Add debug log to cosmoaudio and add examples

examples/loudness.c

@@ -0,0 +1,133 @@
+#if 0
+/*─────────────────────────────────────────────────────────────────╗
+│ To the extent possible under law, Justine Tunney has waived      │
+│ all copyright and related or neighboring rights to this file,    │
+│ as it is written in the following disclaimers:                   │
+│   • http://unlicense.org/                                        │
+│   • http://creativecommons.org/publicdomain/zero/1.0/            │
+╚─────────────────────────────────────────────────────────────────*/
+#endif
+#include <cosmoaudio.h>
+#include <math.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+
+/**
+ * @fileoverview prints ascii meter of microphone loudness
+ *
+ * 0. -60 dB is nearly silent, barely audible, even in a quiet room
+ * 1. -50 dB is very quiet background sounds
+ * 2. -40 dB is quiet ambient noise
+ * 3. -30 dB is clear but soft sounds
+ * 4. -20 dB is moderate volume, comfortable for extended listening
+ * 5. -10 dB is fairly loud, but not uncomfortable
+ * 6.  -6 dB is loud, but not at full volume
+ * 7.  -3 dB is very loud, approaching system limits
+ * 8.  -1 dB is extremely loud, just below maximum
+ * 9.  -0 dB is maximum volume without distortion
+ */
+
+#define SAMPLING_RATE     44100
+#define ASCII_METER_WIDTH 20
+#define FRAMES_PER_SECOND 30
+#define MIN_DECIBEL       -60
+#define MAX_DECIBEL       0
+#define DEBUG_LOG         1
+
+sig_atomic_t g_done;
+
+void on_signal(int sig) {
+  g_done = 1;
+}
+
+// computes root of mean squares
+double rms(float* p, int n) {
+  double s = 0;
+  for (int i = 0; i < n; ++i)
+    s += p[i] * p[i];
+  return sqrt(s / n);
+}
+
+// converts rms to decibel
+double rms_to_db(double rms) {
+  double db = 20 * log10(rms);
+  db = fmin(db, MAX_DECIBEL);
+  db = fmax(db, MIN_DECIBEL);
+  return db;
+}
+
+int main() {
+  signal(SIGINT, on_signal);
+
+  // how many samples should we process at once
+  int chunkFrames = SAMPLING_RATE / FRAMES_PER_SECOND;
+
+  // configure cosmo audio
+  struct CosmoAudioOpenOptions cao = {0};
+  cao.sizeofThis = sizeof(struct CosmoAudioOpenOptions);
+  cao.deviceType = kCosmoAudioDeviceTypeCapture;
+  cao.sampleRate = SAMPLING_RATE;
+  cao.bufferFrames = chunkFrames * 2;
+  cao.debugLog = DEBUG_LOG;
+  cao.channels = 1;
+
+  // connect to microphone
+  int status;
+  struct CosmoAudio* ca;
+  status = cosmoaudio_open(&ca, &cao);
+  if (status != COSMOAUDIO_SUCCESS) {
+    fprintf(stderr, "failed to open microphone: %d\n", status);
+    return 1;
+  }
+
+  // allocate memory for audio work area
+  float* chunk = malloc(chunkFrames * sizeof(float));
+  if (!chunk) {
+    fprintf(stderr, "out of memory\n");
+    return 1;
+  }
+
+  while (!g_done) {
+
+    // wait for full chunk of audio to become available
+    int need_in_frames = chunkFrames;
+    status = cosmoaudio_poll(ca, &need_in_frames, NULL);
+    if (status != COSMOAUDIO_SUCCESS) {
+      fprintf(stderr, "failed to poll microphone: %d\n", status);
+      return 2;
+    }
+
+    // read audio frames from microphone ring buffer
+    status = cosmoaudio_read(ca, chunk, chunkFrames);
+    if (status != chunkFrames) {
+      fprintf(stderr, "failed to read microphone: %d\n", status);
+      return 3;
+    }
+
+    // convert audio chunk to to ascii meter
+    char s[ASCII_METER_WIDTH + 1] = {0};
+    double db = rms_to_db(rms(chunk, chunkFrames));
+    double db_range = MAX_DECIBEL - MIN_DECIBEL;
+    int filled_length = (db - MIN_DECIBEL) / db_range * ASCII_METER_WIDTH;
+    for (int i = 0; i < ASCII_METER_WIDTH; ++i) {
+      if (i < filled_length) {
+        s[i] = '=';
+      } else {
+        s[i] = ' ';
+      }
+    }
+    printf("\r%s| %+6.2f dB", s, db);
+    fflush(stdout);
+  }
+  printf("\n");
+
+  // clean up resources
+  status = cosmoaudio_close(ca);
+  if (status != COSMOAUDIO_SUCCESS) {
+    fprintf(stderr, "failed to close microphone: %d\n", status);
+    return 5;
+  }
+  free(chunk);
+}