According to the format specification (3GPP TS 26.245, section 5.2) "storage
lengths are specified as byte-counts, wheras highlighting is specified using
character offsets." This patch replaces byte counting with character counting
for highlighting. See the following page for a link to the specification:
https://gpac.wp.mines-telecom.fr/mp4box/ttxt-format-documentation/
---
libavcodec/movtextenc.c | 24 +++++++++++++++---------
1 file changed, 15 insertions(+), 9 deletions(-)
diff --git a/libavcodec/movtextenc.c b/libavcodec/movtextenc.c
index 20e01e2..3ae015a 100644
--- a/libavcodec/movtextenc.c
+++ b/libavcodec/movtextenc.c
@@ -70,6 +70,7 @@ typedef struct {
uint8_t style_fontsize;
uint32_t style_color;
uint16_t text_pos;
+ uint16_t text_pos_chars;
} MovTextContext;
typedef struct {
@@ -216,10 +217,10 @@ static void mov_text_style_cb(void *priv, const char
style, int close)
}
s->style_attributes_temp->style_flag = 0;
- s->style_attributes_temp->style_start = AV_RB16(&s->text_pos);
+ s->style_attributes_temp->style_start =
AV_RB16(&s->text_pos_chars);
} else {
if (s->style_attributes_temp->style_flag) { //break the style
record here and start a new one
- s->style_attributes_temp->style_end = AV_RB16(&s->text_pos);
+ s->style_attributes_temp->style_end =
AV_RB16(&s->text_pos_chars);
av_dynarray_add(&s->style_attributes, &s->count,
s->style_attributes_temp);
s->style_attributes_temp =
av_malloc(sizeof(*s->style_attributes_temp));
if (!s->style_attributes_temp) {
@@ -230,10 +231,10 @@ static void mov_text_style_cb(void *priv, const char
style, int close)
}
s->style_attributes_temp->style_flag =
s->style_attributes[s->count - 1]->style_flag;
- s->style_attributes_temp->style_start = AV_RB16(&s->text_pos);
+ s->style_attributes_temp->style_start =
AV_RB16(&s->text_pos_chars);
} else {
s->style_attributes_temp->style_flag = 0;
- s->style_attributes_temp->style_start = AV_RB16(&s->text_pos);
+ s->style_attributes_temp->style_start =
AV_RB16(&s->text_pos_chars);
}
}
switch (style){
@@ -248,7 +249,7 @@ static void mov_text_style_cb(void *priv, const char style,
int close)
break;
}
} else {
- s->style_attributes_temp->style_end = AV_RB16(&s->text_pos);
+ s->style_attributes_temp->style_end = AV_RB16(&s->text_pos_chars);
av_dynarray_add(&s->style_attributes, &s->count,
s->style_attributes_temp);
s->style_attributes_temp =
av_malloc(sizeof(*s->style_attributes_temp));
@@ -273,7 +274,7 @@ static void mov_text_style_cb(void *priv, const char style,
int close)
break;
}
if (s->style_attributes_temp->style_flag) { //start of new style record
- s->style_attributes_temp->style_start = AV_RB16(&s->text_pos);
+ s->style_attributes_temp->style_start =
AV_RB16(&s->text_pos_chars);
}
}
s->box_flags |= STYL_BOX;
@@ -284,11 +285,11 @@ static void mov_text_color_cb(void *priv, unsigned int
color, unsigned int color
MovTextContext *s = priv;
if (color_id == 2) { //secondary color changes
if (s->box_flags & HLIT_BOX) { //close tag
- s->hlit.end = AV_RB16(&s->text_pos);
+ s->hlit.end = AV_RB16(&s->text_pos_chars);
} else {
s->box_flags |= HCLR_BOX;
s->box_flags |= HLIT_BOX;
- s->hlit.start = AV_RB16(&s->text_pos);
+ s->hlit.start = AV_RB16(&s->text_pos_chars);
s->hclr.color = color | (0xFF << 24); //set alpha value to FF
}
}
@@ -302,7 +303,10 @@ static void mov_text_text_cb(void *priv, const char *text,
int len)
{
MovTextContext *s = priv;
av_bprint_append_data(&s->buffer, text, len);
- s->text_pos += len;
+ s->text_pos += len; // length of text in bytes
+ for (int i = 0; i < len; i++) // length of text in UTF-8 characters
+ if ((text[i] & 0xC0) != 0x80)
+ s->text_pos_chars++;
}
static void mov_text_new_line_cb(void *priv, int forced)
@@ -310,6 +314,7 @@ static void mov_text_new_line_cb(void *priv, int forced)
MovTextContext *s = priv;
av_bprint_append_data(&s->buffer, "\n", 1);
s->text_pos += 1;
+ s->text_pos_chars += 1;
}
static const ASSCodesCallbacks mov_text_callbacks = {
@@ -328,6 +333,7 @@ static int mov_text_encode_frame(AVCodecContext *avctx,
unsigned char *buf,
size_t j;
s->text_pos = 0;
+ s->text_pos_chars = 0;
s->count = 0;
s->box_flags = 0;
s->style_entries = 0;
--
1.9.5 (Apple Git-50.3)
_______________________________________________
ffmpeg-devel mailing list
ffmpeg-devel@ffmpeg.org
http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
