From cf1bf7b872aafeb66b54260a916ca523b27d6e3c Mon Sep 17 00:00:00 2001
From: WyattBlue <wyattblue@auto-editor.com>
Date: Mon, 2 Nov 2026 14:18:16 -0500
Subject: [PATCH] Share AudioFrame plane count with AudioPlane

Factor the plane-count formula into AudioFrame._nb_planes() so
AudioFrame.planes and AudioPlane.__cinit__ cannot disagree, and add a
regression test for layouts with more than 8 channels.
---
 av/audio/frame.pxd       |  1 +
 av/audio/frame.py        |  6 +++++-
 av/audio/plane.py        |  4 +---
 tests/test_audioframe.py | 11 +++++++++++
 4 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/av/audio/frame.pxd b/av/audio/frame.pxd
index c1daa283d..7db0714a6 100644
--- a/av/audio/frame.pxd
+++ b/av/audio/frame.pxd
@@ -27,5 +27,6 @@ cdef class AudioFrame(Frame):
 
     cdef void _init(self, lib.AVSampleFormat format, lib.AVChannelLayout layout, unsigned int nb_samples, unsigned int align)
     cdef void _init_user_attributes(self)
+    cdef int _nb_planes(self)
 
 cdef AudioFrame alloc_audio_frame()
diff --git a/av/audio/frame.py b/av/audio/frame.py
index db4575e45..9cc644bb8 100644
--- a/av/audio/frame.py
+++ b/av/audio/frame.py
@@ -141,6 +141,10 @@ def from_ndarray(array, format="s16", layout="stereo"):
             plane.update(array[i, :])
         return frame
 
+    @cython.cfunc
+    def _nb_planes(self) -> cython.int:
+        return self.layout.nb_channels if self.format.is_planar else 1
+
     @property
     def planes(self):
         """
@@ -148,7 +152,7 @@ def planes(self):
 
         :type: tuple
         """
-        nb_planes: cython.int = self.layout.nb_channels if self.format.is_planar else 1
+        nb_planes: cython.int = self._nb_planes()
         plane_count: cython.int = 0
         while plane_count < nb_planes and self.ptr.extended_data[plane_count]:
             plane_count += 1
diff --git a/av/audio/plane.py b/av/audio/plane.py
index ab37ff217..cb1443c64 100644
--- a/av/audio/plane.py
+++ b/av/audio/plane.py
@@ -6,9 +6,7 @@
 @cython.cclass
 class AudioPlane(Plane):
     def __cinit__(self, frame: AudioFrame, index: cython.int):
-        nb_planes: cython.int = (
-            frame.layout.nb_channels if frame.format.is_planar else 1
-        )
+        nb_planes: cython.int = frame._nb_planes()
         if index < 0 or index >= nb_planes:
             raise ValueError(f"plane index {index} out of range for {nb_planes} planes")
 
diff --git a/tests/test_audioframe.py b/tests/test_audioframe.py
index 80c06de0e..37c3bdef0 100644
--- a/tests/test_audioframe.py
+++ b/tests/test_audioframe.py
@@ -56,6 +56,17 @@ def test_manual_fltp_7_1_constructor() -> None:
     assertNdarraysEqual(frame.to_ndarray(), array)
 
 
+def test_manual_fltp_22_2_constructor() -> None:
+    # More than 8 planes: extended_data is a separate heap array of exactly
+    # nb_channels pointers, so reading past it would be out of bounds.
+    frame = AudioFrame(format="fltp", layout="22.2", samples=160)
+    assert len(frame.planes) == 24
+
+    array = np.arange(24 * 160, dtype="f4").reshape(24, 160)
+    frame = AudioFrame.from_ndarray(array, format="fltp", layout="22.2")
+    assertNdarraysEqual(frame.to_ndarray(), array)
+
+
 def test_manual_s16_mono_constructor() -> None:
     frame = AudioFrame(format="s16", layout="mono", samples=160)
     assert frame.format.name == "s16"