text: /*
   * Teletext decoding for ffmpeg
   * Copyright (c) 2005-2010, 2012 Wolfram Gloger
   * Copyright (c) 2013 Marton Balint
   *
   * This library 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 of the License, or (at your option) any later version.
   *
   * This library 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 this library; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
   */
  
  #include "avcodec.h"
  #include "libavcodec/ass.h"
  #include "libavcodec/dvbtxt.h"
  #include "libavutil/opt.h"
  #include "libavutil/bprint.h"
  #include "libavutil/internal.h"
  #include "libavutil/intreadwrite.h"
  #include "libavutil/log.h"
  
  #include <libzvbi.h>
  
  #define TEXT_MAXSZ    (25 * (56 + 1) * 4 + 2)
  #define VBI_NB_COLORS 40
  #define VBI_TRANSPARENT_BLACK 8
  #define RGBA(r,g,b,a) (((a) << 24) | ((r) << 16) | ((g) << 8) | (b))
  #define VBI_R(rgba)   (((rgba) >> 0) & 0xFF)
  #define VBI_G(rgba)   (((rgba) >> 8) & 0xFF)
  #define VBI_B(rgba)   (((rgba) >> 16) & 0xFF)
  #define VBI_A(rgba)   (((rgba) >> 24) & 0xFF)
  #define MAX_BUFFERED_PAGES 25
  #define BITMAP_CHAR_WIDTH  12
  #define BITMAP_CHAR_HEIGHT 10
  #define MAX_SLICES 64
  
  typedef struct TeletextPage
  {
      AVSubtitleRect *sub_rect;
      int pgno;
      int subno;
      int64_t pts;
  } TeletextPage;
  
  typedef struct TeletextContext
  {
      AVClass        *class;
      char           *pgno;
      int             x_offset;
      int             y_offset;
      int             format_id; /* 0 = bitmap, 1 = text/ass */
      int             chop_top;
      int             sub_duration; /* in msec */
      int             transparent_bg;
      int             opacity;
      int             chop_spaces;
  
      int             lines_processed;
      TeletextPage    *pages;
      int             nb_pages;
      int64_t         pts;
      int             handler_ret;
  
      vbi_decoder *   vbi;
  #ifdef DEBUG
      vbi_export *    ex;
  #endif
      vbi_sliced      sliced[MAX_SLICES];
  
      int             readorder;
  } TeletextContext;
  
  static int chop_spaces_utf8(const unsigned char* t, int len)
  {
      t += len;
      while (len > 0) {
          if (*--t != ' ' || (len-1 > 0 && *(t-1) & 0x80))
              break;
          --len;
      }
      return len;
  }
  
  static void subtitle_rect_free(AVSubtitleRect **sub_rect)
  {
      av_freep(&(*sub_rect)->data[0]);
      av_freep(&(*sub_rect)->data[1]);
      av_freep(&(*sub_rect)->ass);
      av_freep(sub_rect);
  }
  
  static char *create_ass_text(TeletextContext *ctx, const char *text)
  {
      char *dialog;
      AVBPrint buf;
  
      av_bprint_init(&buf, 0, AV_BPRINT_SIZE_UNLIMITED);
      ff_ass_bprint_text_event(&buf, text, strlen(text), "", 0);
      if (!av_bprint_is_complete(&buf)) {
          av_bprint_finalize(&buf, NULL);
          return NULL;
      }
      dialog = ff_ass_get_dialog(ctx->readorder++, 0, NULL, NULL, buf.str);
      av_bprint_finalize(&buf, NULL);
      return dialog;
  }
  
