small fixes, reuse _get_video_metadata

Author: Dan-Flores

src/torchcodec/_core/Encoder.cpp

@@ -644,7 +644,11 @@ void sortCodecOptions(
 }
 
 void validateFrameRate(int frameRate) {
-  TORCH_CHECK(frameRate > 0, "frame_rate=", frameRate, " must be > 0.");
+  TORCH_CHECK(
+      frameRate > 0,
+      "Invalid frame_rate: ",
+      frameRate,
+      ". Frame rate must be a positive integer.");
 }
 } // namespace
 
@@ -796,7 +800,6 @@ void VideoEncoder::initializeEncoder(
   avCodecContext_->width = outWidth_;
   avCodecContext_->height = outHeight_;
   avCodecContext_->pix_fmt = outPixelFormat_;
-  // TODO-VideoEncoder: Verify that frame_rate and time_base are correct
   avCodecContext_->time_base = {1, outFrameRate_};
   avCodecContext_->framerate = {outFrameRate_, 1};
 

src/torchcodec/encoders/_video_encoder.py

@@ -67,7 +67,7 @@ def to_file(
                 encoder options to pass, e.g. ``{"qp": 5, "tune": "film"}``.
                 Values will be converted to strings before passing to the encoder.
             frame_rate (int, optional): The frame rate of the output video. If not specified,
-                uses the frame rate provided to the VideoEncoder constructor.
+                uses the frame rate of the input ``frames``.
         """
         preset = str(preset) if isinstance(preset, int) else preset
         _core.encode_video_to_file(
@@ -116,7 +116,7 @@ def to_tensor(
                 encoder options to pass, e.g. ``{"qp": 5, "tune": "film"}``.
                 Values will be converted to strings before passing to the encoder.
             frame_rate (int, optional): The frame rate of the output video. If not specified,
-                uses the frame rate provided to the VideoEncoder constructor.
+                uses the frame rate of the input ``frames``.
 
         Returns:
             Tensor: The raw encoded bytes as 1D uint8 Tensor.
@@ -174,7 +174,7 @@ def to_file_like(
                 encoder options to pass, e.g. ``{"qp": 5, "tune": "film"}``.
                 Values will be converted to strings before passing to the encoder.
             frame_rate (int, optional): The frame rate of the output video. If not specified,
-                uses the frame rate provided to the VideoEncoder constructor.
+                uses the frame rate of the input ``frames``.
         """
         preset = str(preset) if isinstance(preset, int) else preset
         _core.encode_video_to_file_like(

test/test_encoders.py

@@ -659,7 +659,7 @@ def test_bad_input_parameterized(self, tmp_path, method):
         ):
             encoder.to_tensor(format="mp4", preset="fake_preset")
 
-        with pytest.raises(RuntimeError, match=r"frame_rate"):
+        with pytest.raises(RuntimeError, match="Invalid frame_rate: "):
             encoder = VideoEncoder(
                 frames=torch.zeros((5, 3, 64, 64), dtype=torch.uint8),
                 frame_rate=30,
@@ -1191,29 +1191,6 @@ def test_extra_options_utilized(self, tmp_path, profile, colorspace, color_range
     @pytest.mark.parametrize("output_frame_rate", [10, 60, None])
     def test_frame_rate_parameter(self, tmp_path, method, output_frame_rate):
 
-        # Use ffprobe to get frame rate
-        def get_frame_rate(file_path):
-            result = subprocess.run(
-                [
-                    "ffprobe",
-                    "-v",
-                    "error",
-                    "-select_streams",
-                    "v:0",
-                    "-show_entries",
-                    "stream=r_frame_rate",
-                    "-of",
-                    "default=noprint_wrappers=1:nokey=1",
-                    str(file_path),
-                ],
-                capture_output=True,
-                check=True,
-                text=True,
-            )
-            # Frame rate is returned as a fraction like "60/1"
-            numerator, denominator = result.stdout.strip().split("/")
-            return int(numerator) / int(denominator)
-
         frames = (
             VideoDecoder(TEST_SRC_2_720P.path)
             .get_frames_in_range(start=0, stop=60)
@@ -1245,7 +1222,10 @@ def get_frame_rate(file_path):
         else:
             raise ValueError(f"Unknown method: {method}")
 
-        actual_frame_rate = get_frame_rate(output_path)
+        metadata = self._get_video_metadata(output_path, ["r_frame_rate"])
+        # Frame rate is returned as a fraction like "60/1"
+        numerator, denominator = metadata["r_frame_rate"].split("/")
+        actual_frame_rate = int(numerator) / int(denominator)
         # Ensure frame_rate=None uses the input_frame_rate
         if output_frame_rate is None:
             output_frame_rate = input_frame_rate