comp_scaled_rtp_ts.h

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/*
 * Copyright 2010,2011,2012,2013 Didier Barvaux
 * Copyright 2007,2009,2010,2012,2013 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   schemes/comp_scaled_rtp_ts.h
 * @brief  Scaled RTP Timestamp encoding
 * @author David Moreau from TAS
 * @author Didier Barvaux <didier.barvaux@toulouse.viveris.com>
 * @author Didier Barvaux <didier@barvaux.org>
 *
 * See section 4.5.3 of RFC 3095 for details about Scaled RTP Timestamp
 * encoding.
 */

#ifndef ROHC_COMP_SCHEMES_SCALED_RTP_TS_H
#define ROHC_COMP_SCHEMES_SCALED_RTP_TS_H

#include "comp_wlsb.h"
#include "rohc_traces.h"

#ifdef __KERNEL__
#  include <linux/types.h>
#else
#  include <stdbool.h>
#endif


/**
 * @brief State of scaled RTP Timestamp encoding
 *
 * See section 4.5.3 of RFC 3095 for details about Scaled RTP Timestamp
 * encoding.
 */
typedef enum
{
        /// Initialization state (TS_STRIDE value not yet computed)
        INIT_TS = 1,
        /// Initialization state (TS_STRIDE value computed and sent)
        INIT_STRIDE = 2,
        /// Compression state (TS_SCALED value computed and sent)
        SEND_SCALED = 3,
} ts_sc_state;


/**
 * @brief Scaled RTP Timestamp encoding object
 *
 * See section 4.5.3 of RFC 3095 for details about Scaled RTP Timestamp
 * encoding.
 */
struct ts_sc_comp
{
        /// The TS_STRIDE value
        uint32_t ts_stride;

        /// The TS_SCALED value
        uint32_t ts_scaled;
        /** The W-LSB object used to encode the TS_SCALED value */
        struct c_wlsb *ts_scaled_wlsb;

        /// The TS_OFFSET value
        uint32_t ts_offset;

        /// The timestamp (TS)
        uint32_t ts;
        /** The W-LSB object used to encode the TS value */
        struct c_wlsb *ts_unscaled_wlsb;
        /// The previous timestamp
        uint32_t old_ts;

        /// The sequence number (SN)
        uint16_t sn;
        /// The previous sequence number
        uint16_t old_sn;

        /// Whether timestamp is deducible from SN or not
        bool is_deducible;

        /// The state of the scaled RTP Timestamp encoding object
        ts_sc_state state;
        /** Whether old SN/TS values are initialized or not */
        bool are_old_val_init;
        /// The number of packets sent in state INIT_STRIDE
        size_t nr_init_stride_packets;

        /// The difference between old and current TS
        uint32_t ts_delta;

        /** The callback function used to manage traces */
        rohc_trace_callback2_t trace_callback;
        /** The private context of the callback function used to manage traces */
        void *trace_callback_priv;
};



/*
 * Function prototypes
 */

bool c_create_sc(struct ts_sc_comp *const ts_sc,
                 const size_t wlsb_window_width,
                 rohc_trace_callback2_t trace_cb,
                 void *const trace_cb_priv)
        __attribute__((warn_unused_result));
void c_destroy_sc(struct ts_sc_comp *const ts_sc);

void c_add_ts(struct ts_sc_comp *const ts_sc,
              const uint32_t ts,
              const uint16_t sn);

void nb_bits_unscaled(const struct ts_sc_comp *const ts_sc,
                      size_t *const bits_nr_less_equal_than_2,
                      size_t *const bits_nr_more_than_2)
        __attribute__((nonnull(1, 2, 3)));
void add_unscaled(const struct ts_sc_comp *const ts_sc, const uint16_t sn);

void nb_bits_scaled(const struct ts_sc_comp *const ts_sc,
                    size_t *const bits_nr_less_equal_than_2,
                    size_t *const bits_nr_more_than_2)
        __attribute__((nonnull(1, 2, 3)));
void add_scaled(const struct ts_sc_comp *const ts_sc, const uint16_t sn);

uint32_t get_ts_stride(const struct ts_sc_comp *const ts_sc)
        __attribute__((nonnull(1), warn_unused_result, pure));
uint32_t get_ts_scaled(const struct ts_sc_comp *const ts_sc)
        __attribute__((nonnull(1), warn_unused_result, pure));
uint32_t get_ts_unscaled(const struct ts_sc_comp *const ts_sc)
        __attribute__((nonnull(1), warn_unused_result, pure));

bool rohc_ts_sc_is_deducible(const struct ts_sc_comp *const ts_sc)
        __attribute__((nonnull(1), warn_unused_result, pure));

#endif

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