rtp.c

本源码是H.26L标准的Visual C++源代码

/*
***********************************************************************
* COPYRIGHT AND WARRANTY INFORMATION
*
* Copyright 2001, International Telecommunications Union, Geneva
*
* DISCLAIMER OF WARRANTY
*
* These software programs are available to the user without any
* license fee or royalty on an "as is" basis. The ITU disclaims
* any and all warranties, whether express, implied, or
* statutory, including any implied warranties of merchantability
* or of fitness for a particular purpose.  In no event shall the
* contributor or the ITU be liable for any incidental, punitive, or
* consequential damages of any kind whatsoever arising from the
* use of these programs.
*
* This disclaimer of warranty extends to the user of these programs
* and user's customers, employees, agents, transferees, successors,
* and assigns.
*
* The ITU does not represent or warrant that the programs furnished
* hereunder are free of infringement of any third-party patents.
* Commercial implementations of ITU-T Recommendations, including
* shareware, may be subject to royalty fees to patent holders.
* Information regarding the ITU-T patent policy is available from
* the ITU Web site at http://www.itu.int.
*
* THIS IS NOT A GRANT OF PATENT RIGHTS - SEE THE ITU-T PATENT POLICY.
************************************************************************
*/

/*!
 *****************************************************************************
 *
 * \file rtp.c
 *
 * \brief
 *    Functions to handle RTP headers and packets per RFC1889 and RTP NAL spec
 *    Functions support little endian systems only (Intel, not Motorola/Sparc)
 *
 * \date
 *    30 September 2001
 *
 * \author
 *    Stephan Wenger   [e-mail]
 *****************************************************************************/

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include <memory.h>
#include <malloc.h>

#include "rtp.h"
#include "elements.h"
#include "defines.h"
#include "header.h"

#include "global.h"


// A little trick to avoid those horrible #if TRACE all over the source code
#if TRACE
#define SYMTRACESTRING(s) strncpy(sym.tracestring,s,TRACESTRING_SIZE)
#else
#define SYMTRACESTRING(s) // to nothing
#endif


int CurrentRTPTimestamp = 0;      //! The RTP timestamp of the current packet,
                                  //! incremented with all P and I frames
int CurrentRTPSequenceNumber = 0; //! The RTP sequence number of the current packet
                                  //! incremented by one for each sent packet

/*!
 *****************************************************************************
 *
 * \brief 
 *    ComposeRTPpacket composes the complete RTP packet using the various
 *    structure members of the RTPpacket_t structure
 *
 * \return
 *    0 in case of success
 *    negative error code in case of failure
 *
 * \para Parameters
 *    Caller is responsible to allocate enough memory for the generated packet
 *    in parameter->packet. Typically a malloc of 12+paylen bytes is sufficient
 *
 * \para Side effects
 *    none
 *
 * \para Other Notes
 *    Function contains assert() tests for debug purposes (consistency checks
 *    for RTP header fields
 *
 * \date
 *    30 Spetember 2001
 *
 * \author
 *    Stephan Wenger   [e-mail]
 *****************************************************************************/


int ComposeRTPPacket (RTPpacket_t *p)

{
  // Consistency checks through assert, only used for debug purposes
  assert (p->v == 2);
  assert (p->p == 0);
  assert (p->x == 0);
  assert (p->cc == 0);    // mixer designers need to change this one
  assert (p->m == 0 || p->m == 1);
  assert (p->pt < 128);
  assert (p->seq < 65536);
  assert (p->payload != NULL);
  assert (p->paylen < 65536 - 40);  // 2**16 -40 for IP/UDP/RTP header
  assert (p->packet != NULL);

  // Compose RTP header, little endian

  p->packet[0] = (   (p->v)
                  |  (p->p << 2)
                  |  (p->x << 3)
                  |  (p->cc << 4) );
  p->packet[1] = (   (p->m)
                  |  (p->pt << 1) );
  p->packet[2] = p->seq & 0xff;
  p->packet[3] = (p->seq >> 8) & 0xff;

  memcpy (&p->packet[4], &p->timestamp, 4);  // change to shifts for unified byte sex
  memcpy (&p->packet[8], &p->ssrc, 4);// change to shifts for unified byte sex

  // Copy payload 

  memcpy (&p->packet[12], p->payload, p->paylen);
  p->packlen = p->paylen+12;
  return 0;
}



/*!
 *****************************************************************************
 *
 * \brief 
 *    WriteRTPPacket writes the supplied RTP packet to the output file
 *
 * \return
 *    0 in case of access
 *    <0 in case of write failure (typically fatal)
 *
 * \para Parameters
 *    p: the RTP packet to be written (after ComposeRTPPacket() )
 *    f: output file
 *
 * \para Side effects
 *    none
 *
 * \date
 *    October 23, 2001
 *
 * \author
 *    Stephan Wenger   [e-mail]
 *****************************************************************************/

int WriteRTPPacket (RTPpacket_t *p, FILE *f)

