Author: Martin Guy <martinwguy@gmail.com>
Date:   Thu Jul 26 13:56:00 2012 +0200

    Remove upper limits on output image size
    
    This commit removes the upper limits of 8192x4096 pixels output image
    by allocating all memory dynamically and changing the square arrays to
    an array of pointers to arrays of pixels (the columns).
    This also reduces the memory consumption for smaller images, for example
    for 640x480 from 141MB to 14MB. Tested up to 10000 x 10000.

diff --git a/src/spectrogram.c b/src/spectrogram.c
index 5f72fab..6c04cbf 100644
--- a/src/spectrogram.c
+++ b/src/spectrogram.c
@@ -33,6 +33,7 @@
 #include <string.h>
 #include <stdbool.h>
 #include <math.h>
+#include <limits.h>
 
 #include <cairo.h>
 #include <fftw3.h>
@@ -44,8 +45,6 @@
 
 #define	MIN_WIDTH	640
 #define	MIN_HEIGHT	480
-#define	MAX_WIDTH	8192
-#define	MAX_HEIGHT	4096
 
 #define TICK_LEN			6
 #define	BORDER_LINE_WIDTH	1.8
@@ -182,18 +181,19 @@ read_mono_audio (SNDFILE * file, sf_count_t filelen, double * data, int datalen,
 static void
 apply_window (double * data, int datalen)
 {
-	static double window [10 * MAX_HEIGHT] ;
+	static double *window = NULL;
 	static int window_len = 0 ;
 	int k ;
 
 	if (window_len != datalen)
 	{
-		window_len = datalen ;
-		if (datalen > ARRAY_LEN (window))
+		window = realloc( window, datalen * sizeof(double) );
+		if (window == NULL)
 		{
-			printf ("%s : datalen >  MAX_HEIGHT\n", __func__) ;
+			printf ("%s : Not enough memory.\n", __func__) ;
 			exit (1) ;
 		} ;
+		window_len = datalen ;
 
 		calc_kaiser_window (window, datalen, 20.0) ;
 	} ;
@@ -205,7 +205,7 @@ apply_window (double * data, int datalen)
 } /* apply_window */
 
 static void
-render_spectrogram (cairo_surface_t * surface, double spec_floor_db, float mag2d [MAX_WIDTH][MAX_HEIGHT], double maxval, double left, double top, double width, double height, bool gray_scale)
+render_spectrogram (cairo_surface_t * surface, double spec_floor_db, float **mag2d, double maxval, double left, double top, double width, double height, bool gray_scale)
 {
 	unsigned char colour [3] = { 0, 0, 0 } ;
 	unsigned char *data ;
@@ -489,10 +489,10 @@ interp_spec (float * mag, int maglen, const double *spec, int speclen)
 static void
 render_to_surface (const RENDER * render, SNDFILE *infile, int samplerate, sf_count_t filelen, cairo_surface_t * surface)
 {
-	static double time_domain [10 * MAX_HEIGHT] ;
-	static double freq_domain [10 * MAX_HEIGHT] ;
-	static double single_mag_spec [5 * MAX_HEIGHT] ;
-	static float mag_spec [MAX_WIDTH][MAX_HEIGHT] ;
+	double * time_domain = NULL ;
+	double * freq_domain = NULL ;
+	double * single_mag_spec = NULL ;
+	float ** mag_spec = NULL ; // Indexed by [w][h]
 
 	fftw_plan plan ;
 	double max_mag = 0.0 ;
@@ -515,10 +515,22 @@ render_to_surface (const RENDER * render, SNDFILE *infile, int samplerate, sf_co
 	speclen = height * (samplerate / 20 / height + 1) ;
 	speclen += 0x40 - (speclen & 0x3f) ;
 
-	if (2 * speclen > ARRAY_LEN (time_domain))
-	{	printf ("%s : 2 * speclen > ARRAY_LEN (time_domain)\n", __func__) ;
+	time_domain     = calloc (2 * speclen, sizeof(double));
+	freq_domain     = calloc (2 * speclen, sizeof(double));
+	single_mag_spec = calloc (speclen, sizeof(double));
+	mag_spec        = calloc (width, sizeof(float *)); 
+	if ( time_domain == NULL || freq_domain == NULL ||
+	     single_mag_spec == NULL || mag_spec == NULL )
+	{	printf ("%s : Not enough memory.\n", __func__) ;
 		exit (1) ;
 		} ;
+	for (w = 0 ; w < width ; w++)
+	{
+		if ( (mag_spec[w] = calloc(height, sizeof(float))) == NULL )
+		{	printf ("%s : Not enough memory.\n", __func__) ;
+			exit (1) ;
+			} ;
+		};
 
 	plan = fftw_plan_r2r_1d (2 * speclen, time_domain, freq_domain, FFTW_R2HC, FFTW_MEASURE | FFTW_PRESERVE_INPUT) ;
 	if (plan == NULL)
@@ -542,6 +554,9 @@ render_to_surface (const RENDER * render, SNDFILE *infile, int samplerate, sf_co
 		} ;
 
 	fftw_destroy_plan (plan) ;
+	free (time_domain) ;
+	free (freq_domain) ;
+	free (single_mag_spec) ;
 
 	if (render->border)
 	{	RECT heat_rect ;
@@ -561,6 +576,10 @@ render_to_surface (const RENDER * render, SNDFILE *infile, int samplerate, sf_co
 	else
 		render_spectrogram (surface, render->spec_floor_db, mag_spec, max_mag, 0, 0, width, height, render->gray_scale) ;
 
+	for (w = 0 ; w < width ; w++)
+		free( mag_spec[w] );
+	free( mag_spec );
+
 	return ;
 } /* render_to_surface */
 
@@ -701,8 +720,8 @@ main (int argc, char * argv [])
 	render.height = atoi (argv [k + 2]) ;
 	render.pngfilepath = argv [k + 3] ;
 
-	check_int_range ("width", render.width, MIN_WIDTH, MAX_WIDTH) ;
-	check_int_range ("height", render.height, MIN_HEIGHT, MAX_HEIGHT) ;
+	check_int_range ("width", render.width, MIN_WIDTH, INT_MAX) ;
+	check_int_range ("height", render.height, MIN_HEIGHT, INT_MAX) ;
 
 
 	render.filename = strrchr (render.sndfilepath, '/') ;