ts_sc_decomp.h

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/*
 * 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 2 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, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

/**
 * @file ts_sc_decomp.h
 * @brief Scaled RTP Timestamp decoding
 * @author David Moreau from TAS
 * @author Didier Barvaux <didier@barvaux.org>
 */

#ifndef TS_SC_DECOMP_H
#define TS_SC_DECOMP_H

#include "lsb.h"

#include <stdint.h>


/**
 * @brief Scaled RTP Timestamp decoding object
 *
 * See section 4.5.3 of RFC 3095 for details about Scaled RTP Timestamp
 * decoding.
 */
struct ts_sc_decomp
{
        /// The last computed or received TS_STRIDE value (validated by CRC)
        uint32_t ts_stride;

        /// The last computed or received TS_SCALED value (validated by CRC)
        uint32_t ts_scaled;
        /// The LSB-encoded TS_SCALED value
        struct d_lsb_decode lsb_ts_scaled;

        /// The last computed or received TS_OFFSET value (validated by CRC)
        uint32_t ts_offset;

        /// The timestamp (TS) value
        uint32_t ts;
        /// The previous timestamp value
        uint32_t old_ts;

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


        /* the attributes below are new TS_* values computed by not yet validated
           by CRC check */

        /// The last computed or received TS_STRIDE value (not validated by CRC)
        uint32_t new_ts_stride;
        /// The last computed or received TS_SCALED value (not validated by CRC)
        uint32_t new_ts_scaled;
        /// The last computed or received TS_OFFSET value (not validated by CRC)
        uint32_t new_ts_offset;

};



/*
 * Function prototypes
 */

void d_create_sc(struct ts_sc_decomp *const ts_sc);

void ts_update_context(struct ts_sc_decomp *const ts_sc,
                       const uint32_t ts,
                       const uint16_t sn);

void d_record_ts_stride(struct ts_sc_decomp *const ts_sc,
                        const uint32_t ts_stride);

int ts_decode_scaled(struct ts_sc_decomp *const ts_sc,
                     const uint32_t ts_scaled,
                     const size_t bits_nr,
                     uint32_t *const decoded_ts);

uint32_t ts_decode_unscaled(struct ts_sc_decomp *const ts_sc,
                            const uint32_t ts_bits);

uint32_t ts_deduce_from_sn(struct ts_sc_decomp *const ts_sc,
                           const uint16_t sn);

#endif