avcodec/libzvbi-teletextdec: add option to set default G0 character set

Signed-off-by: Kirill Savkov <k.savkov@inventos.ru>
Signed-off-by: Marton Balint <cus@passwd.hu>

doc/decoders.texi

@@ -316,6 +316,11 @@ List of teletext page numbers to decode. Pages that do not match the specified
 list are dropped. You may use the special @code{*} string to match all pages,
 or @code{subtitle} to match all subtitle pages.
 Default value is *.
+@item txt_default_region
+Set default G0 character set used for decoding, a value between 0 and 80 (see
+ETS 300 706, Section 15, Table 32). Default value is -1, which does not
+override the libzvbi default. This option is needed for some legacy level 1.0
+transmissions which cannot signal the proper charset.
 @item txt_chop_top
 Discards the top teletext line. Default value is 1.
 @item txt_format

libavcodec/libzvbi-teletextdec.c

@@ -55,6 +55,7 @@ typedef struct TeletextContext
 {
     AVClass        *class;
     char           *pgno;
+    int             default_region;
     int             x_offset;
     int             y_offset;
     int             format_id; /* 0 = bitmap, 1 = text/ass, 2 = ass */
@@ -645,6 +646,10 @@ static int teletext_decode_frame(AVCodecContext *avctx, void *data, int *data_si
     if (!ctx->vbi) {
         if (!(ctx->vbi = vbi_decoder_new()))
             return AVERROR(ENOMEM);
+        if (ctx->default_region != -1) {
+            av_log(avctx, AV_LOG_INFO, "Setting default zvbi region to %i\n", ctx->default_region);
+            vbi_teletext_set_default_region(ctx->vbi, ctx->default_region);
+        }
         if (!vbi_event_handler_register(ctx->vbi, VBI_EVENT_TTX_PAGE, handler, ctx)) {
             vbi_decoder_delete(ctx->vbi);
             ctx->vbi = NULL;
@@ -792,6 +797,7 @@ static void teletext_flush(AVCodecContext *avctx)
 #define SD AV_OPT_FLAG_SUBTITLE_PARAM | AV_OPT_FLAG_DECODING_PARAM
 static const AVOption options[] = {
     {"txt_page",        "page numbers to decode, subtitle for subtitles, * for all", OFFSET(pgno),   AV_OPT_TYPE_STRING, {.str = "*"},      0, 0,        SD},
+    {"txt_default_region", "default G0 character set used for decoding",     OFFSET(default_region), AV_OPT_TYPE_INT,    {.i64 = -1},      -1, 80,       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 or ass)",   OFFSET(format_id),      AV_OPT_TYPE_INT,    {.i64 = 0},        0, 2,        SD,  "txt_format"},
     {"bitmap",          NULL,                                                0,                      AV_OPT_TYPE_CONST,  {.i64 = 0},        0, 0,        SD,  "txt_format"},

libavcodec/version.h

@@ -29,7 +29,7 @@
 
 #define LIBAVCODEC_VERSION_MAJOR  58
 #define LIBAVCODEC_VERSION_MINOR  73
-#define LIBAVCODEC_VERSION_MICRO 101
+#define LIBAVCODEC_VERSION_MICRO 102
 
 #define LIBAVCODEC_VERSION_INT  AV_VERSION_INT(LIBAVCODEC_VERSION_MAJOR, \
                                                LIBAVCODEC_VERSION_MINOR, \