lavc: add teletext decoder using libzvbi

Based on a patch by Wolfram Gloger <wmglo@dent.med.uni-muenchen.de>.
http://lists.ffmpeg.org/pipermail/ffmpeg-devel/2012-December/136677.html

The original patch was rebased by Tudor SUCIU <tudor.suciu@gmail.com>.

Lots of additional features and fixes are made by me.

Fixes ticket #2086.

Changes since last version:
- change default page to all pages

Signed-off-by: Marton Balint <cus@passwd.hu>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

8 files changed, 537 insertions, 1 deletions

diff --git a/Changelog b/Changelog
index 4a6c60c..1ec6e9b 100644
--- a/Changelog
+++ b/Changelog
@@ -15,6 +15,7 @@ version <next>
   data read from an input file
 - incomplete Voxware MetaSound decoder
 - read EXIF metadata from JPEG
+- DVB teletext decoder
 
 
 version 2.0:
diff --git a/configure b/configure
index 6767c6a..590d67f 100755
--- a/configure
+++ b/configure
@@ -242,6 +242,7 @@ External library support:
   --enable-libxvid         enable Xvid encoding via xvidcore,
                            native MPEG-4/Xvid encoder exists [no]
   --enable-libzmq          enable message passing via libzmq [no]
+  --enable-libzvbi         enable teletext support via libzvbi [no]
   --enable-openal          enable OpenAL 1.1 capture support [no]
   --enable-opencl          enable OpenCL code
   --enable-openssl         enable openssl [no]
@@ -1205,6 +1206,7 @@ EXTERNAL_LIBRARY_LIST="
     libxavs
     libxvid
     libzmq
+    libzvbi
     openal
     opencl
     openssl
@@ -2044,6 +2046,7 @@ libxavs_encoder_deps="libxavs"
 libxvid_encoder_deps="libxvid"
 libutvideo_decoder_deps="libutvideo"
 libutvideo_encoder_deps="libutvideo"
+libzvbi_teletext_decoder_deps="libzvbi"
 
 # demuxers / muxers
 ac3_demuxer_select="ac3_parser"
@@ -3767,6 +3770,7 @@ die_license_disabled gpl libvidstab
 die_license_disabled gpl libx264
 die_license_disabled gpl libxavs
 die_license_disabled gpl libxvid
+die_license_disabled gpl libzvbi
 die_license_disabled gpl x11grab
 
 die_license_disabled nonfree libaacplus
@@ -4245,6 +4249,7 @@ enabled libx264           && require libx264 x264.h x264_encoder_encode -lx264 &
 enabled libxavs           && require libxavs xavs.h xavs_encoder_encode -lxavs
 enabled libxvid           && require libxvid xvid.h xvid_global -lxvidcore
 enabled libzmq            && require_pkg_config libzmq zmq.h zmq_ctx_new
+enabled libzvbi           && require libzvbi libzvbi.h vbi_decoder_new -lzvbi
 enabled openal            && { { for al_libs in "${OPENAL_LIBS}" "-lopenal" "-lOpenAL32"; do
                                check_lib 'AL/al.h' alGetError "${al_libs}" && break; done } ||
                                die "ERROR: openal not found"; } &&
@@ -4635,6 +4640,7 @@ echo "threading support         ${thread_type-no}"
 echo "safe bitstream reader     ${safe_bitstream_reader-no}"
 echo "SDL support               ${sdl-no}"
 echo "opencl enabled            ${opencl-no}"
+echo "libzvbi enabled           ${libzvbi-no}"
 echo "texi2html enabled         ${texi2html-no}"
 echo "perl enabled              ${perl-no}"
 echo "pod2man enabled           ${pod2man-no}"
diff --git a/doc/decoders.texi b/doc/decoders.texi
index aa82add..9d9f298 100644
--- a/doc/decoders.texi
+++ b/doc/decoders.texi
@@ -158,4 +158,45 @@ ee450d, 101010, eaeaea, 0ce60b, ec14ed, ebff0b, 0d617a, 7b7b7b, d1d1d1,
 7b2a0e, 0d950c, 0f007b, cf0dec, cfa80c, 7c127b}.
 @end table
 
