text: /*
   * DVB subtitle decoding
   * Copyright (c) 2005 Ian Caulfield
   *
   * This file is part of FFmpeg.
   *
   * FFmpeg is free software; you can redistribute it and/or
   * modify it under the terms of the GNU Lesser General Public
   * License as published by the Free Software Foundation; either
   * version 2.1 of the License, or (at your option) any later version.
   *
   * FFmpeg 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
   * Lesser General Public License for more details.
   *
   * You should have received a copy of the GNU Lesser General Public
   * License along with FFmpeg; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
   */
  
  #include "avcodec.h"
  #include "get_bits.h"
  #include "bytestream.h"
  #include "internal.h"
  #include "libavutil/colorspace.h"
  #include "libavutil/imgutils.h"
  #include "libavutil/opt.h"
  #include "libavutil/thread.h"
  
  #define DVBSUB_PAGE_SEGMENT     0x10
  #define DVBSUB_REGION_SEGMENT   0x11
  #define DVBSUB_CLUT_SEGMENT     0x12
  #define DVBSUB_OBJECT_SEGMENT   0x13
  #define DVBSUB_DISPLAYDEFINITION_SEGMENT 0x14
  #define DVBSUB_DISPLAY_SEGMENT  0x80
  
  #define cm (ff_crop_tab + MAX_NEG_CROP)
  
  #define RGBA(r,g,b,a) (((unsigned)(a) << 24) | ((r) << 16) | ((g) << 8) | (b))
  
  typedef struct DVBSubCLUT {
      int id;
      int version;
  
      uint32_t clut4[4];
      uint32_t clut16[16];
      uint32_t clut256[256];
  
      struct DVBSubCLUT *next;
  } DVBSubCLUT;
  
  static DVBSubCLUT default_clut;
  
  typedef struct DVBSubObjectDisplay {
      int object_id;
      int region_id;
  
      int x_pos;
      int y_pos;
  
      int fgcolor;
      int bgcolor;
  
      struct DVBSubObjectDisplay *region_list_next;
      struct DVBSubObjectDisplay *object_list_next;
  } DVBSubObjectDisplay;
  
  typedef struct DVBSubObject {
      int id;
      int version;
  
      int type;
  
      DVBSubObjectDisplay *display_list;
  
      struct DVBSubObject *next;
  } DVBSubObject;
  
  typedef struct DVBSubRegionDisplay {
      int region_id;
  
      int x_pos;
      int y_pos;
  
      struct DVBSubRegionDisplay *next;
  } DVBSubRegionDisplay;
  
  typedef struct DVBSubRegion {
      int id;
      int version;
  
      int width;
      int height;
      int depth;
  
      int clut;
      int bgcolor;
  
      uint8_t computed_clut[4*256];
      int has_computed_clut;
  
      uint8_t *pbuf;
      int buf_size;
      int dirty;
  
      DVBSubObjectDisplay *display_list;
  
      struct DVBSubRegion *next;
  } DVBSubRegion;
  
  typedef struct DVBSubDisplayDefinition {
      int version;
  
      int x;
      int y;
      int width;
      int height;
  } DVBSubDisplayDefinition;
  
  typedef struct DVBSubContext {
      AVClass *class;
      int composition_id;
      int ancillary_id;
  
      int version;
      int time_out;
      int compute_edt; /**< if 1 end display time calculated using pts
                            if 0 (Default) calculated using time out */
      int compute_clut;
      int clut_count2[257][256];
      int substream;
      int64_t prev_start;
      DVBSubRegion *region_list;
      DVBSubCLUT   *clut_list;
      DVBSubObject *object_list;
  
      DVBSubRegionDisplay *display_list;
      DVBSubDisplayDefinition *display_definition;
  } DVBSubContext;
  
  
  static DVBSubObject* get_object(DVBSubContext *ctx, int object_id)
  {
      DVBSubObject *ptr = ctx->object_list;
  
      while (ptr && ptr->id != object_id) {
          ptr = ptr->next;
      }
  
      return ptr;
  }
  
  static DVBSubCLUT* get_clut(DVBSubContext *ctx, int clut_id)
  {
      DVBSubCLUT *ptr = ctx->clut_list;
  
      while (ptr && ptr->id != clut_id) {
          ptr = ptr->next;
      }
  
      return ptr;
  }
  
  static DVBSubRegion* get_region(DVBSubContext *ctx, int region_id)
  {
      DVBSubRegion *ptr = ctx->region_list;
  
      while (ptr && ptr->id != region_id) {
          ptr = ptr->next;
      }
  
      return ptr;
  }
  
  static void delete_region_display_list(DVBSubContext *ctx, DVBSubRegion *region)
  {
      DVBSubObject *object, *obj2, **obj2_ptr;
      DVBSubObjectDisplay *display, *obj_disp, **obj_disp_ptr;
  
      while (region->display_list) {
          display = region->display_list;
  
          object = get_object(ctx, display->object_id);
  
          if (object) {
              obj_disp_ptr = &object->display_list;
              obj_disp = *obj_disp_ptr;
  
              while (obj_disp && obj_disp != display) {
                  obj_disp_ptr = &obj_disp->object_list_next;
                  obj_disp = *obj_disp_ptr;
              }
  
              if (obj_disp) {
                  *obj_disp_ptr = obj_disp->object_list_next;
  
                  if (!object->display_list) {
                      obj2_ptr = &ctx->object_list;
                      obj2 = *obj2_ptr;
  
                      while (obj2 != object) {
                          av_assert0(obj2);
                          obj2_ptr = &obj2->next;
                          obj2 = *obj2_ptr;
                      }
  
                      *obj2_ptr = obj2->next;
  
                      av_freep(&obj2);
                  }
              }
          }
  
          region->display_list = display->region_list_next;
  
          av_freep(&display);
      }
  
  }
  
  static void delete_cluts(DVBSubContext *ctx)
  {
      while (ctx->clut_list) {
          DVBSubCLUT *clut = ctx->clut_list;
  
          ctx->clut_list = clut->next;
  
          av_freep(&clut);
      }
  }
  
  static void delete_objects(DVBSubContext *ctx)
  {
      while (ctx->object_list) {
          DVBSubObject *object = ctx->object_list;
  
          ctx->object_list = object->next;
  
          av_freep(&object);
      }
  }
  
  static void delete_regions(DVBSubContext *ctx)
  {
      while (ctx->region_list) {
          DVBSubRegion *region = ctx->region_list;
  
          ctx->region_list = region->next;
  
          delete_region_display_list(ctx, region);
  
          av_freep(&region->pbuf);
          av_freep(&region);
      }
  }
  
  static av_cold void init_default_clut(void)
  {
      int i, r, g, b, a = 0;
  
      default_clut.id = -1;
      default_clut.next = NULL;
  
