Expose av_display_rotation_get

Author: lgeiger

av/video/__init__.py

@@ -1,2 +1,3 @@
 from .frame import VideoFrame
 from .stream import VideoStream
+from . import display

av/video/display.pyi

@@ -0,0 +1,16 @@
+from av.sidedata.sidedata import SideData
+
+def get_display_rotation(matrix: SideData) -> float:
+    """Extract the rotation component of the `DISPLAYMATRIX` transformation matrix.
+
+    Args:
+        matrix (SideData): The transformation matrix.
+
+    Returns:
+        float: The angle (in degrees) by which the transformation rotates the frame
+               counterclockwise. The angle will be in range [-180.0, 180.0].
+
+    Note:
+        Floating point numbers are inherently inexact, so callers are
+        recommended to round the return value to the nearest integer before use.
+    """

av/video/display.pyx

@@ -0,0 +1,17 @@
+cimport libav as lib
+from libc.stdint cimport int32_t
+
+import numpy as np
+
+from av.sidedata.sidedata import SideData
+from av.sidedata.sidedata import Type as SideDataType
+
+
+def get_display_rotation(matrix):
+    if not isinstance(matrix, SideData) or matrix.type != SideDataType.DISPLAYMATRIX:
+        raise ValueError("Matrix must be `SideData` of type `DISPLAYMATRIX`")
+    cdef const int32_t[:] view = np.frombuffer(matrix, dtype=np.int32)
+    if view.shape[0] != 9:
+        raise ValueError("Matrix must be 3x3 represented as a 9-element array")
+    return lib.av_display_rotation_get(&view[0])
+

include/libavutil/avutil.pxd

@@ -4,6 +4,9 @@ from libc.stdint cimport int64_t, uint8_t, uint64_t, int32_t
 cdef extern from "libavutil/mathematics.h" nogil:
     pass
 
+cdef extern from "libavutil/display.h" nogil:
+    cdef double av_display_rotation_get(const int32_t matrix[9])
+
 cdef extern from "libavutil/rational.h" nogil:
     cdef int av_reduce(int *dst_num, int *dst_den, int64_t num, int64_t den, int64_t max)
 

tests/test_decode.py

@@ -155,3 +155,16 @@ def test_flush_decoded_video_frame_count(self) -> None:
             output_count += 1
 
         assert output_count == input_count
+
+    def test_no_side_data(self):
+        container = av.open(fate_suite("h264/interlaced_crop.mp4"))
+        frame = next(container.decode(video=0))
+        matrix = frame.side_data.get(av.sidedata.sidedata.Type.DISPLAYMATRIX)
+        assert matrix is None
+
+    def test_side_data(self):
+        container = av.open(fate_suite("mov/displaymatrix.mov"))
+        frame = next(container.decode(video=0))
+        matrix = frame.side_data.get(av.sidedata.sidedata.Type.DISPLAYMATRIX)
+        rotation = av.video.display.get_display_rotation(matrix)
+        self.assertEqual(rotation, -90.0)