New plugin: pitch detector (FS#8768) by Michael Lechner and David Johnston

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@22663 a1c6a512-1295-4272-9138-f99709370657

4 files changed, 1061 insertions, 0 deletions

diff --git a/apps/plugins/CATEGORIES b/apps/plugins/CATEGORIES
index 3dc11b636e..ae764ca125 100644
--- a/apps/plugins/CATEGORIES
+++ b/apps/plugins/CATEGORIES
@@ -58,6 +58,7 @@ pacbox,games
 pdbox,viewers
 pegbox,games
 pictureflow,demos
+pitch_detector,apps
 plasma,demos
 png,viewers
 pong,games
diff --git a/apps/plugins/SOURCES b/apps/plugins/SOURCES
index 95ffb1c9de..b9061ee74b 100644
--- a/apps/plugins/SOURCES
+++ b/apps/plugins/SOURCES
@@ -29,6 +29,10 @@ firmware_flash.c
 rockbox_flash.c
 #endif /* CONFIG_CPU */
 
+#if (CONFIG_CODEC == SWCODEC) && defined(HAVE_RECORDING) && \
+    (defined(HAVE_LINE_IN) || defined(HAVE_MIC_IN))
+pitch_detector.c
+#endif
 
 #if (CONFIG_CODEC == SWCODEC) || !defined(SIMULATOR)
 metronome.c
diff --git a/apps/plugins/pitch_detector.c b/apps/plugins/pitch_detector.c
new file mode 100644
index 0000000000..8d0b3b7957
--- /dev/null
+++ b/apps/plugins/pitch_detector.c
@@ -0,0 +1,1055 @@
+/**************************************************************************
+ *             __________               __   ___.
+ *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
+ *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
+ *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
+ *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
+ *                     \/            \/     \/    \/            \/
+ * $Id:$    
+ *
+ * Copyright (C) 2008    Lechner Michael / smoking gnu
+ *
+ * All files in this archive are subject to the GNU General Public License.
+ * See the file COPYING in the source tree root for full license agreement.
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+ * KIND, either express or implied.
+ *
+ * ----------------------------------------------------------------------------
+ *
+ * INTRODUCTION:
+ * OK, this is an attempt to write an instrument tuner for rockbox.
+ * It uses a Schmitt trigger algorithm, which I copied from 
+ * tuneit [ (c) 2004 Mario Lang <mlang@delysid.org> ], for detecting the 
+ * fundamental freqency of a sound. A FFT algorithm would be more accurate 
+ * but also much slower.
+ * 
+ * TODO:
+ * - Find someone who knows how recording actually works, and rewrite the 
+ *   recording code to use proper, gapless recording with a callback function
+ *   that provides new buffer, instead of stopping and restarting recording
+ *   everytime the buffer is full
+ * - Convert all floating point operations to fixed-point
+ * - Adapt the Yin FFT algorithm, which would reduce complexity from O(n^2)
+ *   to O(nlogn), theoretically reducing latency by a factor of ~10. -David
+ * 
+ * MAJOR CHANGES:
+ * 08.03.2008        Started coding
+ * 21.03.2008        Pitch detection works more or less
+ *                   Button definitions for most targets added
+ * 02.04.2008        Proper GUI added
+ *                   Todo, Major Changes and Current Limitations added
+ * 08.19.2009        Brought the code up to date with current plugin standards
+ *                   Made it work more nicely with color, BW and grayscale
+ *                   Changed pitch detection to use the Yin algorithm (better
+ *                      detection, but slower -- would be ~4x faster with
+ *                      fixed point math, I think).  Code was poached from the
+ *                      Aubio sound processing library (aubio.org). -David
+ * 08.31.2009        Lots of changes:
+ *                   Added a menu to tweak settings
+ *                   Converted everything to fixed point (greatly improving 
+ *                       latency)
+ *                   Improved the display
+ *                   Improved efficiency with judicious use of cpu_boost, the
+ *                       backlight, and volume detection to limit unneeded
+ *                       calculation
+ *                   Fixed a problem that caused an octave-off error
+ *                   -David
+ *                   
+ * 
+ * CURRENT LIMITATIONS:
+ * - No gapless recording.  Strictly speaking true gappless isn't possible,
+ *   since the algorithm takes longer to calculate than the length of the
+ *   sample, but latency could be improved a bit with proper use of the DMA
+ *   recording functions.
+ * - Due to how the Yin algorithm works, latency is higher for lower 
+ *   frequencies.
