Enable setting of global output samplerate on certain targets.

Replaces the NATIVE_FREQUENCY constant with a configurable frequency.

The user may select 48000Hz if the hardware supports it. The default is
still 44100Hz and the minimum is 44100Hz. The setting is located in the
playback settings, under "Frequency".

"Frequency" was duplicated in english.lang for now to avoid having to
fix every .lang file for the moment and throwing everything out of sync
because of the new play_frequency feature in features.txt. The next
cleanup should combine it with the one included for recording and
generalize the ID label.

If the hardware doesn't support 48000Hz, no setting will be available.

On particular hardware where very high rates are practical and desireable,
the upper bound can be extended by patching.

The PCM mixer can be configured to play at the full hardware frequency
range. The DSP core can configure to the hardware minimum up to the
maximum playback setting (some buffers must be reserved according to
the maximum rate).

If only 44100Hz is supported or possible on a given target for playback,
using the DSP and mixer at other samperates is possible if the hardware
offers them.

Change-Id: I6023cf0c0baa8bc6292b6919b4dd3618a6a25622
Reviewed-on: http://gerrit.rockbox.org/479
Reviewed-by: Michael Sevakis <jethead71@rockbox.org>
Tested-by: Michael Sevakis <jethead71@rockbox.org>

1 files changed, 55 insertions, 22 deletions

diff --git a/lib/rbcodec/dsp/eq.c b/lib/rbcodec/dsp/eq.c
index 94cb61deec..e4d7bf5e02 100644
--- a/lib/rbcodec/dsp/eq.c
+++ b/lib/rbcodec/dsp/eq.c
@@ -25,6 +25,7 @@
 #include "dsp_filter.h"
 #include "dsp_proc_entry.h"
 #include "dsp_core.h"
+#include "dsp_misc.h"
 #include "eq.h"
 #include "pga.h"
 #include "replaygain.h"
@@ -42,6 +43,9 @@
 #error Band count must be greater than or equal to 3
 #endif
 
+/* Cached band settings */
+static struct eq_band_setting settings[EQ_NUM_BANDS];
+
 static struct eq_state
 {
     uint32_t enabled;                        /* Mask of enabled bands */
@@ -49,16 +53,48 @@ static struct eq_state
     struct dsp_filter filters[EQ_NUM_BANDS]; /* Data for each filter */
 } eq_data IBSS_ATTR;
 
+#define FOR_EACH_ENB_BAND(b) \
+    for (uint8_t *b = eq_data.bands; *b < EQ_NUM_BANDS; b++)
+
 /* Clear histories of all enabled bands */
 static void eq_flush(void)
 {
     if (eq_data.enabled == 0)
         return; /* Not initialized yet/no bands on */
 
-    for (uint8_t *b = eq_data.bands; *b < EQ_NUM_BANDS; b++)
+    FOR_EACH_ENB_BAND(b)
         filter_flush(&eq_data.filters[*b]);
 }
 
+static void update_band_filter(int band, unsigned int fout)
+{
+    /* Convert user settings to format required by coef generator
+       functions */
+    typeof (filter_pk_coefs) *coef_gen = filter_pk_coefs;
+
+    /* Only first and last bands are not peaking filters */
+    if (band == 0)
+        coef_gen = filter_ls_coefs;
+    else if (band == EQ_NUM_BANDS-1)
+        coef_gen = filter_hs_coefs;
+
+    const struct eq_band_setting *setting = &settings[band];
+    struct dsp_filter *filter = &eq_data.filters[band];
+
+    coef_gen(fp_div(setting->cutoff, fout, 32), setting->q ?: 1,
+             setting->gain, filter);
+}
+
+/* Resync all bands to a new DSP output frequency */
+static void update_samplerate(unsigned int fout)
+{
+    if (eq_data.enabled == 0)
+        return; /* Not initialized yet/no bands on */
+
+    FOR_EACH_ENB_BAND(b)
+        update_band_filter(*b, fout);
+}
+
 /** DSP interface **/
 
