/*
 *
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 * Copyright (c) 1999-2001 Apple Computer, Inc.  All Rights Reserved. The
 * contents of this file constitute Original Code as defined in and are
 * subject to the Apple Public Source License Version 1.2 (the 'License').
 * You may not use this file except in compliance with the License.  Please
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 * read it before using this file.
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 * This Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
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// $Id: RTPMetaInfoPacket.h,v 1.3 2001/07/16 08:09:55 mythili Exp $
//
// RTPMetaInfoPacket.h:
//   Some defs for RTP-Meta-Info payloads. This class also parses RTP meta info packets

#ifndef __QTRTP_META_INFO_PACKET_H__
#define __QTRTP_META_INFO_PACKET_H__

#include <stdlib.h>
#include "OSHeaders.h"
#include "StrPtrLen.h"

class RTPMetaInfoPacket
{
	public:
	
		//
		// RTP Meta Info Fields
		
		enum
		{
			kPacketPosField 		= 0, //TW0_CHARS_TO_INT('p', 'p'),
			kTransTimeField 		= 1, //TW0_CHARS_TO_INT('t', 't'),
			kFrameTypeField 		= 2, //TW0_CHARS_TO_INT('f', 't'),
			kPacketNumField			= 3, //TW0_CHARS_TO_INT('p', 'n'),
			kSeqNumField 			= 4, //TW0_CHARS_TO_INT('s', 'q'),
			kMediaDataField 		= 5, //TW0_CHARS_TO_INT('m', 'd'),
			
			kIllegalField			= 6,
			kNumFields				= 6
		};
		typedef UInt16 FieldIndex;
		
		//
		// Types
		
		typedef UInt16 FieldName;
		typedef SInt16 FieldID;
		
		//
		// Special field IDs
		enum
		{
			kUncompressed = -1,		// No field ID (not a compressed field)
			kFieldNotUsed = -2		// This field is not being used
		};
		
		//
		// Routine that converts the above enum items into real field names
		static FieldName GetFieldNameForIndex(FieldIndex inIndex) { return kFieldNameMap[inIndex]; }
		static FieldIndex GetFieldIndexForName(FieldName inName);
		
		//
		// Routine that constructs a standard FieldID Array out of a x-RTP-Meta-Info header
		static void	ConstructFieldIDArrayFromHeader(StrPtrLen* inHeader, FieldID* ioFieldIDArray);
		
		//
		// Values for the Frame Type Field	
		enum
		{
			kUnknownFrameType 	= 0,
			kKeyFrameType 		= 1,
			kBFrameType 		= 2,
			kPFrameType 		= 3
		};
		typedef UInt16 FrameTypeField;
		
		
		//
		// CONSTRUCTOR
		
		RTPMetaInfoPacket() :	fPacketBuffer(NULL),
								fPacketLen(0),
								fTransmitTime(0),
								fFrameType(kUnknownFrameType),
								fPacketNumber(0),
								fPacketPosition(0),
								fMediaDataP(NULL),
								fMediaDataLen(0),
								fSeqNum(0)	 		{}
		~RTPMetaInfoPacket() {}
		
		//
		// Call this to parse the RTP-Meta-Info packet.
		// Pass in an array of FieldIDs, make sure it is kNumFields in length.
		// This function will use the array as a guide to tell which field IDs in the
		// packet refer to which fields.
		Bool16	ParsePacket(UInt8* inPacketBuffer, UInt32 inPacketLen, FieldID* inFieldIDArray);
		
		//
		// Call this if you would like to rewrite the Meta-Info packet
		// as a normal RTP packet (strip off the extensions). Note that
		// this will overwrite data in the buffer!
		// Returns a pointer to the new RTP packet, and its length
		UInt8*			MakeRTPPacket(UInt32* outPacketLen);
		
		//
		// Field Accessors
		SInt64			GetTransmitTime() 		{ return fTransmitTime; }
		FrameTypeField	GetFrameType() 			{ return fFrameType; }
		UInt64			GetPacketNumber() 		{ return fPacketNumber; }
		UInt64			GetPacketPosition() 	{ return fPacketPosition; }
		UInt8*			GetMediaDataP()			{ return fMediaDataP; }
		UInt32			GetMediaDataLen()		{ return fMediaDataLen; }
		UInt16			GetSeqNum()				{ return fSeqNum; }
	
	private:
	
		UInt8*			fPacketBuffer;
		UInt32			fPacketLen;
		
		SInt64			fTransmitTime;
		FrameTypeField	fFrameType;
		UInt64			fPacketNumber;
		UInt64			fPacketPosition;
		UInt8*			fMediaDataP;
		UInt32			fMediaDataLen;
		UInt16			fSeqNum;
		
		static const FieldName kFieldNameMap[];
		static const UInt32 kFieldLengthValidator[];
};

#endif // __QTRTP_META_INFO_PACKET_H__