pjmedia/src/pjmedia-codec/h263_packetizer.c - pjproject - Gitiles

 /* $Id$ */
 /*
  * Copyright (C) 2008-2011 Teluu Inc. (http://www.teluu.com)
  *
  * 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
  */
 #include <pjmedia-codec/h263_packetizer.h>
 #include <pjmedia/types.h>
 #include <pj/assert.h>
 #include <pj/errno.h>
 #include <pj/string.h>


 #if defined(PJMEDIA_HAS_VIDEO) && (PJMEDIA_HAS_VIDEO != 0)


 #define THIS_FILE	"h263_packetizer.c"


 /* H.263 packetizer definition */
 struct pjmedia_h263_packetizer {
     /* Current settings */
     pjmedia_h263_packetizer_cfg cfg;

     /* Unpacketizer state */
     unsigned	    unpack_last_sync_pos;
     pj_bool_t	    unpack_prev_lost;
 };


 /*
  * Find synchronization point (PSC, slice, GSBC, EOS, EOSBS) in H.263
  * bitstream.
  */
 static pj_uint8_t* find_sync_point(pj_uint8_t *data,
 				   pj_size_t data_len)
 {
     pj_uint8_t *p = data, *end = data+data_len-1;

     while (p < end && (*p || *(p+1)))
         ++p;

     if (p == end)
         return NULL;

     return p;
 }


 /*
  * Find synchronization point (PSC, slice, GSBC, EOS, EOSBS) in H.263
  * bitstream, in reversed manner.
  */
 static pj_uint8_t* find_sync_point_rev(pj_uint8_t *data,
                                        pj_size_t data_len)
 {
     pj_uint8_t *p = data+data_len-2;

     while (p >= data && (*p || *(p+1)))
         --p;

     if (p < data)
         return (data + data_len);

     return p;
 }


 /*
  * Create H263 packetizer.
  */
 PJ_DEF(pj_status_t) pjmedia_h263_packetizer_create(
 				pj_pool_t *pool,
 				const pjmedia_h263_packetizer_cfg *cfg,
 				pjmedia_h263_packetizer **p)
 {
     pjmedia_h263_packetizer *p_;

     PJ_ASSERT_RETURN(pool && p, PJ_EINVAL);

     if (cfg && cfg->mode != PJMEDIA_H263_PACKETIZER_MODE_RFC4629)
 	return PJ_ENOTSUP;

     p_ = PJ_POOL_ZALLOC_T(pool, pjmedia_h263_packetizer);
     if (cfg) {
 	pj_memcpy(&p_->cfg, cfg, sizeof(*cfg));
     } else {
 	p_->cfg.mode = PJMEDIA_H263_PACKETIZER_MODE_RFC4629;
 	p_->cfg.mtu = PJMEDIA_MAX_MTU;
     }

     *p = p_;

     return PJ_SUCCESS;
 }


 /*
  * Generate an RTP payload from H.263 frame bitstream, in-place processing.
  */
 PJ_DEF(pj_status_t) pjmedia_h263_packetize(pjmedia_h263_packetizer *pktz,
 					   pj_uint8_t *bits,
                                            pj_size_t bits_len,
                                            unsigned *pos,
                                            const pj_uint8_t **payload,
                                            pj_size_t *payload_len)
 {
     pj_uint8_t *p, *end;

     pj_assert(pktz && bits && pos && payload && payload_len);
     pj_assert(*pos <= bits_len);

     p = bits + *pos;
     end = bits + bits_len;

     /* Put two octets payload header */
     if ((end-p > 2) && *p==0 && *(p+1)==0) {
         /* The bitstream starts with synchronization point, just override
          * the two zero octets (sync point mark) for payload header.
          */
         *p = 0x04;
     } else {
         /* Not started in synchronization point, we will use two octets
          * preceeding the bitstream for payload header!
          */

 	if (*pos < 2) {
 	    /* Invalid H263 bitstream, it's not started with PSC */
 	    return PJ_EINVAL;
 	}

 	p -= 2;
         *p = 0;
     }
     *(p+1) = 0;

     /* When bitstream truncation needed because of payload length/MTU
      * limitation, try to use sync point for the payload boundary.
      */
     if (end-p > pktz->cfg.mtu) {
 	end = find_sync_point_rev(p+2, pktz->cfg.mtu-2);
     }

