install go2rtc on bob

2026-04-04 19:36:14 +02:00
parent f0b56e63d1
commit ccf88187b8
537 changed files with 69213 additions and 0 deletions
@@ -0,0 +1,53 @@
+// Package pcm
+// https://www.codeproject.com/Articles/14237/Using-the-G711-standard
+package pcm
+
+const alawMax = 0x7FFF
+
+func PCMAtoPCM(alaw byte) int16 {
+	alaw ^= 0xD5
+
+	data := int16(((alaw & 0x0F) << 4) + 8)
+	exponent := (alaw & 0x70) >> 4
+
+	if exponent != 0 {
+		data |= 0x100
+	}
+
+	if exponent > 1 {
+		data <<= exponent - 1
+	}
+
+	// sign
+	if alaw&0x80 == 0 {
+		return data
+	} else {
+		return -data
+	}
+}
+
+func PCMtoPCMA(pcm int16) byte {
+	var alaw byte
+
+	if pcm < 0 {
+		pcm = -pcm
+		alaw = 0x80
+	}
+
+	if pcm > alawMax {
+		pcm = alawMax
+	}
+
+	exponent := byte(7)
+	for expMask := int16(0x4000); (pcm&expMask) == 0 && exponent > 0; expMask >>= 1 {
+		exponent--
+	}
+
+	if exponent == 0 {
+		alaw |= byte(pcm>>4) & 0x0F
+	} else {
+		alaw |= (exponent << 4) | (byte(pcm>>(exponent+3)) & 0x0F)
+	}
+
+	return alaw ^ 0xD5
+}