Make audio/layout pure

Author: WyattBlue

av/audio/layout.pxd

@@ -3,6 +3,5 @@ cimport libav as lib
 
 cdef class AudioLayout:
     cdef lib.AVChannelLayout layout
-    cdef _init(self, lib.AVChannelLayout layout)
 
 cdef AudioLayout get_audio_layout(lib.AVChannelLayout c_layout)

av/audio/layout.py

@@ -0,0 +1,101 @@
+from dataclasses import dataclass
+
+import cython
+from cython.cimports import libav as lib
+from cython.cimports.cpython.bytes import PyBytes_FromStringAndSize
+
+
+@dataclass
+class AudioChannel:
+    name: str
+    description: str
+
+    def __repr__(self):
+        return f"<av.AudioChannel '{self.name}' ({self.description})>"
+
+
+_cinit_bypass_sentinel = cython.declare(object, object())
+
+
+@cython.cfunc
+def get_audio_layout(c_layout: lib.AVChannelLayout) -> AudioLayout:
+    """Get an AudioLayout from Cython land."""
+    layout: AudioLayout = AudioLayout(_cinit_bypass_sentinel)
+    layout.layout = c_layout
+    return layout
+
+
+@cython.cclass
+class AudioLayout:
+    def __cinit__(self, layout):
+        if layout is _cinit_bypass_sentinel:
+            return
+
+        if type(layout) is str:
+            ret = lib.av_channel_layout_from_string(cython.address(c_layout), layout)
+            if ret != 0:
+                raise ValueError(f"Invalid layout: {layout}")
+        elif isinstance(layout, AudioLayout):
+            c_layout = cython.cast(AudioLayout, layout).layout
+        else:
+            raise TypeError(
+                f"layout must be of type: string | av.AudioLayout, got {type(layout)}"
+            )
+
+        self.layout = c_layout
+
+    def __repr__(self):
+        return f"<av.{self.__class__.__name__} {self.name!r}>"
+
+    def __eq__(self, other):
+        return (
+            isinstance(other, AudioLayout)
+            and self.name == other.name
+            and self.nb_channels == other.nb_channels
+        )
+
+    @property
+    def nb_channels(self):
+        return self.layout.nb_channels
+
+    @property
+    def channels(self):
+        buf: cython.char[16]
+        buf2: cython.char[128]
+
+        results: list = []
+        for index in range(self.layout.nb_channels):
+            size = lib.av_channel_name(
+                buf,
+                cython.sizeof(buf),
+                lib.av_channel_layout_channel_from_index(
+                    cython.address(self.layout), index
+                ),
+            )
+            size2 = lib.av_channel_description(
+                buf2,
+                cython.sizeof(buf2),
+                lib.av_channel_layout_channel_from_index(
+                    cython.address(self.layout), index
+                ),
+            )
+            results.append(
+                AudioChannel(
+                    PyBytes_FromStringAndSize(buf, size - 1).decode("utf-8"),
+                    PyBytes_FromStringAndSize(buf2, size2 - 1).decode("utf-8"),
+                )
+            )
+
+        return tuple(results)
+
+    @property
+    def name(self) -> str:
+        """The canonical name of the audio layout."""
+        layout_name: cython.char[129]
+        ret: cython.int = lib.av_channel_layout_describe(
+            cython.address(self.layout), layout_name, cython.sizeof(layout_name)
+        )
+        if ret < 0:
+            raise RuntimeError(f"Failed to get layout name: {ret}")
+
+        return layout_name

av/audio/layout.pyx

@@ -43,7 +43,7 @@ def __iter__(self):
             yield element.key
 
     def __repr__(self):
-        return f"bv.Dictionary({dict(self)!r})"
+        return f"av.Dictionary({dict(self)!r})"
 
     def copy(self):
         other = cython.declare(_Dictionary, Dictionary())