+ */
+ 
+#include "plugin.h"
+#include "lib/pluginlib_actions.h"
+
+PLUGIN_HEADER
+
+/* First figure out what sample rate we're going to use */
+#if (REC_SAMPR_CAPS & SAMPR_CAP_44)
+#define SAMPLE_RATE     SAMPR_44
+#elif (REC_SAMPR_CAPS & SAMPR_CAP_22)
+#define SAMPLE_RATE     SAMPR_22
+#elif (REC_SAMPR_CAPS & SAMPR_CAP_11)
+#define SAMPLE_RATE     SAMPR_11
+#endif
+
+/* Some fixed point calculation stuff */
+typedef int32_t fixed_data;
+struct _fixed
+{
+    fixed_data a;
+};
+typedef struct _fixed fixed;
+#define FIXED_PRECISION 18
+#define FP_MAX ((fixed) {0x7fffffff})
+#define FP_MIN ((fixed) {-0x80000000})
+#define int2fixed(x)    ((fixed){(x) << FIXED_PRECISION})
+#define int2mantissa(x) ((fixed){x})
+#define fixed2int(x)    ((int)((x).a >> FIXED_PRECISION))
+#define fixed2float(x)  (((float)(x).a) / ((float)(1 << FIXED_PRECISION)))
+#define float2fixed(x) \
+    ((fixed){(fixed_data)(x * (float)(1 << FIXED_PRECISION))})
+/* I adapted these ones from the Rockbox fixed point library */
+#define fp_mul(x, y) \
+    ((fixed){(((int64_t)((x).a)) * ((int64_t)((y).a))) >> (FIXED_PRECISION)})
+#define fp_div(x, y) \
+    ((fixed){(((int64_t)((x).a)) << (FIXED_PRECISION)) / ((int64_t)((y).a))})
+/* Operators for fixed point */
+#define fp_add(x, y) ((fixed){(x).a + (y).a})
+#define fp_sub(x, y) ((fixed){(x).a - (y).a})
+#define fp_shl(x, y) ((fixed){(x).a << y})
+#define fp_shr(x, y) ((fixed){(x).a >> y})
+#define fp_neg(x)    ((fixed){-(x).a})
+#define fp_gt(x, y)  ((x).a > (y).a)
+#define fp_gte(x, y) ((x).a >= (y).a)
+#define fp_lt(x, y)  ((x).a < (y).a)
+#define fp_lte(x, y) ((x).a <= (y).a)
+#define fp_sqr(x)    fp_mul((x), (x))
+#define fp_equal(x, y) ((x).a == (y).a)
+#define fp_round(x)  (fixed2int(fp_add((x), float2fixed(0.5))))
+#define fp_data(x)   ((x).a)
+#define fp_frac(x)   (fp_sub((x), int2fixed(fixed2int(x))))
+#define FP_ZERO      ((fixed){0})
+#define FP_LOW       ((fixed){1})
+
+/* Some defines for converting between period and frequency  */
+/* I introduce some divisors in this because the fixed point */
+/* variables aren't big enough to hold higher than a certain */
+/* vallue.  This loses a bit of precision but it means we    */
+/* don't have to use 32.32 variables (yikes).                */
+/* With an 18-bit decimal precision, the max value in the    */
+/* integer part is 8192.  Divide 44100 by 7 and it'll fit in */
+/* that variable.                                            */
+#define fp_period2freq(x) fp_div(int2fixed(SAMPLE_RATE / 7), \
+                                 fp_div((x),int2fixed(7)))
+#define fp_freq2period(x) fp_period2freq(x)
+#define period2freq(x)    (SAMPLE_RATE / (x))
+#define freq2period(x)    period2freq(x)
+
+#define sqr(x)    ((x)*(x))
+
+/* Some constants for tuning */
+#define A_FREQ          float2fixed(440.0f)
+#define D_NOTE          float2fixed(1.059463094359f)
+#define LOG_D_NOTE      float2fixed(1.0f/12.0f)
+#define D_NOTE_SQRT     float2fixed(1.029302236643f)
+#define LOG_2           float2fixed(1.0f)
+
+/* The recording buffer size */
+/* This is how much is sampled at a time. */
+/* It also determines latency -- if BUFFER_SIZE == SAMPLE_RATE then */
+/*   there'll be one sample per second, or a latency of one second. */
+/* Furthermore, the lowest detectable frequency will be about twice */
+/*   the number of reads per second                                 */
+/* If we ever switch to Yin FFT algorithm then this needs to be 
+   a power of 2 */
+#define BUFFER_SIZE 4096
+#define SAMPLE_SIZE 4096
+#define SAMPLE_SIZE_MIN 1024
+#define YIN_BUFFER_SIZE (BUFFER_SIZE / 4)
+
+#define LCD_FACTOR (fp_div(int2fixed(LCD_WIDTH), int2fixed(100)))
+/* The threshold for the YIN algorithm */
+#define YIN_THRESHOLD float2fixed(0.05f)
+
+/* How loud the audio has to be to start displaying pitch  */
+/* Must be between 0 and 100                               */
+#define VOLUME_THRESHOLD (50)
+/* Change to AUDIO_SRC_LINEIN if you want to record from line-in */
+#define INPUT_TYPE AUDIO_SRC_MIC
+
+/* How many decimal places to display for the Hz value */
+#define DISPLAY_HZ_PRECISION 100
+
+typedef signed short audio_sample_type;
+/* It's stereo, so make the buffer twice as big */
+audio_sample_type audio_data[BUFFER_SIZE];
+fixed yin_buffer[YIN_BUFFER_SIZE];
+static int recording=0;
+
+/* Frequencies of all the notes of the scale */
+static const fixed freqs[12] = 
+{
+    float2fixed(440.0f),        /* A */
+    float2fixed(466.1637615f),  /* A# */
+    float2fixed(493.8833013f),  /* etc... */
+    float2fixed(523.2511306f),
+    float2fixed(554.3652620f),
+    float2fixed(587.3295358f),
+    float2fixed(622.2539674f),
+    float2fixed(659.2551138f),
