searching.c

linux下的MPEG1

/*
 * Copyright (C) 2000 Rich Wareham <[e-mail]>
 * 
 * This file is part of libdvdnav, a DVD navigation library.
 * 
 * libdvdnav 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.
 * 
 * libdvdnav 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
 *
 * $Id: searching.c,v 1.20 2006/09/17 13:01:08 valtri Exp $
 *
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <assert.h>
#include "dvdnav_internal.h"
#include "dvdnav.h"

/*
#define LOG_DEBUG
*/

/* Searching API calls */

/* Scan the ADMAP for a particular block number. */
/* Return placed in vobu. */
/* Returns error status */
/* FIXME: Maybe need to handle seeking outside current cell. */
static dvdnav_status_t dvdnav_scan_admap(dvdnav_t *this, int32_t domain, uint32_t seekto_block, uint32_t *vobu) {
  vobu_admap_t *admap = NULL;

#ifdef LOG_DEBUG
  fprintf(MSG_OUT, "libdvdnav: Seeking to target %u ...\n", seekto_block);
#endif
  *vobu = -1;

  /* Search through the VOBU_ADMAP for the nearest VOBU
   * to the target block */
  switch(domain) {
  case FP_DOMAIN:
  case VMGM_DOMAIN:
    admap = this->vm->vmgi->menu_vobu_admap;
    break;
  case VTSM_DOMAIN:
    admap = this->vm->vtsi->menu_vobu_admap;
    break;
  case VTS_DOMAIN:
    admap = this->vm->vtsi->vts_vobu_admap;
    break;
  default:
    fprintf(MSG_OUT, "libdvdnav: Error: Unknown domain for seeking.\n");
  }
  if(admap) {
    uint32_t address = 0;
    uint32_t vobu_start, next_vobu;
    int32_t found = 0;

    /* Search through ADMAP for best sector */
    vobu_start = SRI_END_OF_CELL;
    /* FIXME: Implement a faster search algorithm */
    while((!found) && ((address<<2) < admap->last_byte)) {
      next_vobu = admap->vobu_start_sectors[address];

      /* fprintf(MSG_OUT, "libdvdnav: Found block %u\n", next_vobu); */

      if(vobu_start <= seekto_block &&
          next_vobu > seekto_block) {
        found = 1;
      } else {
        vobu_start = next_vobu;
      }
      address ++;
    }
    if(found) {
      *vobu = vobu_start;
      return DVDNAV_STATUS_OK;
    } else {
      fprintf(MSG_OUT, "libdvdnav: Could not locate block\n");
      return DVDNAV_STATUS_ERR;
    }
  }
  fprintf(MSG_OUT, "libdvdnav: admap not located\n");
  return DVDNAV_STATUS_ERR;
}

dvdnav_status_t dvdnav_time_search(dvdnav_t *this,
				   uint64_t time) {
  
  uint64_t target = time;
  uint64_t length = 0;
  uint32_t first_cell_nr, last_cell_nr, cell_nr;
  int32_t found;
  cell_playback_t *cell;
  dvd_state_t *state;

  if(this->position_current.still != 0) {
    printerr("Cannot seek in a still frame.");
    return DVDNAV_STATUS_ERR;
  }
  
  pthread_mutex_lock(&this->vm_lock);
  state = &(this->vm->state);
  if(!state->pgc) {
    printerr("No current PGC.");
    pthread_mutex_unlock(&this->vm_lock);
    return DVDNAV_STATUS_ERR;
  }

  
  if (this->pgc_based) {
    first_cell_nr = 1;
    last_cell_nr = state->pgc->nr_of_cells;
  } else {
    /* Find start cell of program. */
    first_cell_nr = state->pgc->program_map[state->pgN-1];
    /* Find end cell of program */
    if(state->pgN < state->pgc->nr_of_programs)
      last_cell_nr = state->pgc->program_map[state->pgN] - 1;
    else
      last_cell_nr = state->pgc->nr_of_cells;
  }

  found = 0;
  for(cell_nr = first_cell_nr; (cell_nr <= last_cell_nr) && !found; cell_nr ++) {
    cell =  &(state->pgc->cell_playback[cell_nr-1]);
    length = dvdnav_convert_time(&cell->playback_time);
    if (target >= length) {
      target -= length;
    } else {
      /* FIXME: there must be a better way than interpolation */
      target = target * (cell->last_sector - cell->first_sector + 1) / length;
      target += cell->first_sector;
      
      found = 1;
      break;
    }
  }

  if(found) {
    int32_t vobu;
#ifdef LOG_DEBUG
    fprintf(MSG_OUT, "libdvdnav: Seeking to cell %i from choice of %i to %i\n",
	    cell_nr, first_cell_nr, last_cell_nr);
#endif
    if (dvdnav_scan_admap(this, state->domain, target, &vobu) == DVDNAV_STATUS_OK) {
      int32_t start = state->pgc->cell_playback[cell_nr-1].first_sector;
      
