Allow codecs and parameters in wav and raw export

pydub/audio_segment.py

@@ -767,15 +767,15 @@ def export(self, out_f=None, format='mp3', codec=None, bitrate=None, parameters=
             ('mp3', 'wav', 'raw', 'ogg' or other ffmpeg/avconv supported files)
 
         codec (string)
-            Codec used to encoding for the destination.
+            Codec used to encode the destination file.
 
         bitrate (string)
             Bitrate used when encoding destination file. (64, 92, 128, 256, 312k...)
             Each codec accepts different bitrate arguments so take a look at the
             ffmpeg documentation for details (bitrate usually shown as -b, -ba or
             -a:b).
 
-        parameters (string)
+        parameters (list of strings)
             Aditional ffmpeg/avconv parameters
 
         tags (dict)
@@ -790,6 +790,12 @@ def export(self, out_f=None, format='mp3', codec=None, bitrate=None, parameters=
         """
         id3v2_allowed_versions = ['3', '4']
 
+        if format == "raw" and (codec is not None or parameters is not None):
+            raise AttributeError(
+                    'Can not invoke ffmpeg when export format is "raw"; '
+                    'specify an ffmpeg raw format like format="s16le" instead '
+                    'or call export(format="raw") with no codec or parameters')
+
         out_f, _ = _fd_or_path_or_tempfile(out_f, 'wb+')
         out_f.seek(0)
 
@@ -798,8 +804,10 @@ def export(self, out_f=None, format='mp3', codec=None, bitrate=None, parameters=
             out_f.seek(0)
             return out_f
 
-        # for wav output we can just write the data directly to out_f
-        if format == "wav":
+        # wav with no ffmpeg parameters can just be written directly to out_f
+        easy_wav = format == "wav" and codec is None and parameters is None
+
+        if easy_wav:
             data = out_f
         else:
             data = NamedTemporaryFile(mode="wb", delete=False)
@@ -814,8 +822,8 @@ def export(self, out_f=None, format='mp3', codec=None, bitrate=None, parameters=
         wave_data.writeframesraw(self._data)
         wave_data.close()
 
-        # for wav files, we're done (wav data is written directly to out_f)
-        if format == 'wav':
+        # for easy wav files, we're done (wav data is written directly to out_f)
+        if easy_wav:
             return out_f
 
         output = NamedTemporaryFile(mode="w+b", delete=False)

test/test.py

@@ -560,6 +560,27 @@ def test_export_as_wav(self):
                                    len(seg),
                                    percentage=0.01)
 
+    def test_export_as_wav_with_codec(self):
+        seg = self.seg1
+        exported_wav = seg.export(format='wav', codec='pcm_s32le')
+        seg_exported_wav = AudioSegment.from_wav(exported_wav)
+
+        self.assertWithinTolerance(len(seg_exported_wav),
+                                   len(seg),
+                                   percentage=0.01)
+        self.assertEqual(seg_exported_wav.sample_width, 4)
+
+    def test_export_as_wav_with_parameters(self):
+        seg = self.seg1
+        exported_wav = seg.export(format='wav', parameters=['-ar', '16000', '-ac', '1'])
+        seg_exported_wav = AudioSegment.from_wav(exported_wav)
+
+        self.assertWithinTolerance(len(seg_exported_wav),
+                                   len(seg),
+                                   percentage=0.01)
+        self.assertEqual(seg_exported_wav.frame_rate, 16000)
+        self.assertEqual(seg_exported_wav.channels, 1)
+
     def test_export_as_raw(self):
         seg = self.seg1
         exported_raw = seg.export(format='raw')
@@ -570,6 +591,16 @@ def test_export_as_raw(self):
                                    len(seg),
                                    percentage=0.01)
 
+    def test_export_as_raw_with_codec(self):
+        seg = self.seg1
+        with self.assertRaises(AttributeError):
+            seg.export(format='raw', codec='pcm_s32le')
+
+    def test_export_as_raw_with_parameters(self):
+        seg = self.seg1
+        with self.assertRaises(AttributeError):
+            seg.export(format='raw', parameters=['-ar', '16000', '-ac', '1'])
+
     def test_export_as_ogg(self):
         seg = self.seg1
         exported_ogg = seg.export(format='ogg')