  /* Draw a page as text */
  static int gen_sub_text(TeletextContext *ctx, AVSubtitleRect *sub_rect, vbi_page *page, int chop_top)
  {
      const char *in;
      AVBPrint buf;
      char *vbi_text = av_malloc(TEXT_MAXSZ);
      int sz;
  
      if (!vbi_text)
          return AVERROR(ENOMEM);
  
      sz = vbi_print_page_region(page, vbi_text, TEXT_MAXSZ-1, "UTF-8",
                                     /*table mode*/ TRUE, FALSE,
                                     0,             chop_top,
                                     page->columns, page->rows-chop_top);
      if (sz <= 0) {
          av_log(ctx, AV_LOG_ERROR, "vbi_print error\n");
          av_free(vbi_text);
          return AVERROR_EXTERNAL;
      }
      vbi_text[sz] = '\0';
      in  = vbi_text;
      av_bprint_init(&buf, 0, TEXT_MAXSZ);
  
      if (ctx->chop_spaces) {
          for (;;) {
              int nl, sz;
  
              // skip leading spaces and newlines
              in += strspn(in, " \n");
              // compute end of row
              for (nl = 0; in[nl]; ++nl)
                  if (in[nl] == '\n' && (nl==0 || !(in[nl-1] & 0x80)))
                      break;
              if (!in[nl])
                  break;
              // skip trailing spaces
              sz = chop_spaces_utf8(in, nl);
              av_bprint_append_data(&buf, in, sz);
              av_bprintf(&buf, "\n");
              in += nl;
          }
      } else {
          av_bprintf(&buf, "%s\n", vbi_text);
      }
      av_free(vbi_text);
  
      if (!av_bprint_is_complete(&buf)) {
          av_bprint_finalize(&buf, NULL);
          return AVERROR(ENOMEM);
      }
  
      if (buf.len) {
          sub_rect->type = SUBTITLE_ASS;
          sub_rect->ass = create_ass_text(ctx, buf.str);
  
          if (!sub_rect->ass) {
              av_bprint_finalize(&buf, NULL);
              return AVERROR(ENOMEM);
          }
          av_log(ctx, AV_LOG_DEBUG, "subtext:%s:txetbus\n", sub_rect->ass);
      } else {
          sub_rect->type = SUBTITLE_NONE;
      }
      av_bprint_finalize(&buf, NULL);
      return 0;
  }
  
  static void fix_transparency(TeletextContext *ctx, AVSubtitleRect *sub_rect, vbi_page *page,
                               int chop_top, int resx, int resy)
  {
      int iy;
  
      // Hack for transparency, inspired by VLC code...
      for (iy = 0; iy < resy; iy++) {
          uint8_t *pixel = sub_rect->data[0] + iy * sub_rect->linesize[0];
          vbi_char *vc = page->text + (iy / BITMAP_CHAR_HEIGHT + chop_top) * page->columns;
          vbi_char *vcnext = vc + page->columns;
          for (; vc < vcnext; vc++) {
              uint8_t *pixelnext = pixel + BITMAP_CHAR_WIDTH;
              switch (vc->opacity) {
                  case VBI_TRANSPARENT_SPACE:
                      memset(pixel, VBI_TRANSPARENT_BLACK, BITMAP_CHAR_WIDTH);
                      break;
                  case VBI_OPAQUE:
                      if (!ctx->transparent_bg)
                          break;
                  case VBI_SEMI_TRANSPARENT:
                      if (ctx->opacity > 0) {
                          if (ctx->opacity < 255)
                              for(; pixel < pixelnext; pixel++)
                                  if (*pixel == vc->background)
                                      *pixel += VBI_NB_COLORS;
                          break;
                      }
                  case VBI_TRANSPARENT_FULL:
                      for(; pixel < pixelnext; pixel++)
                          if (*pixel == vc->background)
                              *pixel = VBI_TRANSPARENT_BLACK;
                      break;
              }
              pixel = pixelnext;
          }
      }
  }
  
  /* Draw a page as bitmap */
  static int gen_sub_bitmap(TeletextContext *ctx, AVSubtitleRect *sub_rect, vbi_page *page, int chop_top)
  {
      int resx = page->columns * BITMAP_CHAR_WIDTH;
      int resy = (page->rows - chop_top) * BITMAP_CHAR_HEIGHT;
      uint8_t ci;
      vbi_char *vc = page->text + (chop_top * page->columns);
      vbi_char *vcend = page->text + (page->rows * page->columns);
  
      for (; vc < vcend; vc++) {
          if (vc->opacity != VBI_TRANSPARENT_SPACE)
              break;
      }
  
