wave: sampwidth for IEEE Float must be 4 or 8

This is also similar to what libsndfile does

Author: mbeijen

Doc/library/wave.rst

@@ -218,6 +218,9 @@ Wave_write Objects
 
       Set the sample width to *n* bytes.
 
+      For :data:`WAVE_FORMAT_IEEE_FLOAT`, only 4-byte (32-bit) and
+      8-byte (64-bit) sample widths are supported.
+
 
    .. method:: getsampwidth()
 
@@ -273,6 +276,9 @@ Wave_write Objects
       Supported values are :data:`WAVE_FORMAT_PCM` and
       :data:`WAVE_FORMAT_IEEE_FLOAT`.
 
+      When setting :data:`WAVE_FORMAT_IEEE_FLOAT`, the sample width must be
+      4 or 8 bytes.
+
 
    .. method:: getformat()
 
@@ -288,6 +294,8 @@ Wave_write Objects
       For backwards compatibility, a 6-item tuple without *format* is also
       accepted and defaults to :data:`WAVE_FORMAT_PCM`.
 
+      For ``format=WAVE_FORMAT_IEEE_FLOAT``, *sampwidth* must be 4 or 8.
+
 
    .. method:: getparams()
 

Lib/test/test_wave.py

@@ -189,20 +189,31 @@ def test_setparams_7_tuple_uses_format(self):
         self.addCleanup(unlink, filename)
 
         with wave.open(filename, 'wb') as w:
-            w.setparams((1, 2, 22050, 0, 'NONE', 'not compressed',
+            w.setparams((1, 4, 22050, 0, 'NONE', 'not compressed',
                          wave.WAVE_FORMAT_IEEE_FLOAT))
             self.assertEqual(w.getformat(), wave.WAVE_FORMAT_IEEE_FLOAT)
 
+    def test_setparams_7_tuple_ieee_64bit_sampwidth(self):
+        with tempfile.NamedTemporaryFile(delete_on_close=False) as fp:
+            filename = fp.name
+        self.addCleanup(unlink, filename)
+
+        with wave.open(filename, 'wb') as w:
+            w.setparams((1, 8, 22050, 0, 'NONE', 'not compressed',
+                         wave.WAVE_FORMAT_IEEE_FLOAT))
+            self.assertEqual(w.getformat(), wave.WAVE_FORMAT_IEEE_FLOAT)
+            self.assertEqual(w.getsampwidth(), 8)
+
     def test_getparams_backward_compatible_shape(self):
         with tempfile.NamedTemporaryFile(delete_on_close=False) as fp:
             filename = fp.name
         self.addCleanup(unlink, filename)
 
         with wave.open(filename, 'wb') as w:
-            w.setparams((1, 2, 22050, 0, 'NONE', 'not compressed',
+            w.setparams((1, 4, 22050, 0, 'NONE', 'not compressed',
                          wave.WAVE_FORMAT_IEEE_FLOAT))
             params = w.getparams()
-            self.assertEqual(params, (1, 2, 22050, 0, 'NONE', 'not compressed'))
+            self.assertEqual(params, (1, 4, 22050, 0, 'NONE', 'not compressed'))
 
     def test_getformat_setformat(self):
         with tempfile.NamedTemporaryFile(delete_on_close=False) as fp:
@@ -211,12 +222,51 @@ def test_getformat_setformat(self):
 
         with wave.open(filename, 'wb') as w:
             w.setnchannels(1)
-            w.setsampwidth(2)
+            w.setsampwidth(4)
             w.setframerate(22050)
             self.assertEqual(w.getformat(), wave.WAVE_FORMAT_PCM)
             w.setformat(wave.WAVE_FORMAT_IEEE_FLOAT)
             self.assertEqual(w.getformat(), wave.WAVE_FORMAT_IEEE_FLOAT)
 
