Refactor common buffer utility header (#2962)

Summary:
Put the helper functions in unnamed namespace.

Pull Request resolved: https://github.com/pytorch/audio/pull/2962

Reviewed By: carolineechen

Differential Revision: D42378781

Pulled By: mthrok

fbshipit-source-id: 74daf613f8b78f95141ae4e7c4682d8d0e97f72e

torchaudio/csrc/ffmpeg/stream_reader/buffer/common.cpp

@@ -85,13 +85,17 @@ torch::Tensor convert_audio(AVFrame* pFrame) {
   return t;
 }
 
-torch::Tensor get_buffer(at::IntArrayRef shape, const torch::Device& device) {
+namespace {
+torch::Tensor get_buffer(
+    at::IntArrayRef shape,
+    const torch::Device& device = torch::Device(torch::kCPU)) {
   auto options = torch::TensorOptions()
                      .dtype(torch::kUInt8)
                      .layout(torch::kStrided)
                      .device(device.type(), device.index());
   return torch::empty(shape, options);
 }
+} // namespace
 
 torch::Tensor get_image_buffer(AVFrame* frame, const torch::Device& device) {
   auto fmt = static_cast<AVPixelFormat>(frame->format);
@@ -126,6 +130,7 @@ torch::Tensor get_image_buffer(AVFrame* frame, const torch::Device& device) {
   return get_buffer({1, frame->height, frame->width, channels}, device);
 }
 
+namespace {
 void write_interlaced_image(AVFrame* pFrame, torch::Tensor& frame) {
   auto ptr = frame.data_ptr<uint8_t>();
   uint8_t* buf = pFrame->data[0];
@@ -299,6 +304,8 @@ void write_nv12_cuda(AVFrame* pFrame, torch::Tensor& yuv) {
 }
 #endif
 
+} // namespace
+
 torch::Tensor convert_image(AVFrame* frame, const torch::Device& device) {
   // ref:
   // https://ffmpeg.org/doxygen/4.1/filtering__video_8c_source.html#l00179

torchaudio/csrc/ffmpeg/stream_reader/buffer/common.h

@@ -11,18 +11,7 @@ namespace detail {
 //////////////////////////////////////////////////////////////////////////////
 torch::Tensor convert_audio(AVFrame* frame);
 
-torch::Tensor get_buffer(
-    at::IntArrayRef shape,
-    const torch::Device& device = torch::Device(torch::kCPU));
 torch::Tensor get_image_buffer(AVFrame* pFrame, const torch::Device& device);
-
-void write_yuv420p(AVFrame* pFrame, torch::Tensor& yuv);
-void write_nv12_cpu(AVFrame* pFrame, torch::Tensor& yuv);
-#ifdef USE_CUDA
-void write_nv12_cuda(AVFrame* pFrame, torch::Tensor& yuv);
-#endif
-void write_interlaced_image(AVFrame* pFrame, torch::Tensor& frame);
-void write_planar_image(AVFrame* pFrame, torch::Tensor& frame);
 torch::Tensor convert_image(AVFrame* frame, const torch::Device& device);
 
 } // namespace detail

torchaudio/csrc/ffmpeg/stream_reader/buffer/unchunked_buffer.h

@@ -16,11 +16,12 @@ class UnchunkedBuffer : public Buffer {
   // Each AVFrame is converted to a Tensor and stored here.
   std::deque<torch::Tensor> chunks;
 
- protected:
   // The number of currently stored chunks
   // For video, one Tensor corresponds to one frame, but for audio,
   // one Tensor contains multiple samples, so we track here.
   int64_t num_buffered_frames = 0;
+
+ protected:
   void push_tensor(const torch::Tensor& t);
 
  public: