Set default value to optional arguments (#3208)

Summary:
Pull Request resolved: https://github.com/pytorch/audio/pull/3208

StreamReader/Writer is evolving and the number of arguments in
add_stream methods are growing.

This commit adds default values to these arguments.

Reviewed By: hwangjeff

Differential Revision: D44447263

fbshipit-source-id: e1c09956d78c2b4738bbeafb88195ec8e8ca5513

torchaudio/csrc/ffmpeg/stream_reader/stream_reader.h

@@ -58,8 +58,8 @@ class StreamReader {
   /// (opening source).
   explicit StreamReader(
       const std::string& src,
-      const c10::optional<std::string>& format = {},
-      const c10::optional<OptionDict>& option = {});
+      const c10::optional<std::string>& format = c10::nullopt,
+      const c10::optional<OptionDict>& option = c10::nullopt);
 
   /// @cond
 
@@ -72,8 +72,8 @@ class StreamReader {
   // TODO: Move this to wrapper class
   explicit StreamReader(
       AVIOContext* io_ctx,
-      const c10::optional<std::string>& format = {},
-      const c10::optional<OptionDict>& option = {});
+      const c10::optional<std::string>& format = c10::nullopt,
+      const c10::optional<OptionDict>& option = c10::nullopt);
 
   /// @endcond
 
@@ -190,9 +190,9 @@ class StreamReader {
       int64_t i,
       int64_t frames_per_chunk,
       int64_t num_chunks,
-      const c10::optional<std::string>& filter_desc,
-      const c10::optional<std::string>& decoder,
-      const c10::optional<OptionDict>& decoder_option);
+      const c10::optional<std::string>& filter_desc = c10::nullopt,
+      const c10::optional<std::string>& decoder = c10::nullopt,
+      const c10::optional<OptionDict>& decoder_option = c10::nullopt);
   /// Define an output video stream.
   ///
   /// @param i,frames_per_chunk,num_chunks,filter_desc,decoder,decoder_option
@@ -211,10 +211,10 @@ class StreamReader {
       int64_t i,
       int64_t frames_per_chunk,
       int64_t num_chunks,
-      const c10::optional<std::string>& filter_desc,
-      const c10::optional<std::string>& decoder,
-      const c10::optional<OptionDict>& decoder_option,
-      const c10::optional<std::string>& hw_accel);
+      const c10::optional<std::string>& filter_desc = c10::nullopt,
+      const c10::optional<std::string>& decoder = c10::nullopt,
+      const c10::optional<OptionDict>& decoder_option = c10::nullopt,
+      const c10::optional<std::string>& hw_accel = c10::nullopt);
   /// Remove an output stream.
   ///
   /// @param i The index of the output stream to be removed.
@@ -288,7 +288,7 @@ class StreamReader {
   /// @param timeout See `process_packet_block()`
   /// @param backoff See `process_packet_block()`
   int fill_buffer(
-      const c10::optional<double>& timeout = {},
+      const c10::optional<double>& timeout = c10::nullopt,
       const double backoff = 10.);
 
   ///@}

torchaudio/csrc/ffmpeg/stream_writer/stream_writer.h

 #pragma once
 
-#include <torch/torch.h>
+#include <torch/types.h>
 #include <torchaudio/csrc/ffmpeg/ffmpeg.h>
 #include <torchaudio/csrc/ffmpeg/filter_graph.h>
 #include <torchaudio/csrc/ffmpeg/stream_writer/encode_process.h>
@@ -34,7 +34,7 @@ class StreamWriter {
   /// ``dst``.
   explicit StreamWriter(
       const std::string& dst,
-      const c10::optional<std::string>& format = {});
+      const c10::optional<std::string>& format = c10::nullopt);
 
   /// @cond
 
@@ -45,7 +45,7 @@ class StreamWriter {
   // TODO: Move this into wrapper class.
   explicit StreamWriter(
       AVIOContext* io_ctx,
-      const c10::optional<std::string>& format);
+      const c10::optional<std::string>& format = c10::nullopt);
 
   /// @endcond
 
@@ -104,10 +104,10 @@ class StreamWriter {
       int sample_rate,
       int num_channels,
       const std::string& format,
-      const c10::optional<std::string>& encoder,
-      const c10::optional<OptionDict>& encoder_option,
-      const c10::optional<std::string>& encoder_format,
-      const c10::optional<CodecConfig>& codec_config);
+      const c10::optional<std::string>& encoder = c10::nullopt,
+      const c10::optional<OptionDict>& encoder_option = c10::nullopt,
+      const c10::optional<std::string>& encoder_format = c10::nullopt,
+      const c10::optional<CodecConfig>& codec_config = c10::nullopt);
 
   /// Add an output video stream.
   ///
@@ -144,11 +144,11 @@ class StreamWriter {
       int width,
       int height,
       const std::string& format,
-      const c10::optional<std::string>& encoder,
-      const c10::optional<OptionDict>& encoder_option,
-      const c10::optional<std::string>& encoder_format,
-      const c10::optional<std::string>& hw_accel,
-      const c10::optional<CodecConfig>& codec_config);
+      const c10::optional<std::string>& encoder = c10::nullopt,
+      const c10::optional<OptionDict>& encoder_option = c10::nullopt,
+      const c10::optional<std::string>& encoder_format = c10::nullopt,
+      const c10::optional<std::string>& hw_accel = c10::nullopt,
+      const c10::optional<CodecConfig>& codec_config = c10::nullopt);
   /// Set file-level metadata
   /// @param metadata metadata.
   void set_metadata(const OptionDict& metadata);
@@ -160,7 +160,7 @@ class StreamWriter {
   /// Open the output file / device and write the header.
   ///
   /// @param opt Private options for protocol, device and muxer.
-  void open(const c10::optional<OptionDict>& opt);
+  void open(const c10::optional<OptionDict>& opt = c10::nullopt);
   /// Close the output file / device and finalize metadata.
   void close();
 
@@ -182,7 +182,7 @@ class StreamWriter {
   void write_audio_chunk(
       int i,
       const torch::Tensor& frames,
-      const c10::optional<double>& pts = {});
+      const c10::optional<double>& pts = c10::nullopt);
   /// Write video data
   /// @param i Stream index.
   /// @param frames Video/image tensor. Shape: ``(time, channel, height,
@@ -203,7 +203,7 @@ class StreamWriter {
   void write_video_chunk(
       int i,
       const torch::Tensor& frames,
-      const c10::optional<double>& pts = {});
+      const c10::optional<double>& pts = c10::nullopt);
   /// Flush the frames from encoders and write the frames to the destination.
   void flush();
 };