     *payload = p;
     *payload_len = end-p;
     *pos = end - bits;

     return PJ_SUCCESS;
 }


 /*
  * Append an RTP payload to a H.263 picture bitstream.
  */
 PJ_DEF(pj_status_t) pjmedia_h263_unpacketize (pjmedia_h263_packetizer *pktz,
 					      const pj_uint8_t *payload,
                                               pj_size_t payload_len,
                                               pj_uint8_t *bits,
                                               pj_size_t bits_size,
 					      unsigned *pos)
 {
     pj_uint8_t P, V, PLEN;
     const pj_uint8_t *p = payload;
     pj_uint8_t *q;

     q = bits + *pos;

     /* Check if this is a missing/lost packet */
     if (payload == NULL) {
 	pktz->unpack_prev_lost = PJ_TRUE;
 	return PJ_SUCCESS;
     }

     /* H263 payload header size is two octets */
     if (payload_len < 2) {
 	/* Invalid bitstream, discard this payload */
 	pktz->unpack_prev_lost = PJ_TRUE;
 	return PJ_EINVAL;
     }

     /* Reset last sync point for every new picture bitstream */
     if (*pos == 0)
 	pktz->unpack_last_sync_pos = 0;

     /* Get payload header info */
     P = *p & 0x04;
     V = *p & 0x02;
     PLEN = ((*p & 0x01) << 5) + ((*(p+1) & 0xF8)>>3);

     /* Get start bitstream pointer */
     p += 2;	    /* Skip payload header */
     if (V)
         p += 1;	    /* Skip VRC data */
     if (PLEN)
         p += PLEN;  /* Skip extra picture header data */

     /* Get bitstream length */
     if (payload_len > (pj_size_t)(p - payload)) {
 	payload_len -= (p - payload);
     } else {
 	/* Invalid bitstream, discard this payload */
 	pktz->unpack_prev_lost = PJ_TRUE;
 	return PJ_EINVAL;
     }

     /* Validate bitstream length */
     if (bits_size < *pos + payload_len + 2) {
 	/* Insufficient bistream buffer, discard this payload */
 	pj_assert(!"Insufficient H.263 bitstream buffer");
 	pktz->unpack_prev_lost = PJ_TRUE;
 	return PJ_ETOOSMALL;
     }

     /* Start writing bitstream */

     /* No sync point flag */
     if (!P) {
 	if (*pos == 0) {
 	    /* Previous packet must be lost */
 	    pktz->unpack_prev_lost = PJ_TRUE;

 	    /* If there is extra picture header, let's use it. */
 	    if (PLEN) {
 		/* Write two zero octets for PSC */
 		*q++ = 0;
 		*q++ = 0;
 		/* Copy the picture header */
 		p -= PLEN;
 		pj_memcpy(q, p, PLEN);
 		p += PLEN;
 		q += PLEN;
 	    }
 	} else if (pktz->unpack_prev_lost) {
 	    /* If prev packet was lost, revert the bitstream pointer to
 	     * the last sync point.
 	     */
 	    pj_assert(pktz->unpack_last_sync_pos <= *pos);
 	    q = bits + pktz->unpack_last_sync_pos;
 	}

 	/* There was packet lost, see if this payload contain sync point
 	 * (usable data).
 	 */
 	if (pktz->unpack_prev_lost) {
 	    pj_uint8_t *sync;
 	    sync = find_sync_point((pj_uint8_t*)p, payload_len);
 	    if (sync) {
 		/* Got sync point, update P/sync-point flag */
 		P = 1;
 		/* Skip the two zero octets */
 		sync += 2;
 		/* Update payload length and start bitstream pointer */
 		payload_len -= (sync - p);
 		p = sync;
 	    } else {
 		/* No sync point in it, just discard this payload */
 		return PJ_EIGNORED;
 	    }
 	}
     }

     /* Write two zero octets when payload flagged with sync point */
     if (P) {
 	pktz->unpack_last_sync_pos = q - bits;
         *q++ = 0;
         *q++ = 0;
     }

     /* Write the payload to the bitstream */
     pj_memcpy(q, p, payload_len);
     q += payload_len;

