Refactor `get_encodinginfo` logic (#1233)

* Distinguish get_encodinginfo for Tensor I/O and save output

* Isolate get_tensor_encodinginfo so as not to use the same helper function

torchaudio/csrc/sox/effects.cpp

@@ -60,8 +60,8 @@ std::tuple<torch::Tensor, int64_t> apply_effects_tensor(
   // Create SoxEffectsChain
   const auto dtype = waveform.dtype();
   torchaudio::sox_effects_chain::SoxEffectsChain chain(
-      /*input_encoding=*/get_encodinginfo("wav", dtype),
-      /*output_encoding=*/get_encodinginfo("wav", dtype));
+      /*input_encoding=*/get_tensor_encodinginfo(dtype),
+      /*output_encoding=*/get_tensor_encodinginfo(dtype));
 
   // Prepare output buffer
   std::vector<sox_sample_t> out_buffer;
@@ -112,7 +112,7 @@ std::tuple<torch::Tensor, int64_t> apply_effects_file(
   // Create and run SoxEffectsChain
   torchaudio::sox_effects_chain::SoxEffectsChain chain(
       /*input_encoding=*/sf->encoding,
-      /*output_encoding=*/get_encodinginfo("wav", dtype));
+      /*output_encoding=*/get_tensor_encodinginfo(dtype));
 
   chain.addInputFile(sf);
   for (const auto& effect : effects) {
@@ -214,7 +214,7 @@ std::tuple<torch::Tensor, int64_t> apply_effects_fileobj(
   const auto dtype = get_dtype(sf->encoding.encoding, sf->signal.precision);
   torchaudio::sox_effects_chain::SoxEffectsChain chain(
       /*input_encoding=*/sf->encoding,
-      /*output_encoding=*/get_encodinginfo("wav", dtype));
+      /*output_encoding=*/get_tensor_encodinginfo(dtype));
   chain.addInputFileObj(sf, in_buf, in_buffer_size, &fileobj);
   for (const auto& effect : effects) {
     chain.addEffect(effect);

torchaudio/csrc/sox/io.cpp

@@ -143,7 +143,8 @@ void save_audio_file(
   }
   const auto signal_info =
       get_signalinfo(&tensor, sample_rate, filetype, channels_first);
-  const auto encoding_info = get_encodinginfo(filetype, tgt_dtype, compression);
+  const auto encoding_info =
+      get_encodinginfo_for_save(filetype, tgt_dtype, compression);
 
   SoxFormat sf(sox_open_write(
       path.c_str(),
@@ -158,7 +159,7 @@ void save_audio_file(
   }
 
   torchaudio::sox_effects_chain::SoxEffectsChain chain(
-      /*input_encoding=*/get_encodinginfo("wav", tensor.dtype()),
+      /*input_encoding=*/get_tensor_encodinginfo(tensor.dtype()),
       /*output_encoding=*/sf->encoding);
   chain.addInputTensor(&tensor, sample_rate, channels_first);
   chain.addOutputFile(sf);
@@ -281,7 +282,8 @@ void save_audio_fileobj(
   }
   const auto signal_info =
       get_signalinfo(&tensor, sample_rate, filetype, channels_first);
-  const auto encoding_info = get_encodinginfo(filetype, tgt_dtype, compression);
+  const auto encoding_info =
+      get_encodinginfo_for_save(filetype, tgt_dtype, compression);
 
   AutoReleaseBuffer buffer;
 
@@ -299,7 +301,7 @@ void save_audio_fileobj(
   }
 
   torchaudio::sox_effects_chain::SoxEffectsChain chain(
-      /*input_encoding=*/get_encodinginfo("wav", tensor.dtype()),
+      /*input_encoding=*/get_tensor_encodinginfo(tensor.dtype()),
       /*output_encoding=*/sf->encoding);
   chain.addInputTensor(&tensor, sample_rate, channels_first);
   chain.addOutputFileObj(sf, &buffer.ptr, &buffer.size, &fileobj);

torchaudio/csrc/sox/utils.cpp

@@ -291,12 +291,32 @@ sox_signalinfo_t get_signalinfo(
       /*length=*/static_cast<uint64_t>(waveform->numel())};
 }
 
-sox_encodinginfo_t get_encodinginfo(
-    const std::string filetype,
-    const caffe2::TypeMeta dtype) {
+sox_encodinginfo_t get_tensor_encodinginfo(const caffe2::TypeMeta dtype) {
+  sox_encoding_t encoding = [&]() {
+    if (dtype == torch::kUInt8)
+      return SOX_ENCODING_UNSIGNED;
+    if (dtype == torch::kInt16)
+      return SOX_ENCODING_SIGN2;
+    if (dtype == torch::kInt32)
+      return SOX_ENCODING_SIGN2;
+    if (dtype == torch::kFloat32)
+      return SOX_ENCODING_FLOAT;
+    throw std::runtime_error("Unsupported dtype.");
+  }();
+  unsigned bits_per_sample = [&]() {
+    if (dtype == torch::kUInt8)
+      return 8;
+    if (dtype == torch::kInt16)
+      return 16;
+    if (dtype == torch::kInt32)
+      return 32;
+    if (dtype == torch::kFloat32)
+      return 32;
+    throw std::runtime_error("Unsupported dtype.");
+  }();
   return sox_encodinginfo_t{
-      /*encoding=*/get_encoding(filetype, dtype),
-      /*bits_per_sample=*/get_precision(filetype, dtype),
+      /*encoding=*/encoding,
+      /*bits_per_sample=*/bits_per_sample,
       /*compression=*/HUGE_VAL,
       /*reverse_bytes=*/sox_option_default,
       /*reverse_nibbles=*/sox_option_default,
@@ -304,7 +324,7 @@ sox_encodinginfo_t get_encodinginfo(
       /*opposite_endian=*/sox_false};
 }
 
-sox_encodinginfo_t get_encodinginfo(
+sox_encodinginfo_t get_encodinginfo_for_save(
     const std::string filetype,
     const caffe2::TypeMeta dtype,
     c10::optional<double>& compression) {

torchaudio/csrc/sox/utils.h

@@ -108,12 +108,11 @@ sox_signalinfo_t get_signalinfo(
     const std::string filetype,
     const bool channels_first);
 
-/// Get sox_encofinginfo_t for saving audoi file
-sox_encodinginfo_t get_encodinginfo(
-    const std::string filetype,
-    const caffe2::TypeMeta dtype);
+/// Get sox_encodinginfo_t for Tensor I/O
+sox_encodinginfo_t get_tensor_encodinginfo(const caffe2::TypeMeta dtype);
 
-sox_encodinginfo_t get_encodinginfo(
+/// Get sox_encodinginfo_t for saving to file/file object
+sox_encodinginfo_t get_encodinginfo_for_save(
     const std::string filetype,
     const caffe2::TypeMeta dtype,
     c10::optional<double>& compression);