+@section libzvbi-teletext
+
+Libzvbi allows libavcodec to decode DVB teletext pages and DVB teletext
+subtitles. Requires the presence of the libzvbi headers and library during
+configuration. You need to explicitly configure the build with
+@code{--enable-libzvbi}.
+
+@subsection Options
+
+@table @option
+@item txt_page
+List of teletext page numbers to decode. You may use the special * string to
+match all pages. Pages that do not match the specified list are dropped.
+Default value is *.
+@item txt_chop_top
+Discards the top teletext line. Default value is 1.
+@item txt_format
+Specifies the format of the decoded subtitles. The teletext decoder is capable
+of decoding the teletext pages to bitmaps or to simple text, you should use
+"bitmap" for teletext pages, because certain graphics and colors cannot be
+expressed in simple text. You might use "text" for teletext based subtitles if
+your application can handle simple text based subtitles. Default value is
+bitmap.
+@item txt_left
+X offset of generated bitmaps, default is 0.
+@item txt_top
+Y offset of generated bitmaps, default is 0.
+@item txt_chop_spaces
+Chops leading and trailing spaces and removes empty lines from the generated
+text. This option is useful for teletext based subtitles where empty spaces may
+be present at the start or at the end of the lines or empty lines may be
+present between the subtitle lines because of double-sized teletext charactes.
+Default value is 1.
+@item txt_duration
+Sets the display duration of the decoded teletext pages or subtitles in
+miliseconds. Default value is 30000 which is 30 seconds.
+@item txt_transparent
+Force transparent background of the generated teletext bitmaps. Default value
+is 0 which means an opaque (black) background.
+@end table
+
 @c man end SUBTILES DECODERS
diff --git a/doc/general.texi b/doc/general.texi
index b755c18..2a72d2e 100644
--- a/doc/general.texi
+++ b/doc/general.texi
@@ -133,6 +133,20 @@ Go to @url{https://github.com/dekkers/libilbc} and follow the instructions for
 installing the library. Then pass @code{--enable-libilbc} to configure to
 enable it.
 
+@section libzvbi
+
+libzvbi is a VBI decoding library which can be used by FFmpeg to decode DVB
+teletext pages and DVB teletext subtitles.
+
+Go to @url{http://sourceforge.net/projects/zapping/} and follow the instructions for
+installing the library. Then pass @code{--enable-libzvbi} to configure to
+enable it.
+
+@float NOTE
+libzvbi is licensed under the GNU General Public License Version 2 or later
+(see @url{http://www.gnu.org/licenses/old-licenses/gpl-2.0.html} for details),
+you must upgrade FFmpeg's license to GPL in order to use it.
+@end float
 
 
 @chapter Supported File Formats, Codecs or Features
@@ -947,6 +961,7 @@ performance on systems without hardware floating point support).
 @item 3GPP Timed Text  @tab   @tab   @tab X @tab X
 @item AQTitle          @tab   @tab X @tab   @tab X
 @item DVB              @tab X @tab X @tab X @tab X
+@item DVB teletext     @tab   @tab X @tab   @tab E
 @item DVD              @tab X @tab X @tab X @tab X
 @item JACOsub          @tab X @tab X @tab   @tab X
 @item MicroDVD         @tab X @tab X @tab   @tab X
@@ -969,6 +984,8 @@ performance on systems without hardware floating point support).
 
 @code{X} means that the feature is supported.
 
+@code{E} means that support is provided through an external library.
+
 @section Network Protocols
 
 @multitable @columnfractions .4 .1
diff --git a/libavcodec/Makefile b/libavcodec/Makefile
index f5ce4e1..987b849 100644
--- a/libavcodec/Makefile
+++ b/libavcodec/Makefile
@@ -727,6 +727,7 @@ OBJS-$(CONFIG_LIBWAVPACK_ENCODER)         += libwavpackenc.o
 OBJS-$(CONFIG_LIBX264_ENCODER)            += libx264.o
 OBJS-$(CONFIG_LIBXAVS_ENCODER)            += libxavs.o
 OBJS-$(CONFIG_LIBXVID_ENCODER)            += libxvid.o
+OBJS-$(CONFIG_LIBZVBI_TELETEXT_DECODER)   += libzvbi-teletextdec.o
 
 # parsers
 OBJS-$(CONFIG_AAC_PARSER)              += aac_parser.o aac_ac3_parser.o \
diff --git a/libavcodec/allcodecs.c b/libavcodec/allcodecs.c
index c930cc7..12f334e 100644
--- a/libavcodec/allcodecs.c
+++ b/libavcodec/allcodecs.c
@@ -505,6 +505,7 @@ void avcodec_register_all(void)
     REGISTER_ENCODER(LIBX264RGB,        libx264rgb);
     REGISTER_ENCODER(LIBXAVS,           libxavs);
     REGISTER_ENCODER(LIBXVID,           libxvid);
+    REGISTER_DECODER(LIBZVBI_TELETEXT,  libzvbi_teletext);
     REGISTER_ENCODER(LIBAACPLUS,        libaacplus);
 