      if (vc >= vcend) {
          av_log(ctx, AV_LOG_DEBUG, "dropping empty page %3x\n", page->pgno);
          sub_rect->type = SUBTITLE_NONE;
          return 0;
      }
  
      sub_rect->data[0] = av_mallocz(resx * resy);
      sub_rect->linesize[0] = resx;
      if (!sub_rect->data[0])
          return AVERROR(ENOMEM);
  
      vbi_draw_vt_page_region(page, VBI_PIXFMT_PAL8,
                              sub_rect->data[0], sub_rect->linesize[0],
                              0, chop_top, page->columns, page->rows - chop_top,
                              /*reveal*/ 1, /*flash*/ 1);
  
      fix_transparency(ctx, sub_rect, page, chop_top, resx, resy);
      sub_rect->x = ctx->x_offset;
      sub_rect->y = ctx->y_offset + chop_top * BITMAP_CHAR_HEIGHT;
      sub_rect->w = resx;
      sub_rect->h = resy;
      sub_rect->nb_colors = ctx->opacity > 0 && ctx->opacity < 255 ? 2 * VBI_NB_COLORS : VBI_NB_COLORS;
      sub_rect->data[1] = av_mallocz(AVPALETTE_SIZE);
      if (!sub_rect->data[1]) {
          av_freep(&sub_rect->data[0]);
          return AVERROR(ENOMEM);
      }
      for (ci = 0; ci < VBI_NB_COLORS; ci++) {
          int r, g, b, a;
  
          r = VBI_R(page->color_map[ci]);
          g = VBI_G(page->color_map[ci]);
          b = VBI_B(page->color_map[ci]);
          a = VBI_A(page->color_map[ci]);
          ((uint32_t *)sub_rect->data[1])[ci] = RGBA(r, g, b, a);
          ((uint32_t *)sub_rect->data[1])[ci + VBI_NB_COLORS] = RGBA(r, g, b, ctx->opacity);
          ff_dlog(ctx, "palette %0x\n", ((uint32_t *)sub_rect->data[1])[ci]);
      }
      ((uint32_t *)sub_rect->data[1])[VBI_TRANSPARENT_BLACK] = RGBA(0, 0, 0, 0);
      ((uint32_t *)sub_rect->data[1])[VBI_TRANSPARENT_BLACK + VBI_NB_COLORS] = RGBA(0, 0, 0, 0);
      sub_rect->type = SUBTITLE_BITMAP;
      return 0;
  }
  
  static void handler(vbi_event *ev, void *user_data)
  {
      TeletextContext *ctx = user_data;
      TeletextPage *new_pages;
      vbi_page page;
      int res;
      char pgno_str[12];
      vbi_subno subno;
      vbi_page_type vpt;
      int chop_top;
      char *lang;
  
      snprintf(pgno_str, sizeof pgno_str, "%03x", ev->ev.ttx_page.pgno);
      av_log(ctx, AV_LOG_DEBUG, "decoded page %s.%02x\n",
             pgno_str, ev->ev.ttx_page.subno & 0xFF);
  
      if (strcmp(ctx->pgno, "*") && !strstr(ctx->pgno, pgno_str))
          return;
      if (ctx->handler_ret < 0)
          return;
  
      res = vbi_fetch_vt_page(ctx->vbi, &page,
                              ev->ev.ttx_page.pgno,
                              ev->ev.ttx_page.subno,
                              VBI_WST_LEVEL_3p5, 25, TRUE);
  
      if (!res)
          return;
  