+    float2fixed(698.4564629f),
+    float2fixed(739.9888454f),
+    float2fixed(783.9908720f),
+    float2fixed(830.6093952f),
+};
+/* logarithm of all the notes of the scale */
+static const fixed lfreqs[12] =
+{
+    float2fixed(8.781359714f),
+    float2fixed(8.864693047f),
+    float2fixed(8.948026380f),
+    float2fixed(9.031359714f),
+    float2fixed(9.114693047f),
+    float2fixed(9.198026380f),
+    float2fixed(9.281359714f),
+    float2fixed(9.364693047f),
+    float2fixed(9.448026380f),
+    float2fixed(9.531359714f),
+    float2fixed(9.614693047f),
+    float2fixed(9.698026380f),
+};
+
+/* GUI */
+static unsigned back_color, front_color;            
+static int font_w, font_h;
+static int bar_x_minus_50, bar_x_minus_20, bar_x_0, bar_x_20, bar_x_50;
+static int letter_y;     /* y of the notes letters */
+static int note_bar_y;   /* y of the yellow bars (under the notes) */
+static int bar_h;        /* height of the yellow (note) and red (error) bars */
+static int freq_y;       /* y of the line with the frequency */
+static int error_ticks_y; /* y of the error values (-50, -20, ...) */
+static int error_hline_y; /* y of the top line for error bar */
+static int error_hline_y2;/* y of the bottom line for error bar */
+static int error_bar_y;   /* y of the error bar */
+static int error_bar_margin; /* distance between the error bar and the hline  */
+
+static const char *english_notes[12] = {"A","A#","B","C","C#","D","D#","E",
+                                        "F","F#", "G", "G#"};
+static const char gui_letters[8] = {'A', 'B', 'C', 'D', 'E', 'F', 'G', '#'};
+static const char **notes = english_notes;
+
+/*Settings for the plugin */
+
+struct tuner_settings
+{
+    unsigned volume_threshold;
+    unsigned record_gain;
+    unsigned sample_size;
+    unsigned lowest_freq;
+    unsigned yin_threshold;
+} tuner_settings;
+
+/*=================================================================*/
+/* MENU                                                            */
+/*=================================================================*/
+
+/* Keymaps */
+const struct button_mapping* plugin_contexts[]={
+    generic_actions,
+    generic_increase_decrease,
+    generic_directions,
+#if NB_SCREENS == 2
+    remote_directions
+#endif
+};
+#define PLA_ARRAY_COUNT sizeof(plugin_contexts)/sizeof(plugin_contexts[0])
+
+fixed yin_threshold_table[] =
+{
+    float2fixed(0.01),
+    float2fixed(0.02),
+    float2fixed(0.03),
+    float2fixed(0.04),
+    float2fixed(0.05),
+    float2fixed(0.10),
+    float2fixed(0.15),
+    float2fixed(0.20),
+    float2fixed(0.25),
+    float2fixed(0.30),
+    float2fixed(0.35),
+    float2fixed(0.40),
+    float2fixed(0.45),
+    float2fixed(0.50),
+};
+
+#define DEFAULT_YIN_THRESHOLD 5  /* 0.10 */
+
+/* Option strings */
+static const struct opt_items yin_threshold_text[] = 
+{
+    { "0.01", -1 },
+    { "0.02", -1 },
+    { "0.03", -1 },
+    { "0.04", -1 },
+    { "0.05", -1 },
+    { "0.10", -1 },
+    { "0.15", -1 },
+    { "0.20", -1 },
+    { "0.25", -1 },
+    { "0.30", -1 },
+    { "0.35", -1 },
+    { "0.40", -1 },
+    { "0.45", -1 },
+    { "0.50", -1 },
+};
+
+void set_min_freq(int new_freq)
+{
+    tuner_settings.sample_size = freq2period(new_freq) * 4;
+
+    /* clamp the sample size between min and max */
+    if(tuner_settings.sample_size <= SAMPLE_SIZE_MIN)
+        tuner_settings.sample_size = SAMPLE_SIZE_MIN;
+    else if(tuner_settings.sample_size >= BUFFER_SIZE)
+        tuner_settings.sample_size = BUFFER_SIZE;
+    /* sample size must be divisible by 4 */
+    else if(tuner_settings.sample_size % 4 != 0)
+        tuner_settings.sample_size += 4 - (tuner_settings.sample_size % 4);
+}
+
+bool main_menu(void)
+{
+    int selection=0;
+    bool done = false;
+    bool exit_tuner=false;
+    int choice;
+
+    MENUITEM_STRINGLIST(menu,"Tuner Settings",NULL,
+                        "Return to Tuner",
+                        "Volume Threshold",
+                        "Listening Volume",
+                        "Lowest Frequency",
+                        "Algorithm Pickiness",
+                        "Quit");
+
+    while(!done)
+    {
+        choice = rb->do_menu(&menu, &selection, NULL, false);
+        switch(choice)
+        {
+            case 1:
+                rb->set_int("Volume Threshold", "%", UNIT_INT,
+                               &tuner_settings.volume_threshold,
+                               NULL, 5, 5, 95, NULL);
+                break;
+            case 2:
+                rb->set_int("Listening Volume", "%", UNIT_INT,
+                               &tuner_settings.record_gain,
+                               NULL, 1, rb->sound_min(SOUND_MIC_GAIN), 
