Stop side data holding its frame in a reference cycle

Author: WyattBlue

CHANGELOG.rst

@@ -29,11 +29,14 @@ We are operating with `semantic versioning <https://semver.org>`_.
     - $CHANGE by :gh-user:`mikeboers` in (:pr:`1`).
 
 
-v19.0.1
--------
+v19.0.1 (Unreleased)
+--------------------
 
 Fixes:
 
+- Reading :attr:`.Frame.side_data` no longer holds the frame in a reference cycle, which kept its picture buffer alive until gc ran. By :gh-user:`WyattBlue`.
+- :class:`.MotionVectors` no longer memoizes the vectors it hands out, a cache that never evicted and put every one of them in a reference cycle with the side data, retaining 1640 objects for a single 640x360 frame. By :gh-user:`WyattBlue`.
+- :attr:`.Stream.index_entries` is now a view built on access rather than an object allocated for every stream whether or not anything reads it, which also takes the stream out of a reference cycle with it. Fixes (:issue:`2425`) by :gh-user:`WyattBlue`.
 
 
 v19.0.0

av/frame.pxd

@@ -1,14 +1,12 @@
 cimport libav as lib
 
 from av.packet cimport Packet
-from av.sidedata.sidedata cimport _SideDataContainer
 
 
 cdef class Frame:
     cdef lib.AVFrame *ptr
     # We define our own time.
     cdef lib.AVRational _time_base
     cdef void _rebase_time(self, lib.AVRational)
-    cdef _SideDataContainer _side_data
     cdef void _copy_internal_attributes(self, Frame source, bint data_layout=?)
     cdef void _init_user_attributes(self)

av/frame.py

@@ -181,9 +181,7 @@ def key_frame(self, v):
 
     @property
     def side_data(self):
-        if self._side_data is None:
-            self._side_data = SideDataContainer(self)
-        return self._side_data
+        return SideDataContainer(self)
 
     @property
     def metadata(self):

av/frame.pyi

@@ -11,7 +11,8 @@ class Frame:
     def time_base(self) -> AVRational: ...
     @time_base.setter
     def time_base(self, value: AVRational | Fraction | int) -> None: ...
-    side_data: SideDataContainer
+    @property
+    def side_data(self) -> SideDataContainer: ...
     opaque: object
     @property
     def metadata(self) -> dict[str, str]: ...

av/sidedata/motionvectors.pxd

@@ -5,7 +5,6 @@ from av.sidedata.sidedata cimport SideData
 
 
 cdef class MotionVectors(SideData):
-    cdef dict _vectors
     cdef Py_ssize_t _len
 
 

av/sidedata/motionvectors.py

@@ -11,7 +11,6 @@
 class MotionVectors(SideData):
     def __init__(self, sentinel, frame: Frame, index: cython.int):
         SideData.__init__(self, sentinel, frame, index)
-        self._vectors = {}
         self._len = self.ptr.size // cython.sizeof(lib.AVMotionVector)
 
     def __repr__(self):
@@ -29,15 +28,7 @@ def __getitem__(self, index: cython.Py_ssize_t):
         if index < 0 or index >= self._len:
             raise IndexError(index)
 
-        try:
-            return self._vectors[index]
-        except KeyError:
-            pass
-
-        vector = self._vectors[index] = MotionVector(
-            _cinit_bypass_sentinel, self, index
-        )
-        return vector
+        return MotionVector(_cinit_bypass_sentinel, self, index)
 
     def __iter__(self):
         """Iterate over all motion vectors."""

av/sidedata/motionvectors.pyi

@@ -1,14 +1,13 @@
-from typing import Any, overload
+from collections.abc import Iterator
+from typing import Any
 
 import numpy as np
 
 from .sidedata import SideData
 
 class MotionVectors(SideData):
-    @overload
     def __getitem__(self, index: int) -> MotionVector: ...
-    @overload
-    def __getitem__(self, index: slice) -> list[MotionVector]: ...
+    def __iter__(self) -> Iterator[MotionVector]: ...
     def __len__(self) -> int: ...
     def to_ndarray(self) -> np.ndarray[Any, Any]: ...
 

av/sidedata/sidedata.pyi

@@ -3,7 +3,6 @@ from enum import Enum
 from typing import ClassVar, cast, overload
 
 from av.buffer import Buffer
-from av.frame import Frame
 
 class Type(Enum):
     PANSCAN = cast(ClassVar[Type], ...)
@@ -43,7 +42,6 @@ class SideData(Buffer):
     type: Type
 
 class SideDataContainer(Mapping):
-    frame: Frame
     def __len__(self) -> int: ...
     def __iter__(self) -> Iterator[Type]: ...
     @overload