[FFmpeg-devel] [PATCH 2/2] avcodec/libzvbi-teletextdec: formatted ass output
Aman Gupta
ffmpeg at tmm1.net
Mon May 7 22:50:20 EEST 2018
On Sun, May 6, 2018 at 2:05 PM, Marton Balint <cus at passwd.hu> wrote:
> Inspired by the VideoLAN text decoder and its port to FFmpeg made by Aman
> Gupta.
>
Thanks for incorporating my changes.
I ran some tests, and colors work as expected. Positioning also works well,
and is also pretty close to my version.
I found that some live streams are not chopping empty lines correctly. I
see extra newlines at the end:
Dialogue:
0,0:13:21.66,9:59:59.99,Default,,0,0,0,,{\an1}Simson,\hPeter\hHartcher,\hRobyn\hParker
\Nand\hBenjamin \N \N \N
Here's a sample which shows extra newlines:
https://s3.amazonaws.com/tmm1/teletext/capture_live1.mpg
It also looks like the "erase page" command is not being processed, which
causes stale captions to stay on the screen in some cases.
This is especially confusing when part of an old caption remains on one
line, but then newer captions appear on another line.
Here's a sample that shows lines not being cleared correctly:
https://s3.amazonaws.com/tmm1/teletext/simple.mpg
I also have several other samples which use various features, available at
the same URL:
capture_formatting1.mpg
capture_formatting2.mpg
capture_formatting3.mpg
capture_live1.mpg
capture_live2.mpg
capture_notCaptionedMessage.mpg
capture_threeLines1.mpg
capture_threeLines2.mpg
capture_threeLines3.mpg
capture_threeLines4.mpg
capture_yOffset1.mpg
three.ts
four.ts
Thanks,
Aman
>
> Signed-off-by: Marton Balint <cus at passwd.hu>
> ---
> doc/decoders.texi | 18 ++-
> libavcodec/libzvbi-teletextdec.c | 265 ++++++++++++++++++++++++++++++
> +++++++--
> 2 files changed, 270 insertions(+), 13 deletions(-)
>
> diff --git a/doc/decoders.texi b/doc/decoders.texi
> index 8f07bc1afb..cc9b2ef123 100644
> --- a/doc/decoders.texi
> +++ b/doc/decoders.texi
> @@ -255,12 +255,18 @@ 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.
> +Specifies the format of the decoded subtitles.
> + at table @option
> + at item bitmap
> +The default format, you should use this for teletext pages, because
> certain
> +graphics and colors cannot be expressed in simple text or even ASS.
> + at item text
> +Simple text based output without formatting.
> + at item ass
> +Formatted ASS output, subtitle pages and teletext pages are returned in
> +different styles, subtitle pages are stripped down to text, but an effort
> is
> +made to keep the text alignment and the formatting.
> + at end table
> @item txt_left
> X offset of generated bitmaps, default is 0.