+                               rb->sound_max(SOUND_MIC_GAIN), NULL);
+                break;
+            case 3:
+                rb->set_int("Lowest Frequency", "Hz", UNIT_INT,
+                               &tuner_settings.lowest_freq, set_min_freq, 1,
+                               /* Range depends on the size of the buffer */
+                               SAMPLE_RATE / (BUFFER_SIZE / 4), 
+                               SAMPLE_RATE / (SAMPLE_SIZE_MIN / 4), NULL);
+                break;
+            case 4:
+                rb->set_option(
+                    "Algorithm Pickiness (Lower -> more discriminating)",
+                    &tuner_settings.yin_threshold,
+                    INT, yin_threshold_text, 
+                    sizeof(yin_threshold_text) / 
+                    sizeof(yin_threshold_text[0]), 
+                    NULL);
+                break;
+            case 5:
+                exit_tuner = true;
+                done = true;
+                break;
+            case 0:
+            default: /* Return to the tuner */
+                done = true;
+                break;
+
+        }
+    }
+    return(exit_tuner);
+}
+
+/*=================================================================*/
+/* Settings loading and saving(adapted from the clock plugin)      */
+/*=================================================================*/
+
+#define SETTINGS_FILENAME PLUGIN_APPS_DIR "/.pitch_settings"
+
+enum message
+{
+    MESSAGE_LOADING,
+    MESSAGE_LOADED,
+    MESSAGE_ERRLOAD,
+    MESSAGE_SAVING,
+    MESSAGE_SAVED,
+    MESSAGE_ERRSAVE
+};
+
+enum settings_file_status
+{
+    LOADED, ERRLOAD,
+    SAVED, ERRSAVE
+};
+
+/* The settings as they exist on the hard disk, so that 
+ * we can know at saving time if changes have been made */
+struct tuner_settings hdd_tuner_settings;
+
+/*---------------------------------------------------------------------*/
+
+bool settings_needs_saving(struct tuner_settings* settings)
+{
+    return(rb->memcmp(settings, &hdd_tuner_settings, sizeof(*settings)));
+}
+
+/*---------------------------------------------------------------------*/
+
+void tuner_settings_reset(struct tuner_settings* settings)
+{
+    settings->volume_threshold = VOLUME_THRESHOLD;
+    settings->record_gain = rb->global_settings->rec_mic_gain;
+    settings->sample_size = BUFFER_SIZE;
+    settings->lowest_freq = period2freq(BUFFER_SIZE / 4);
+    settings->yin_threshold = DEFAULT_YIN_THRESHOLD;
+}
+
+/*---------------------------------------------------------------------*/
+
+enum settings_file_status tuner_settings_load(struct tuner_settings* settings,
+                                              char* filename)
+{
+    int fd = rb->open(filename, O_RDONLY);
+    if(fd >= 0){ /* does file exist? */
+        /* basic consistency check */
+        if(rb->filesize(fd) == sizeof(*settings)){
+            rb->read(fd, settings, sizeof(*settings));
+            rb->close(fd);
+            rb->memcpy(&hdd_tuner_settings, settings, sizeof(*settings));
+            return(LOADED);
+        }
+    }
+    /* Initializes the settings with default values at least */
+    tuner_settings_reset(settings);
+    return(ERRLOAD);
+}
+
+/*---------------------------------------------------------------------*/
+
+enum settings_file_status tuner_settings_save(struct tuner_settings* settings,
+                                              char* filename)
+{
+    int fd = rb->creat(filename);
+    if(fd >= 0){ /* does file exist? */
+        rb->write (fd, settings, sizeof(*settings));
+        rb->close(fd);
+        return(SAVED);
+    }
+    return(ERRSAVE);
+}
+
+/*---------------------------------------------------------------------*/
+
+void load_settings(void)
+{
+    tuner_settings_load(&tuner_settings, SETTINGS_FILENAME);
+
+    rb->storage_sleep();
+}
+
+/*---------------------------------------------------------------------*/
+
+void save_settings(void)
+{
+    if(!settings_needs_saving(&tuner_settings))
+        return;
+
+    tuner_settings_save(&tuner_settings, SETTINGS_FILENAME);
+}
+
+/*=================================================================*/
+/* Binary Log                                                      */
+/*=================================================================*/
+
+/* Fixed-point log base 2*/
+/* Adapted from python code at 
+   http://en.wikipedia.org/wiki/Binary_logarithm#Algorithm
+*/
+fixed log(fixed inp)
+{
+    fixed x = inp;
+    fixed fp = int2fixed(1);
+    fixed res = int2fixed(0);
+ 
+    if(fp_lte(x, FP_ZERO))
+    {
+        return FP_MIN;
+    }
+
+    /* Integer part*/
+    /* while x<1 */
+    while(fp_lt(x, int2fixed(1)))
