gvrtppacket.h

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//
// Copyright (C) 2017 Graeme Walker
// 
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
// 
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
// 
// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.
// ===
///
/// \file gvrtppacket.h
///

#ifndef GV_RTPPACKET__H
#define GV_RTPPACKET__H

#include "gdef.h"
#include "gexception.h"
#include <string>

namespace Gv
{
    class RtpPacket ;
}

/// \class Gv::RtpPacket
/// An RTP packet parser, as per RFC 3550 (section 5). An RTP packet contains a 
/// header, an optional list of sources (eg. separate cameras with their own 
/// sequence numbers), and a payload.
/// 
/// Payload formats are defined wrt. a profile sepecification, eg. RFC 3551 for 
/// the "RTP/AVP" profile. The profile defines mappings from a payload type
/// to a payload encoding.
/// 
/// See also RFC 2435 for the JPEG profile.
/// 
class Gv::RtpPacket
{
public:
    G_EXCEPTION( Error , "rtp packet error" ) ;

    RtpPacket( const char * p , size_t n ) ;
        ///< Constructor. Beware that the data is not copied so it must
        ///< remain valid for payload methods (begin(), end() etc).
        ///< Precondition: n >= smallest()

    static size_t smallest() ; 
        ///< Returns the smallest valid packet size.

    bool valid() const ;
        ///< Returns true if a valid packet.

    std::string reason() const ;
        ///< Returns the in-valid() reason.

    std::string str() const ;
        ///< Returns a one-line summary of header fields.

    std::string hexdump() const ;
        ///< Returns a complete hex dump.

    ///< header...

    bool marker() const ;
        ///< Returns the marker bit. The interpretation is
        ///< defined by the profile.

    unsigned int seq() const ;
        ///< Returns the sequence number.

    unsigned long timestamp() const ;
        ///< Returns the timestamp.

    unsigned long src() const ;
        ///< Returns the source id.

    ///< payload...

    unsigned int type() const ;
        ///< Returns the payload type.

    bool typeJpeg() const ;
        ///< Returns true if the payload type is 26. 

    bool typeDynamic() const ;
        ///< Returns true if the payload type is in the dynamic range,
        ///< 96 to 127.

    const char * begin() const ;
        ///< Returns the payload begin iterator.

    const char * end() const ;
        ///< Returns the payload end iterator.

    size_t offset() const ;
        ///< Returns the payload offset.

    size_t size() const ;
        ///< Returns the payload size.

    const unsigned char * ubegin() const ;
        ///< Returns the payload begin iterator.

    const unsigned char * uend() const ;
        ///< Returns the payload end iterator.

private:
    RtpPacket( const RtpPacket & ) ;
    void operator=( const RtpPacket & ) ;
    static unsigned int make_word( const unsigned char * p ) ;
    static unsigned long make_dword( const unsigned char * p ) ;

private:
    const unsigned char * m_p ;
    size_t m_n ;
    unsigned int m_version ;
    bool m_padding ;
    bool m_extension ;
    unsigned int m_cc ;
    bool m_marker ;
    unsigned int m_pt ;
    unsigned int m_seq ;
    unsigned long m_timestamp ;
    unsigned long m_src_id ;
    unsigned int m_ehl ;
    unsigned int m_padsize ;
    size_t m_header_size ;
    size_t m_payload_size ;
    std::string m_reason ;
} ;

#endif