      if (vm_jump_cell_block(this->vm, cell_nr, vobu - start)) {
#ifdef LOG_DEBUG
        fprintf(MSG_OUT, "libdvdnav: After cellN=%u blockN=%u target=%x vobu=%x start=%x\n" ,
          state->cellN, state->blockN, target, vobu, start);
#endif
        this->vm->hop_channel += HOP_SEEK;
        pthread_mutex_unlock(&this->vm_lock);
        return DVDNAV_STATUS_OK;
      }
    }
  }
  
  fprintf(MSG_OUT, "libdvdnav: Error when seeking\n");
  printerr("Error when seeking.");
  pthread_mutex_unlock(&this->vm_lock);
  return DVDNAV_STATUS_ERR;
}

dvdnav_status_t dvdnav_sector_search(dvdnav_t *this,
				     uint64_t offset, int32_t origin) {
  uint32_t target = 0;
  uint32_t length = 0;
  uint32_t first_cell_nr, last_cell_nr, cell_nr;
  int32_t found;
  cell_playback_t *cell;
  dvd_state_t *state;
  dvdnav_status_t result;

  if(this->position_current.still != 0) {
    printerr("Cannot seek in a still frame.");
    return DVDNAV_STATUS_ERR;
  }
  
  result = dvdnav_get_position(this, &target, &length);
  if(!result) {
    return DVDNAV_STATUS_ERR;
  }
 
  pthread_mutex_lock(&this->vm_lock);
  state = &(this->vm->state);
  if(!state->pgc) {
    printerr("No current PGC.");
    pthread_mutex_unlock(&this->vm_lock);
    return DVDNAV_STATUS_ERR;
  }
#ifdef LOG_DEBUG
  fprintf(MSG_OUT, "libdvdnav: seeking to offset=%lu pos=%u length=%u\n", offset, target, length); 
  fprintf(MSG_OUT, "libdvdnav: Before cellN=%u blockN=%u\n", state->cellN, state->blockN);
#endif

  switch(origin) {
   case SEEK_SET:
    if(offset > length) {
      printerr("Request to seek behind end.");
      pthread_mutex_unlock(&this->vm_lock);
      return DVDNAV_STATUS_ERR;
    }
    target = offset;
    break;
   case SEEK_CUR:
    if(target + offset > length) {
      printerr("Request to seek behind end.");
      pthread_mutex_unlock(&this->vm_lock);
      return DVDNAV_STATUS_ERR;
    }
    target += offset;
    break;
   case SEEK_END:
    if(length - offset < 0) {
      printerr("Request to seek before start.");
      pthread_mutex_unlock(&this->vm_lock);
      return DVDNAV_STATUS_ERR;
    }
    target = length - offset;
    break;
   default:
    /* Error occured */
    printerr("Illegal seek mode.");
    pthread_mutex_unlock(&this->vm_lock);
    return DVDNAV_STATUS_ERR;
  }
  
  if (this->pgc_based) {
    first_cell_nr = 1;
    last_cell_nr = state->pgc->nr_of_cells;
  } else {
    /* Find start cell of program. */
    first_cell_nr = state->pgc->program_map[state->pgN-1];
    /* Find end cell of program */
    if(state->pgN < state->pgc->nr_of_programs)
      last_cell_nr = state->pgc->program_map[state->pgN] - 1;
    else
      last_cell_nr = state->pgc->nr_of_cells;
  }

  found = 0;
  for(cell_nr = first_cell_nr; (cell_nr <= last_cell_nr) && !found; cell_nr ++) {
    cell =  &(state->pgc->cell_playback[cell_nr-1]);
    length = cell->last_sector - cell->first_sector + 1;
    if (target >= length) {
      target -= length;
    } else {
      /* convert the target sector from Cell-relative to absolute physical sector */
      target += cell->first_sector;
      found = 1;
      break;
    }
  }

  if(found) {
    int32_t vobu;
#ifdef LOG_DEBUG
    fprintf(MSG_OUT, "libdvdnav: Seeking to cell %i from choice of %i to %i\n",
	    cell_nr, first_cell_nr, last_cell_nr);
#endif
    if (dvdnav_scan_admap(this, state->domain, target, &vobu) == DVDNAV_STATUS_OK) {
      int32_t start = state->pgc->cell_playback[cell_nr-1].first_sector;
      
      if (vm_jump_cell_block(this->vm, cell_nr, vobu - start)) {
#ifdef LOG_DEBUG
        fprintf(MSG_OUT, "libdvdnav: After cellN=%u blockN=%u target=%x vobu=%x start=%x\n" ,
          state->cellN, state->blockN, target, vobu, start);
#endif
        this->vm->hop_channel += HOP_SEEK;