Dynamically allocate more memory to AudioBlockFifo

media/base/audio_block_fifo.cc

Index: media/base/audio_block_fifo.cc
diff --git a/media/base/audio_block_fifo.cc b/media/base/audio_block_fifo.cc
index 5e8c9b37949babea29b10a464b2a6e3fd9189610..407150b1dec15b0a603edeb3b3fa330e8c831f75 100644
--- a/media/base/audio_block_fifo.cc
+++ b/media/base/audio_block_fifo.cc
@@ -9,17 +9,13 @@
 namespace media {
 
 AudioBlockFifo::AudioBlockFifo(int channels, int frames, int blocks)
-    : block_frames_(frames),
+    : channels_(channels),
+      block_frames_(frames),
       write_block_(0),
       read_block_(0),
       available_blocks_(0),
       write_pos_(0) {
-  // Create |blocks| of audio buses and push them to the containers.
-  audio_blocks_.reserve(blocks);
-  for (int i = 0; i < blocks; ++i) {
-    scoped_ptr<AudioBus> audio_bus = AudioBus::Create(channels, frames);
-    audio_blocks_.push_back(audio_bus.release());
-  }
+  Append(blocks);
 }
 
 AudioBlockFifo::~AudioBlockFifo() {}
@@ -31,6 +27,7 @@ void AudioBlockFifo::Push(const void* source,
   DCHECK_GT(frames, 0);
   DCHECK_GT(bytes_per_sample, 0);
   DCHECK_LT(available_blocks_, static_cast<int>(audio_blocks_.size()));
+  CHECK_LT(frames, GetUnfilledFrames());
 
   const uint8* source_ptr = static_cast<const uint8*>(source);
   int frames_to_push = frames;
@@ -54,7 +51,7 @@ void AudioBlockFifo::Push(const void* source,
       ++available_blocks_;
     }
 
-    source_ptr += push_frames * bytes_per_sample * current_block->channels();
+    source_ptr += push_frames * bytes_per_sample * channels_;
     frames_to_push -= push_frames;
     DCHECK_GE(frames_to_push, 0);
   }
@@ -86,4 +83,13 @@ int AudioBlockFifo::GetUnfilledFrames() const {
   return unfilled_frames;
 }
 
+void AudioBlockFifo::Append(int blocks) {

[DaleCurtis, 2014/09/12 17:14:00]

Append feels like it may be giving too much of the internal structure of
AudioBlockFIFO away. I wonder if this should instead be something like
IncreaseCapacity(<frames>).

The AudioBlockFIFO can then determine the correct number of blocks and such as
well as any internal reshuffling that needs to be done to accommodate the new
blocks.

I.e., consider what happens right now if block are added to the end when the
read pointer points to the back of the block list and the write pointer has
already wrapped to the front somewhere. You'll need to be careful that
read/write pointers are in the right place after this operation.

+  // Create |blocks| of audio buses and add them to the containers.
+  audio_blocks_.reserve(audio_blocks_.size() + blocks);
+  for (int i = 0; i < blocks; ++i) {
+    scoped_ptr<AudioBus> audio_bus = AudioBus::Create(channels_, block_frames_);
+    audio_blocks_.push_back(audio_bus.release());
+  }
+}
+
 }  // namespace media