 /* Set the precut gain value */
@@ -73,11 +109,14 @@ void dsp_set_eq_coefs(int band, const struct eq_band_setting *setting)
     if (band < 0 || band >= EQ_NUM_BANDS)
         return;
 
+    settings[band] = *setting; /* cache setting */
+
+    struct dsp_config *dsp = dsp_get_config(CODEC_IDX_AUDIO);
+
     /* NOTE: The coef functions assume the EMAC unit is in fractional mode,
        which it should be, since we're executed from the main thread. */
 
     uint32_t mask = eq_data.enabled;
-    struct dsp_filter *filter = &eq_data.filters[band];
 
     /* Assume a band is disabled if the gain is zero */
     mask &= ~BIT_N(band);
@@ -85,33 +124,19 @@ void dsp_set_eq_coefs(int band, const struct eq_band_setting *setting)
     if (setting->gain != 0)
     {
         mask |= BIT_N(band);
-
-        /* Convert user settings to format required by coef generator
-           functions */
-        void (* coef_gen)(unsigned long cutoff, unsigned long Q, long db,
-                          struct dsp_filter *f) = filter_pk_coefs;
-
-        /* Only first and last bands are not peaking filters */
-        if (band == 0)
-            coef_gen = filter_ls_coefs;
-        else if (band == EQ_NUM_BANDS-1)
-            coef_gen = filter_hs_coefs;
-
-        coef_gen(0xffffffff / NATIVE_FREQUENCY * setting->cutoff,
-                 setting->q ?: 1, setting->gain, filter);
+        update_band_filter(band, dsp_get_output_frequency(dsp));
     }
 
     if (mask == eq_data.enabled)
         return; /* No change in band-enable state */
 
     if (mask & BIT_N(band))
-        filter_flush(filter); /* Coming online */
+        filter_flush(&eq_data.filters[band]); /* Coming online */
 
     eq_data.enabled = mask;
 
     /* Only be active if there are bands to process - if EQ is off, then
        this call has no effect */
-    struct dsp_config *dsp = dsp_get_config(CODEC_IDX_AUDIO);
     dsp_proc_activate(dsp, DSP_PROC_EQUALIZER, mask != 0);
   
     /* Prepare list of enabled bands for efficient iteration */
@@ -125,6 +150,11 @@ void dsp_set_eq_coefs(int band, const struct eq_band_setting *setting)
 void dsp_eq_enable(bool enable)
 {
     struct dsp_config *dsp = dsp_get_config(CODEC_IDX_AUDIO);
+    bool enabled = dsp_proc_enabled(dsp, DSP_PROC_EQUALIZER);
+
+    if (enable == enabled)
+        return;
+
     dsp_proc_enable(dsp, DSP_PROC_EQUALIZER, enable);
 
     if (enable && eq_data.enabled != 0)
@@ -139,7 +169,7 @@ static void eq_process(struct dsp_proc_entry *this,
     int count = buf->remcount;
     unsigned int channels = buf->format.num_channels;
 
-    for (uint8_t *b = eq_data.bands; *b < EQ_NUM_BANDS; b++)
+    FOR_EACH_ENB_BAND(b)
         filter_process(&eq_data.filters[*b], buf->p32, count, channels);
 
     (void)this;
@@ -154,10 +184,9 @@ static intptr_t eq_configure(struct dsp_proc_entry *this,
     switch (setting)
     {
     case DSP_PROC_INIT:
-        if (value != 0)
-            break; /* Already enabled */
-
         this->process = eq_process;
+        /* Wouldn't have been getting frequency updates */
+        update_samplerate(dsp_get_output_frequency(dsp));
         /* Fall-through */
     case DSP_PROC_CLOSE:
         pga_enable_gain(PGA_EQ_PRECUT, setting == DSP_PROC_INIT);
@@ -166,6 +195,10 @@ static intptr_t eq_configure(struct dsp_proc_entry *this,
     case DSP_FLUSH:
         eq_flush();
         break;
+
+    case DSP_SET_OUT_FREQUENCY:
+        update_samplerate(value);
+        break;
     }
 
     return 0;