atsc_stt.c

Dvbstreamer 用在解析MPTS的部分内容

/*
Copyright (C) 2006  Adam Charrett

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., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA

stt.c

Decode PSIP System Time Table.

*/
#include "config.h"

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdint.h>

#include "dvbpsi.h"
#include "dvbpsi_private.h"
#include "psi.h"
#include "descriptor.h"
#include "demux.h"
#include "atsc/stt.h"

#include "objects.h"

typedef struct dvbpsi_atsc_stt_decoder_s
{
  dvbpsi_atsc_stt_callback      pf_callback;
  void *                        p_cb_data;

} dvbpsi_atsc_stt_decoder_t;

dvbpsi_descriptor_t *dvbpsi_atsc_STTAddDescriptor(
                                               dvbpsi_atsc_stt_t *p_stt,
                                               uint8_t i_tag, uint8_t i_length,
                                               uint8_t *p_data);

void dvbpsi_atsc_GatherSTTSections(dvbpsi_decoder_t * p_psi_decoder,
                              void * p_private_decoder,
                              dvbpsi_psi_section_t * p_section);

void dvbpsi_atsc_DecodeSTTSections(dvbpsi_atsc_stt_t* p_stt,
                              dvbpsi_psi_section_t* p_section);

/*****************************************************************************
 * dvbpsi_atsc_AttachSTT
 *****************************************************************************
 * Initialize a STT subtable decoder.
 *****************************************************************************/
int dvbpsi_atsc_AttachSTT(dvbpsi_decoder_t * p_psi_decoder, uint8_t i_table_id, 
                          dvbpsi_atsc_stt_callback pf_callback, void* p_cb_data)
{
  dvbpsi_demux_t* p_demux = (dvbpsi_demux_t*)p_psi_decoder->p_private_decoder;
  dvbpsi_demux_subdec_t* p_subdec;
  dvbpsi_atsc_stt_decoder_t*  p_stt_decoder;

  if(dvbpsi_demuxGetSubDec(p_demux, i_table_id, 0))
  {
    DVBPSI_ERROR_ARG("STT decoder",
                     "Already a decoder for (table_id == 0x%02x)",
                     i_table_id);

    return 1;
  }

  p_subdec = (dvbpsi_demux_subdec_t*)malloc(sizeof(dvbpsi_demux_subdec_t));
  if(p_subdec == NULL)
  {
    return 1;
  }

  p_stt_decoder = (dvbpsi_atsc_stt_decoder_t*)malloc(sizeof(dvbpsi_atsc_stt_decoder_t));

  if(p_stt_decoder == NULL)
  {
    free(p_subdec);
    return 1;
  }

  /* subtable decoder configuration */
  p_subdec->pf_callback = &dvbpsi_atsc_GatherSTTSections;
  p_subdec->p_cb_data = p_stt_decoder;
  p_subdec->i_id = (uint32_t)i_table_id << 16;
  p_subdec->pf_detach = dvbpsi_atsc_DetachSTT;

  /* Attach the subtable decoder to the demux */
  p_subdec->p_next = p_demux->p_first_subdec;
  p_demux->p_first_subdec = p_subdec;

  /* STT decoder information */
  p_stt_decoder->pf_callback = pf_callback;
  p_stt_decoder->p_cb_data = p_cb_data;

  return 0;
}


/*****************************************************************************
 * dvbpsi_atsc_DetachSTT
 *****************************************************************************
 * Close a STT decoder.
 *****************************************************************************/
void dvbpsi_atsc_DetachSTT(dvbpsi_demux_t * p_demux, uint8_t i_table_id, uint16_t i_extension)
{
  dvbpsi_demux_subdec_t* p_subdec;
  dvbpsi_demux_subdec_t** pp_prev_subdec;
  dvbpsi_atsc_stt_decoder_t* p_stt_decoder;

  p_subdec = dvbpsi_demuxGetSubDec(p_demux, i_table_id, 0);

  if(p_demux == NULL)
  {
    DVBPSI_ERROR_ARG("STT Decoder",
                     "No such STT decoder (table_id == 0x%02x,"
                     "extension == 0x00)",
                     i_table_id);
    return;
  }

  p_stt_decoder = (dvbpsi_atsc_stt_decoder_t*)p_subdec->p_cb_data;

  free(p_subdec->p_cb_data);

  pp_prev_subdec = &p_demux->p_first_subdec;
  while(*pp_prev_subdec != p_subdec)
    pp_prev_subdec = &(*pp_prev_subdec)->p_next;

