Fix bug whereby encoding large ogg vorbis files caused a segfault

zounds/timeseries/audiosamples.py

@@ -209,7 +209,22 @@ def encode(self, flo=None, fmt='WAV', subtype='PCM_16'):
                 format=fmt,
                 subtype=subtype,
                 samplerate=self.samples_per_second) as f:
-            f.write(self)
+
+            if fmt == 'OGG':
+                # KLUDGE: Trying to write too-large chunks to an ogg file seems
+                # to cause a segfault in libsndfile
+                # KLUDGE: This logic is very similar to logic in the OggVorbis
+                # processing node, and should probably be factored into a common
+                # location
+                factor = 20
+                chunksize = self.samples_per_second * factor
+                for i in xrange(0, len(self), chunksize):
+                    chunk = self[i: i + chunksize]
+                    f.write(chunk)
+            else:
+                # write everything in one chunk
+                f.write(self)
+
         flo.seek(0)
         return flo
 

zounds/timeseries/test_audiosamples.py

@@ -5,7 +5,7 @@
 from zounds.timeseries import TimeDimension, TimeSlice
 from zounds.core import IdentityDimension
 from audiosamples import AudioSamples
-from zounds.synthesize import SineSynthesizer
+from zounds.synthesize import SineSynthesizer, SilenceSynthesizer
 
 
 class AudioSamplesTest(unittest2.TestCase):
@@ -188,3 +188,12 @@ def test_sum_along_second_axis(self):
         self.assertIsInstance(result, AudioSamples)
         self.assertEqual(1, len(result.dimensions))
         self.assertIsInstance(result.dimensions[0], TimeDimension)
+
+    def test_encode_large_ogg(self):
+        sr = SR11025()
+        synth = SilenceSynthesizer(sr)
+        samples = synth.synthesize(Seconds(190))
+        raw = samples.encode(fmt='OGG', subtype='VORBIS')
+        # prior to this test, the line above caused a segfault, so the assertion
+        # below is fairly worthless, and mostly a formality
+        self.assertIsNotNone(raw)