three new DSPs

perceptual bass enhancement
- a bbe-ish group delay corrction with Biophonic EQ boost.
- precut

auditory fatigue reduction
-reduce signal in frequency that may trigger temporary threshold shift

haas surround
-frequency between f(x1) and f(x2) is always bypassed.
-can apply to side only.

Change-Id: Icb6355ce9b1c99bf2c58c9385c3c411c0ae209d3

lib/rbcodec/dsp/afr.c

@@ -0,0 +1,147 @@
+/***************************************************************************
+ *             __________               __   ___.
+ *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
+ *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
+ *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
+ *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
+ *                     \/            \/     \/    \/            \/
+ * $Id$
+ *
+ * Copyright (C) 2014 by Chiwen Chang
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+ * KIND, either express or implied.
+ *
+ ****************************************************************************/
+#include "afr.h"
+#include "config.h"
+#include "fixedpoint.h"
+#include "fracmul.h"
+#include "settings.h"
+#include "dsp_proc_entry.h"
+#include "dsp_filter.h"
+
+/* Auditory fatigue reduction */
+
+static int afr_strength = 0;
+static struct dsp_filter afr_filters[4];
+
+static void dsp_afr_flush(void)
+{
+    for (int i = 0 ;i < 4;i++)
+        filter_flush(&afr_filters[i]);
+}
+
+static void strength_update(unsigned int fout)
+{
+    int hs=0, ls=0, drop3k=0;
+
+    switch (afr_strength)
+    {
+    /* not called if afr_strength == 0 (disabled) */
+    case 1:
+        hs=-29; ls=0; drop3k=-13;
+        break;
+    case 2:
+        hs=-58; ls=-5; drop3k=-29;
+        break;
+    case 3:
+        hs=-72; ls=-5; drop3k=-48;
+        break;
+    }
+
+    filter_bishelf_coefs(fp_div(8000, fout, 32),
+                         fp_div(20000, fout, 32),
+                         0, (hs/2), 0,
+                         &afr_filters[0]);
+
+    filter_pk_coefs(fp_div(8000, fout, 32), 28, hs,
+                     &afr_filters[1]);
+
+    filter_pk_coefs(fp_div(3150, fout, 32), 28, drop3k,
+                     &afr_filters[2]);
+
+    filter_bishelf_coefs(fp_div(200, fout, 32),
+                         fp_div(1280, fout, 32),
+                         ls, 0, 0,
+                         &afr_filters[3]);
+}
+
+void dsp_afr_enable(int var)
+{
+    if (var == afr_strength)
+        return; /* No setting change */
+
+    bool was_enabled = afr_strength > 0;
+    afr_strength = var;
+
+    bool now_enabled = var > 0;
+
+    if (was_enabled == now_enabled && !now_enabled)
+        return;
+
+    /* If changing status, enable or disable it; if already enabled push
+       additional DSP_PROC_INIT messages with value = 1 to force-update the
+       filters */
+    struct dsp_config *dsp = dsp_get_config(CODEC_IDX_AUDIO);
+    dsp_proc_enable(dsp, DSP_PROC_AFR, now_enabled);
+}
+
+static void afr_reduce_process(struct dsp_proc_entry *this,
+                               struct dsp_buffer **buf_p)
+{
+    struct dsp_buffer *buf = *buf_p;
+
+    for (int i = 0; i < 4; i++)
+        filter_process(&afr_filters[i], buf->p32, buf->remcount,
+                       buf->format.num_channels);
+
+    (void)this;
+}
+
+/* DSP message hook */
+static intptr_t afr_configure(struct dsp_proc_entry *this,
+                              struct dsp_config *dsp,
+                              unsigned int setting,
+                              intptr_t value)
+{
+    /* This only attaches to the audio (codec) DSP */
+
+    switch (setting)
+    {
+    case DSP_PROC_INIT:
+        if (value == 0)
+        {
+            /* Coming online; was disabled */
+            this->process = afr_reduce_process;
+            dsp_afr_flush();
+            dsp_proc_activate(dsp, DSP_PROC_AFR, true);
+        }
+        /* else additional forced messages */
+
+        strength_update(dsp_get_output_frequency(dsp));
+        break;
+
+    case DSP_FLUSH:
+        /* Discontinuity; clear filters */
+        dsp_afr_flush();
+        break;
+
+    case DSP_SET_OUT_FREQUENCY:
+        /* New output frequency */
+        strength_update(value);
+        break;
+    }
+
+    return 1;
+}
+
+/* Database entry */
+DSP_PROC_DB_ENTRY(
+    AFR,
+    afr_configure);