Make device and device_variant have a default instead of being std::optional

Author: NicolasHug

src/torchcodec/_core/custom_ops.cpp

@@ -43,9 +43,9 @@ TORCH_LIBRARY(torchcodec_ns, m) {
   m.def(
       "_create_from_file_like(int file_like_context, str? seek_mode=None) -> Tensor");
   m.def(
-      "_add_video_stream(Tensor(a!) decoder, *, int? width=None, int? height=None, int? num_threads=None, str? dimension_order=None, int? stream_index=None, str? device=None, str? device_variant=None, (Tensor, Tensor, Tensor)? custom_frame_mappings=None, str? color_conversion_library=None) -> ()");
+      "_add_video_stream(Tensor(a!) decoder, *, int? width=None, int? height=None, int? num_threads=None, str? dimension_order=None, int? stream_index=None, str device=\"cpu\", str device_variant=\"default\", (Tensor, Tensor, Tensor)? custom_frame_mappings=None, str? color_conversion_library=None) -> ()");
   m.def(
-      "add_video_stream(Tensor(a!) decoder, *, int? width=None, int? height=None, int? num_threads=None, str? dimension_order=None, int? stream_index=None, str? device=None, str? device_variant=None, (Tensor, Tensor, Tensor)? custom_frame_mappings=None) -> ()");
+      "add_video_stream(Tensor(a!) decoder, *, int? width=None, int? height=None, int? num_threads=None, str? dimension_order=None, int? stream_index=None, str device=\"cpu\", str device_variant=\"default\", (Tensor, Tensor, Tensor)? custom_frame_mappings=None) -> ()");
   m.def(
       "add_audio_stream(Tensor(a!) decoder, *, int? stream_index=None, int? sample_rate=None, int? num_channels=None) -> ()");
   m.def("seek_to_pts(Tensor(a!) decoder, float seconds) -> ()");
@@ -257,8 +257,8 @@ void _add_video_stream(
     std::optional<int64_t> num_threads = std::nullopt,
     std::optional<std::string_view> dimension_order = std::nullopt,
     std::optional<int64_t> stream_index = std::nullopt,
-    std::optional<std::string_view> device = std::nullopt,
-    std::optional<std::string_view> device_variant = std::nullopt,
+    std::string_view device = "cpu",
+    std::string_view device_variant = "default",
     std::optional<std::tuple<at::Tensor, at::Tensor, at::Tensor>>
         custom_frame_mappings = std::nullopt,
     std::optional<std::string_view> color_conversion_library = std::nullopt) {
@@ -289,16 +289,10 @@ void _add_video_stream(
     }
   }
 
-  if (!device.has_value()) {
-    device = "cpu";
-  }
-  if (!device_variant.has_value()) {
-    device_variant = "default";
-  }
-  validateDeviceInterface(std::string(*device), std::string(*device_variant));
+  validateDeviceInterface(std::string(device), std::string(device_variant));
 
-  videoStreamOptions.device = torch::Device(std::string(*device));
-  videoStreamOptions.deviceVariant = *device_variant;
+  videoStreamOptions.device = torch::Device(std::string(device));
+  videoStreamOptions.deviceVariant = device_variant;
 
   std::optional<SingleStreamDecoder::FrameMappings> converted_mappings =
       custom_frame_mappings.has_value()
@@ -317,8 +311,8 @@ void add_video_stream(
     std::optional<int64_t> num_threads = std::nullopt,
     std::optional<std::string_view> dimension_order = std::nullopt,
     std::optional<int64_t> stream_index = std::nullopt,
-    std::optional<std::string_view> device = std::nullopt,
-    std::optional<std::string_view> device_variant = std::nullopt,
+    std::string_view device = "cpu",
+    std::string_view device_variant = "default",
     const std::optional<std::tuple<at::Tensor, at::Tensor, at::Tensor>>&
         custom_frame_mappings = std::nullopt) {
   _add_video_stream(

src/torchcodec/_core/ops.py

@@ -275,7 +275,7 @@ def _add_video_stream_abstract(
     num_threads: Optional[int] = None,
     dimension_order: Optional[str] = None,
     stream_index: Optional[int] = None,
-    device: Optional[str] = None,
+    device: str = "cpu",
     device_variant: str = "default",
     custom_frame_mappings: Optional[
         tuple[torch.Tensor, torch.Tensor, torch.Tensor]
@@ -294,7 +294,7 @@ def add_video_stream_abstract(
     num_threads: Optional[int] = None,
     dimension_order: Optional[str] = None,
     stream_index: Optional[int] = None,
-    device: Optional[str] = None,
+    device: str = "cpu",
     device_variant: str = "default",
     custom_frame_mappings: Optional[
         tuple[torch.Tensor, torch.Tensor, torch.Tensor]