Document the stereo width control.

diff --git a/audio.rst b/audio.rst
index 1266397466f3127f9ccc05471697fccaab70bac0..e17a2acd2bb5807a3602e9d63e77414f86b9bbfa 100644 (file)
--- a/audio.rst
+++ b/audio.rst
@@ -319,7 +319,7 @@ a skilled audio engineer will know how to adjust these to each speaker's
 antics—some speak at a pretty even volume and thus can get a bit of
 headroom, while some are much more variable and need tighter settings.
 
-Finally (or, well, first), there's the EQ section. The **lo-cut** is again
+Nearly at the top (and nearly first in the chain), there's the EQ section. The **lo-cut** is again
 well-known from the simple audio mode (the filter is separate for each
 bus, the cutoff **frequency** is the same across all buses),
 but there's now also a simple **three-band EQ** per bus. Simply ask the speaker
@@ -329,6 +329,21 @@ and if you have a reasonable ear, you can use the EQ to your advantage to
 make them sound a little more even on the stream. Either that, or just
 put it in neutral, and the entire EQ code will be bypassed.
 
+Finally (or, well, first), since 1.7.3, there's the **stereo width** knob.
+At the default, 100%, it makes no change to the signal, but if you turn it
+to 0% (at the middle), the signal becomes perfect mono. Between these two,
+there's a range where the channels leak partially over into each other.
+This can be useful if you have a very hard-panned signal (say, two microphones
+that point in diametrically opposite directions), which can sound odd when
+the listener is using headphones. Going further to the left, at -100%, the
+left and right channels are exactly swapped and between -100% and 0% is again
+a reversion with partial leaking. The range between -100% and 0%
+is for convenience only, as you could achieve the same effect by swapping the
+two channels in the input mapping. Note that the entire control is grayed out
+if the signal is provably mono (ie., the same input channel is mapped to both
+left and right).
+
+
 .. _midi-control:
 
 MIDI controllers

diff --git a/images/audio-bus-controls.png b/images/audio-bus-controls.png
index b4fe1146f52a4d741885851a3c8c9c6031597204..8b4d360097f8d85dea685527ee806f06488c0860 100644 (file)
Binary files a/images/audio-bus-controls.png and b/images/audio-bus-controls.png differ