      default_clut.clut4[0] = RGBA(  0,   0,   0,   0);
      default_clut.clut4[1] = RGBA(255, 255, 255, 255);
      default_clut.clut4[2] = RGBA(  0,   0,   0, 255);
      default_clut.clut4[3] = RGBA(127, 127, 127, 255);
  
      default_clut.clut16[0] = RGBA(  0,   0,   0,   0);
      for (i = 1; i < 16; i++) {
          if (i < 8) {
              r = (i & 1) ? 255 : 0;
              g = (i & 2) ? 255 : 0;
              b = (i & 4) ? 255 : 0;
          } else {
              r = (i & 1) ? 127 : 0;
              g = (i & 2) ? 127 : 0;
              b = (i & 4) ? 127 : 0;
          }
          default_clut.clut16[i] = RGBA(r, g, b, 255);
      }
  
      default_clut.clut256[0] = RGBA(  0,   0,   0,   0);
      for (i = 1; i < 256; i++) {
          if (i < 8) {
              r = (i & 1) ? 255 : 0;
              g = (i & 2) ? 255 : 0;
              b = (i & 4) ? 255 : 0;
              a = 63;
          } else {
              switch (i & 0x88) {
              case 0x00:
                  r = ((i & 1) ? 85 : 0) + ((i & 0x10) ? 170 : 0);
                  g = ((i & 2) ? 85 : 0) + ((i & 0x20) ? 170 : 0);
                  b = ((i & 4) ? 85 : 0) + ((i & 0x40) ? 170 : 0);
                  a = 255;
                  break;
              case 0x08:
                  r = ((i & 1) ? 85 : 0) + ((i & 0x10) ? 170 : 0);
                  g = ((i & 2) ? 85 : 0) + ((i & 0x20) ? 170 : 0);
                  b = ((i & 4) ? 85 : 0) + ((i & 0x40) ? 170 : 0);
                  a = 127;
                  break;
              case 0x80:
                  r = 127 + ((i & 1) ? 43 : 0) + ((i & 0x10) ? 85 : 0);
                  g = 127 + ((i & 2) ? 43 : 0) + ((i & 0x20) ? 85 : 0);
                  b = 127 + ((i & 4) ? 43 : 0) + ((i & 0x40) ? 85 : 0);
                  a = 255;
                  break;
              case 0x88:
                  r = ((i & 1) ? 43 : 0) + ((i & 0x10) ? 85 : 0);
                  g = ((i & 2) ? 43 : 0) + ((i & 0x20) ? 85 : 0);
                  b = ((i & 4) ? 43 : 0) + ((i & 0x40) ? 85 : 0);
                  a = 255;
                  break;
              }
          }
          default_clut.clut256[i] = RGBA(r, g, b, a);
      }
  }
  
  static av_cold int dvbsub_init_decoder(AVCodecContext *avctx)
  {
      static AVOnce init_static_once = AV_ONCE_INIT;
      DVBSubContext *ctx = avctx->priv_data;
  
      if (ctx->substream < 0) {
          ctx->composition_id = -1;
          ctx->ancillary_id   = -1;
      } else if (!avctx->extradata || (avctx->extradata_size < 4) || ((avctx->extradata_size % 5 != 0) && (avctx->extradata_size != 4))) {
          av_log(avctx, AV_LOG_WARNING, "Invalid DVB subtitles stream extradata!\n");
          ctx->composition_id = -1;
          ctx->ancillary_id   = -1;
      } else {
          if (avctx->extradata_size > 5*ctx->substream + 2) {
              ctx->composition_id = AV_RB16(avctx->extradata + 5*ctx->substream);
              ctx->ancillary_id   = AV_RB16(avctx->extradata + 5*ctx->substream + 2);
          } else {
              av_log(avctx, AV_LOG_WARNING, "Selected DVB subtitles sub-stream %d is not available\n", ctx->substream);
              ctx->composition_id = AV_RB16(avctx->extradata);
              ctx->ancillary_id   = AV_RB16(avctx->extradata + 2);
          }
      }
  
      ctx->version = -1;
      ctx->prev_start = AV_NOPTS_VALUE;
  
      ff_thread_once(&init_static_once, init_default_clut);
  
      return 0;
  }
  
  static av_cold int dvbsub_close_decoder(AVCodecContext *avctx)
  {
      DVBSubContext *ctx = avctx->priv_data;
      DVBSubRegionDisplay *display;
  
      delete_regions(ctx);
  
      delete_objects(ctx);
  
      delete_cluts(ctx);
  
      av_freep(&ctx->display_definition);
  
      while (ctx->display_list) {
          display = ctx->display_list;
          ctx->display_list = display->next;
  
          av_freep(&display);
      }
  
      return 0;
  }
  
  static int dvbsub_read_2bit_string(AVCodecContext *avctx,
                                     uint8_t *destbuf, int dbuf_len,
                                     const uint8_t **srcbuf, int buf_size,
                                     int non_mod, uint8_t *map_table, int x_pos)
  {
      GetBitContext gb;
  
      int bits;
      int run_length;
      int pixels_read = x_pos;
  
      init_get_bits(&gb, *srcbuf, buf_size << 3);
  
      destbuf += x_pos;
  
      while (get_bits_count(&gb) < buf_size << 3 && pixels_read < dbuf_len) {
          bits = get_bits(&gb, 2);
  
          if (bits) {
              if (non_mod != 1 || bits != 1) {
                  if (map_table)
                      *destbuf++ = map_table[bits];
                  else
                      *destbuf++ = bits;
              }
              pixels_read++;
          } else {
              bits = get_bits1(&gb);
              if (bits == 1) {
                  run_length = get_bits(&gb, 3) + 3;
                  bits = get_bits(&gb, 2);
  
                  if (non_mod == 1 && bits == 1)
                      pixels_read += run_length;
                  else {
                      if (map_table)
                          bits = map_table[bits];
                      while (run_length-- > 0 && pixels_read < dbuf_len) {
                          *destbuf++ = bits;
                          pixels_read++;
                      }
                  }
              } else {
                  bits = get_bits1(&gb);
                  if (bits == 0) {
                      bits = get_bits(&gb, 2);
                      if (bits == 2) {
                          run_length = get_bits(&gb, 4) + 12;
                          bits = get_bits(&gb, 2);
  
                          if (non_mod == 1 && bits == 1)
                              pixels_read += run_length;
                          else {
                              if (map_table)
                                  bits = map_table[bits];
                              while (run_length-- > 0 && pixels_read < dbuf_len) {
                                  *destbuf++ = bits;
                                  pixels_read++;
                              }
                          }
                      } else if (bits == 3) {
                          run_length = get_bits(&gb, 8) + 29;
                          bits = get_bits(&gb, 2);
  
