[pitivi] Use at least 1 sample-per-pixel when previewing audio stream. Fixes #597790.

[Edward Hervey <edwardrv src gnome org>]

commit 197faca416e2c53590049b04f6efddec00362c0b
Author: Tim Waugh <twaugh redhat com>
Date:   Thu Oct 8 15:50:32 2009 +0100

    Use at least 1 sample-per-pixel when previewing audio stream. Fixes #597790.

 pitivi/ui/previewer.py |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)
---
diff --git a/pitivi/ui/previewer.py b/pitivi/ui/previewer.py
index ab285e6..3048dac 100644
--- a/pitivi/ui/previewer.py
+++ b/pitivi/ui/previewer.py
@@ -482,6 +482,8 @@ class RandomAccessAudioPreviewer(RandomAccessPreviewer):
 
         # find the samples-per-pixel ratio
         spp = len(samples) / self.base_width
+        if spp == 0:
+            spp = 1
         channels = self.audioSink.channels
         stride = spp * channels
         hscale = self.theight / (2 * channels)