+    {
+        res = fp_sub(res, int2fixed(1));
+        x = fp_shl(x, 1);
+    }
+    /* while x>=2 */
+    while(fp_gte(x, int2fixed(2)))
+    {
+        res = fp_add(res, int2fixed(1));
+        x = fp_shr(x, 1);
+    }
+
+    /* Fractional part */
+    /* while fp > 0 */
+    while(fp_gt(fp, FP_ZERO))
+    {
+        fp = fp_shr(fp, 1);
+        x = fp_mul(x, x);
+        /* if x >= 2 */
+        if(fp_gte(x, int2fixed(2)))
+        {
+            x = fp_shr(x, 1);
+            res = fp_add(res, fp);
+        }
+    }
+
+    return res;
+}
+
+/*=================================================================*/
+/* GUI Stuff                                                       */
+/*=================================================================*/
+
+/* The function name is pretty self-explaining ;) */
+void print_int_xy(int x, int y, int v)
+{
+    char temp[20];
+    
+    rb->lcd_set_foreground(front_color);
+    rb->snprintf(temp,20,"%d",v);
+    rb->lcd_putsxy(x,y,temp);
+    rb->lcd_update();
+}
+
+/* Print out the frequency etc - will be removed later on */
+void print_str(char* s)
+{
+    rb->lcd_set_foreground(front_color);
+    rb->lcd_putsxy(0, freq_y, s);
+    rb->lcd_update();
+}
+
+/* What can I say? Read the function name... */
+void print_char_xy(int x, int y, char c)
+{
+    char temp[2];
+    
+    temp[0]=c;
+    temp[1]=0;
+    rb->lcd_set_foreground(front_color);
+    
+    rb->lcd_putsxy(x, y, temp);
+}
+
+/* Draw the red bar and the white lines */
+void draw_bar(fixed wrong_by_cents)
+{ 
+#ifdef HAVE_LCD_COLOR
+    rb->lcd_set_foreground(LCD_RGBPACK(255,0,0));   /* Color screens */
+#elif LCD_DEPTH > 1
+    rb->lcd_set_foreground(LCD_DARKGRAY);           /* Greyscale screens */
+#else
+    rb->lcd_set_foreground(LCD_BLACK);      /* Black and white screens */
+#endif
+
+    if (fp_gt(wrong_by_cents, FP_ZERO))
+    {
+        rb->lcd_fillrect(bar_x_0, error_bar_y, 
+            fixed2int(fp_mul(wrong_by_cents, LCD_FACTOR)), bar_h);
+    }
+    else
+    {
+        rb->lcd_fillrect(bar_x_0 + fixed2int(fp_mul(wrong_by_cents,LCD_FACTOR)),
+                         error_bar_y,
+                         fixed2int(fp_mul(wrong_by_cents, LCD_FACTOR)) * -1, 
+                         bar_h);
+    }
+#ifdef HAVE_LCD_COLOR
+    rb->lcd_set_foreground(LCD_RGBPACK(255,255,255));   /* Color screens */
+#elif LCD_DEPTH > 1
+    rb->lcd_set_foreground(LCD_BLACK);      /* Greyscale screens */
+#else
+    rb->lcd_set_foreground(LCD_BLACK);      /* Black and white screens */
+#endif
+
+    rb->lcd_hline(0,LCD_WIDTH-1, error_hline_y);
+    rb->lcd_hline(0,LCD_WIDTH-1, error_hline_y2);
+    rb->lcd_vline(LCD_WIDTH / 2, error_hline_y, error_hline_y2);
+    
+    print_int_xy(bar_x_minus_50    , error_ticks_y, -50);
+    print_int_xy(bar_x_minus_20    , error_ticks_y, -20);
+    print_int_xy(bar_x_0           , error_ticks_y,   0);
+    print_int_xy(bar_x_20          , error_ticks_y,  20);
+    print_int_xy(bar_x_50          , error_ticks_y,  50);
+}
+
+/* Print the letters A-G and the # on the screen */
+void draw_letters(void)
+{
+    int i;
+
+    rb->lcd_set_foreground(front_color);
+    
+    for (i=0; i<8; i++)
+    {
+        print_char_xy(i*(LCD_WIDTH / 8 ) + font_w, letter_y, gui_letters[i]);
+    }
+}
+
+/* Draw the yellow point(s) below the letters and the '#' */
+void draw_points(const char *s)
+{
+    int i;
+    
+    i = s[0]-'A';
+#ifdef HAVE_LCD_COLOR
+    rb->lcd_set_foreground(LCD_RGBPACK(255,255,0));     /* Color screens */
+#elif LCD_DEPTH > 1
+    rb->lcd_set_foreground(LCD_DARKGRAY);           /* Grey screens */
+#else
+    rb->lcd_set_foreground(LCD_BLACK);      /* Black and White screens */
+#endif
+    
+    rb->lcd_fillrect(i*(LCD_WIDTH / 8 ) + font_w, note_bar_y, font_w, font_h);
+    
+    if (s[1] == '#')
+        rb->lcd_fillrect(7*(LCD_WIDTH / 8 ) + font_w, note_bar_y, font_w, font_h);
+}
+
+/* Calculate how wrong the note is and draw the GUI */
+void display_frequency (fixed freq)                    
+{                                                     
+    fixed ldf, mldf;
+    fixed lfreq, nfreq;
+    int i, note = 0;
+    bool draw_freq;
+    char str_buf[30];
+
+    if (fp_lt(freq, FP_LOW))
+        freq = FP_LOW;
+    lfreq = log(freq);
+
+    /* Get the frequency to within the range of our reference table */
+    while (fp_lt(lfreq, fp_sub(lfreqs[0], fp_shr(LOG_D_NOTE, 1))))
+        lfreq = fp_add(lfreq, LOG_2);
+    while (fp_gte(lfreq, fp_sub(fp_add(lfreqs[0], LOG_2), 
+           fp_shr(LOG_D_NOTE, 1))))
+        lfreq = fp_sub(lfreq, LOG_2);
+    mldf = LOG_D_NOTE;
+    for (i=0; i<12; i++) 
+    {
+        ldf = fp_gt(fp_sub(lfreq,lfreqs[i]), FP_ZERO) ? 