+    def test_setformat_ieee_requires_32_or_64_bit_sampwidth(self):
+        with tempfile.NamedTemporaryFile(delete_on_close=False) as fp:
+            filename = fp.name
+        self.addCleanup(unlink, filename)
+
+        with wave.open(filename, 'wb') as w:
+            w.setnchannels(1)
+            w.setsampwidth(2)
+            w.setframerate(22050)
+            with self.assertRaisesRegex(wave.Error,
+                                        'unsupported sample width for IEEE float format'):
+                w.setformat(wave.WAVE_FORMAT_IEEE_FLOAT)
+
+    def test_setsampwidth_ieee_requires_32_or_64_bit(self):
+        with tempfile.NamedTemporaryFile(delete_on_close=False) as fp:
+            filename = fp.name
+        self.addCleanup(unlink, filename)
+
+        with wave.open(filename, 'wb') as w:
+            w.setnchannels(1)
+            w.setframerate(22050)
+            w.setformat(wave.WAVE_FORMAT_IEEE_FLOAT)
+            with self.assertRaisesRegex(wave.Error,
+                                        'unsupported sample width for IEEE float format'):
+                w.setsampwidth(2)
+            w.setsampwidth(4)
+
+    def test_setsampwidth_ieee_accepts_64_bit(self):
+        with tempfile.NamedTemporaryFile(delete_on_close=False) as fp:
+            filename = fp.name
+        self.addCleanup(unlink, filename)
+
+        with wave.open(filename, 'wb') as w:
+            w.setnchannels(1)
+            w.setframerate(22050)
+            w.setformat(wave.WAVE_FORMAT_IEEE_FLOAT)
+            w.setsampwidth(8)
+            self.assertEqual(w.getsampwidth(), 8)
+
     def test_read_getformat(self):
         b = b'RIFF' + struct.pack('<L', 36) + b'WAVE'
         b += b'fmt ' + struct.pack('<LHHLLHH', 16, 1, 1, 11025, 11025, 1, 8)
@@ -297,10 +347,10 @@ def test_ieee_float_has_fact_chunk(self):
 
         with wave.open(filename, 'wb') as w:
             w.setnchannels(1)
-            w.setsampwidth(2)
+            w.setsampwidth(4)
             w.setframerate(22050)
             w.setformat(wave.WAVE_FORMAT_IEEE_FLOAT)
-            w.writeframes(b'\x00\x00' * nframes)
+            w.writeframes(b'\x00\x00\x00\x00' * nframes)
 
         with open(filename, 'rb') as f:
             f.read(12)

Lib/wave.py

@@ -506,7 +506,10 @@ def getnchannels(self):
     def setsampwidth(self, sampwidth):
         if self._datawritten:
             raise Error('cannot change parameters after starting to write')
-        if sampwidth < 1 or sampwidth > 4:
+        if self._format == WAVE_FORMAT_IEEE_FLOAT:
+            if sampwidth not in (4, 8):
+                raise Error('unsupported sample width for IEEE float format')
+        elif sampwidth < 1 or sampwidth > 4:
             raise Error('bad sample width')
         self._sampwidth = sampwidth
 
@@ -548,6 +551,8 @@ def setformat(self, format):
             raise Error('cannot change parameters after starting to write')
         if format not in (WAVE_FORMAT_IEEE_FLOAT, WAVE_FORMAT_PCM):
             raise Error('unsupported wave format')
+        if format == WAVE_FORMAT_IEEE_FLOAT and self._sampwidth and self._sampwidth not in (4, 8):
+            raise Error('unsupported sample width for IEEE float format')
         self._format = format
 
     def getformat(self):
@@ -568,11 +573,11 @@ def setparams(self, params):
         else:
             nchannels, sampwidth, framerate, nframes, comptype, compname, format = params
         self.setnchannels(nchannels)
+        self.setformat(format)
         self.setsampwidth(sampwidth)
         self.setframerate(framerate)
         self.setnframes(nframes)
         self.setcomptype(comptype, compname)
-        self.setformat(format)
 
     def getparams(self):
         if not self._nchannels or not self._sampwidth or not self._framerate: