diff options
author | Chris Robinson <[email protected]> | 2019-07-28 18:56:04 -0700 |
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committer | Chris Robinson <[email protected]> | 2019-07-28 18:56:04 -0700 |
commit | cb3e96e75640730b9391f0d2d922eecd9ee2ce79 (patch) | |
tree | 23520551bddb2a80354e44da47f54201fdc084f0 /Alc/uhjfilter.h | |
parent | 93e60919c8f387c36c267ca9faa1ac653254aea6 (diff) |
Rename Alc to alc
Diffstat (limited to 'Alc/uhjfilter.h')
-rw-r--r-- | Alc/uhjfilter.h | 54 |
1 files changed, 0 insertions, 54 deletions
diff --git a/Alc/uhjfilter.h b/Alc/uhjfilter.h deleted file mode 100644 index 53e4f89e..00000000 --- a/Alc/uhjfilter.h +++ /dev/null @@ -1,54 +0,0 @@ -#ifndef UHJFILTER_H -#define UHJFILTER_H - -#include "AL/al.h" - -#include "alcmain.h" -#include "almalloc.h" - - -struct AllPassState { - ALfloat z[2]{0.0f, 0.0f}; -}; - -/* Encoding 2-channel UHJ from B-Format is done as: - * - * S = 0.9396926*W + 0.1855740*X - * D = j(-0.3420201*W + 0.5098604*X) + 0.6554516*Y - * - * Left = (S + D)/2.0 - * Right = (S - D)/2.0 - * - * where j is a wide-band +90 degree phase shift. - * - * The phase shift is done using a Hilbert transform, described here: - * https://web.archive.org/web/20060708031958/http://www.biochem.oulu.fi/~oniemita/dsp/hilbert/ - * It works using 2 sets of 4 chained filters. The first filter chain produces - * a phase shift of varying magnitude over a wide range of frequencies, while - * the second filter chain produces a phase shift 90 degrees ahead of the - * first over the same range. - * - * Combining these two stages requires the use of three filter chains. S- - * channel output uses a Filter1 chain on the W and X channel mix, while the D- - * channel output uses a Filter1 chain on the Y channel plus a Filter2 chain on - * the W and X channel mix. This results in the W and X input mix on the D- - * channel output having the required +90 degree phase shift relative to the - * other inputs. - */ - -struct Uhj2Encoder { - AllPassState mFilter1_Y[4]; - AllPassState mFilter2_WX[4]; - AllPassState mFilter1_WX[4]; - ALfloat mLastY{0.0f}, mLastWX{0.0f}; - - /* Encodes a 2-channel UHJ (stereo-compatible) signal from a B-Format input - * signal. The input must use FuMa channel ordering and scaling. - */ - void encode(FloatBufferLine &LeftOut, FloatBufferLine &RightOut, FloatBufferLine *InSamples, - const ALsizei SamplesToDo); - - DEF_NEWDEL(Uhj2Encoder) -}; - -#endif /* UHJFILTER_H */ |