                          if (non_mod == 1 && bits == 1)
                              pixels_read += run_length;
                          else {
                              if (map_table)
                                  bits = map_table[bits];
                              while (run_length-- > 0 && pixels_read < dbuf_len) {
                                  *destbuf++ = bits;
                                  pixels_read++;
                              }
                          }
                      } else if (bits == 1) {
                          if (map_table)
                              bits = map_table[0];
                          else
                              bits = 0;
                          run_length = 2;
                          while (run_length-- > 0 && pixels_read < dbuf_len) {
                              *destbuf++ = bits;
                              pixels_read++;
                          }
                      } else {
                          (*srcbuf) += (get_bits_count(&gb) + 7) >> 3;
                          return pixels_read;
                      }
                  } else {
                      if (map_table)
                          bits = map_table[0];
                      else
                          bits = 0;
                      *destbuf++ = bits;
                      pixels_read++;
                  }
              }
          }
      }
  
      if (get_bits(&gb, 6))
          av_log(avctx, AV_LOG_ERROR, "line overflow\n");
  
      (*srcbuf) += (get_bits_count(&gb) + 7) >> 3;
  
      return pixels_read;
  }
  
  static int dvbsub_read_4bit_string(AVCodecContext *avctx, uint8_t *destbuf, int dbuf_len,
                                     const uint8_t **srcbuf, int buf_size,
                                     int non_mod, uint8_t *map_table, int x_pos)
  {
      GetBitContext gb;
  
      int bits;
      int run_length;
      int pixels_read = x_pos;
  
      init_get_bits(&gb, *srcbuf, buf_size << 3);
  
      destbuf += x_pos;
  
      while (get_bits_count(&gb) < buf_size << 3 && pixels_read < dbuf_len) {
          bits = get_bits(&gb, 4);
  
          if (bits) {
              if (non_mod != 1 || bits != 1) {
                  if (map_table)
                      *destbuf++ = map_table[bits];
                  else
                      *destbuf++ = bits;
              }
              pixels_read++;
          } else {
              bits = get_bits1(&gb);
              if (bits == 0) {
                  run_length = get_bits(&gb, 3);
  
                  if (run_length == 0) {
                      (*srcbuf) += (get_bits_count(&gb) + 7) >> 3;
                      return pixels_read;
                  }
  
                  run_length += 2;
  
                  if (map_table)
                      bits = map_table[0];
                  else
                      bits = 0;
  
                  while (run_length-- > 0 && pixels_read < dbuf_len) {
                      *destbuf++ = bits;
                      pixels_read++;
                  }
              } else {
                  bits = get_bits1(&gb);
                  if (bits == 0) {
                      run_length = get_bits(&gb, 2) + 4;
                      bits = get_bits(&gb, 4);
  
                      if (non_mod == 1 && bits == 1)
                          pixels_read += run_length;
                      else {
                          if (map_table)
                              bits = map_table[bits];
                          while (run_length-- > 0 && pixels_read < dbuf_len) {
                              *destbuf++ = bits;
                              pixels_read++;
                          }
                      }
                  } else {
                      bits = get_bits(&gb, 2);
                      if (bits == 2) {
                          run_length = get_bits(&gb, 4) + 9;
                          bits = get_bits(&gb, 4);
  
                          if (non_mod == 1 && bits == 1)
                              pixels_read += run_length;
                          else {
                              if (map_table)
                                  bits = map_table[bits];
                              while (run_length-- > 0 && pixels_read < dbuf_len) {
                                  *destbuf++ = bits;
                                  pixels_read++;
                              }
                          }
                      } else if (bits == 3) {
                          run_length = get_bits(&gb, 8) + 25;
                          bits = get_bits(&gb, 4);
  
                          if (non_mod == 1 && bits == 1)
                              pixels_read += run_length;
                          else {
                              if (map_table)
                                  bits = map_table[bits];
                              while (run_length-- > 0 && pixels_read < dbuf_len) {
                                  *destbuf++ = bits;
                                  pixels_read++;
                              }
                          }
                      } else if (bits == 1) {
                          if (map_table)
                              bits = map_table[0];
                          else
                              bits = 0;
                          run_length = 2;
                          while (run_length-- > 0 && pixels_read < dbuf_len) {
                              *destbuf++ = bits;
                              pixels_read++;
                          }
                      } else {
                          if (map_table)
                              bits = map_table[0];
                          else
                              bits = 0;
                          *destbuf++ = bits;
                          pixels_read ++;
                      }
                  }
              }
          }
      }
  
      if (get_bits(&gb, 8))
          av_log(avctx, AV_LOG_ERROR, "line overflow\n");
  
      (*srcbuf) += (get_bits_count(&gb) + 7) >> 3;
  
      return pixels_read;
  }
  
  static int dvbsub_read_8bit_string(AVCodecContext *avctx,
                                     uint8_t *destbuf, int dbuf_len,
                                      const uint8_t **srcbuf, int buf_size,
                                      int non_mod, uint8_t *map_table, int x_pos)
  {
      const uint8_t *sbuf_end = (*srcbuf) + buf_size;
      int bits;
      int run_length;
      int pixels_read = x_pos;
  
      destbuf += x_pos;
  
      while (*srcbuf < sbuf_end && pixels_read < dbuf_len) {
          bits = *(*srcbuf)++;
  
          if (bits) {
              if (non_mod != 1 || bits != 1) {
                  if (map_table)
                      *destbuf++ = map_table[bits];
                  else
                      *destbuf++ = bits;
              }
              pixels_read++;
          } else {
              bits = *(*srcbuf)++;
              run_length = bits & 0x7f;
              if ((bits & 0x80) == 0) {
                  if (run_length == 0) {
                      return pixels_read;
                  }
  
                  bits = 0;
              } else {
                  bits = *(*srcbuf)++;
              }
              if (non_mod == 1 && bits == 1)
                  pixels_read += run_length;
              else {
                  if (map_table)
                      bits = map_table[bits];
                  while (run_length-- > 0 && pixels_read < dbuf_len) {
                      *destbuf++ = bits;
                      pixels_read++;
                  }
              }
          }
      }
  
      if (*(*srcbuf)++)
          av_log(avctx, AV_LOG_ERROR, "line overflow\n");
  
      return pixels_read;
  }
  
  static void compute_default_clut(DVBSubContext *ctx, uint8_t *clut, AVSubtitleRect *rect, int w, int h)
  {
      uint8_t list[256] = {0};
      uint8_t list_inv[256];
      int counttab[256] = {0};
      int (*counttab2)[256] = ctx->clut_count2;
      int count, i, x, y;
      ptrdiff_t stride = rect->linesize[0];
  
      memset(ctx->clut_count2, 0 , sizeof(ctx->clut_count2));
  