  *pp_prev_subdec = p_subdec->p_next;
  free(p_subdec);
}


/*****************************************************************************
 * dvbpsi_atsc_InitSTT
 *****************************************************************************
 * Initialize a pre-allocated dvbpsi_atsc_stt_t structure.
 *****************************************************************************/
void dvbpsi_atsc_InitSTT(dvbpsi_atsc_stt_t *p_stt, uint8_t i_protocol)
{
  p_stt->i_protocol = i_protocol;
  p_stt->p_first_descriptor = NULL;
}


/*****************************************************************************
 * dvbpsi_atsc_EmptySTT
 *****************************************************************************
 * Clean a dvbpsi_atsc_stt_t structure.
 *****************************************************************************/
void dvbpsi_atsc_EmptySTT(dvbpsi_atsc_stt_t* p_stt)
{
  dvbpsi_DeleteDescriptors(p_stt->p_first_descriptor);    
  p_stt->p_first_descriptor = NULL;
}

/*****************************************************************************
 * dvbpsi_atsc_STTAddDescriptor
 *****************************************************************************
 * Add a descriptor to the STT table.
 *****************************************************************************/
dvbpsi_descriptor_t *dvbpsi_atsc_STTAddDescriptor(
                                               dvbpsi_atsc_stt_t *p_stt,
                                               uint8_t i_tag, uint8_t i_length,
                                               uint8_t *p_data)
{
  dvbpsi_descriptor_t * p_descriptor
                        = dvbpsi_NewDescriptor(i_tag, i_length, p_data);

  if(p_descriptor)
  {
    if(p_stt->p_first_descriptor == NULL)
    {
      p_stt->p_first_descriptor = p_descriptor;
    }
    else
    {
      dvbpsi_descriptor_t * p_last_descriptor = p_stt->p_first_descriptor;
      while(p_last_descriptor->p_next != NULL)
        p_last_descriptor = p_last_descriptor->p_next;
      p_last_descriptor->p_next = p_descriptor;
    }
  }

  return p_descriptor;
}

/*****************************************************************************
 * dvbpsi_atsc_GatherSTTSections
 *****************************************************************************
 * Callback for the subtable demultiplexor.
 *****************************************************************************/
void dvbpsi_atsc_GatherSTTSections(dvbpsi_decoder_t * p_psi_decoder,
                              void * p_private_decoder,
                              dvbpsi_psi_section_t * p_section)
{
  dvbpsi_atsc_stt_decoder_t * p_stt_decoder
                        = (dvbpsi_atsc_stt_decoder_t*)p_private_decoder;

  dvbpsi_atsc_stt_t *p_stt;
  
  if(!p_section->b_syntax_indicator)
  {
    /* Invalid section_syntax_indicator */
    DVBPSI_ERROR("STT decoder",
                 "invalid section (section_syntax_indicator == 0)");
    
  }
  else
  {
      dvbpsi_atsc_NewSTT(p_stt, p_section->p_payload_start[0]);
      if (p_stt)
      {
          /* Decode the sections */
          dvbpsi_atsc_DecodeSTTSections(p_stt,
                                  p_section);
          /* Delete the sections */
          dvbpsi_ReleasePSISections(p_psi_decoder,p_section);
          /* signal the new STT */
          p_stt_decoder->pf_callback(p_stt_decoder->p_cb_data,
                                     p_stt);
      }

  }

}


/*****************************************************************************
 * dvbpsi_DecodeSTTSection
 *****************************************************************************
 * STT decoder.
 *****************************************************************************/
void dvbpsi_atsc_DecodeSTTSections(dvbpsi_atsc_stt_t* p_stt,
                              dvbpsi_psi_section_t* p_section)
{
    uint8_t *p_byte, *p_end;
    uint16_t i_length = 0;

    p_byte = p_section->p_payload_start + 1; 
    p_stt->i_system_time = (((uint32_t)p_byte[0]) << 24) |
                           (((uint32_t)p_byte[1]) << 16) |
                           (((uint32_t)p_byte[2]) <<  8) |
                           ((uint32_t)p_byte[3]);
    p_stt->i_gps_utc_offset = p_byte[4];
    p_stt->i_daylight_savings = (((uint16_t)p_byte[5]) << 16) |
                                 ((uint16_t)p_byte[6]);
    p_byte += 7;
    /* Table descriptors */
    i_length = (p_section->i_length - 17);
    p_end = p_byte + i_length;

    while(p_byte + 2 <= p_end)
    {
        uint8_t i_tag = p_byte[0];
        uint8_t i_length = p_byte[1];
        if(i_length + 2 <= p_end - p_byte)
          dvbpsi_atsc_STTAddDescriptor(p_stt, i_tag, i_length, p_byte + 2);
        p_byte += 2 + i_length;
    }

}