+                 fp_sub(lfreq,lfreqs[i]) : fp_neg(fp_sub(lfreq,lfreqs[i]));
+        if (fp_lt(ldf, mldf)) 
+        {
+              mldf = ldf;
+              note = i;
+        }
+    }
+    nfreq = freqs[note];
+    while (fp_gt(fp_div(nfreq, freq), D_NOTE_SQRT)) 
+        nfreq = fp_shr(nfreq, 1);
+    while (fp_gt(fp_div(freq, nfreq), D_NOTE_SQRT))
+    {
+        nfreq = fp_shl(nfreq, 1);
+    }
+    
+    ldf=fp_mul(int2fixed(1200), log(fp_div(freq,nfreq)));
+
+    draw_freq = (fp_round(freq) != 0);
+    if (draw_freq)
+    { 
+        rb->snprintf(str_buf,30, "%s : %d cents (%d.%dHz)", 
+                     notes[note], fp_round(ldf) ,fixed2int(freq),
+                     fp_round(fp_mul(fp_frac(freq), 
+                                     int2fixed(DISPLAY_HZ_PRECISION))));
+    }
+    else
+    {
+        ldf = FP_ZERO;      /* prevents red bar at -32 cents when freq= 0*/
+    }
+
+    rb->lcd_clear_display();
+    draw_bar(ldf);                /* The red bar */
+    draw_letters();               /* The A-G letters and the # */
+    if (draw_freq)
+    {
+        draw_points(notes[note]);     /* The yellow point(s) */
+        print_str(str_buf);
+    }
+    rb->lcd_update();
+}
+
+/*-----------------------------------------------------------------------
+ * Functions for the Yin algorithm                                       
+ *                                                                       
+ * These were all adapted from the versions in Aubio v0.3.2                              
+ * Here's what the Aubio documentation has to say:
+ *
+ * This algorithm was developped by A. de Cheveigne and H. Kawahara and
+ * published in:
+ * 
+ * de Cheveign?, A., Kawahara, H. (2002) "YIN, a fundamental frequency
+ * estimator for speech and music", J. Acoust. Soc. Am. 111, 1917-1930.  
+ *
+ * see http://recherche.ircam.fr/equipes/pcm/pub/people/cheveign.html
+-------------------------------------------------------------------------*/
+
+/* Find the index of the minimum element of an array of floats */
+unsigned vec_min_elem(fixed *s, unsigned buflen) 
+{
+    unsigned j, pos=0.0f;
+    fixed tmp = s[0];
+    for (j=0; j < buflen; j++) 
+    {
+        if(fp_gt(tmp, s[j]))
+        {
+            pos = j;
+            tmp = s[j];
+        }
+    }
+    return pos;
+}
+
+
+fixed aubio_quadfrac(fixed s0, fixed s1, fixed s2, fixed pf) 
+{
+    /* Original floating point version: */
+    /* tmp = s0 + (pf/2.0f) * (pf * ( s0 - 2.0f*s1 + s2 ) - 
+             3.0f*s0 + 4.0f*s1 - s2);*/
+    /* Converted to explicit operator precedence: */
+    /* tmp = s0 + ((pf/2.0f) * ((((pf * ((s0 - (2*s1)) + s2)) - 
+            (3*s0)) + (4*s1)) - s2)); */
+
+    /* I made it look like this so I could easily track the precedence and */
+    /* make sure it matched the original expression                        */
+    /* Oy, this is when I really wish I could do C++ operator overloading  */
+    fixed tmp = fp_add
+                (
+                  s0,
+                  fp_mul
+                  (
+                    fp_shr(pf, 1),
+                    fp_sub
+                    (
+                      fp_add
+                      (
+                        fp_sub
+                        (
+                          fp_mul
+                          (
+                            pf,
+                            fp_add
+                            (
+                              fp_sub
+                              (
+                                s0,
+                                fp_shl(s1, 1)
+                              ),
+                              s2 
+                            )
+                          ),
+                          fp_mul
+                          (
+                            float2fixed(3.0f),
+                            s0
+                          )
+                        ),
+                        fp_shl(s1, 2)
+                      ),
+                      s2
+                    )
+                  )
+                );
+    return tmp;
+}
+
+#define QUADINT_STEP float2fixed(1.0f/200.0f)
+
+fixed vec_quadint_min(fixed *x, unsigned bufsize, unsigned pos, unsigned span)
+{
+    fixed res, frac, s0, s1, s2;
+    fixed exactpos = int2fixed(pos);
+    /* init resold to something big (in case x[pos+-span]<0)) */