  #ifdef DEBUG
      fprintf(stderr, "\nSaving res=%d dy0=%d dy1=%d...\n",
              res, page.dirty.y0, page.dirty.y1);
      fflush(stderr);
  
      if (!vbi_export_stdio(ctx->ex, stderr, &page))
          fprintf(stderr, "failed: %s\n", vbi_export_errstr(ctx->ex));
  #endif
  
      vpt = vbi_classify_page(ctx->vbi, ev->ev.ttx_page.pgno, &subno, &lang);
      chop_top = ctx->chop_top ||
          ((page.rows > 1) && (vpt == VBI_SUBTITLE_PAGE));
  
      av_log(ctx, AV_LOG_DEBUG, "%d x %d page chop:%d\n",
             page.columns, page.rows, chop_top);
  
      if (ctx->nb_pages < MAX_BUFFERED_PAGES) {
          if ((new_pages = av_realloc_array(ctx->pages, ctx->nb_pages + 1, sizeof(TeletextPage)))) {
              TeletextPage *cur_page = new_pages + ctx->nb_pages;
              ctx->pages = new_pages;
              cur_page->sub_rect = av_mallocz(sizeof(*cur_page->sub_rect));
              cur_page->pts = ctx->pts;
              cur_page->pgno = ev->ev.ttx_page.pgno;
              cur_page->subno = ev->ev.ttx_page.subno;
              if (cur_page->sub_rect) {
                  res = (ctx->format_id == 0) ?
                      gen_sub_bitmap(ctx, cur_page->sub_rect, &page, chop_top) :
                      gen_sub_text  (ctx, cur_page->sub_rect, &page, chop_top);
                  if (res < 0) {
                      av_freep(&cur_page->sub_rect);
                      ctx->handler_ret = res;
                  } else {
                      ctx->pages[ctx->nb_pages++] = *cur_page;
                  }
              } else {
                  ctx->handler_ret = AVERROR(ENOMEM);
              }
          } else {
              ctx->handler_ret = AVERROR(ENOMEM);
          }
      } else {
          //TODO: If multiple packets contain more than one page, pages may got queued up, and this may happen...
          av_log(ctx, AV_LOG_ERROR, "Buffered too many pages, dropping page %s.\n", pgno_str);
          ctx->handler_ret = AVERROR(ENOSYS);
      }
  
      vbi_unref_page(&page);
  }
  
  static int slice_to_vbi_lines(TeletextContext *ctx, uint8_t* buf, int size)
  {
      int lines = 0;
      while (size >= 2 && lines < MAX_SLICES) {
          int data_unit_id     = buf[0];
          int data_unit_length = buf[1];
          if (data_unit_length + 2 > size)
              return AVERROR_INVALIDDATA;
          if (ff_data_unit_id_is_teletext(data_unit_id)) {
              if (data_unit_length != 0x2c)
                  return AVERROR_INVALIDDATA;
              else {
                  int line_offset  = buf[2] & 0x1f;
                  int field_parity = buf[2] & 0x20;
                  int i;
                  ctx->sliced[lines].id = VBI_SLICED_TELETEXT_B;
                  ctx->sliced[lines].line = (line_offset > 0 ? (line_offset + (field_parity ? 0 : 313)) : 0);
                  for (i = 0; i < 42; i++)
                      ctx->sliced[lines].data[i] = vbi_rev8(buf[4 + i]);
                  lines++;
              }
          }
          size -= data_unit_length + 2;
          buf += data_unit_length + 2;
      }
      if (size)
          av_log(ctx, AV_LOG_WARNING, "%d bytes remained after slicing data\n", size);
      return lines;
  }
  
  static int teletext_decode_frame(AVCodecContext *avctx, void *data, int *data_size, AVPacket *pkt)
  {
      TeletextContext *ctx = avctx->priv_data;
      AVSubtitle      *sub = data;
      int             ret = 0;
      int j;
  
      if (!ctx->vbi) {
          if (!(ctx->vbi = vbi_decoder_new()))
              return AVERROR(ENOMEM);
          if (!vbi_event_handler_add(ctx->vbi, VBI_EVENT_TTX_PAGE, handler, ctx)) {
              vbi_decoder_delete(ctx->vbi);
              ctx->vbi = NULL;
              return AVERROR(ENOMEM);
          }
      }
  
      if (avctx->pkt_timebase.num && pkt->pts != AV_NOPTS_VALUE)
          ctx->pts = av_rescale_q(pkt->pts, avctx->pkt_timebase, AV_TIME_BASE_Q);
  
      if (pkt->size) {
          int lines;
          const int full_pes_size = pkt->size + 45; /* PES header is 45 bytes */
  
