + (ola_window_size_ - 1));
   target_block_ = AudioBus::Create(channels_, ola_window_size_);
 }
 
-int AudioRendererAlgorithm::FillBuffer(AudioBus* dest, int requested_frames) {
-  if (playback_rate_ == 0)
+int AudioRendererAlgorithm::FillBuffer(AudioBus* dest,
+                                       int requested_frames,
+                                       float playback_rate) {
+  if (playback_rate == 0)
     return 0;
 
   DCHECK_EQ(channels_, dest->channels());
 
-  // Optimize the |muted_| case to issue a single clear instead of performing
+  // Optimize the muted case to issue a single clear instead of performing
   // the full crossfade and clearing each crossfaded frame.
-  if (muted_) {
+  if (playback_rate < kMinPlaybackRate || playback_rate > kMaxPlaybackRate) {
     int frames_to_render =
-        std::min(static_cast<int>(audio_buffer_.frames() / playback_rate_),
+        std::min(static_cast<int>(audio_buffer_.frames() / playback_rate),
                  requested_frames);
 
     // Compute accurate number of frames to actually skip in the source data.
     // Includes the leftover partial frame from last request. However, we can
     // only skip over complete frames, so a partial frame may remain for next
     // time.
-    muted_partial_frame_ += frames_to_render * playback_rate_;
+    muted_partial_frame_ += frames_to_render * playback_rate;
     int seek_frames = static_cast<int>(muted_partial_frame_);
     dest->ZeroFrames(frames_to_render);
     audio_buffer_.SeekFrames(seek_frames);
 
     // Determine the partial frame that remains to be skipped for next call. If
     // the user switches back to playing, it may be off time by this partial
     // frame, which would be undetectable. If they subsequently switch to
     // another playback rate that mutes, the code will attempt to line up the
     // frames again.
     muted_partial_frame_ -= seek_frames;
     return frames_to_render;
   }
 
-  int slower_step = ceil(ola_window_size_ * playback_rate_);
-  int faster_step = ceil(ola_window_size_ / playback_rate_);
+  int slower_step = ceil(ola_window_size_ * playback_rate);
+  int faster_step = ceil(ola_window_size_ / playback_rate);
 
-  // Optimize the most common |playback_rate_| ~= 1 case to use a single copy
+  // Optimize the most common |playback_rate| ~= 1 case to use a single copy
   // instead of copying frame by frame.
   if (ola_window_size_ <= faster_step && slower_step >= ola_window_size_) {
     const int frames_to_copy =
         std::min(audio_buffer_.frames(), requested_frames);
     const int frames_read = audio_buffer_.ReadFrames(frames_to_copy, 0, dest);
     DCHECK_EQ(frames_read, frames_to_copy);
     return frames_read;
   }
 
   int rendered_frames = 0;
   do {
     rendered_frames += WriteCompletedFramesTo(
         requested_frames - rendered_frames, rendered_frames, dest);
-  } while (rendered_frames < requested_frames && RunOneWsolaIteration());
+  } while (rendered_frames < requested_frames &&
+           RunOneWsolaIteration(playback_rate));
   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;
-}
-
 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;
 
   // Reset |capacity_| so growth triggered by underflows doesn't penalize
@@ skipping 22 matching lines @@
   capacity_ = std::min(2 * capacity_, max_capacity);
 }
 
 bool AudioRendererAlgorithm::CanPerformWsola() const {
   const int search_block_size = num_candidate_blocks_ + (ola_window_size_ - 1);
   const int frames = audio_buffer_.frames();
   return target_block_index_ + ola_window_size_ <= frames &&
       search_block_index_ + search_block_size <= frames;
 }
 
-bool AudioRendererAlgorithm::RunOneWsolaIteration() {
+bool AudioRendererAlgorithm::RunOneWsolaIteration(float playback_rate) {
   if (!CanPerformWsola())
     return false;
 
   GetOptimalBlock();
 
   // Overlap-and-add.
   for (int k = 0; k < channels_; ++k) {
     const float* const ch_opt_frame = optimal_block_->channel(k);
     float* ch_output = wsola_output_->channel(k) + num_complete_frames_;
     for (int n = 0; n < ola_hop_size_; ++n) {
       ch_output[n] = ch_output[n] * ola_window_[ola_hop_size_ + n] +
           ch_opt_frame[n] * ola_window_[n];
     }
 
     // Copy the second half to the output.
     memcpy(&ch_output[ola_hop_size_], &ch_opt_frame[ola_hop_size_],
            sizeof(*ch_opt_frame) * ola_hop_size_);
   }
 
   num_complete_frames_ += ola_hop_size_;
-  UpdateOutputTime(ola_hop_size_);
-  RemoveOldInputFrames();
+  UpdateOutputTime(playback_rate, ola_hop_size_);
+  RemoveOldInputFrames(playback_rate);
   return true;
 }
 
-void AudioRendererAlgorithm::UpdateOutputTime(double time_change) {
+void AudioRendererAlgorithm::UpdateOutputTime(float playback_rate,
+                                              double time_change) {
   output_time_ += time_change;
   // Center of the search region, in frames.
   const int search_block_center_index = static_cast<int>(
-      output_time_ * playback_rate_ + 0.5);
+      output_time_ * playback_rate + 0.5);
   search_block_index_ = search_block_center_index - search_block_center_offset_;
 }
 
-void AudioRendererAlgorithm::RemoveOldInputFrames() {
+void AudioRendererAlgorithm::RemoveOldInputFrames(float playback_rate) {
   const int earliest_used_index = std::min(target_block_index_,
                                            search_block_index_);
   if (earliest_used_index <= 0)
     return;  // Nothing to remove.
 
   // Remove frames from input and adjust indices accordingly.
   audio_buffer_.SeekFrames(earliest_used_index);
   target_block_index_ -= earliest_used_index;
 
   // Adjust output index.
   double output_time_change = static_cast<double>(earliest_used_index) /
-      playback_rate_;
+      playback_rate;
   CHECK_GE(output_time_, output_time_change);
-  UpdateOutputTime(-output_time_change);
+  UpdateOutputTime(playback_rate, -output_time_change);
 }
 
 int AudioRendererAlgorithm::WriteCompletedFramesTo(
     int requested_frames, int dest_offset, AudioBus* dest) {
   int rendered_frames = std::min(num_complete_frames_, requested_frames);
 
   if (rendered_frames == 0)
     return 0;  // There is nothing to read from |wsola_output_|, return.
 
   wsola_output_->CopyPartialFramesTo(0, rendered_frames, dest_offset, dest);
@@ skipping 79 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