c_rtp.h

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/*
 * Copyright 2007,2008 CNES
 * Copyright 2010,2011,2012,2013 Didier Barvaux
 * Copyright 2007,2008 Thales Alenia Space
 * Copyright 2007,2009,2010 Viveris Technologies
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 */

/**
 * @file c_rtp.h
 * @brief ROHC compression context for the RTP profile.
 * @author David Moreau from TAS
 * @author Didier Barvaux <didier.barvaux@toulouse.viveris.com>
 */

#ifndef ROHC_COMP_RTP_H
#define ROHC_COMP_RTP_H

#include "c_generic.h"
#include "schemes/scaled_rtp_ts.h"
#include "protocols/udp.h"
#include "protocols/rtp.h"


/**
 * @brief Define the RTP and UDP specific temporary variables in the profile
 *        compression context.
 *
 * This object must be used by the RTP-specific decompression context
 * sc_rtp_context.
 *
 * @see sc_rtp_context
 */
struct rtp_tmp_vars
{
        /// The number of UDP/RTP fields that changed in the UDP/RTP headers
        int send_rtp_dynamic;

        /// The number of bits needed to encode ts_send
        size_t nr_ts_bits;

        /// The number of bits of TS to place in the extension 3 header
        size_t nr_ts_bits_ext3;

        /// The TS field to send (ts_scaled or ts)
        uint32_t ts_send;

        /// Whether the Marker (M) bit is set in the RTP header or not
        bool is_marker_bit_set;

        /** Whether the Padding (P) bit changed or not */
        bool padding_bit_changed;

        /// Whether the eXtension (X) bit changed or not
        bool extension_bit_changed;

        /// Whether the Payload Type (PT) field changed or not
        int rtp_pt_changed;
};


/**
 * @brief Define the RTP part of the profile decompression context.
 *
 * This object must be used with the generic part of the decompression
 * context c_generic_context.
 *
 * @warning The 2 first fields MUST stay at the beginning of the structure
 *          to be compatible with \ref sc_udp_context
 *
 * @see c_generic_context
 */
struct sc_rtp_context
{
        /// @brief The number of times the UDP checksum field was added to the
        ///        compressed header
        int udp_checksum_change_count;

        /// The previous UDP header
        struct udphdr old_udp;

        /// @brief The number of times the RTP Payload Type (PT) field was added to
        ///        the compressed header
        int rtp_pt_change_count;

        /// @brief The number of times the RTP Padding (P) bit was added to
        ///        the compressed header
        size_t rtp_padding_change_count;

        /// @brief The number of times the RTP eXtension (X) bit was added to
        ///        the compressed header
        size_t rtp_extension_change_count;

        /// The previous RTP header
        struct rtphdr old_rtp;

        /// @brief RTP-specific temporary variables that are used during one single
        ///        compression of packet
        struct rtp_tmp_vars tmp;

        /// Scaled RTP Time Stamp
        int tss;

        /// Whether the Time Stride field is present or not
        int tis;

        /// Structure to encode the TS field
        struct ts_sc_comp ts_sc;
};


/*
 * Function prototypes.
 */

/* no public function */

#endif