Implement static compression curve parameters for DynamicsCompressorNode
Created attachment 127665 [details] Patch
Dynamic range compression has parametric control of the static compression curve: threshold: the dB value above which the compression will start taking effect knee: historically this has often been simply "hard" or "soft" knee, but this is a value (in dB) representing the range above the threshold where the curve smoothly transitions to the "ratio" portion ratio: this value represents the amount of dB change in input for a 1 dB change in output The "reduction" parameter is a read-only value for metering purposes, representing the current amount of gain reduction that the compressor is applying to the signal
Here's an interactive graphing app to show the parametric curve: http://chromium.googlecode.com/svn/trunk/samples/audio/compression-curve2.html
Created attachment 128832 [details] Patch
Comment on attachment 128832 [details] Patch View in context: https://bugs.webkit.org/attachment.cgi?id=128832&action=review This looks fine per your walking through the algorithm with me offline. A couple of minor nits. r=me > Source/WebCore/platform/audio/DynamicsCompressor.cpp:58 > + if (parameterID < ParamLast) Is this worth an ASSERT? > Source/WebCore/platform/audio/DynamicsCompressorKernel.cpp:174 > + k = sqrt(minK * maxK); sqrtf? > Source/WebCore/webaudio/DynamicsCompressorNode.idl:33 > + readonly attribute AudioParam reduction; // in Decibels I assume these changes are being specified?
Committed r109023: <http://trac.webkit.org/changeset/109023>