> @item txt_top
> diff --git a/libavcodec/libzvbi-teletextdec.c b/libavcodec/libzvbi-
> teletextdec.c
> index 56a7182882..7541de0d53 100644
> --- a/libavcodec/libzvbi-teletextdec.c
> +++ b/libavcodec/libzvbi-teletextdec.c
> @@ -26,6 +26,7 @@
> #include "libavutil/internal.h"
> #include "libavutil/intreadwrite.h"
> #include "libavutil/log.h"
> +#include "libavutil/common.h"
>
> #include <libzvbi.h>
>
> @@ -56,7 +57,7 @@ typedef struct TeletextContext
> char *pgno;
> int x_offset;
> int y_offset;
> - int format_id; /* 0 = bitmap, 1 = text/ass */
> + int format_id; /* 0 = bitmap, 1 = text/ass, 2 = ass */
> int chop_top;
> int sub_duration; /* in msec */
> int transparent_bg;
> @@ -74,8 +75,55 @@ typedef struct TeletextContext
>
> int readorder;
> uint8_t subtitle_map[2048];
> + int last_ass_alignment;
> } TeletextContext;
>
> +static int my_ass_subtitle_header(AVCodecContext *avctx)
> +{
> + int ret = ff_ass_subtitle_header_default(avctx);
> + char *new_header;
> + uint8_t *event_pos;
> +
> + if (ret < 0)
> + return ret;
> +
> + event_pos = strstr(avctx->subtitle_header, "\r\n[Events]\r\n");
> + if (!event_pos)
> + return AVERROR_BUG;
> +
> + new_header = av_asprintf("%.*s%s%s",
> + (int)(event_pos - avctx->subtitle_header), avctx->subtitle_header,
> + "Style: "
> + "Teletext," /* Name */
> + "Monospace,11," /* Font{name,size} */
> + "&Hffffff,&Hffffff,&H0,&H0," /* {Primary,Secondary,Outline,Back}Colour
> */
> + "0,0,0,0," /* Bold, Italic, Underline, StrikeOut */
> + "160,100," /* Scale{X,Y} */
> + "0,0," /* Spacing, Angle */
> + "3,0.1,0," /* BorderStyle, Outline, Shadow */
> + "5,1,1,1," /* Alignment, Margin[LRV] */
> + "0\r\n" /* Encoding */
> + "Style: "
> + "Subtitle," /* Name */
> + "Monospace,16," /* Font{name,size} */
> + "&Hffffff,&Hffffff,&H0,&H0," /* {Primary,Secondary,Outline,Back}Colour
> */
> + "0,0,0,0," /* Bold, Italic, Underline, StrikeOut */
> + "100,100," /* Scale{X,Y} */
> + "0,0," /* Spacing, Angle */
> + "1,1,1," /* BorderStyle, Outline, Shadow */
> + "8,48,48,20," /* Alignment, Margin[LRV] */
> + "0\r\n" /* Encoding */
> + , event_pos);
> +
> + if (!new_header)
> + return AVERROR(ENOMEM);
> +
> + av_free(avctx->subtitle_header);
> + avctx->subtitle_header = new_header;
> + avctx->subtitle_header_size = strlen(new_header);
> + return 0;
> +}
> +
> static int chop_spaces_utf8(const unsigned char* t, int len)
> {
> t += len;
> @@ -179,6 +227,186 @@ static int gen_sub_text(TeletextContext *ctx,
> AVSubtitleRect *sub_rect, vbi_page
> return 0;
> }
>
> +static void bprint_color(const char *type, AVBPrint *buf, vbi_page *page,
> unsigned ci)
> +{
> + int r = VBI_R(page->color_map[ci]);
> + int g = VBI_G(page->color_map[ci]);
> + int b = VBI_B(page->color_map[ci]);
> + av_bprintf(buf, "{\\%s&H%02X%02X%02X&}", type, b, g, r);
> +}
> +
> +#define IS_TXT_SPACE(ch) ((ch).unicode < 0x0020 || (ch).unicode >= 0xe000
> || (ch).unicode == 0x00a0 ||\
> + (ch).size > VBI_DOUBLE_SIZE || (ch).opacity ==
> VBI_TRANSPARENT_SPACE)
> +
> +static void get_trim_info(vbi_page *page, vbi_char *row, int *leading,
> int *trailing, int *olen)
> +{
> + int i, len = 0;
> + int char_seen = 0;
> +
> + *leading = 0;
> +
> + for (i = 0; i < page->columns; i++) {
> + uint16_t out = IS_TXT_SPACE(row[i]) ? 32 : row[i].unicode;
> +
> + if (out == 32 && !char_seen)
> + (*leading)++;
> + else if (out != 32)
> + char_seen = 1, len = i - (*leading) + 1;
> + }
> +
> + *olen = len;
