Videre

linedance-app/venv/lib/python3.12/site-packages/audioread/rawread.py

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+# This file is part of audioread.
+# Copyright 2011, Adrian Sampson.
+#
+# Permission is hereby granted, free of charge, to any person obtaining
+# a copy of this software and associated documentation files (the
+# "Software"), to deal in the Software without restriction, including
+# without limitation the rights to use, copy, modify, merge, publish,
+# distribute, sublicense, and/or sell copies of the Software, and to
+# permit persons to whom the Software is furnished to do so, subject to
+# the following conditions:
+#
+# The above copyright notice and this permission notice shall be
+# included in all copies or substantial portions of the Software.
+
+"""Uses standard-library modules to read AIFF, AIFF-C, and WAV files."""
+import aifc
+import audioop
+import struct
+import sunau
+import wave
+
+from .exceptions import DecodeError
+from .base import AudioFile
+
+# Produce two-byte (16-bit) output samples.
+TARGET_WIDTH = 2
+
+# Python 3.4 added support for 24-bit (3-byte) samples.
+SUPPORTED_WIDTHS = (1, 2, 3, 4)
+
+
+class UnsupportedError(DecodeError):
+    """File is not an AIFF, WAV, or Au file."""
+
+
+class BitWidthError(DecodeError):
+    """The file uses an unsupported bit width."""
+
+
+def byteswap(s):
+    """Swaps the endianness of the bytestring s, which must be an array
+    of shorts (16-bit signed integers). This is probably less efficient
+    than it should be.
+    """
+    assert len(s) % 2 == 0
+    parts = []
+    for i in range(0, len(s), 2):
+        chunk = s[i:i + 2]
+        newchunk = struct.pack('<h', *struct.unpack('>h', chunk))
+        parts.append(newchunk)
+    return b''.join(parts)
+
+
+class RawAudioFile(AudioFile):
+    """An AIFF, WAV, or Au file that can be read by the Python standard
+    library modules ``wave``, ``aifc``, and ``sunau``.
+    """
+    def __init__(self, filename):
+        self._fh = open(filename, 'rb')
+
+        try:
+            self._file = aifc.open(self._fh)
+        except aifc.Error:
+            # Return to the beginning of the file to try the next reader.
+            self._fh.seek(0)
+        else:
+            self._needs_byteswap = True
+            self._check()
+            return
+
+        try:
+            self._file = wave.open(self._fh)
+        except wave.Error:
+            self._fh.seek(0)
+            pass
+        else:
+            self._needs_byteswap = False
+            self._check()
+            return
+
+        try:
+            self._file = sunau.open(self._fh)
+        except sunau.Error:
+            self._fh.seek(0)
+            pass
+        else:
+            self._needs_byteswap = True
+            self._check()
+            return
+
+        # None of the three libraries could open the file.
+        self._fh.close()
+        raise UnsupportedError()
+
+    def _check(self):
+        """Check that the files' parameters allow us to decode it and
+        raise an error otherwise.
+        """
+        if self._file.getsampwidth() not in SUPPORTED_WIDTHS:
+            self.close()
+            raise BitWidthError()
+
+    def close(self):
+        """Close the underlying file."""
+        self._file.close()
+        self._fh.close()
+
+    @property
+    def channels(self):
+        """Number of audio channels."""
+        return self._file.getnchannels()
+
+    @property
+    def samplerate(self):
+        """Sample rate in Hz."""
+        return self._file.getframerate()
+
+    @property
+    def duration(self):
+        """Length of the audio in seconds (a float)."""
+        return float(self._file.getnframes()) / self.samplerate
+
+    def read_data(self, block_samples=1024):
+        """Generates blocks of PCM data found in the file."""
+        old_width = self._file.getsampwidth()
+
+        while True:
+            data = self._file.readframes(block_samples)
+            if not data:
+                break
+
+            # Make sure we have the desired bitdepth and endianness.
+            data = audioop.lin2lin(data, old_width, TARGET_WIDTH)
+            if self._needs_byteswap and self._file.getcomptype() != 'sowt':
+                # Big-endian data. Swap endianness.
+                data = byteswap(data)
+            yield data
+
+    # Context manager.
+    def __enter__(self):
+        return self
+
+    def __exit__(self, exc_type, exc_val, exc_tb):
+        self.close()
+        return False
+
+    # Iteration.
+    def __iter__(self):
+        return self.read_data()