  #define V(x,y) rect->data[0][(x) + (y)*stride]
      for (y = 0; y<h; y++) {
          for (x = 0; x<w; x++) {
              int v = V(x,y) + 1;
              int vl = x     ? V(x-1,y) + 1 : 0;
              int vr = x+1<w ? V(x+1,y) + 1 : 0;
              int vt = y     ? V(x,y-1) + 1 : 0;
              int vb = y+1<h ? V(x,y+1) + 1 : 0;
              counttab[v-1] += !!((v!=vl) + (v!=vr) + (v!=vt) + (v!=vb));
              counttab2[vl][v-1] ++;
              counttab2[vr][v-1] ++;
              counttab2[vt][v-1] ++;
              counttab2[vb][v-1] ++;
          }
      }
  #define L(x,y) list[d[(x) + (y)*stride]]
  
      for (i = 0; i<256; i++) {
          counttab2[i+1][i] = 0;
      }
      for (i = 0; i<256; i++) {
          int bestscore = 0;
          int bestv = 0;
  
          for (x = 0; x < 256; x++) {
              int scorev = 0;
              if (list[x])
                  continue;
              scorev += counttab2[0][x];
              for (y = 0; y < 256; y++) {
                  scorev += list[y] * counttab2[y+1][x];
              }
  
              if (scorev) {
                  int score = 1024LL*scorev / counttab[x];
                  if (score > bestscore) {
                      bestscore = score;
                      bestv = x;
                  }
              }
          }
          if (!bestscore)
              break;
          list    [ bestv ] = 1;
          list_inv[     i ] = bestv;
      }
  
      count = FFMAX(i - 1, 1);
      for (i--; i >= 0; i--) {
          int v = i * 255 / count;
          AV_WN32(clut + 4*list_inv[i], RGBA(v/2,v,v/2,v));
      }
  }
  
  
  static int save_subtitle_set(AVCodecContext *avctx, AVSubtitle *sub, int *got_output)
  {
      DVBSubContext *ctx = avctx->priv_data;
      DVBSubRegionDisplay *display;
      DVBSubDisplayDefinition *display_def = ctx->display_definition;
      DVBSubRegion *region;
      AVSubtitleRect *rect;
      const DVBSubCLUT *clut;
      const uint32_t *clut_table;
      int i;
      int offset_x=0, offset_y=0;
      int ret = 0;
  
  
      if (display_def) {
          offset_x = display_def->x;
          offset_y = display_def->y;
      }
  
      /* Not touching AVSubtitles again*/
      if (sub->num_rects) {
          avpriv_request_sample(ctx, "Different Version of Segment asked Twice");
          return AVERROR_PATCHWELCOME;
      }
      for (display = ctx->display_list; display; display = display->next) {
          region = get_region(ctx, display->region_id);
          if (region && region->dirty)
              sub->num_rects++;
      }
  
      if (ctx->compute_edt == 0) {
          sub->end_display_time = ctx->time_out * 1000;
          *got_output = 1;
      } else if (ctx->prev_start != AV_NOPTS_VALUE) {
          sub->end_display_time = av_rescale_q((sub->pts - ctx->prev_start ), AV_TIME_BASE_Q, (AVRational){ 1, 1000 }) - 1;
          *got_output = 1;
      }
      if (sub->num_rects > 0) {
  
          sub->rects = av_calloc(sub->num_rects, sizeof(*sub->rects));
          if (!sub->rects) {
              ret = AVERROR(ENOMEM);
              goto fail;
          }
  
          for (i = 0; i < sub->num_rects; i++) {
              sub->rects[i] = av_mallocz(sizeof(*sub->rects[i]));
              if (!sub->rects[i]) {
                  ret = AVERROR(ENOMEM);
                  goto fail;
              }
          }
  
          i = 0;
  
          for (display = ctx->display_list; display; display = display->next) {
              region = get_region(ctx, display->region_id);
  
              if (!region)
                  continue;
  
              if (!region->dirty)
                  continue;
  
              rect = sub->rects[i];
              rect->x = display->x_pos + offset_x;
              rect->y = display->y_pos + offset_y;
              rect->w = region->width;
              rect->h = region->height;
              rect->nb_colors = (1 << region->depth);
              rect->type      = SUBTITLE_BITMAP;
              rect->linesize[0] = region->width;
  
              clut = get_clut(ctx, region->clut);
  
              if (!clut)
                  clut = &default_clut;
  
              switch (region->depth) {
              case 2:
                  clut_table = clut->clut4;
                  break;
              case 8:
                  clut_table = clut->clut256;
                  break;
              case 4:
              default:
                  clut_table = clut->clut16;
                  break;
              }
  
              rect->data[1] = av_mallocz(AVPALETTE_SIZE);
              if (!rect->data[1]) {
                  ret = AVERROR(ENOMEM);
                  goto fail;
              }
              memcpy(rect->data[1], clut_table, (1 << region->depth) * sizeof(*clut_table));
  
              rect->data[0] = av_malloc(region->buf_size);
              if (!rect->data[0]) {
                  ret = AVERROR(ENOMEM);
                  goto fail;
              }
  
              memcpy(rect->data[0], region->pbuf, region->buf_size);
  
              if ((clut == &default_clut && ctx->compute_clut < 0) || ctx->compute_clut == 1) {
                  if (!region->has_computed_clut) {
                      compute_default_clut(ctx, region->computed_clut, rect, rect->w, rect->h);
                      region->has_computed_clut = 1;
                  }
  
                  memcpy(rect->data[1], region->computed_clut, sizeof(region->computed_clut));
              }
  
              i++;
          }
      }
  
      return 0;
  fail:
      if (sub->rects) {
          for (i=0; i < sub->num_rects; i++) {
              rect = sub->rects[i];
              if (rect) {
                  av_freep(&rect->data[0]);
                  av_freep(&rect->data[1]);
              }
              av_freep(&sub->rects[i]);
          }
          av_freep(&sub->rects);
      }
      sub->num_rects = 0;
      return ret;
  }
  
  static void dvbsub_parse_pixel_data_block(AVCodecContext *avctx, DVBSubObjectDisplay *display,
                                            const uint8_t *buf, int buf_size, int top_bottom, int non_mod)
  {
      DVBSubContext *ctx = avctx->priv_data;
  
      DVBSubRegion *region = get_region(ctx, display->region_id);
      const uint8_t *buf_end = buf + buf_size;
      uint8_t *pbuf;
      int x_pos, y_pos;
      int i;
  
      uint8_t map2to4[] = { 0x0,  0x7,  0x8,  0xf};
      uint8_t map2to8[] = {0x00, 0x77, 0x88, 0xff};
      uint8_t map4to8[] = {0x00, 0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77,
                           0x88, 0x99, 0xaa, 0xbb, 0xcc, 0xdd, 0xee, 0xff};
      uint8_t *map_table;
  