          // We allow unreasonably big packets, even if the standard only allows a max size of 1472
          if (full_pes_size < 184 || full_pes_size > 65504 || full_pes_size % 184 != 0)
              return AVERROR_INVALIDDATA;
  
          ctx->handler_ret = pkt->size;
  
          if (ff_data_identifier_is_teletext(*pkt->data)) {
              if ((lines = slice_to_vbi_lines(ctx, pkt->data + 1, pkt->size - 1)) < 0)
                  return lines;
              ff_dlog(avctx, "ctx=%p buf_size=%d lines=%u pkt_pts=%7.3f\n",
                      ctx, pkt->size, lines, (double)pkt->pts/90000.0);
              if (lines > 0) {
  #ifdef DEBUG
                  int i;
                  av_log(avctx, AV_LOG_DEBUG, "line numbers:");
                  for(i = 0; i < lines; i++)
                      av_log(avctx, AV_LOG_DEBUG, " %d", ctx->sliced[i].line);
                  av_log(avctx, AV_LOG_DEBUG, "\n");
  #endif
                  vbi_decode(ctx->vbi, ctx->sliced, lines, 0.0);
                  ctx->lines_processed += lines;
              }
          }
          ctx->pts = AV_NOPTS_VALUE;
          ret = ctx->handler_ret;
      }
  
      if (ret < 0)
          return ret;
  
      // is there a subtitle to pass?
      if (ctx->nb_pages) {
          int i;
          sub->format = ctx->format_id;
          sub->start_display_time = 0;
          sub->end_display_time = ctx->sub_duration;
          sub->num_rects = 0;
          sub->pts = ctx->pages->pts;
  
          if (ctx->pages->sub_rect->type != SUBTITLE_NONE) {
              sub->rects = av_malloc(sizeof(*sub->rects));
              if (sub->rects) {
                  sub->num_rects = 1;
                  sub->rects[0] = ctx->pages->sub_rect;
  #if FF_API_AVPICTURE
  FF_DISABLE_DEPRECATION_WARNINGS
                  for (j = 0; j < 4; j++) {
                      sub->rects[0]->pict.data[j] = sub->rects[0]->data[j];
                      sub->rects[0]->pict.linesize[j] = sub->rects[0]->linesize[j];
                  }
  FF_ENABLE_DEPRECATION_WARNINGS
  #endif
              } else {
                  ret = AVERROR(ENOMEM);
              }
          } else {
              av_log(avctx, AV_LOG_DEBUG, "sending empty sub\n");
              sub->rects = NULL;
          }
          if (!sub->rects) // no rect was passed
              subtitle_rect_free(&ctx->pages->sub_rect);
  
          for (i = 0; i < ctx->nb_pages - 1; i++)
              ctx->pages[i] = ctx->pages[i + 1];
          ctx->nb_pages--;
  
          if (ret >= 0)
              *data_size = 1;
      } else
          *data_size = 0;
  
      return ret;
  }
  
  static int teletext_init_decoder(AVCodecContext *avctx)
  {
      TeletextContext *ctx = avctx->priv_data;
      unsigned int maj, min, rev;
  
      vbi_version(&maj, &min, &rev);
      if (!(maj > 0 || min > 2 || min == 2 && rev >= 26)) {
          av_log(avctx, AV_LOG_ERROR, "decoder needs zvbi version >= 0.2.26.\n");
          return AVERROR_EXTERNAL;
      }
  
      if (ctx->format_id == 0) {
          avctx->width  = 41 * BITMAP_CHAR_WIDTH;
          avctx->height = 25 * BITMAP_CHAR_HEIGHT;
      }
  
      ctx->vbi = NULL;
      ctx->pts = AV_NOPTS_VALUE;
  
      if (ctx->opacity == -1)
          ctx->opacity = ctx->transparent_bg ? 0 : 255;
  
