diff --git a/rtmp/rtmp.go b/rtmp/rtmp.go
index 7f330aac..97a07498 100644
--- a/rtmp/rtmp.go
+++ b/rtmp/rtmp.go
@@ -48,6 +48,7 @@ import (
 	"strconv"
 	"unsafe"
 	_"fmt"
+	"math"
 )
 
 const (
@@ -83,7 +84,7 @@ func NewSession(url string, connectTimeout uint) Session {
 func AVC(str string) C.AVal {
 	var aval C.AVal
 	aval.av_val = C.CString(str)
-	aval.av_len = C.int(unsafe.Sizeof(aval.av_val)-1)
+	aval.av_len = C.int(len(str))
 	return aval
 }
 
@@ -119,6 +120,14 @@ func (s *session) Write(data []byte) (int, error) {
 	return len(data), nil
 }
 
+const (
+			RTMP_PACKET_SIZE_LARGE = 0
+			RTMP_PACKET_SIZE_MEDIUM = 1
+			RTMP_PACKET_SIZE_SMALL = 2
+			RTMP_PACKET_TYPE_INFO = 0x12
+			RTMP_PACKET_TYPE_AUDIO = 0x08
+			RTMP_PACKET_TYPE_VIDEO = 0x09
+)
 func rtmpWrite(r *C.RTMP, data []byte) int {
 	buf := (*C.char)(unsafe.Pointer(&data[0]))
 	var pkt = &r.m_write
@@ -150,21 +159,21 @@ func rtmpWrite(r *C.RTMP, data []byte) int {
 			buf = (*C.char)(unsafe.Pointer(uintptr(unsafe.Pointer(buf)) + uintptr(3)))
 			pkt.m_nTimeStamp = C.AMF_DecodeInt24(buf)
 			buf = (*C.char)(unsafe.Pointer(uintptr(unsafe.Pointer(buf)) + uintptr(3)))
-			pkt.m_nTimeStamp |= C.uint(*(*byte)(unsafe.Pointer(buf)) << 24)
+			pkt.m_nTimeStamp |= C.uint(*((*byte)(unsafe.Pointer(buf)))) << 24
 			buf = (*C.char)(unsafe.Pointer(uintptr(unsafe.Pointer(buf)) + uintptr(4)))
 			s2 -= 11
 
-			if ((pkt.m_packetType == C.RTMP_PACKET_TYPE_AUDIO ||
-				pkt.m_packetType == C.RTMP_PACKET_TYPE_VIDEO) &&
-				pkt.m_nTimeStamp == 0) || pkt.m_packetType == C.RTMP_PACKET_TYPE_INFO {
+			if ((pkt.m_packetType == RTMP_PACKET_TYPE_AUDIO ||
+				pkt.m_packetType == RTMP_PACKET_TYPE_VIDEO) &&
+				pkt.m_nTimeStamp == 0) || pkt.m_packetType == RTMP_PACKET_TYPE_INFO {
 
-				pkt.m_headerType = C.RTMP_PACKET_SIZE_LARGE
+				pkt.m_headerType = RTMP_PACKET_SIZE_LARGE
 
-				if pkt.m_packetType == C.RTMP_PACKET_TYPE_INFO {
+				if pkt.m_packetType == RTMP_PACKET_TYPE_INFO {
 					pkt.m_nBodySize += 16
 				}
 			} else {
-				pkt.m_headerType = C.RTMP_PACKET_SIZE_MEDIUM
+				pkt.m_headerType = RTMP_PACKET_SIZE_MEDIUM
 			}
 
 			if int(C.RTMPPacket_Alloc(pkt, pkt.m_nBodySize)) == 0 {
@@ -176,10 +185,10 @@ func rtmpWrite(r *C.RTMP, data []byte) int {
 			pend = (*C.char)(unsafe.Pointer(uintptr(unsafe.Pointer(enc)) +
 				uintptr(pkt.m_nBodySize)))
 
-			if pkt.m_packetType == C.RTMP_PACKET_TYPE_INFO {
+			if pkt.m_packetType == RTMP_PACKET_TYPE_INFO {
 				enc = C.AMF_EncodeString(enc, pend, &av_setDataFrame)
-				pkt.m_nBytesRead = (C.uint)(uintptr(unsafe.Pointer(enc)) -
-					uintptr(unsafe.Pointer(pkt.m_body)))
+				pkt.m_nBytesRead = C.uint(math.Abs(float64(uintptr(unsafe.Pointer(enc)) -
+					uintptr(unsafe.Pointer(pkt.m_body)))))
 			}
 		} else {
 			enc = (*C.char)(unsafe.Pointer(uintptr(unsafe.Pointer(pkt.m_body)) +