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author Olivier Galibert <galibert@pobox.com>2025-05-10 13:15:19 +0200
committer Olivier Galibert <galibert@pobox.com>2025-05-10 14:09:03 +0200
commitc0fa1306b8cb9e7681f10dd3e60896fbf2b3fdf6 (patch)
tree9a904dc56b01d7b576c9857a277ce415f599cd3b /docs
parentf081f8ca51bc203a3c0ef761944aff2ca9374c69 (diff)
sound: Add a compressor. May need some tuning
Diffstat (limited to 'docs')
-rw-r--r--docs/source/techspecs/device_sound_interface.rst1
-rw-r--r--docs/source/usingmame/mamemenus.rst37
2 files changed, 37 insertions, 1 deletions
diff --git a/docs/source/techspecs/device_sound_interface.rst b/docs/source/techspecs/device_sound_interface.rst
index 8355781effc..6e229d7ffa0 100644
--- a/docs/source/techspecs/device_sound_interface.rst
+++ b/docs/source/techspecs/device_sound_interface.rst
@@ -242,6 +242,7 @@ can be avoided later in the chain.
~~~~~~~~~~
.. code-block:: C++
+
u32 sample_rate() const;
attotime sample_period() const;
diff --git a/docs/source/usingmame/mamemenus.rst b/docs/source/usingmame/mamemenus.rst
index efc40c37868..c84e015195f 100644
--- a/docs/source/usingmame/mamemenus.rst
+++ b/docs/source/usingmame/mamemenus.rst
@@ -384,7 +384,42 @@ the cutoff though, which can be surprising.
Compression effect
~~~~~~~~~~~~~~~~~~
-Not implemented yet.
+This effect implements a somewhat complex compressor which is a
+reimplementation of the Versatile Compressor by Alain Paul. The
+general effect of a compressor is to amplify sounds under a volume
+threshold while keeping the louder sounds as-is. It's particularly
+useful when one is not in a very quiet environment and softer sounds
+are just lost otherwise.
+
+The parameters are:
+
+* Attack: reaction time to loud sounds to reduce the amplification.
+
+* Release: reaction time to allow the amplification to go back up.
+
+* Ratio: maximum amplification.
+
+* Input gain: amplification level at the input.
+
+* Output gain: amplification level at the output.
+
+* Convexity: shape of the relationship between distance to the
+ threshold and ratio value. Steeper the high it is.
+
+* Threshold: level at which the amplification fully stops.
+
+* Channel link: at 100 all channels of the same speaker are amplified
+ identically, at 0 they are fully independant, intermediate values
+ have intermediate behaviour.
+
+* Feedback: allows to loop back some of the output to the input.
+
+* Inertia: makes the ratio move slower.
+
+* Inertia decay: tweaks the impact of the inertia.
+
+* Ceiling: maximum allowed level at exit, just before the output
+ amplification. Does soft-clipping at that level.
Reverb effect