     /* Update the bitstream writing offset */
     *pos = q - bits;

     pktz->unpack_prev_lost = PJ_FALSE;

     return PJ_SUCCESS;
 }


 #endif /* PJMEDIA_HAS_VIDEO */
	/* $Id$ */
	/*
	* Copyright (C) 2008-2011 Teluu Inc. (http://www.teluu.com)
	*
	* 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
	*/
	#include <pjmedia-codec/h263_packetizer.h>
	#include <pjmedia/types.h>
	#include <pj/assert.h>
	#include <pj/errno.h>
	#include <pj/string.h>


	#if defined(PJMEDIA_HAS_VIDEO) && (PJMEDIA_HAS_VIDEO != 0)


	#define THIS_FILE "h263_packetizer.c"


	/* H.263 packetizer definition */
	struct pjmedia_h263_packetizer {
	/* Current settings */
	pjmedia_h263_packetizer_cfg cfg;

	/* Unpacketizer state */
	unsigned unpack_last_sync_pos;
	pj_bool_t unpack_prev_lost;
	};


	/*
	* Find synchronization point (PSC, slice, GSBC, EOS, EOSBS) in H.263
	* bitstream.
	*/
	static pj_uint8_t* find_sync_point(pj_uint8_t *data,
	pj_size_t data_len)
	{
	pj_uint8_t p = data, end = data+data_len-1;

	while (p < end && (p \|\| (p+1)))
	++p;

	if (p == end)
	return NULL;

	return p;
	}


	/*
	* Find synchronization point (PSC, slice, GSBC, EOS, EOSBS) in H.263
	* bitstream, in reversed manner.
	*/
	static pj_uint8_t* find_sync_point_rev(pj_uint8_t *data,
	pj_size_t data_len)
	{
	pj_uint8_t *p = data+data_len-2;

	while (p >= data && (p \|\| (p+1)))
	--p;

	if (p < data)
	return (data + data_len);

	return p;
	}


	/*
	* Create H263 packetizer.
	*/
	PJ_DEF(pj_status_t) pjmedia_h263_packetizer_create(
	pj_pool_t *pool,
	const pjmedia_h263_packetizer_cfg *cfg,
	pjmedia_h263_packetizer **p)
	{
	pjmedia_h263_packetizer *p_;

	PJ_ASSERT_RETURN(pool && p, PJ_EINVAL);

	if (cfg && cfg->mode != PJMEDIA_H263_PACKETIZER_MODE_RFC4629)
	return PJ_ENOTSUP;

	p_ = PJ_POOL_ZALLOC_T(pool, pjmedia_h263_packetizer);
	if (cfg) {
	pj_memcpy(&p_->cfg, cfg, sizeof(*cfg));
	} else {
	p_->cfg.mode = PJMEDIA_H263_PACKETIZER_MODE_RFC4629;
	p_->cfg.mtu = PJMEDIA_MAX_MTU;
	}

	*p = p_;

	return PJ_SUCCESS;
	}


	/*
	* Generate an RTP payload from H.263 frame bitstream, in-place processing.
	*/
	PJ_DEF(pj_status_t) pjmedia_h263_packetize(pjmedia_h263_packetizer *pktz,
	pj_uint8_t *bits,
	pj_size_t bits_len,
	unsigned *pos,
	const pj_uint8_t **payload,
	pj_size_t *payload_len)
	{
	pj_uint8_t p, end;

	pj_assert(pktz && bits && pos && payload && payload_len);
	pj_assert(*pos <= bits_len);

	p = bits + *pos;
	end = bits + bits_len;

	/* Put two octets payload header */
	if ((end-p > 2) && p==0 && (p+1)==0) {
	/* The bitstream starts with synchronization point, just override
	* the two zero octets (sync point mark) for payload header.
	*/
	*p = 0x04;
	} else {
	/* Not started in synchronization point, we will use two octets
	* preceeding the bitstream for payload header!
	*/

	if (*pos < 2) {
	/* Invalid H263 bitstream, it's not started with PSC */
	return PJ_EINVAL;
	}

	p -= 2;
	*p = 0;
	}
	*(p+1) = 0;

	/* When bitstream truncation needed because of payload length/MTU
	* limitation, try to use sync point for the payload boundary.
	*/
	if (end-p > pktz->cfg.mtu) {
	end = find_sync_point_rev(p+2, pktz->cfg.mtu-2);
	}