  #if 0
      ff_dlog(avctx, "DVB pixel block size %d, %s field:\n", buf_size,
              top_bottom ? "bottom" : "top");
  
      for (i = 0; i < buf_size; i++) {
          if (i % 16 == 0)
              ff_dlog(avctx, "0x%8p: ", buf+i);
  
          ff_dlog(avctx, "%02x ", buf[i]);
          if (i % 16 == 15)
              ff_dlog(avctx, "\n");
      }
  
      if (i % 16)
          ff_dlog(avctx, "\n");
  #endif
  
      if (!region)
          return;
  
      pbuf = region->pbuf;
      region->dirty = 1;
  
      x_pos = display->x_pos;
      y_pos = display->y_pos;
  
      y_pos += top_bottom;
  
      while (buf < buf_end) {
          if ((*buf!=0xf0 && x_pos >= region->width) || y_pos >= region->height) {
              av_log(avctx, AV_LOG_ERROR, "Invalid object location! %d-%d %d-%d %02x\n", x_pos, region->width, y_pos, region->height, *buf);
              return;
          }
  
          switch (*buf++) {
          case 0x10:
              if (region->depth == 8)
                  map_table = map2to8;
              else if (region->depth == 4)
                  map_table = map2to4;
              else
                  map_table = NULL;
  
              x_pos = dvbsub_read_2bit_string(avctx, pbuf + (y_pos * region->width),
                                              region->width, &buf, buf_end - buf,
                                              non_mod, map_table, x_pos);
              break;
          case 0x11:
              if (region->depth < 4) {
                  av_log(avctx, AV_LOG_ERROR, "4-bit pixel string in %d-bit region!\n", region->depth);
                  return;
              }
  
              if (region->depth == 8)
                  map_table = map4to8;
              else
                  map_table = NULL;
  
              x_pos = dvbsub_read_4bit_string(avctx, pbuf + (y_pos * region->width),
                                              region->width, &buf, buf_end - buf,
                                              non_mod, map_table, x_pos);
              break;
          case 0x12:
              if (region->depth < 8) {
                  av_log(avctx, AV_LOG_ERROR, "8-bit pixel string in %d-bit region!\n", region->depth);
                  return;
              }
  
              x_pos = dvbsub_read_8bit_string(avctx, pbuf + (y_pos * region->width),
                                              region->width, &buf, buf_end - buf,
                                              non_mod, NULL, x_pos);
              break;
  
          case 0x20:
              map2to4[0] = (*buf) >> 4;
              map2to4[1] = (*buf++) & 0xf;
              map2to4[2] = (*buf) >> 4;
              map2to4[3] = (*buf++) & 0xf;
              break;
          case 0x21:
              for (i = 0; i < 4; i++)
                  map2to8[i] = *buf++;
              break;
          case 0x22:
              for (i = 0; i < 16; i++)
                  map4to8[i] = *buf++;
              break;
  
          case 0xf0:
              x_pos = display->x_pos;
              y_pos += 2;
              break;
          default:
              av_log(avctx, AV_LOG_INFO, "Unknown/unsupported pixel block 0x%x\n", *(buf-1));
          }
      }
  
      if (ctx->compute_clut != -2)
          region->has_computed_clut = 0;
  }
  
  static int dvbsub_parse_object_segment(AVCodecContext *avctx,
                                         const uint8_t *buf, int buf_size)
  {
      DVBSubContext *ctx = avctx->priv_data;
  
      const uint8_t *buf_end = buf + buf_size;
      int object_id;
      DVBSubObject *object;
      DVBSubObjectDisplay *display;
      int top_field_len, bottom_field_len;
  
      int coding_method, non_modifying_color;
  
      object_id = AV_RB16(buf);
      buf += 2;
  
      object = get_object(ctx, object_id);
  
      if (!object)
          return AVERROR_INVALIDDATA;
  
      coding_method = ((*buf) >> 2) & 3;
      non_modifying_color = ((*buf++) >> 1) & 1;
  
      if (coding_method == 0) {
          top_field_len = AV_RB16(buf);
          buf += 2;
          bottom_field_len = AV_RB16(buf);
          buf += 2;
  
          if (buf + top_field_len + bottom_field_len > buf_end) {
              av_log(avctx, AV_LOG_ERROR, "Field data size %d+%d too large\n", top_field_len, bottom_field_len);
              return AVERROR_INVALIDDATA;
          }
  
          for (display = object->display_list; display; display = display->object_list_next) {
              const uint8_t *block = buf;
              int bfl = bottom_field_len;
  
              dvbsub_parse_pixel_data_block(avctx, display, block, top_field_len, 0,
                                              non_modifying_color);
  
              if (bottom_field_len > 0)
                  block = buf + top_field_len;
              else
                  bfl = top_field_len;
  
              dvbsub_parse_pixel_data_block(avctx, display, block, bfl, 1,
                                              non_modifying_color);
          }
      } else if (coding_method == 1) {
          avpriv_report_missing_feature(avctx, "coded as a string of characters");
          return AVERROR_PATCHWELCOME;
      } else if (coding_method == 2) {
          avpriv_report_missing_feature(avctx, "progressive coding of pixels");
          return AVERROR_PATCHWELCOME;
      } else {
          av_log(avctx, AV_LOG_ERROR, "Unknown object coding %d\n", coding_method);
          return AVERROR_INVALIDDATA;
      }
  
      return 0;
  }
  
  static int dvbsub_parse_clut_segment(AVCodecContext *avctx,
                                       const uint8_t *buf, int buf_size)
  {
      DVBSubContext *ctx = avctx->priv_data;
  
      const uint8_t *buf_end = buf + buf_size;
      int i, clut_id;
      int version;
      DVBSubCLUT *clut;
      int entry_id, depth , full_range;
      int y, cr, cb, alpha;
      int r, g, b, r_add, g_add, b_add;
  
      ff_dlog(avctx, "DVB clut packet:\n");
  
      for (i=0; i < buf_size; i++) {
          ff_dlog(avctx, "%02x ", buf[i]);
          if (i % 16 == 15)
              ff_dlog(avctx, "\n");
      }
  
      if (i % 16)
          ff_dlog(avctx, "\n");
  
      clut_id = *buf++;
      version = ((*buf)>>4)&15;
      buf += 1;
  
      clut = get_clut(ctx, clut_id);
  
      if (!clut) {
          clut = av_malloc(sizeof(*clut));
          if (!clut)
              return AVERROR(ENOMEM);
  
          memcpy(clut, &default_clut, sizeof(*clut));
  
          clut->id = clut_id;
          clut->version = -1;
  
          clut->next = ctx->clut_list;
          ctx->clut_list = clut;
      }
  
      if (clut->version != version) {
  
          clut->version = version;
  
          while (buf + 4 < buf_end) {
              entry_id = *buf++;
  
              depth = (*buf) & 0xe0;
  
              if (depth == 0) {
                  av_log(avctx, AV_LOG_ERROR, "Invalid clut depth 0x%x!\n", *buf);
              }
  
              full_range = (*buf++) & 1;
  
              if (full_range) {
                  y     = *buf++;
                  cr    = *buf++;
                  cb    = *buf++;
                  alpha = *buf++;
              } else {
                  y     = buf[0] & 0xfc;
                  cr    = (((buf[0] & 3) << 2) | ((buf[1] >> 6) & 3)) << 4;
                  cb    = (buf[1] << 2) & 0xf0;
                  alpha = (buf[1] << 6) & 0xc0;
  
                  buf += 2;
              }
  
              if (y == 0)
                  alpha = 0xff;
  
