mic support

janus/src/au.c

@@ -37,10 +37,42 @@ void us_au_pcm_destroy(us_au_pcm_s *pcm) {
 	free(pcm);
 }
 
+void us_au_pcm_mix(us_au_pcm_s *dest, us_au_pcm_s *src) {
+	const uz size = src->frames * US_RTP_OPUS_CH * 2; // 2 for 16 bit
+	if (src->frames == 0) {
+		return;
+	} else if (dest->frames == 0) {
+		memcpy(dest->data, src->data, size);
+		dest->frames = src->frames;
+	} else if (dest->frames == src->frames) {
+		// https://stackoverflow.com/questions/12089662
+		for (uz index = 0; index < size; ++index) {
+			int a = dest->data[index];
+			int b = src->data[index];
+			int m;
+
+			a += 32768;
+			b += 32768;
+
+			if ((a < 32768) && (b < 32768)) {
+				m = a * b / 32768;
+			} else {
+				m = 2 * (a + b) - (a * b) / 32768 - 65536;
+			}
+			if (m == 65536) {
+				m = 65535;
+			}
+			m -= 32768;
+
+			dest->data[index] = m;
+		}
+	}
+}
+
 us_au_encoded_s *us_au_encoded_init(void) {
-    us_au_encoded_s *enc;
-    US_CALLOC(enc, 1);
-    return enc;
+	us_au_encoded_s *enc;
+	US_CALLOC(enc, 1);
+	return enc;
 }
 
 void us_au_encoded_destroy(us_au_encoded_s *enc) {