+    fixed resold = FP_MAX;
+
+    if ((pos > span) && (pos < bufsize-span)) 
+    {
+        s0 = x[pos-span];
+        s1 = x[pos]     ;
+        s2 = x[pos+span];
+        /* increase frac */
+        for (frac = float2fixed(0.0f); 
+             fp_lt(frac, float2fixed(2.0f)); 
+             frac = fp_add(frac, QUADINT_STEP)) 
+        {
+            res = aubio_quadfrac(s0, s1, s2, frac);
+            if (fp_lt(res, resold)) 
+            {
+                resold = res;
+            } 
+            else 
+            {   
+                /* exactpos += (frac-QUADINT_STEP)*span - span/2.0f; */
+                exactpos = fp_add(exactpos, 
+                                  fp_sub(
+                                    fp_mul(
+                                      fp_sub(frac, QUADINT_STEP),
+                                      int2fixed(span)
+                                    ),
+                                    int2fixed(span)
+                                  )
+                                 );
+                break;
+            }
+        }
+    }
+    return exactpos;
+}
+
+
+/* Calculate the period of the note in the 
+     buffer using the YIN algorithm */
+/* The yin pointer is just a buffer that the algorithm uses as a work
+     space.  It needs to be half the length of the input buffer. */
+
+fixed pitchyin(audio_sample_type *input, fixed *yin)
+{
+    fixed retval;
+    unsigned j,tau = 0;
+    int period;
+    unsigned yin_size = tuner_settings.sample_size / 4;
+
+    fixed tmp = FP_ZERO, tmp2 = FP_ZERO;
+    yin[0] = int2fixed(1);
+    for (tau = 1; tau < yin_size; tau++)
+    {
+        yin[tau] = FP_ZERO;
+        for (j = 0; j < yin_size; j++)
+        {
+            tmp = fp_sub(int2mantissa(input[2 * j]), 
+                         int2mantissa(input[2 * (j + tau)]));
+            yin[tau] = fp_add(yin[tau], fp_mul(tmp, tmp));
+        }
+        tmp2 = fp_add(tmp2, yin[tau]);
+        if(!fp_equal(tmp2, FP_ZERO))
+        {
+            yin[tau] = fp_mul(yin[tau], fp_div(int2fixed(tau), tmp2));
+        }
+        period = tau - 3;
+        if(tau > 4 && fp_lt(yin[period], 
+                            yin_threshold_table[tuner_settings.yin_threshold])
+                   && fp_lt(yin[period], yin[period+1]))
+        {
+            retval = vec_quadint_min(yin, yin_size, period, 1);
+            return retval;
+        }
+    }
+    retval =  vec_quadint_min(yin, yin_size, 
+                             vec_min_elem(yin, yin_size), 1);
+    return retval;
+    /*return FP_ZERO;*/
+}
+
+/*-----------------------------------------------------------------*/
+
+uint32_t buffer_magnitude(audio_sample_type *input)
+{
+    unsigned n;
+    uint64_t tally = 0;
+
+    /* Operate on only one channel of the stereo signal */
+    for(n = 0; n < tuner_settings.sample_size; n+=2)
+    {
+        tally += (uint64_t)input[n] * (uint64_t)input[n];
+    }
+
+    tally /= tuner_settings.sample_size / 2;
+
+    /* now tally holds the average of the squares of all the samples */
+    /* It must be between 0 and 0x7fff^2, so it fits in 32 bits      */
+    return (uint32_t)tally;
+}
+
+/* Stop the recording when the buffer is full */
+int recording_callback(int status)
+{
+    (void) status;
+    
+    rb->pcm_stop_recording();
+    recording=0;
+    return -1;  
+}
+
+/* The main program loop */
+void record_and_get_pitch(void)
+{
+    int quit=0, button;
+    bool redraw = true;
+    /* For tracking the latency */
+    /*
+    long timer;
+    char debug_string[20];
+    */
+    fixed period;
+    bool waiting = false;
+
+    while(!quit) 
+    {
+                                        /* Start recording */
+        rb->pcm_record_data(recording_callback, (void *) audio_data, 
+                            (size_t) tuner_settings.sample_size * 
+                                     sizeof(audio_sample_type));
+        recording=1;    
+        
+        while (recording && !quit)      /* wait for the buffer to be filled */
+        {        
+            rb->yield();
+            button=pluginlib_getaction(0, plugin_contexts, PLA_ARRAY_COUNT);
+            switch(button) 
+            {
+                case PLA_QUIT:
+                    quit=true;
+                    rb->yield();
+                    break;