     /* text */
diff --git a/libavcodec/libzvbi-teletextdec.c b/libavcodec/libzvbi-teletextdec.c
new file mode 100644
index 0000000..11ce4b0
--- a/dev/null
+++ b/libavcodec/libzvbi-teletextdec.c
@@ -0,0 +1,469 @@
+/*
+ * 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#include "avcodec.h"
+#include "libavutil/opt.h"
+#include "libavutil/intreadwrite.h"
+
+#include <libzvbi.h>
+
+#define TEXT_MAXSZ    (25 * (56 + 1) * 4 + 2)
+#define VBI_NB_COLORS 40
+#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)
+
+/* main data structure */
+typedef struct TeletextContext
+{
+    AVClass        *class;
+    char           *pgno;
+    int             x_offset;
+    int             y_offset;
+    char           *format;
+    int             format_id; /* 0 = bitmap, 1 = text */
+    int             chop_top;
+    int             sub_duration; /* in msec */
+    int             transparent_bg;
+    int             chop_spaces;
+
+    int             lines_processed;
+    AVSubtitleRect *sub_rect;
+
+    vbi_decoder *   vbi;
+    vbi_dvb_demux * dx;
+#ifdef DEBUG
+    vbi_export *    ex;
+#endif
+    /* Don't even _think_ about making sliced stack-local! */
+    vbi_sliced      sliced[64];
+} 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;
+}
+
+// draw a page as text
+static int
+gen_sub_text(TeletextContext *ctx, vbi_page *page, int chop_top)
+{
+    AVSubtitleRect *sub_rect = ctx->sub_rect;
+    char *text;
+    const char *in;
+    char *out;
+    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;
+    out = text = av_malloc(TEXT_MAXSZ);
+    if (!text) {
+        av_free(vbi_text);
+        return AVERROR(ENOMEM);
+    }
+    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);
+            memcpy(out, in, sz);
+            out += sz;
+            *out++ = '\n';
+            in += nl;
+        }
+    } else {
+        strcpy(text, vbi_text);
+        out += sz;
+        *out++ = '\n';
+    }
+    av_free(vbi_text);
+    *out = '\0';
+    if (out > text) {
+        sub_rect->type = SUBTITLE_TEXT;
+        sub_rect->text = text;
+        av_log(ctx, AV_LOG_DEBUG, "subtext:%s:txetbus\n", text);
+    } else {
+        sub_rect->type = SUBTITLE_NONE;
+        av_free(text);
+    }
+    return 0;
+}
+
+static void
+fix_transparency(TeletextContext *ctx, vbi_page *page, int chop_top, uint8_t transparent_color, int resx, int resy)
+{
+    AVSubtitleRect *sub_rect = ctx->sub_rect;
+    int iy;
+
+    // Hack for transparency, inspired by VLC code...
+    for (iy = 0; iy < resy; iy++) {
+        uint8_t *pixel = sub_rect->pict.data[0] + iy * sub_rect->pict.linesize[0];
+        vbi_char *vc = page->text + (iy / 10 + chop_top) * page->columns;
+        vbi_char *vcnext = vc + page->columns;
+        for (; vc < vcnext; vc++) {
+            uint8_t *pixelnext = pixel + 12;
+            switch (vc->opacity) {
+                case VBI_TRANSPARENT_SPACE:
+                    memset(pixel, transparent_color, 12);
+                    break;
+                case VBI_OPAQUE:
+                case VBI_SEMI_TRANSPARENT:
+                    if (!ctx->transparent_bg)
+                        break;
+                case VBI_TRANSPARENT_FULL:
+                    for(; pixel < pixelnext; pixel++)
+                        if (*pixel == vc->background)
+                            *pixel = transparent_color;
+                    break;
+            }
+            pixel = pixelnext;
+        }
+    }
+}
+
+// draw a page as bitmap
+static int
+gen_sub_bitmap(TeletextContext *ctx, vbi_page *page, int chop_top)
+{
+    AVSubtitleRect *sub_rect = ctx->sub_rect;
+    int resx = page->columns * 12;
