From c089980175afabdc7694c7829fe6334dc3df9311 Mon Sep 17 00:00:00 2001
From: Trek H <trek.hopton@gmail.com>
Date: Fri, 26 Apr 2019 20:28:53 +0930
Subject: [PATCH] adpcm: added function for calculating number of adpcm bytes
 output per given pcm bytes

---
 codec/adpcm/adpcm.go | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/codec/adpcm/adpcm.go b/codec/adpcm/adpcm.go
index f32c8875..58942f74 100644
--- a/codec/adpcm/adpcm.go
+++ b/codec/adpcm/adpcm.go
@@ -390,3 +390,10 @@ func (d *decoder) Write(inAdpcm []byte) (int, error) {
 
 	return n, nil
 }
+
+// BytesOutput will return the number of adpcm bytes that will be generated for the given pcm data
+func BytesOutput(pcm int) int {
+	// for X pcm bytes, 2 bytes are left uncompressed, the rest is compressed by a factor of 4
+	// and a start index and padding byte are added.
+	return (pcm-2)/4 + 2 + 1 + 1
+}