Finish the code

1 files changed, 100 insertions, 14 deletions

diff --git a/dbmeasure.c b/dbmeasure.c
index f9140c8..2c40e9d 100644
--- a/dbmeasure.c
+++ b/dbmeasure.c
@@ -108,27 +108,50 @@ static double compute_level(const float *buffer, float *sum, unsigned n_samples,
         for (i = 0; i < n_samples; i++) {
                 sum[i] += buffer[i];
 
-                if (sum[i] > max)
-                        max = sum[i];
+                if (fabs(sum[i]) > max)
+                        max = fabs(sum[i]);
         }
 
         return max / (double) iteration;
 }
 
+static int prompt(const char *t) {
+        char r[64];
+        fputs(t, stderr);
+
+        if (!fgets(r, sizeof(r), stdin))
+                return 0;
+
+        return 1;
+}
+
+static double linear_to_dB(double f) {
+        return 20.0 * log10(f);
+}
+
 int main(int argc, char *argv[]) {
         int ret = 1;
-        float *signal = NULL, *silence = NULL, *buffer = NULL, *sum = NULL;
+        float *signal = NULL, *silence = NULL, *buffer = NULL, *sum = NULL, *current = NULL;
         snd_pcm_t *input = NULL, *output = NULL;
         unsigned rate = 44100;
         unsigned rindex = 0, windex = 0;
-        double frequency = 440.0, amplitude = 0.5;
+        double frequency = 440.0, amplitude = 0.5, noise_level_dB = -80.0, initial_level_max = 0.97, initial_level_min = 0.8, reference_level;
         unsigned iteration = 0;
         int icount, ocount;
         struct pollfd *pollfd;
         int e;
+        unsigned needed_iterations = 0;
+        int skip = 1;
+        FILE *log;
+        int level_count = 0;
+
+        if (argc < 3) {
+                fprintf(stderr, "Need to specify device and output log file.\n");
+                goto finish;
+        }
 
-        if (argc < 2) {
-                fprintf(stderr, "Need to specify device.\n");
+        if (!(log = fopen(argv[2], "w"))) {
+                fprintf(stderr, "Failed to open log file %s: %s\n", argv[2], strerror(errno));
                 goto finish;
         }
 
@@ -180,6 +203,12 @@ int main(int argc, char *argv[]) {
                 goto finish;
         }
 
+        current = silence;
+
+        prompt("Please set your control to the highest volume possible and press return.\n");
+
+        fprintf(stderr, "Measuring noise level.\n");
+
         for (;;) {
                 snd_pcm_sframes_t n;
                 unsigned short irevents, orevents;
@@ -202,9 +231,9 @@ int main(int argc, char *argv[]) {
                 }
 
                 if (orevents) {
-                        if ((n = snd_pcm_writei(output, signal + windex, rate - windex)) < 0) {
+                        if ((n = snd_pcm_writei(output, current + windex, rate - windex)) < 0) {
 
-                                if (snd_pcm_recover(output, n, 0) < 0) {
+                                if (snd_pcm_recover(output, n, 1) < 0) {
                                         fprintf(stderr, "Cannot write samples: %s\n", snd_strerror(n));
                                         goto finish;
                                 } else
@@ -220,7 +249,7 @@ int main(int argc, char *argv[]) {
                 if (irevents)  {
                         if ((n = snd_pcm_readi(input, buffer + rindex, rate - rindex)) < 0) {
 
-                                if (snd_pcm_recover(input, n, 0) < 0) {
+                                if (snd_pcm_recover(input, n, 1) < 0) {
                                         fprintf(stderr, "Cannot read samples: %s\n", snd_strerror(n));
                                         goto finish;
                                 }
@@ -235,13 +264,67 @@ int main(int argc, char *argv[]) {
 
                         rindex += n;
                         if (rindex == rate) {
-                                double level;
-
                                 rindex = 0;
 
-                                iteration++;
-                                level = compute_level(buffer, sum, rate, iteration);
-                                fprintf(stderr, "Iteration %u, level is %g.\n", iteration, level);
+                                if (skip)
+                                        skip = 0;
+                                else {
+                                        double level;
+
+                                        iteration++;
+                                        level = compute_level(buffer, sum, rate, iteration);
+                                        fprintf(stderr, "Iteration %u, level is %g (%g dB).\n", iteration, level, linear_to_dB(level));
+
+                                        if (needed_iterations == 0) {
+                                                if (linear_to_dB(level) < noise_level_dB) {
+                                                        fprintf(stderr, "%u iterations necessary to push noise level below %g dB\n", iteration, noise_level_dB);
+
+                                                        needed_iterations = iteration;
+                                                        current = signal;
+                                                        windex = 0;
+                                                        skip = 1;
+                                                        iteration = 0;
+                                                        memset(sum, 0, rate * sizeof(float));
+
+                                                        fprintf(stderr, "Generating signal.\n");
+                                                }
+                                        } else {
+
+                                                if (iteration >= needed_iterations) {
+
+                                                        if (level_count <= 0) {
+
+                                                                if (level < initial_level_min ||
+                                                                    level > initial_level_max) {
+                                                                        fprintf(stderr,
+                                                                                "Volume level measured (%g) was too high or too low.\n"
+                                                                                "Please adjust mixer so that initial level is between %g and %g.\n"
+                                                                                "Test run canceled.\n", level, initial_level_min, initial_level_max);
+                                                                        goto finish;
+                                                                }
+
+                                                                reference_level = level;
+                                                        }
+
+                                                        fprintf(log, "%i\t%g\t%g\t%g\t%g\n",
+                                                                level_count,
+                                                                level, linear_to_dB(level),
+                                                                level/reference_level, linear_to_dB(level/reference_level));
+
+                                                        fflush(log);
+
+                                                        level_count++;
+
+                                                        windex = 0;
+                                                        skip = 1;
+                                                        iteration = 0;
+                                                        memset(sum, 0, rate * sizeof(float));
+
+                                                        if (!(prompt("Please reduce volume by one step and press return. Press C-D when finished.\n")))
+                                                                break;
+                                                }
+                                        }
+                                }
                         }
                 }
         }
@@ -256,6 +339,9 @@ finish:
         if (output)
                 snd_pcm_close(output);
 
+        if (log)
+                fclose(log);
+
         free(signal);
         free(silence);
         free(buffer);