              YUV_TO_RGB1_CCIR(cb, cr);
              YUV_TO_RGB2_CCIR(r, g, b, y);
  
              ff_dlog(avctx, "clut %d := (%d,%d,%d,%d)\n", entry_id, r, g, b, alpha);
              if (!!(depth & 0x80) + !!(depth & 0x40) + !!(depth & 0x20) > 1) {
                  ff_dlog(avctx, "More than one bit level marked: %x\n", depth);
                  if (avctx->strict_std_compliance > FF_COMPLIANCE_NORMAL)
                      return AVERROR_INVALIDDATA;
              }
  
              if (depth & 0x80 && entry_id < 4)
                  clut->clut4[entry_id] = RGBA(r,g,b,255 - alpha);
              else if (depth & 0x40 && entry_id < 16)
                  clut->clut16[entry_id] = RGBA(r,g,b,255 - alpha);
              else if (depth & 0x20)
                  clut->clut256[entry_id] = RGBA(r,g,b,255 - alpha);
          }
      }
  
      return 0;
  }
  
  
  static int dvbsub_parse_region_segment(AVCodecContext *avctx,
                                         const uint8_t *buf, int buf_size)
  {
      DVBSubContext *ctx = avctx->priv_data;
  
      const uint8_t *buf_end = buf + buf_size;
      int region_id, object_id;
      int av_unused version;
      DVBSubRegion *region;
      DVBSubObject *object;
      DVBSubObjectDisplay *display;
      int fill;
      int ret;
  
      if (buf_size < 10)
          return AVERROR_INVALIDDATA;
  
      region_id = *buf++;
  
      region = get_region(ctx, region_id);
  
      if (!region) {
          region = av_mallocz(sizeof(*region));
          if (!region)
              return AVERROR(ENOMEM);
  
          region->id = region_id;
          region->version = -1;
  
          region->next = ctx->region_list;
          ctx->region_list = region;
      }
  
      version = ((*buf)>>4) & 15;
      fill = ((*buf++) >> 3) & 1;
  
      region->width = AV_RB16(buf);
      buf += 2;
      region->height = AV_RB16(buf);
      buf += 2;
  
      ret = av_image_check_size2(region->width, region->height, avctx->max_pixels, AV_PIX_FMT_PAL8, 0, avctx);
      if (ret >= 0 && region->width * region->height * 2 > 320 * 1024 * 8) {
          ret = AVERROR_INVALIDDATA;
          av_log(avctx, AV_LOG_ERROR, "Pixel buffer memory constraint violated\n");
      }
      if (ret < 0) {
          region->width= region->height= 0;
          return ret;
      }
  
      if (region->width * region->height != region->buf_size) {
          av_free(region->pbuf);
  
          region->buf_size = region->width * region->height;
  
          region->pbuf = av_malloc(region->buf_size);
          if (!region->pbuf) {
              region->buf_size =
              region->width =
              region->height = 0;
              return AVERROR(ENOMEM);
          }
  
          fill = 1;
          region->dirty = 0;
      }
  
      region->depth = 1 << (((*buf++) >> 2) & 7);
      if (region->depth < 2 || region->depth > 8) {
          av_log(avctx, AV_LOG_ERROR, "region depth %d is invalid\n", region->depth);
          region->depth= 4;
      }
      region->clut = *buf++;
  
      if (region->depth == 8) {
          region->bgcolor = *buf++;
          buf += 1;
      } else {
          buf += 1;
  
          if (region->depth == 4)
              region->bgcolor = (((*buf++) >> 4) & 15);
          else
              region->bgcolor = (((*buf++) >> 2) & 3);
      }
  
      ff_dlog(avctx, "Region %d, (%dx%d)\n", region_id, region->width, region->height);
  
      if (fill) {
          memset(region->pbuf, region->bgcolor, region->buf_size);
          ff_dlog(avctx, "Fill region (%d)\n", region->bgcolor);
      }
  
      delete_region_display_list(ctx, region);
  
      while (buf + 5 < buf_end) {
          object_id = AV_RB16(buf);
          buf += 2;
  
          object = get_object(ctx, object_id);
  
          if (!object) {
              object = av_mallocz(sizeof(*object));
              if (!object)
                  return AVERROR(ENOMEM);
  
              object->id = object_id;
              object->next = ctx->object_list;
              ctx->object_list = object;
          }
  
          object->type = (*buf) >> 6;
  
          display = av_mallocz(sizeof(*display));
          if (!display)
              return AVERROR(ENOMEM);
  
          display->object_id = object_id;
          display->region_id = region_id;
  
          display->x_pos = AV_RB16(buf) & 0xfff;
          buf += 2;
          display->y_pos = AV_RB16(buf) & 0xfff;
          buf += 2;
  
          if (display->x_pos >= region->width ||
              display->y_pos >= region->height) {
              av_log(avctx, AV_LOG_ERROR, "Object outside region\n");
              av_free(display);
              return AVERROR_INVALIDDATA;
          }
  
          if ((object->type == 1 || object->type == 2) && buf+1 < buf_end) {
              display->fgcolor = *buf++;
              display->bgcolor = *buf++;
          }
  
          display->region_list_next = region->display_list;
          region->display_list = display;
  
          display->object_list_next = object->display_list;
          object->display_list = display;
      }
  
      return 0;
  }
  
  static int dvbsub_parse_page_segment(AVCodecContext *avctx,
                                       const uint8_t *buf, int buf_size, AVSubtitle *sub, int *got_output)
  {
      DVBSubContext *ctx = avctx->priv_data;
      DVBSubRegionDisplay *display;
      DVBSubRegionDisplay *tmp_display_list, **tmp_ptr;
  
      const uint8_t *buf_end = buf + buf_size;
      int region_id;
      int page_state;
      int timeout;
      int version;
  
      if (buf_size < 1)
          return AVERROR_INVALIDDATA;
  
      timeout = *buf++;
      version = ((*buf)>>4) & 15;
      page_state = ((*buf++) >> 2) & 3;
  
      if (ctx->version == version) {
          return 0;
      }
  
      ctx->time_out = timeout;
      ctx->version = version;
  
      ff_dlog(avctx, "Page time out %ds, state %d\n", ctx->time_out, page_state);
  
      if (ctx->compute_edt == 1)
          save_subtitle_set(avctx, sub, got_output);
  
      if (page_state == 1 || page_state == 2) {
          delete_regions(ctx);
          delete_objects(ctx);
          delete_cluts(ctx);
      }
  
      tmp_display_list = ctx->display_list;
      ctx->display_list = NULL;
  
      while (buf + 5 < buf_end) {
          region_id = *buf++;
          buf += 1;
  
          display = ctx->display_list;
          while (display && display->region_id != region_id) {
              display = display->next;
          }
          if (display) {
              av_log(avctx, AV_LOG_ERROR, "duplicate region\n");
              break;
          }
  
          display = tmp_display_list;
          tmp_ptr = &tmp_display_list;
  
          while (display && display->region_id != region_id) {
              tmp_ptr = &display->next;
              display = display->next;
          }
  
          if (!display) {
              display = av_mallocz(sizeof(*display));
              if (!display)
                  return AVERROR(ENOMEM);
          }
  
          display->region_id = region_id;
  
          display->x_pos = AV_RB16(buf);
          buf += 2;
          display->y_pos = AV_RB16(buf);
          buf += 2;
  