	*payload = p;
	*payload_len = end-p;
	*pos = end - bits;

	return PJ_SUCCESS;
	}


	/*
	* Append an RTP payload to a H.263 picture bitstream.
	*/
	PJ_DEF(pj_status_t) pjmedia_h263_unpacketize (pjmedia_h263_packetizer *pktz,
	const pj_uint8_t *payload,
	pj_size_t payload_len,
	pj_uint8_t *bits,
	pj_size_t bits_size,
	unsigned *pos)
	{
	pj_uint8_t P, V, PLEN;
	const pj_uint8_t *p = payload;
	pj_uint8_t *q;

	q = bits + *pos;

	/* Check if this is a missing/lost packet */
	if (payload == NULL) {
	pktz->unpack_prev_lost = PJ_TRUE;
	return PJ_SUCCESS;
	}

	/* H263 payload header size is two octets */
	if (payload_len < 2) {
	/* Invalid bitstream, discard this payload */
	pktz->unpack_prev_lost = PJ_TRUE;
	return PJ_EINVAL;
	}

	/* Reset last sync point for every new picture bitstream */
	if (*pos == 0)
	pktz->unpack_last_sync_pos = 0;

	/* Get payload header info */
	P = *p & 0x04;
	V = *p & 0x02;
	PLEN = ((p & 0x01) << 5) + (((p+1) & 0xF8)>>3);

	/* Get start bitstream pointer */
	p += 2; /* Skip payload header */
	if (V)
	p += 1; /* Skip VRC data */
	if (PLEN)
	p += PLEN; /* Skip extra picture header data */

	/* Get bitstream length */
	if (payload_len > (pj_size_t)(p - payload)) {
	payload_len -= (p - payload);
	} else {
	/* Invalid bitstream, discard this payload */
	pktz->unpack_prev_lost = PJ_TRUE;
	return PJ_EINVAL;
	}

	/* Validate bitstream length */
	if (bits_size < *pos + payload_len + 2) {
	/* Insufficient bistream buffer, discard this payload */
	pj_assert(!"Insufficient H.263 bitstream buffer");
	pktz->unpack_prev_lost = PJ_TRUE;
	return PJ_ETOOSMALL;
	}

	/* Start writing bitstream */

	/* No sync point flag */
	if (!P) {
	if (*pos == 0) {
	/* Previous packet must be lost */
	pktz->unpack_prev_lost = PJ_TRUE;

	/* If there is extra picture header, let's use it. */
	if (PLEN) {
	/* Write two zero octets for PSC */
	*q++ = 0;
	*q++ = 0;
	/* Copy the picture header */
	p -= PLEN;
	pj_memcpy(q, p, PLEN);
	p += PLEN;
	q += PLEN;
	}
	} else if (pktz->unpack_prev_lost) {
	/* If prev packet was lost, revert the bitstream pointer to
	* the last sync point.
	*/
	pj_assert(pktz->unpack_last_sync_pos <= *pos);
	q = bits + pktz->unpack_last_sync_pos;
	}

	/* There was packet lost, see if this payload contain sync point
	* (usable data).
	*/
	if (pktz->unpack_prev_lost) {
	pj_uint8_t *sync;
	sync = find_sync_point((pj_uint8_t*)p, payload_len);
	if (sync) {
	/* Got sync point, update P/sync-point flag */
	P = 1;
	/* Skip the two zero octets */
	sync += 2;
	/* Update payload length and start bitstream pointer */
	payload_len -= (sync - p);
	p = sync;
	} else {
	/* No sync point in it, just discard this payload */
	return PJ_EIGNORED;
	}
	}
	}

	/* Write two zero octets when payload flagged with sync point */
	if (P) {
	pktz->unpack_last_sync_pos = q - bits;
	*q++ = 0;
	*q++ = 0;
	}

	/* Write the payload to the bitstream */
	pj_memcpy(q, p, payload_len);
	q += payload_len;

	/* Update the bitstream writing offset */
	*pos = q - bits;

	pktz->unpack_prev_lost = PJ_FALSE;

	return PJ_SUCCESS;
	}


	#endif /* PJMEDIA_HAS_VIDEO */