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from cpython cimport PyBUF_WRITABLE, PyBuffer_FillInfo
from libc.string cimport memcpy
from av.bytesource cimport ByteSource, bytesource
cdef class Buffer:
"""A base class for PyAV objects which support the buffer protocol, such
as :class:`.Packet` and :class:`.Plane`.
"""
cdef size_t _buffer_size(self):
return 0
cdef void* _buffer_ptr(self):
return NULL
cdef bint _buffer_writable(self):
return True
def __getbuffer__(self, Py_buffer *view, int flags):
if flags & PyBUF_WRITABLE and not self._buffer_writable():
raise ValueError("buffer is not writable")
PyBuffer_FillInfo(view, self, self._buffer_ptr(), self._buffer_size(), 0, flags)
@property
def buffer_size(self):
"""The size of the buffer in bytes."""
return self._buffer_size()
@property
def buffer_ptr(self):
"""The memory address of the buffer."""
return <size_t>self._buffer_ptr()
def update(self, input):
"""Replace the data in this object with the given buffer.
Accepts anything that supports the `buffer protocol <https://docs.python.org/3/c-api/buffer.html>`_,
e.g. bytes, Numpy arrays, other :class:`Buffer` objects, etc..
"""
if not self._buffer_writable():
raise ValueError("buffer is not writable")
cdef ByteSource source = bytesource(input)
cdef size_t size = self._buffer_size()
if source.length != size:
raise ValueError(f"got {source.length} bytes; need {size} bytes")
memcpy(self._buffer_ptr(), source.ptr, size)
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