+                
+                case PLA_MENU:
+                    if(main_menu())
+                        quit=true;
+                    rb->yield();
+                    redraw = true;
+                    break;
+                
+                default:
+                    rb->yield();
+                
+                break;
+            }
+        } 
+        
+        /* Let's keep track of how long this takes */
+        /* timer = *(rb->current_tick); */
+
+        if(!quit)
+        {
+            /* Only do the heavy lifting if the volume is high enough */
+            if(buffer_magnitude(audio_data) > 
+                sqr(tuner_settings.volume_threshold * 
+                    rb->sound_max(SOUND_MIC_GAIN)))
+            {
+                if(waiting)
+                {
+    #ifdef HAVE_ADJUSTABLE_CPU_FREQ
+                    rb->cpu_boost(true);
+    #endif
+                    waiting = false;
+                }
+                
+                rb->backlight_on();
+                redraw = false;
+
+                /* This returns the period of the detected pitch in samples */
+                period = pitchyin(audio_data, yin_buffer);
+                /* Hz = sample rate / period */
+                if(fp_gt(period, FP_ZERO))
+                {
+                    display_frequency(fp_period2freq(period));
+                }
+                else 
+                {
+                    display_frequency(FP_ZERO);
+                }
+            }
+            else if(redraw || !waiting)
+            {
+                waiting = true;
+                redraw = false;
+    #ifdef HAVE_ADJUSTABLE_CPU_FREQ
+                rb->cpu_boost(false);
+    #endif
+                /*rb->backlight_off();*/
+                display_frequency(FP_ZERO);
+            }
+
+            /*rb->snprintf(debug_string, 20, "%x,%x", 
+                           audio_data[50], audio_data[52]);
+            rb->lcd_putsxy(0, 40, debug_string);
+            rb->lcd_update();
+            */
+
+            /* Print out how long it took to find the pitch */
+            /*
+            rb->snprintf(debug_string, 20, "latency: %ld", 
+                         *(rb->current_tick) - timer);
+            rb->lcd_putsxy(0, 40, debug_string);
+            rb->lcd_update();
+            */
+        }
+    }
+    rb->pcm_close_recording();
+#ifdef HAVE_ADJUSTABLE_CPU_FREQ
+    rb->cpu_boost(false);
+#endif
+}
+
+/* Init recording, tuning, and GUI */
+void init_everything(void)
+{    
+    load_settings();
+
+    /* --------- Init the audio recording ----------------- */
+    rb->audio_set_output_source(AUDIO_SRC_PLAYBACK);  
+    rb->audio_set_input_source(INPUT_TYPE, SRCF_RECORDING); 
+
+    /* set to maximum gain */
+    rb->audio_set_recording_gain(tuner_settings.record_gain,
+                                 tuner_settings.record_gain, 
+                                 AUDIO_GAIN_MIC);
+
+    rb->pcm_set_frequency(SAMPLE_RATE);
+    rb->pcm_apply_settings();
+    
+    rb->pcm_init_recording();
+    
+    /* GUI */
+    back_color  = rb->lcd_get_background();
+    front_color = rb->lcd_get_foreground();
+    rb->lcd_getstringsize("X", &font_w, &font_h);
+    
+    bar_x_minus_50 = 0;
+    bar_x_minus_20 = (LCD_WIDTH / 2) - 
+                     fixed2int(fp_mul(LCD_FACTOR, int2fixed(20))) - font_w;
+    bar_x_0  = LCD_WIDTH / 2; 
+    bar_x_20 = (LCD_WIDTH / 2) + 
+               fixed2int(fp_mul(LCD_FACTOR, int2fixed(20))) - font_w; 
+    bar_x_50 = LCD_WIDTH - 2 * font_w;
+    
+    letter_y = 10;
+    note_bar_y = letter_y + font_h;
+    bar_h = font_h;
+    freq_y = note_bar_y + bar_h + 3;
+    error_ticks_y = freq_y + font_h + 8;
+    error_hline_y = error_ticks_y + font_h + 2;
+    error_bar_margin = 2;
+    error_bar_y = error_hline_y + error_bar_margin;
+    error_hline_y2 = error_bar_y + bar_h + error_bar_margin;
+}
+
+
+enum plugin_status plugin_start(const void* parameter) NO_PROF_ATTR
+{
+    (void)parameter;
+  
+    init_everything();
+    record_and_get_pitch();
+    save_settings();
+
+    return 0;
+}
diff --git a/docs/CREDITS b/docs/CREDITS
index 46a555b681..9066778249 100644
--- a/docs/CREDITS
+++ b/docs/CREDITS
@@ -492,6 +492,7 @@ Johannes Boy
 Jason Yu
 Aaron DeMille
 Tomasz Kowalczyk
+Michael Lechner
 
 The libmad team
 The wavpack team