+    int resy = (page->rows - chop_top) * 10;
+    uint8_t ci, cmax = 0;
+    int ret;
+    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) {
+            cmax = VBI_NB_COLORS;
+            break;
+        }
+    }
+
+    if (cmax == 0) {
+        av_log(ctx, AV_LOG_DEBUG, "dropping empty page %3x\n", page->pgno);
+        sub_rect->type = SUBTITLE_NONE;
+        return 0;
+    }
+
+    if ((ret = avpicture_alloc(&sub_rect->pict, AV_PIX_FMT_PAL8, resx, resy)) < 0)
+        return ret;
+    // Yes, we want to allocate the palette on our own because AVSubtitle works this way
+    sub_rect->pict.data[1] = NULL;
+
+    vbi_draw_vt_page_region(page, VBI_PIXFMT_PAL8,
+                            sub_rect->pict.data[0], sub_rect->pict.linesize[0],
+                            0, chop_top, page->columns, page->rows - chop_top,
+                            /*reveal*/ 1, /*flash*/ 1);
+
+    fix_transparency(ctx, page, chop_top, cmax, resx, resy);
+    sub_rect->x = ctx->x_offset;
+    sub_rect->y = ctx->y_offset;
+    sub_rect->w = resx;
+    sub_rect->h = resy;
+    sub_rect->nb_colors = (int)cmax + 1;
+    sub_rect->pict.data[1] = av_mallocz(AVPALETTE_SIZE);
+    if (!sub_rect->pict.data[1]) {
+        av_freep(&sub_rect->pict.data[0]);
+        return AVERROR(ENOMEM);
+    }
+    for (ci = 0; ci < cmax; 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->pict.data[1])[ci] = RGBA(r, g, b, a);
+#ifdef DEBUG
+        av_log(ctx, AV_LOG_DEBUG, "palette %0x\n",
+               ((uint32_t *)sub_rect->pict.data[1])[ci]);
+#endif
+    }
+    ((uint32_t *)sub_rect->pict.data[1])[cmax] = 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;
+    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;
+
+    /* Fetch the page.  */
+    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->sub_rect) {
+        ctx->sub_rect = av_mallocz(sizeof(*ctx->sub_rect));
+        if (ctx->sub_rect) {
+            res = (ctx->format_id == 0) ?
+                gen_sub_bitmap(ctx, &page, chop_top) :
+                gen_sub_text  (ctx, &page, chop_top);
+            if (res)
+                av_freep(&ctx->sub_rect);
+        }
+    } else {
+        // FIXME: Multiple teletext pages in a single packet, some kind of buffering should be done instead of dropping the page...
+        av_log(ctx, AV_LOG_WARNING, "Missed page %s.%02x.\n", pgno_str, ev->ev.ttx_page.subno & 0xFF);
+    }
+
+    vbi_unref_page(&page);
+}
+
+static int
+teletext_decode_frame(AVCodecContext *avctx,
+                      void *data, int *data_size,
+                      AVPacket *pkt)
+{
+    TeletextContext *ctx = avctx->priv_data;
+    AVSubtitle      *sub = data;
+    const uint8_t   *buf = pkt->data;
+    unsigned int    left = pkt->size;
+    uint8_t         pesheader[45] = {0x00, 0x00, 0x01, 0xbd, 0x00, 0x00, 0x85, 0x80, 0x24, 0x21, 0x00, 0x01, 0x00, 0x01};
+    int             pesheader_size = sizeof(pesheader);
+    const uint8_t   *pesheader_buf = pesheader;
+
+    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 (!ctx->dx && (!(ctx->dx = vbi_dvb_pes_demux_new (/* callback */ NULL, NULL))))
+        return AVERROR(ENOMEM);
+
+    // We allow unreasonably big packets, even if the standard only allows a max size of 1472
+    if ((pesheader_size + left) < 184 || (pesheader_size + left) > 65504 || (pesheader_size + left) % 184 != 0)
+        return AVERROR_INVALIDDATA;
+
+    memset(pesheader + 14, 0xff, pesheader_size - 14);
+    AV_WB16(pesheader + 4, left + pesheader_size - 6);
+
+    /* PTS is deliberately left as 0 in the PES header, otherwise libzvbi uses
+     * it to detect dropped frames. Unforunatey the guessed packet PTS values