> + *trailing = len > 0 ? page->columns - *leading - len : page->columns;
> +}
> +
> +static void decode_string(vbi_page *page, vbi_char *row, AVBPrint *buf,
> + int start, int end, vbi_color *cur_color,
> vbi_color *cur_back_color)
> +{
> + int i;
> +
> + for (i = start; i < end; i++) {
> + uint16_t out = IS_TXT_SPACE(row[i]) ? 32 : row[i].unicode;
> +
> + if (*cur_color != row[i].foreground) {
> + bprint_color("c", buf, page, row[i].foreground);
> + *cur_color = row[i].foreground;
> + }
> + if (*cur_back_color != row[i].background) {
> + bprint_color("3c", buf, page, row[i].background);
> + *cur_back_color = row[i].background;
> + }
> +
> + if (out == 32) {
> + av_bprintf(buf, "\\h");
> + } else if (out == '\\' || out == '{' || out == '}') {
> + av_bprintf(buf, "\\%c", (char)out);
> + } else {
> + char tmp;
> + /* convert to utf-8 */
> + PUT_UTF8(out, tmp, av_bprint_chars(buf, tmp, 1););
> + }
> + }
> +}
> +
> +/* Draw a page as ass formatted text */
> +static int gen_sub_ass(TeletextContext *ctx, AVSubtitleRect *sub_rect,
> vbi_page *page, int chop_top)
> +{
> + int i;
> + int leading, trailing, len;
> + int last_trailing = -1, last_leading = -1;
> + int min_trailing = page->columns, min_leading = page->columns;
> + int alignment = 2;
> + int vertical_align = -1;
> + int can_align_left = 1, can_align_right = 1, can_align_center = 1;
> + int is_subtitle_page = ctx->subtitle_map[page->pgno & 0x7ff];
> + int empty_lines = 0;
> + vbi_color cur_color = VBI_WHITE;
> + vbi_color cur_back_color = VBI_BLACK;
> + AVBPrint buf;
> +
> + av_bprint_init(&buf, 0, AV_BPRINT_SIZE_UNLIMITED);
> +
> + for (i = chop_top; i < page->rows; i++) {
> + vbi_char *row = page->text + i * page->columns;
> +
> + get_trim_info(page, row, &leading, &trailing, &len);
> +
> + if (len) {
> + if (last_leading != -1 && last_leading != leading || leading
> > 5)
> + can_align_left = 0;
> + if (last_trailing != -1 && last_trailing != trailing ||
> trailing > 2)
> + can_align_right = 0;
> + if (last_trailing != -1 && (FFABS((trailing - leading) -
> (last_trailing - last_leading)) > 1) || trailing - leading > 4)
> + can_align_center = 0;
> + last_leading = leading;
> + last_trailing = trailing;
> + min_leading = FFMIN(leading, min_leading);
> + min_trailing = FFMIN(trailing, min_trailing);
> + }
> + }
> +
> + if ((can_align_right == can_align_left) && !can_align_center) {
> + alignment = ctx->last_ass_alignment;
> + } else if (!can_align_right && can_align_left && !can_align_center) {
> + ctx->last_ass_alignment = alignment = 1;
> + } else if (!can_align_right && !can_align_left && can_align_center) {
> + ctx->last_ass_alignment = alignment = 2;
> + } else if (can_align_right && !can_align_left && !can_align_center) {
> + ctx->last_ass_alignment = alignment = 3;
> + } else {
> + if (ctx->last_ass_alignment == 1 && can_align_left ||
> + ctx->last_ass_alignment == 2 && can_align_center ||
> + ctx->last_ass_alignment == 3 && can_align_right)
> + alignment = ctx->last_ass_alignment;
> + }
> +
> + for (i = chop_top; i < page->rows; i++) {
> + int j;
> + vbi_char *row = page->text + i * page->columns;
> + int is_transparent_line;
> +
> + for (j = 0; j < page->columns; j++)
> + if (row[j].opacity != VBI_TRANSPARENT_SPACE)
> + break;
> + is_transparent_line = (j == page->columns);
> +
> + len = is_transparent_line ? 0 : page->columns;
> + leading = trailing = is_transparent_line ? page->columns : 0;
> +
> + if (is_subtitle_page) {
> + if (!is_transparent_line)
