[FFmpeg-devel] [PATCH 2/2] Encoding of styles - Bold, Italic, Underlined for timed-text subttiles
Niklesh Lalwani
niklesh.lalwani at iitb.ac.in
Thu Jun 11 06:48:53 CEST 2015
From: Niklesh <niklesh.lalwani at iitb.ac.in>
Encoding of bold, Italic, underlined styles for 3gpp timed text subtitles. All the formatting information is appended into the buffer after the text, unlike other encoders like srt, which can write out styling information as it goes. Another tricky part is to take care of the Endianness properly while writing into the buffer.
Signed-off-by: Niklesh <niklesh.lalwani at iitb.ac.in>
---
libavcodec/movtextenc.c | 104 +++++++++++++++++++++++++++++++++++-------------
1 file changed, 76 insertions(+), 28 deletions(-)
diff --git a/libavcodec/movtextenc.c b/libavcodec/movtextenc.c
index 1b8f454..adbe19d 100644
--- a/libavcodec/movtextenc.c
+++ b/libavcodec/movtextenc.c
@@ -24,14 +24,27 @@
#include "libavutil/avassert.h"
#include "libavutil/avstring.h"
#include "libavutil/intreadwrite.h"
+#include "libavutil/common.h"
#include "ass_split.h"
#include "ass.h"
+#define STYLE_FLAG_BOLD 1
+#define STYLE_FLAG_ITALIC 2
+#define STYLE_FLAG_UNDERLINE 4
+
typedef struct {
ASSSplitContext *ass_ctx;
- char buffer[2048];
- char *ptr;
- char *end;
+ AVBPrint buffer;
+ uint32_t tsmb_size;
+ uint32_t tsmb_type;
+ uint16_t style_entries;
+ uint16_t style_start;
+ uint16_t style_end;
+ uint16_t style_fontID;
+ uint8_t style_flag;
+ uint8_t style_fontsize;
+ uint32_t style_color;
+ uint16_t text_pos;
} MovTextContext;
@@ -47,10 +60,10 @@ static av_cold int mov_text_encode_init(AVCodecContext *avctx)
0xFF, // int8_t vertical-justification
0x00, 0x00, 0x00, 0x00, // uint8_t background-color-rgba[4]
// BoxRecord {
- 0x00, 0x00, // int16_t top
- 0x00, 0x00, // int16_t left
- 0x00, 0x00, // int16_t bottom
- 0x00, 0x00, // int16_t right
+ 0x00, 0x01, // int16_t top
+ 0x00, 0x01, // int16_t left
+ 0x00, 0x1E, // int16_t bottom
+ 0x00, 0xC8, // int16_t right
// };
// StyleRecord {
0x00, 0x00, // uint16_t startChar
@@ -79,32 +92,54 @@ static av_cold int mov_text_encode_init(AVCodecContext *avctx)
if (!avctx->extradata)
return AVERROR(ENOMEM);
+ av_bprint_init(&s->buffer, 0, AV_BPRINT_SIZE_UNLIMITED);
+
memcpy(avctx->extradata, text_sample_entry, avctx->extradata_size);
s->ass_ctx = ff_ass_split(avctx->subtitle_header);
return s->ass_ctx ? 0 : AVERROR_INVALIDDATA;
}
+static void mov_text_style_cb(void *priv, const char style, int close)
+{
+ MovTextContext *s = priv;
+ s->tsmb_type = MKTAG('s','t','y','l');
+ if (!close) {
+ s->style_start = AV_RB16(&s->text_pos);
+ switch (style){
+ case 'b':
+ s->style_flag += STYLE_FLAG_BOLD;
+ break;
+ case 'i':
+ s->style_flag += STYLE_FLAG_ITALIC;
+ break;
+ case 'u':
+ s->style_flag += STYLE_FLAG_UNDERLINE;
+ break;
+ }
+ } else {
+ s->style_end = AV_RB16(&s->text_pos);
+ }
+}
+
static void mov_text_text_cb(void *priv, const char *text, int len)
{