          *tmp_ptr = display->next;
  
          display->next = ctx->display_list;
          ctx->display_list = display;
  
          ff_dlog(avctx, "Region %d, (%d,%d)\n", region_id, display->x_pos, display->y_pos);
      }
  
      while (tmp_display_list) {
          display = tmp_display_list;
  
          tmp_display_list = display->next;
  
          av_freep(&display);
      }
  
      return 0;
  }
  
  
  #ifdef DEBUG
  static void png_save(DVBSubContext *ctx, const char *filename, uint32_t *bitmap, int w, int h)
  {
      int x, y, v;
      FILE *f;
      char fname[40], fname2[40];
      char command[1024];
  
      snprintf(fname, sizeof(fname), "%s.ppm", filename);
  
      f = fopen(fname, "w");
      if (!f) {
          perror(fname);
          return;
      }
      fprintf(f, "P6\n"
              "%d %d\n"
              "%d\n",
              w, h, 255);
      for(y = 0; y < h; y++) {
          for(x = 0; x < w; x++) {
              v = bitmap[y * w + x];
              putc((v >> 16) & 0xff, f);
              putc((v >> 8) & 0xff, f);
              putc((v >> 0) & 0xff, f);
          }
      }
      fclose(f);
  
  
      snprintf(fname2, sizeof(fname2), "%s-a.pgm", filename);
  
      f = fopen(fname2, "w");
      if (!f) {
          perror(fname2);
          return;
      }
      fprintf(f, "P5\n"
              "%d %d\n"
              "%d\n",
              w, h, 255);
      for(y = 0; y < h; y++) {
          for(x = 0; x < w; x++) {
              v = bitmap[y * w + x];
              putc((v >> 24) & 0xff, f);
          }
      }
      fclose(f);
  
      snprintf(command, sizeof(command), "pnmtopng -alpha %s %s > %s.png 2> /dev/null", fname2, fname, filename);
      if (system(command) != 0) {
          av_log(ctx, AV_LOG_ERROR, "Error running pnmtopng\n");
          return;
      }
  
      snprintf(command, sizeof(command), "rm %s %s", fname, fname2);
      if (system(command) != 0) {
          av_log(ctx, AV_LOG_ERROR, "Error removing %s and %s\n", fname, fname2);
          return;
      }
  }
  
  static int save_display_set(DVBSubContext *ctx)
  {
      DVBSubRegion *region;
      DVBSubRegionDisplay *display;
      const DVBSubCLUT *clut;
      const uint32_t *clut_table;
      int x_pos, y_pos, width, height;
      int x, y, y_off, x_off;
      uint32_t *pbuf;
      char filename[32];
      static int fileno_index = 0;
  
      x_pos = -1;
      y_pos = -1;
      width = 0;
      height = 0;
  
      for (display = ctx->display_list; display; display = display->next) {
          region = get_region(ctx, display->region_id);
  
          if (!region)
              return -1;
  
          if (x_pos == -1) {
              x_pos = display->x_pos;
              y_pos = display->y_pos;
              width = region->width;
              height = region->height;
          } else {
              if (display->x_pos < x_pos) {
                  width += (x_pos - display->x_pos);
                  x_pos = display->x_pos;
              }
  
              if (display->y_pos < y_pos) {
                  height += (y_pos - display->y_pos);
                  y_pos = display->y_pos;
              }
  
              if (display->x_pos + region->width > x_pos + width) {
                  width = display->x_pos + region->width - x_pos;
              }
  
              if (display->y_pos + region->height > y_pos + height) {
                  height = display->y_pos + region->height - y_pos;
              }
          }
      }
  
      if (x_pos >= 0) {
  
          pbuf = av_malloc(width * height * 4);
          if (!pbuf)
              return -1;
  
          for (display = ctx->display_list; display; display = display->next) {
              region = get_region(ctx, display->region_id);
  
              if (!region)
                  return -1;
  
              x_off = display->x_pos - x_pos;
              y_off = display->y_pos - y_pos;
  
              clut = get_clut(ctx, region->clut);
  
              if (!clut)
                  clut = &default_clut;
  
              switch (region->depth) {
              case 2:
                  clut_table = clut->clut4;
                  break;
              case 8:
                  clut_table = clut->clut256;
                  break;
              case 4:
              default:
                  clut_table = clut->clut16;
                  break;
              }
  
              for (y = 0; y < region->height; y++) {
                  for (x = 0; x < region->width; x++) {
                      pbuf[((y + y_off) * width) + x_off + x] =
                          clut_table[region->pbuf[y * region->width + x]];
                  }
              }
  
          }
  
          snprintf(filename, sizeof(filename), "dvbs.%d", fileno_index);
  
          png_save(ctx, filename, pbuf, width, height);
  
          av_freep(&pbuf);
      }
  
      fileno_index++;
      return 0;
  }
  #endif /* DEBUG */
  
  static int dvbsub_parse_display_definition_segment(AVCodecContext *avctx,
                                                     const uint8_t *buf,
                                                     int buf_size)
  {
      DVBSubContext *ctx = avctx->priv_data;
      DVBSubDisplayDefinition *display_def = ctx->display_definition;
      int dds_version, info_byte;
  
      if (buf_size < 5)
          return AVERROR_INVALIDDATA;
  
      info_byte   = bytestream_get_byte(&buf);
      dds_version = info_byte >> 4;
      if (display_def && display_def->version == dds_version)
          return 0; // already have this display definition version
  
      if (!display_def) {
          display_def             = av_mallocz(sizeof(*display_def));
          if (!display_def)
              return AVERROR(ENOMEM);
          ctx->display_definition = display_def;
      }
  
      display_def->version = dds_version;
      display_def->x       = 0;
      display_def->y       = 0;
      display_def->width   = bytestream_get_be16(&buf) + 1;
      display_def->height  = bytestream_get_be16(&buf) + 1;
      if (!avctx->width || !avctx->height) {
          int ret = ff_set_dimensions(avctx, display_def->width, display_def->height);
          if (ret < 0)
              return ret;
      }
  