  #ifdef DEBUG
      {
          char *t;
          ctx->ex = vbi_export_new("text", &t);
      }
  #endif
      av_log(avctx, AV_LOG_VERBOSE, "page filter: %s\n", ctx->pgno);
      return (ctx->format_id == 1) ? ff_ass_subtitle_header_default(avctx) : 0;
  }
  
  static int teletext_close_decoder(AVCodecContext *avctx)
  {
      TeletextContext *ctx = avctx->priv_data;
  
      ff_dlog(avctx, "lines_total=%u\n", ctx->lines_processed);
      while (ctx->nb_pages)
          subtitle_rect_free(&ctx->pages[--ctx->nb_pages].sub_rect);
      av_freep(&ctx->pages);
  
      vbi_decoder_delete(ctx->vbi);
      ctx->vbi = NULL;
      ctx->pts = AV_NOPTS_VALUE;
      if (!(avctx->flags2 & AV_CODEC_FLAG2_RO_FLUSH_NOOP))
          ctx->readorder = 0;
      return 0;
  }
  
  static void teletext_flush(AVCodecContext *avctx)
  {
      teletext_close_decoder(avctx);
  }
  
  #define OFFSET(x) offsetof(TeletextContext, x)
  #define SD AV_OPT_FLAG_SUBTITLE_PARAM | AV_OPT_FLAG_DECODING_PARAM
  static const AVOption options[] = {
      {"txt_page",        "list of teletext page numbers to decode, * is all", OFFSET(pgno),           AV_OPT_TYPE_STRING, {.str = "*"},      0, 0,        SD},
      {"txt_chop_top",    "discards the top teletext line",                    OFFSET(chop_top),       AV_OPT_TYPE_INT,    {.i64 = 1},        0, 1,        SD},
      {"txt_format",      "format of the subtitles (bitmap or text)",          OFFSET(format_id),      AV_OPT_TYPE_INT,    {.i64 = 0},        0, 1,        SD,  "txt_format"},
      {"bitmap",          NULL,                                                0,                      AV_OPT_TYPE_CONST,  {.i64 = 0},        0, 0,        SD,  "txt_format"},
      {"text",            NULL,                                                0,                      AV_OPT_TYPE_CONST,  {.i64 = 1},        0, 0,        SD,  "txt_format"},
      {"txt_left",        "x offset of generated bitmaps",                     OFFSET(x_offset),       AV_OPT_TYPE_INT,    {.i64 = 0},        0, 65535,    SD},
      {"txt_top",         "y offset of generated bitmaps",                     OFFSET(y_offset),       AV_OPT_TYPE_INT,    {.i64 = 0},        0, 65535,    SD},
      {"txt_chop_spaces", "chops leading and trailing spaces from text",       OFFSET(chop_spaces),    AV_OPT_TYPE_INT,    {.i64 = 1},        0, 1,        SD},
      {"txt_duration",    "display duration of teletext pages in msecs",       OFFSET(sub_duration),   AV_OPT_TYPE_INT,    {.i64 = 30000},    0, 86400000, SD},
      {"txt_transparent", "force transparent background of the teletext",      OFFSET(transparent_bg), AV_OPT_TYPE_INT,    {.i64 = 0},        0, 1,        SD},
      {"txt_opacity",     "set opacity of the transparent background",         OFFSET(opacity),        AV_OPT_TYPE_INT,    {.i64 = -1},      -1, 255,      SD},
      { NULL },
  };
  
  static const AVClass teletext_class = {
      .class_name = "libzvbi_teletextdec",
      .item_name  = av_default_item_name,
      .option     = options,
      .version    = LIBAVUTIL_VERSION_INT,
  };
  
  AVCodec ff_libzvbi_teletext_decoder = {
      .name      = "libzvbi_teletextdec",
      .long_name = NULL_IF_CONFIG_SMALL("Libzvbi DVB teletext decoder"),
      .type      = AVMEDIA_TYPE_SUBTITLE,
      .id        = AV_CODEC_ID_DVB_TELETEXT,
      .priv_data_size = sizeof(TeletextContext),
      .init      = teletext_init_decoder,
      .close     = teletext_close_decoder,
      .decode    = teletext_decode_frame,
      .capabilities = AV_CODEC_CAP_DELAY,
      .flush     = teletext_flush,
      .priv_class= &teletext_class,
  };
  