> + get_trim_info(page, row, &leading, &trailing, &len);
> +
> + if (vertical_align == -1 && len) {
> + vertical_align = (2 - (av_clip(i + 1, 0, 23) / 8));
> + av_bprintf(&buf, "{\\an%d}", alignment + vertical_align *
> 3);
> + if (vertical_align != 2)
> + empty_lines = 0;
> + }
> +
> + if (len && empty_lines > 1)
> + for (empty_lines /= 2; empty_lines > 0; empty_lines--)
> + av_bprintf(&buf, " \\N");
> +
> + if (alignment == 1)
> + leading = min_leading;
> + if (alignment == 3)
> + trailing = min_trailing;
> + }
> +
> + if (len || !is_subtitle_page) {
> + decode_string(page, row, &buf, leading, page->columns -
> trailing, &cur_color, &cur_back_color);
> + av_bprintf(&buf, " \\N");
> + empty_lines = 0;
> + } else {
> + empty_lines++;
> + }
> + }
> +
> + if (vertical_align == 0)
> + for (empty_lines = (empty_lines - 1) / 2; empty_lines > 0;
> empty_lines--)
> + av_bprintf(&buf, " \\N");
> +
> + 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 = ff_ass_get_dialog(ctx->readorder++, 0,
> is_subtitle_page ? "Subtitle" : "Teletext", NULL, 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)
> {
> @@ -316,9 +544,20 @@ static void handler(vbi_event *ev, void *user_data)
> 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);
> + switch (ctx->format_id) {
> + case 0:
> + res = gen_sub_bitmap(ctx, cur_page->sub_rect,
> &page, chop_top);
> + break;
> + case 1:
> + res = gen_sub_text(ctx, cur_page->sub_rect,
> &page, chop_top);
> + break;
> + case 2:
> + res = gen_sub_ass(ctx, cur_page->sub_rect, &page,
> chop_top);
> + break;
> + default:
> + res = AVERROR_BUG;
> + break;
> + }
> if (res < 0) {
> av_freep(&cur_page->sub_rect);
> ctx->handler_ret = res;
> @@ -435,7 +674,7 @@ static int teletext_decode_frame(AVCodecContext
> *avctx, void *data, int *data_si
> // is there a subtitle to pass?
> if (ctx->nb_pages) {
> int i;
> - sub->format = ctx->format_id;
> + sub->format = !!ctx->format_id;
> sub->start_display_time = 0;
> sub->end_display_time = ctx->sub_duration;
> sub->num_rects = 0;
> @@ -494,12 +733,22 @@ static int teletext_init_decoder(AVCodecContext
> *avctx)
>
> ctx->vbi = NULL;
> ctx->pts = AV_NOPTS_VALUE;
> + ctx->last_ass_alignment = 2;
>
> if (ctx->opacity == -1)
> ctx->opacity = ctx->transparent_bg ? 0 : 255;
>
> av_log(avctx, AV_LOG_VERBOSE, "page filter: %s\n", ctx->pgno);
> - return (ctx->format_id == 1) ? ff_ass_subtitle_header_default(avctx)
> : 0;
> +
> + switch (ctx->format_id) {
> + case 0:
> + return 0;
> + case 1:
> + return ff_ass_subtitle_header_default(avctx);
> + case 2:
> + return my_ass_subtitle_header(avctx);
> + }
> + return AVERROR_BUG;
> }
>
> static int teletext_close_decoder(AVCodecContext *avctx)
> @@ -514,6 +763,7 @@ static int teletext_close_decoder(AVCodecContext
> *avctx)
> vbi_decoder_delete(ctx->vbi);
> ctx->vbi = NULL;
> ctx->pts = AV_NOPTS_VALUE;
> + ctx->last_ass_alignment = 2;
> memset(ctx->subtitle_map, 0, sizeof(ctx->subtitle_map));
> if (!(avctx->flags2 & AV_CODEC_FLAG2_RO_FLUSH_NOOP))
> ctx->readorder = 0;
> @@ -530,9 +780,10 @@ static void teletext_flush(AVCodecContext *avctx)
> 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"},
> + {"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"},
> {"text", NULL,
> 0, AV_OPT_TYPE_CONST, {.i64 = 1}, 0, 0,
> SD, "txt_format"},
> + {"ass", NULL,
> 0, AV_OPT_TYPE_CONST, {.i64 = 2}, 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},
> --
> 2.13.6
>
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