      if (info_byte & 1<<3) { // display_window_flag
          if (buf_size < 13)
              return AVERROR_INVALIDDATA;
  
          display_def->x = bytestream_get_be16(&buf);
          display_def->width  = bytestream_get_be16(&buf) - display_def->x + 1;
          display_def->y = bytestream_get_be16(&buf);
          display_def->height = bytestream_get_be16(&buf) - display_def->y + 1;
      }
  
      return 0;
  }
  
  static int dvbsub_display_end_segment(AVCodecContext *avctx, const uint8_t *buf,
                                        int buf_size, AVSubtitle *sub,int *got_output)
  {
      DVBSubContext *ctx = avctx->priv_data;
  
      if (ctx->compute_edt == 0)
          save_subtitle_set(avctx, sub, got_output);
  #ifdef DEBUG
      save_display_set(ctx);
  #endif
      return 0;
  }
  
  static int dvbsub_decode(AVCodecContext *avctx,
                           void *data, int *got_sub_ptr,
                           AVPacket *avpkt)
  {
      const uint8_t *buf = avpkt->data;
      int buf_size = avpkt->size;
      DVBSubContext *ctx = avctx->priv_data;
      AVSubtitle *sub = data;
      const uint8_t *p, *p_end;
      int segment_type;
      int page_id;
      int segment_length;
      int i;
      int ret = 0;
      int got_segment = 0;
      int got_dds = 0;
  
      ff_dlog(avctx, "DVB sub packet:\n");
  
      for (i=0; i < buf_size; i++) {
          ff_dlog(avctx, "%02x ", buf[i]);
          if (i % 16 == 15)
              ff_dlog(avctx, "\n");
      }
  
      if (i % 16)
          ff_dlog(avctx, "\n");
  
      if (buf_size <= 6 || *buf != 0x0f) {
          ff_dlog(avctx, "incomplete or broken packet");
          return AVERROR_INVALIDDATA;
      }
  
      p = buf;
      p_end = buf + buf_size;
  
      while (p_end - p >= 6 && *p == 0x0f) {
          p += 1;
          segment_type = *p++;
          page_id = AV_RB16(p);
          p += 2;
          segment_length = AV_RB16(p);
          p += 2;
  
          if (avctx->debug & FF_DEBUG_STARTCODE) {
              av_log(avctx, AV_LOG_DEBUG, "segment_type:%d page_id:%d segment_length:%d\n", segment_type, page_id, segment_length);
          }
  
          if (p_end - p < segment_length) {
              ff_dlog(avctx, "incomplete or broken packet");
              ret = -1;
              goto end;
          }
  
          if (page_id == ctx->composition_id || page_id == ctx->ancillary_id ||
              ctx->composition_id == -1 || ctx->ancillary_id == -1) {
              int ret = 0;
              switch (segment_type) {
              case DVBSUB_PAGE_SEGMENT:
                  ret = dvbsub_parse_page_segment(avctx, p, segment_length, sub, got_sub_ptr);
                  got_segment |= 1;
                  break;
              case DVBSUB_REGION_SEGMENT:
                  ret = dvbsub_parse_region_segment(avctx, p, segment_length);
                  got_segment |= 2;
                  break;
              case DVBSUB_CLUT_SEGMENT:
                  ret = dvbsub_parse_clut_segment(avctx, p, segment_length);
                  if (ret < 0) goto end;
                  got_segment |= 4;
                  break;
              case DVBSUB_OBJECT_SEGMENT:
                  ret = dvbsub_parse_object_segment(avctx, p, segment_length);
                  got_segment |= 8;
                  break;
              case DVBSUB_DISPLAYDEFINITION_SEGMENT:
                  ret = dvbsub_parse_display_definition_segment(avctx, p,
                                                                segment_length);
                  got_dds = 1;
                  break;
              case DVBSUB_DISPLAY_SEGMENT:
                  ret = dvbsub_display_end_segment(avctx, p, segment_length, sub, got_sub_ptr);
                  if (got_segment == 15 && !got_dds && !avctx->width && !avctx->height) {
                      // Default from ETSI EN 300 743 V1.3.1 (7.2.1)
                      avctx->width  = 720;
                      avctx->height = 576;
                  }
                  got_segment |= 16;
                  break;
              default:
                  ff_dlog(avctx, "Subtitling segment type 0x%x, page id %d, length %d\n",
                          segment_type, page_id, segment_length);
                  break;
              }
              if (ret < 0)
                  goto end;
          }
  
          p += segment_length;
      }
      // Some streams do not send a display segment but if we have all the other
      // segments then we need no further data.
      if (got_segment == 15) {
          av_log(avctx, AV_LOG_DEBUG, "Missing display_end_segment, emulating\n");
          dvbsub_display_end_segment(avctx, p, 0, sub, got_sub_ptr);
      }
  
  end:
      if (ret < 0) {
          *got_sub_ptr = 0;
          avsubtitle_free(sub);
          return ret;
      } else {
          if (ctx->compute_edt == 1)
              FFSWAP(int64_t, ctx->prev_start, sub->pts);
      }
  
      return p - buf;
  }
  
  #define DS AV_OPT_FLAG_DECODING_PARAM | AV_OPT_FLAG_SUBTITLE_PARAM
  #define OFFSET(x) offsetof(DVBSubContext, x)
  static const AVOption options[] = {
      {"compute_edt", "compute end of time using pts or timeout", OFFSET(compute_edt), AV_OPT_TYPE_BOOL, {.i64 = 0}, 0, 1, DS},
      {"compute_clut", "compute clut when not available(-1) or only once (-2) or always(1) or never(0)", OFFSET(compute_clut), AV_OPT_TYPE_BOOL, {.i64 = -1}, -2, 1, DS},
      {"dvb_substream", "", OFFSET(substream), AV_OPT_TYPE_INT, {.i64 = -1}, -1, 63, DS},
      {NULL}
  };
  static const AVClass dvbsubdec_class = {
      .class_name = "DVB Sub Decoder",
      .item_name  = av_default_item_name,
      .option     = options,
      .version    = LIBAVUTIL_VERSION_INT,
  };
  
  const AVCodec ff_dvbsub_decoder = {
      .name           = "dvbsub",
      .long_name      = NULL_IF_CONFIG_SMALL("DVB subtitles"),
      .type           = AVMEDIA_TYPE_SUBTITLE,
      .id             = AV_CODEC_ID_DVB_SUBTITLE,
      .priv_data_size = sizeof(DVBSubContext),
      .init           = dvbsub_init_decoder,
      .close          = dvbsub_close_decoder,
      .decode         = dvbsub_decode,
      .priv_class     = &dvbsubdec_class,
      .caps_internal  = FF_CODEC_CAP_INIT_THREADSAFE,
  };
  