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ffmpeg/libavcodec/movtextdec.c

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/*
* 3GPP TS 26.245 Timed Text decoder
* Copyright (c) 2012 Philip Langdale <philipl@overt.org>
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "avcodec.h"
#include "ass.h"
#include "libavutil/avstring.h"
#include "libavutil/common.h"
#include "libavutil/bprint.h"
#include "libavutil/intreadwrite.h"
#include "libavutil/mem.h"
#define STYLE_FLAG_BOLD (1<<0)
#define STYLE_FLAG_ITALIC (1<<1)
#define STYLE_FLAG_UNDERLINE (1<<2)
#define STYL_BOX (1<<0)
#define HLIT_BOX (1<<1)
#define HCLR_BOX (1<<2)
typedef struct {
uint16_t style_start;
uint16_t style_end;
uint8_t style_flag;
} StyleBox;
typedef struct {
uint16_t hlit_start;
uint16_t hlit_end;
} HighlightBox;
typedef struct {
uint8_t hlit_color[4];
} HilightcolorBox;
typedef struct {
StyleBox **s;
StyleBox *s_temp;
HighlightBox h;
HilightcolorBox c;
uint8_t box_flags;
uint16_t style_entries;
uint64_t tracksize;
int size_var;
int count_s;
} MovTextContext;
typedef struct {
uint32_t type;
size_t base_size;
int (*decode)(const uint8_t *tsmb, MovTextContext *m, AVPacket *avpkt);
} Box;
static void mov_text_cleanup(MovTextContext *m)
{
int i;
if (m->box_flags & STYL_BOX) {
for(i = 0; i < m->count_s; i++) {
av_freep(&m->s[i]);
}
av_freep(&m->s);
}
}
static int decode_hlit(const uint8_t *tsmb, MovTextContext *m, AVPacket *avpkt)
{
m->box_flags |= HLIT_BOX;
m->h.hlit_start = AV_RB16(tsmb);
tsmb += 2;
m->h.hlit_end = AV_RB16(tsmb);
tsmb += 2;
return 0;
}
static int decode_hclr(const uint8_t *tsmb, MovTextContext *m, AVPacket *avpkt)
{
m->box_flags |= HCLR_BOX;
memcpy(m->c.hlit_color, tsmb, 4);
tsmb += 4;
return 0;
}
static int decode_styl(const uint8_t *tsmb, MovTextContext *m, AVPacket *avpkt)
{
int i;
m->style_entries = AV_RB16(tsmb);
tsmb += 2;
// A single style record is of length 12 bytes.
if (m->tracksize + m->size_var + 2 + m->style_entries * 12 > avpkt->size)
return -1;
m->box_flags |= STYL_BOX;
for(i = 0; i < m->style_entries; i++) {
m->s_temp = av_malloc(sizeof(*m->s_temp));
if (!m->s_temp) {
mov_text_cleanup(m);
return AVERROR(ENOMEM);
}
m->s_temp->style_start = AV_RB16(tsmb);
tsmb += 2;
m->s_temp->style_end = AV_RB16(tsmb);
tsmb += 2;
// fontID = AV_RB16(tsmb);
tsmb += 2;
m->s_temp->style_flag = AV_RB8(tsmb);
av_dynarray_add(&m->s, &m->count_s, m->s_temp);
if(!m->s) {
mov_text_cleanup(m);
return AVERROR(ENOMEM);
}
// fontsize = AV_RB8(tsmb);
tsmb += 2;
// text-color-rgba
tsmb += 4;
}
return 0;
}
static const Box box_types[] = {
{ MKBETAG('s','t','y','l'), 2, decode_styl },
{ MKBETAG('h','l','i','t'), 4, decode_hlit },
{ MKBETAG('h','c','l','r'), 4, decode_hclr }
};
const static size_t box_count = FF_ARRAY_ELEMS(box_types);
static int text_to_ass(AVBPrint *buf, const char *text, const char *text_end,
MovTextContext *m)
{
int i = 0;
int text_pos = 0;
while (text < text_end) {
if (m->box_flags & STYL_BOX) {
for (i = 0; i < m->style_entries; i++) {
if (m->s[i]->style_flag && text_pos == m->s[i]->style_end) {
if (m->s[i]->style_flag & STYLE_FLAG_BOLD)
av_bprintf(buf, "{\\b0}");
if (m->s[i]->style_flag & STYLE_FLAG_ITALIC)
av_bprintf(buf, "{\\i0}");
if (m->s[i]->style_flag & STYLE_FLAG_UNDERLINE)
av_bprintf(buf, "{\\u0}");
}
}
for (i = 0; i < m->style_entries; i++) {
if (m->s[i]->style_flag && text_pos == m->s[i]->style_start) {
if (m->s[i]->style_flag & STYLE_FLAG_BOLD)
av_bprintf(buf, "{\\b1}");
if (m->s[i]->style_flag & STYLE_FLAG_ITALIC)
av_bprintf(buf, "{\\i1}");
if (m->s[i]->style_flag & STYLE_FLAG_UNDERLINE)
av_bprintf(buf, "{\\u1}");
}
}
}
if (m->box_flags & HLIT_BOX) {
if (text_pos == m->h.hlit_start) {
/* If hclr box is present, set the secondary color to the color
* specified. Otherwise, set primary color to white and secondary
* color to black. These colors will come from TextSampleModifier
* boxes in future and inverse video technique for highlight will
* be implemented.