{
  int intime = -1;

  assert (f != NULL);
  assert (p != NULL);


  if (1 != fwrite (&p->packlen, 4, 1, f))
    return -1;
  if (1 != fwrite (&intime, 4, 1, f))
    return -1;
  if (1 != fwrite (p->packet, p->packlen, 1, f))
    return -1;
  return 0;
}


/*!
 *****************************************************************************
 *
 * \brief 
 *    ComposeHeaderPacketPayload generates the payload for a header packet
 *    using the inp-> structure contents.  The header packet contains 
 *    definitions for a single parameter set 0, which is used for all 
 *    slices of the picture
 *
 * \return
 *    len of the genberated payload in bytes
 *    <0 in case of failure (typically fatal)
 *
 * \para Parameters
 *    p: the payload of the RTP packet to be written
 *
 * \para Side effects
 *    none
 *
 * \note
 *    This function should be revisited and checked in case of additional
 *    bit stream parameters that affect the picture header (or higher
 *    entitries).  Typical examples are more entropy coding schemes, other
 *    motion vector resolutiuon, and optional elements
 *
 * \date
 *    October 23, 2001
 *
 * \author
 *    Stephan Wenger   [e-mail]
 *****************************************************************************/


int ComposeHeaderPacketPayload (byte *payload)
{
  int slen=0;
  int multpred;

  assert (img->width%16 == 0);
  assert (img->height%16 == 0);

#ifdef _ADDITIONAL_REFERENCE_FRAME_
  if (input->no_multpred <= 1 && input->add_ref_frame == 0)
#else
  if (input->no_multpred <= 1)
#endif
    multpred=FALSE;
  else
    multpred=TRUE;               // multiple reference frames in motion search

  
  slen = snprintf (payload, MAXRTPPAYLOADLEN, 
             "a=H26L (0) MaxPicID %d\
            \na=H26L (0) UseMultpred %d\
            \na=H26L (0) MaxPn %d\
            \na=H26L (0) BufCycle %d\
            \na=H26L (0) PixAspectRatioX 1\
            \na=H26L (0) PixAspectRatioY 1\
            \na=H26L (0) DisplayWindowOffsetTop 0\
            \na=H26L (0) DisplayWindowOffsetBottom 0\
            \na=H26L (0) DisplayWindowOffsetRight 0\
            \na=H26L (0) DisplayWindowOffsetLeft 0\
            \na=H26L (0) XSizeMB %d\
            \na=H26L (0) YSizeMB %d\
            \na=H26L (0) EntropyCoding %s\
            \na=H26L (0) MotionResolution %s\
            \na=H26L (0) PartitioningType %s\
            \na=H26L (0) IntraPredictionType %s\
            \na=H26L (0) HRCParameters 0\
            \
            \na=H26L (-1) FramesToBeEncoded %d\
            \na=H26L (-1) FrameSkip %d\
            \na=H26L (-1) SequenceFileName %s\
            \na=H26L (0) NumberBFrames %d\
            %c%c",

            256,
            multpred==TRUE?1:0,
            input->no_multpred,
            input->no_multpred,
            input->img_width/16,
            input->img_height/16,
            input->symbol_mode==UVLC?"UVLC":"CABAC",
            input->mv_res==0?"quater":"eigth",
            input->partition_mode==0?"one":"three",
            input->UseConstrainedIntraPred==0?"InterPredicted":"NotInterPredicted",
            
            input->no_frames,
            input->jumpd,
            input->infile,
            input->successive_Bframe,
            4,     // Unix Control D EOF symbol
            26);  // MS-DOS/Windows Control Z EOF Symbol
  return slen;
}



/*!
 *****************************************************************************
 *
 * \brief 
 *    void RTPSequenceHeader (FILE *out) write the RTP Sequence header in the
 *       form of a header packet into the outfile.  It is assumed that the
 *       input-> structure is already filled (config file is parsed)
 *
 * \return
 *    length of sequence header
 *
 * \para Parameters
 *    out: fiel pointer of the output file
 *
 * \para Side effects
 *    header written, statistics are updated, RTP sequence number updated
 *
 * \para Note
 *    This function uses alloca() to reserve memry on the stack -- no freeing and
 *    no return value check necessary, error lead to stack overflows
 *
 * \date
 *    October 24, 2001
 *
 * \author
 *    Stephan Wenger   [e-mail]
 *****************************************************************************/

int RTPSequenceHeader (FILE *out)
{
  RTPpacket_t *p;

  assert (out != NULL);

  // Set RTP structure elements and alloca() memory foor the buffers
  p = (RTPpacket_t *) alloca (sizeof (RTPpacket_t));
  p->packet=alloca (MAXRTPPACKETSIZE);
  p->payload=alloca (MAXRTPPACKETSIZE);
  p->v=2;
  p->p=0;
  p->x=0;
  p->cc=0;
  p->m=1;
  p->pt=H26LPAYLOADTYPE;
  p->seq=CurrentRTPSequenceNumber++;
  p->timestamp=CurrentRTPTimestamp;
  p->ssrc=H26LSSRC;