MovTextContext *s = priv;
- av_assert0(s->end >= s->ptr);
- av_strlcpy(s->ptr, text, FFMIN(s->end - s->ptr, len + 1));
- s->ptr += FFMIN(s->end - s->ptr, len);
+ av_bprint_append_data(&s->buffer, text, len);
+ s->text_pos += len;
}
static void mov_text_new_line_cb(void *priv, int forced)
{
MovTextContext *s = priv;
- av_assert0(s->end >= s->ptr);
- av_strlcpy(s->ptr, "\n", FFMIN(s->end - s->ptr, 2));
- if (s->end > s->ptr)
- s->ptr++;
+ av_bprint_append_data(&s->buffer, "\n", 2);
+ s->text_pos += 2;
}
static const ASSCodesCallbacks mov_text_callbacks = {
.text = mov_text_text_cb,
.new_line = mov_text_new_line_cb,
+ .style = mov_text_style_cb,
};
static int mov_text_encode_frame(AVCodecContext *avctx, unsigned char *buf,
@@ -112,10 +147,9 @@ static int mov_text_encode_frame(AVCodecContext *avctx, unsigned char *buf,
{
MovTextContext *s = avctx->priv_data;
ASSDialog *dialog;
- int i, len, num;
+ int i, num;
- s->ptr = s->buffer;
- s->end = s->ptr + sizeof(s->buffer);
+ av_bprint_clear(&s->buffer);
for (i = 0; i < sub->num_rects; i++) {
@@ -123,33 +157,47 @@ static int mov_text_encode_frame(AVCodecContext *avctx, unsigned char *buf,
av_log(avctx, AV_LOG_ERROR, "Only SUBTITLE_ASS type supported.\n");
return AVERROR(ENOSYS);
}
+ s->text_pos = 0;
dialog = ff_ass_split_dialog(s->ass_ctx, sub->rects[i]->ass, 0, &num);
for (; dialog && num--; dialog++) {
ff_ass_split_override_codes(&mov_text_callbacks, s, dialog->text);
}
+ if (s->tsmb_type == MKTAG('s','t','y','l') && s->style_end) {
+ s->tsmb_size = MKTAG(0x00, 0x00, 0x00, 0x16);
+ s->style_entries = 0x00 | 0x01<<8;
+ s->style_fontID = 0x00 | 0x01<<8;
+ s->style_fontsize = 0x12;
+ s->style_color = MKTAG(0xFF, 0xFF, 0xFF, 0xFF);
+ av_bprint_append_data(&s->buffer, &s->tsmb_size, 4);
+ av_bprint_append_data(&s->buffer, &s->tsmb_type, 4);
+ av_bprint_append_data(&s->buffer, &s->style_entries, 2);
+ av_bprint_append_data(&s->buffer, &s->style_start, 2);
+ av_bprint_append_data(&s->buffer, &s->style_end, 2);
+ av_bprint_append_data(&s->buffer, &s->style_fontID, 2);
+ av_bprint_append_data(&s->buffer, &s->style_flag, 1);
+ av_bprint_append_data(&s->buffer, &s->style_fontsize, 1);
+ av_bprint_append_data(&s->buffer, &s->style_color, 4);
+ }
}
- if (s->ptr == s->buffer)
- return 0;
-
- AV_WB16(buf, strlen(s->buffer));
+ AV_WB16(buf, s->text_pos);
buf += 2;
- len = av_strlcpy(buf, s->buffer, bufsize - 2);
-
- if (len > bufsize-3) {
- av_log(avctx, AV_LOG_ERROR, "Buffer too small for ASS event.\n");
- return AVERROR(EINVAL);
- }
+ if (!av_bprint_is_complete(&s->buffer))
+ return AVERROR(ENOMEM);
+ if (!s->buffer.len)
+ return 0;
- return len + 2;
+ memcpy(buf, s->buffer.str, s->buffer.len);
+ return s->buffer.len + 2;
}
static int mov_text_encode_close(AVCodecContext *avctx)
{
MovTextContext *s = avctx->priv_data;
ff_ass_split_free(s->ass_ctx);
+ av_bprint_finalize(&s->buffer, NULL);
return 0;
}
--
1.9.1
More information about the ffmpeg-devel
mailing list