*/
if (m->box_flags & HCLR_BOX) {
av_bprintf(buf, "{\\2c&H%02x%02x%02x&}", m->c.hlit_color[2],
m->c.hlit_color[1], m->c.hlit_color[0]);
} else {
av_bprintf(buf, "{\\1c&H000000&}{\\2c&HFFFFFF&}");
}
}
if (text_pos == m->h.hlit_end) {
if (m->box_flags & HCLR_BOX) {
av_bprintf(buf, "{\\2c&H000000&}");
} else {
av_bprintf(buf, "{\\1c&HFFFFFF&}{\\2c&H000000&}");
}
}
}
switch (*text) {
case '\r':
break;
case '\n':
av_bprintf(buf, "\\N");
break;
default:
av_bprint_chars(buf, *text, 1);
break;
}
text++;
text_pos++;
}
return 0;
}
static int mov_text_init(AVCodecContext *avctx) {
/*
* TODO: Handle the default text style.
* NB: Most players ignore styles completely, with the result that
* it's very common to find files where the default style is broken
* and respecting it results in a worse experience than ignoring it.
*/
return ff_ass_subtitle_header_default(avctx);
}
static int mov_text_decode_frame(AVCodecContext *avctx,
void *data, int *got_sub_ptr, AVPacket *avpkt)
{
AVSubtitle *sub = data;
MovTextContext *m = avctx->priv_data;
int ret, ts_start, ts_end;
AVBPrint buf;
char *ptr = avpkt->data;
char *end;
int text_length, tsmb_type, ret_tsmb;
uint64_t tsmb_size;
const uint8_t *tsmb;
if (!ptr || avpkt->size < 2)
return AVERROR_INVALIDDATA;
/*
* A packet of size two with value zero is an empty subtitle
* used to mark the end of the previous non-empty subtitle.
* We can just drop them here as we have duration information
* already. If the value is non-zero, then it's technically a
* bad packet.
*/
if (avpkt->size == 2)
return AV_RB16(ptr) == 0 ? 0 : AVERROR_INVALIDDATA;
/*
* The first two bytes of the packet are the length of the text string
* In complex cases, there are style descriptors appended to the string
* so we can't just assume the packet size is the string size.
*/
text_length = AV_RB16(ptr);
end = ptr + FFMIN(2 + text_length, avpkt->size);
ptr += 2;
ts_start = av_rescale_q(avpkt->pts,
avctx->time_base,
(AVRational){1,100});
ts_end = av_rescale_q(avpkt->pts + avpkt->duration,
avctx->time_base,
(AVRational){1,100});
tsmb_size = 0;
m->tracksize = 2 + text_length;
m->style_entries = 0;
m->box_flags = 0;
m->count_s = 0;
// Note that the spec recommends lines be no longer than 2048 characters.
av_bprint_init(&buf, 0, AV_BPRINT_SIZE_UNLIMITED);
if (text_length + 2 != avpkt->size) {
while (m->tracksize + 8 <= avpkt->size) {
// A box is a minimum of 8 bytes.
tsmb = ptr + m->tracksize - 2;
tsmb_size = AV_RB32(tsmb);
tsmb += 4;
tsmb_type = AV_RB32(tsmb);
tsmb += 4;
if (tsmb_size == 1) {
if (m->tracksize + 16 > avpkt->size)
break;
tsmb_size = AV_RB64(tsmb);
tsmb += 8;
m->size_var = 16;
} else
m->size_var = 8;
//size_var is equal to 8 or 16 depending on the size of box
if (m->tracksize + tsmb_size > avpkt->size)
break;
for (size_t i = 0; i < box_count; i++) {
if (tsmb_type == box_types[i].type) {
if (m->tracksize + m->size_var + box_types[i].base_size > avpkt->size)
break;
ret_tsmb = box_types[i].decode(tsmb, m, avpkt);
if (ret_tsmb == -1)
break;
}
}
m->tracksize = m->tracksize + tsmb_size;
}
text_to_ass(&buf, ptr, end, m);
mov_text_cleanup(m);
} else
text_to_ass(&buf, ptr, end, m);
ret = ff_ass_add_rect_bprint(sub, &buf, ts_start, ts_end - ts_start);
av_bprint_finalize(&buf, NULL);
if (ret < 0)
return ret;
*got_sub_ptr = sub->num_rects > 0;
return avpkt->size;
}
AVCodec ff_movtext_decoder = {
.name = "mov_text",
.long_name = NULL_IF_CONFIG_SMALL("3GPP Timed Text subtitle"),
.type = AVMEDIA_TYPE_SUBTITLE,
.id = AV_CODEC_ID_MOV_TEXT,
.priv_data_size = sizeof(MovTextContext),
.init = mov_text_init,
.decode = mov_text_decode_frame,
};
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