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avcodec/ttmlenc: add support for region positioning and sizing

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The ASS margins are utilized to generate percentual values, as
the usage of cell-based sizing and offsetting seems to be not too
well supported by renderers.

Signed-off-by: Jan Ekström <jan.ekstrom@24i.com>
This commit is contained in:
Jan Ekström 2021-03-29 17:19:58 +03:00 committed by Jan Ekström
parent 3ef5a8ba2b
commit b24488e727
2 changed files with 45 additions and 2 deletions
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45
libavcodec/ttmlenc.c
View File

@ -237,11 +237,35 @@ static const char *ttml_get_text_alignment(int alignment)
}
}
static void ttml_get_origin(ASSScriptInfo script_info, ASSStyle style,
int *origin_left, int *origin_top)
{
*origin_left = av_rescale(style.margin_l, 100, script_info.play_res_x);
*origin_top =
av_rescale((style.alignment >= 7) ? style.margin_v : 0,
100, script_info.play_res_y);
}
static void ttml_get_extent(ASSScriptInfo script_info, ASSStyle style,
int *width, int *height)
{
*width = av_rescale(script_info.play_res_x - style.margin_r,
100, script_info.play_res_x);
*height = av_rescale((style.alignment <= 3) ?
script_info.play_res_y - style.margin_v :
script_info.play_res_y,
100, script_info.play_res_y);
}
static int ttml_write_region(AVCodecContext *avctx, AVBPrint *buf,
ASSStyle style)
ASSScriptInfo script_info, ASSStyle style)
{
const char *display_alignment = NULL;
const char *text_alignment = NULL;
int origin_left = 0;
int origin_top = 0;
int width = 0;
int height = 0;
if (!style.name) {
av_log(avctx, AV_LOG_ERROR, "Subtitle style name not set!\n");
@ -254,6 +278,14 @@ static int ttml_write_region(AVCodecContext *avctx, AVBPrint *buf,
return AVERROR_INVALIDDATA;
}
if (style.margin_l < 0 || style.margin_r < 0 || style.margin_v < 0) {
av_log(avctx, AV_LOG_ERROR,
"One or more negative margin values in subtitle style: "
"left: %d, right: %d, vertical: %d!\n",
style.margin_l, style.margin_r, style.margin_v);
return AVERROR_INVALIDDATA;
}
display_alignment = ttml_get_display_alignment(style.alignment);
text_alignment = ttml_get_text_alignment(style.alignment);
if (!display_alignment || !text_alignment) {
@ -265,11 +297,19 @@ static int ttml_write_region(AVCodecContext *avctx, AVBPrint *buf,
return AVERROR_INVALIDDATA;
}
ttml_get_origin(script_info, style, &origin_left, &origin_top);
ttml_get_extent(script_info, style, &width, &height);
av_bprintf(buf, " <region xml:id=\"");
av_bprint_escape(buf, style.name, NULL, AV_ESCAPE_MODE_XML,
AV_ESCAPE_FLAG_XML_DOUBLE_QUOTES);
av_bprintf(buf, "\"\n");
av_bprintf(buf, " tts:origin=\"%d%% %d%%\"\n",
origin_left, origin_top);
av_bprintf(buf, " tts:extent=\"%d%% %d%%\"\n",
width, height);
av_bprintf(buf, " tts:displayAlign=\"");
av_bprint_escape(buf, display_alignment, NULL, AV_ESCAPE_MODE_XML,
AV_ESCAPE_FLAG_XML_DOUBLE_QUOTES);
@ -331,7 +371,8 @@ static int ttml_write_header_content(AVCodecContext *avctx)
av_bprintf(&s->buffer, " <layout>\n");
for (int i = 0; i < ass->styles_count; i++) {
int ret = ttml_write_region(avctx, &s->buffer, ass->styles[i]);
int ret = ttml_write_region(avctx, &s->buffer, script_info,
ass->styles[i]);
if (ret < 0)
return ret;
}

2
tests/ref/fate/sub-ttmlenc
View File

@ -9,6 +9,8 @@
<head>
<layout>
<region xml:id="Default"
tts:origin="3% 0%"
tts:extent="97% 97%"
tts:displayAlign="after"
tts:textAlign="center"
tts:fontSize="16c"