+     * (see mpegts demuxer) are not accurate enough to pass that test. */
+    vbi_dvb_demux_cor(ctx->dx, ctx->sliced, 64, NULL, &pesheader_buf, &pesheader_size);
+
+    while (left > 0) {
+        int64_t pts = 0;
+        unsigned int lines = vbi_dvb_demux_cor(ctx->dx, ctx->sliced, 64, &pts, &buf, &left);
+#ifdef DEBUG
+        av_log(avctx, AV_LOG_DEBUG,
+               "ctx=%p buf_size=%d left=%u lines=%u pts=%f pkt_pts=%f\n",
+               ctx, pkt->size, left, lines, (double)pts/90000.0, (double)pkt->pts/90000.0);
+#endif
+        if (lines > 0) {
+#ifdef DEBUGx
+            int i;
+            for(i=0; i<lines; ++i)
+                av_log(avctx, AV_LOG_DEBUG,
+                       "lines=%d id=%x\n", i, ctx->sliced[i].id);
+#endif
+            vbi_decode(ctx->vbi, ctx->sliced, lines, (double)pts/90000.0);
+            ctx->lines_processed += lines;
+        }
+    }
+
+    // is there a subtitle to pass?
+    if (ctx->sub_rect) {
+        sub->format = (ctx->sub_rect->type == SUBTITLE_TEXT ? 1: 0);
+        sub->start_display_time = 0;
+        sub->end_display_time = ctx->sub_duration;
+        sub->num_rects = 0;
+
+        if (ctx->sub_rect->type != SUBTITLE_NONE) {
+            sub->rects = av_malloc(sizeof(*sub->rects) * 1);
+            if (sub->rects) {
+                sub->num_rects = 1;
+                sub->rects[0] = ctx->sub_rect;
+            }
+        } else {
+            av_log(avctx, AV_LOG_DEBUG, "sending empty sub\n");
+            sub->rects = NULL;
+        }
+        if (!sub->rects) // no rect was passed
+            av_free(ctx->sub_rect);
+        ctx->sub_rect = NULL;
+
+        *data_size = 1;
+    } else
+        *data_size = 0;
+
+    return pkt->size;
+}
+
+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;
+    }
+
+    ctx->dx = NULL;
+    ctx->vbi = NULL;
+    ctx->sub_rect = NULL;
+    if (!strcmp(ctx->format, "bitmap")) {
+        ctx->format_id = 0;
+    } else if (!strcmp(ctx->format, "text")) {
+        ctx->format_id = 1;
+    } else {
+        av_log(avctx, AV_LOG_ERROR, "unkown format %s\n", ctx->format);
+        return AVERROR_OPTION_NOT_FOUND;
+    }
+
+#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 0;
+}
+
+static int teletext_close_decoder(AVCodecContext *avctx)
+{
+    TeletextContext *ctx = avctx->priv_data;
+
+#ifdef DEBUG
+    av_log(avctx, AV_LOG_DEBUG, "lines_total=%u\n", ctx->lines_processed);
+#endif
+
+    vbi_dvb_demux_delete(ctx->dx);
+    vbi_decoder_delete(ctx->vbi);
+    ctx->dx = NULL;
+    ctx->vbi = NULL;
+    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),         AV_OPT_TYPE_STRING, {.str = "bitmap"}, 0, 0,        SD},
+    {"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},
+    { 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",
+    .type      = AVMEDIA_TYPE_SUBTITLE,
+    .id        = CODEC_ID_DVB_TELETEXT,
+    .priv_data_size = sizeof(TeletextContext),
+    .init      = teletext_init_decoder,
+    .close     = teletext_close_decoder,
+    .decode    = teletext_decode_frame,
+    .flush     = teletext_flush,
+    .long_name = NULL_IF_CONFIG_SMALL("Libzvbi DVB teletext decoder"),
+    .priv_class= &teletext_class,
+};
diff --git a/libavcodec/version.h b/libavcodec/version.h
index 8962084..e65c021 100644
--- a/libavcodec/version.h
+++ b/libavcodec/version.h
@@ -29,7 +29,7 @@
 #include "libavutil/avutil.h"
 
 #define LIBAVCODEC_VERSION_MAJOR 55
-#define LIBAVCODEC_VERSION_MINOR  30
+#define LIBAVCODEC_VERSION_MINOR  31
 #define LIBAVCODEC_VERSION_MICRO 100
 
 #define LIBAVCODEC_VERSION_INT  AV_VERSION_INT(LIBAVCODEC_VERSION_MAJOR, \