[Python-checkins] r61842 - python/trunk/Doc/library/audioop.rst
georg.brandl
python-checkins at python.org
Mon Mar 24 10:34:43 CET 2008
Author: georg.brandl
Date: Mon Mar 24 10:34:34 2008
New Revision: 61842
Modified:
python/trunk/Doc/library/audioop.rst
Log:
#1700821: add a note to audioop docs about signedness of sample formats.
Modified: python/trunk/Doc/library/audioop.rst
==============================================================================
--- python/trunk/Doc/library/audioop.rst (original)
+++ python/trunk/Doc/library/audioop.rst Mon Mar 24 10:34:34 2008
@@ -141,6 +141,18 @@
Convert samples between 1-, 2- and 4-byte formats.
+ .. note::
+
+ In some audio formats, such as .WAV files, 16 and 32 bit samples are
+ signed, but 8 bit samples are unsigned. So when converting to 8 bit wide
+ samples for these formats, you need to also add 128 to the result::
+
+ new_frames = audioop.lin2lin(frames, old_width, 1)
+ new_frames = audioop.bias(new_frames, 1, 128)
+
+ The same, in reverse, has to be applied when converting from 8 to 16 or 32
+ bit width samples.
+
.. function:: lin2ulaw(fragment, width)
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