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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/opt.h"
#include "libavutil/avstring.h"
#include "libavutil/common.h"
#include "libavutil/bprint.h"
#include "libavutil/intreadwrite.h"
#include "libavutil/mem.h"
#include "bytestream.h"
#include "codec_internal.h"
#define STYLE_FLAG_BOLD (1<<0)
#define STYLE_FLAG_ITALIC (1<<1)
#define STYLE_FLAG_UNDERLINE (1<<2)
#define BOX_SIZE_INITIAL 40
#define STYL_BOX (1<<0)
#define HLIT_BOX (1<<1)
#define HCLR_BOX (1<<2)
#define TWRP_BOX (1<<3)
#define BOTTOM_LEFT 1
#define BOTTOM_CENTER 2
#define BOTTOM_RIGHT 3
#define MIDDLE_LEFT 4
#define MIDDLE_CENTER 5
#define MIDDLE_RIGHT 6
#define TOP_LEFT 7
#define TOP_CENTER 8
#define TOP_RIGHT 9
#define RGB_TO_BGR(c) (((c) & 0xff) << 16 | ((c) & 0xff00) | (((c) >> 16) & 0xff))
typedef struct {
uint16_t font_id;
char *font;
} FontRecord;
typedef struct {
uint16_t start;
uint16_t end;
uint8_t flags;
uint8_t bold;
uint8_t italic;
uint8_t underline;
int color;
uint8_t alpha;
uint8_t fontsize;
uint16_t font_id;
} StyleBox;
typedef struct {
StyleBox style;
const char *font;
int back_color;
uint8_t back_alpha;
int alignment;
} MovTextDefault;
typedef struct {
uint16_t hlit_start;
uint16_t hlit_end;
} HighlightBox;
typedef struct {
uint8_t hlit_color[4];
} HilightcolorBox;
typedef struct {
uint8_t wrap_flag;
} TextWrapBox;
typedef struct {
AVClass *class;
StyleBox *s;
HighlightBox h;
HilightcolorBox c;
FontRecord *ftab;
TextWrapBox w;
MovTextDefault d;
uint8_t box_flags;
uint16_t style_entries, ftab_entries;
int readorder;
int frame_width;
int frame_height;
} MovTextContext;
typedef struct {
uint32_t type;
unsigned base_size;
int (*decode)(const uint8_t *tsmb, MovTextContext *m, uint64_t size);
} Box;
static void mov_text_cleanup(MovTextContext *m)
{
if (m->box_flags & STYL_BOX) {
av_freep(&m->s);
m->style_entries = 0;
}
}
static void mov_text_cleanup_ftab(MovTextContext *m)
{
for (unsigned i = 0; i < m->ftab_entries; i++)
av_freep(&m->ftab[i].font);
av_freep(&m->ftab);
m->ftab_entries = 0;
}
static void mov_text_parse_style_record(StyleBox *style, const uint8_t **ptr)
{
// fontID
style->font_id = bytestream_get_be16(ptr);
// face-style-flags
style->flags = bytestream_get_byte(ptr);
style->bold = !!(style->flags & STYLE_FLAG_BOLD);
style->italic = !!(style->flags & STYLE_FLAG_ITALIC);
style->underline = !!(style->flags & STYLE_FLAG_UNDERLINE);
// fontsize
style->fontsize = bytestream_get_byte(ptr);
// Primary color
style->color = bytestream_get_be24(ptr);
style->color = RGB_TO_BGR(style->color);
style->alpha = bytestream_get_byte(ptr);
}
static int mov_text_tx3g(AVCodecContext *avctx, MovTextContext *m)
{
const uint8_t *tx3g_ptr = avctx->extradata;
int i, j = -1, font_length, remaining = avctx->extradata_size - BOX_SIZE_INITIAL;
int8_t v_align, h_align;
unsigned ftab_entries;
m->ftab_entries = 0;
if (remaining < 0)
return -1;
// Display Flags
tx3g_ptr += 4;
// Alignment
h_align = bytestream_get_byte(&tx3g_ptr);
v_align = bytestream_get_byte(&tx3g_ptr);
if (h_align == 0) {
if (v_align == 0)
m->d.alignment = TOP_LEFT;
if (v_align == 1)
m->d.alignment = MIDDLE_LEFT;
if (v_align == -1)
m->d.alignment = BOTTOM_LEFT;
}
if (h_align == 1) {
if (v_align == 0)
m->d.alignment = TOP_CENTER;
if (v_align == 1)
m->d.alignment = MIDDLE_CENTER;
if (v_align == -1)
m->d.alignment = BOTTOM_CENTER;
}
if (h_align == -1) {
if (v_align == 0)
m->d.alignment = TOP_RIGHT;
if (v_align == 1)
m->d.alignment = MIDDLE_RIGHT;
if (v_align == -1)
m->d.alignment = BOTTOM_RIGHT;
}
// Background Color
m->d.back_color = bytestream_get_be24(&tx3g_ptr);
m->d.back_color = RGB_TO_BGR(m->d.back_color);
m->d.back_alpha = bytestream_get_byte(&tx3g_ptr);
// BoxRecord
tx3g_ptr += 8;
// StyleRecord
tx3g_ptr += 4;
mov_text_parse_style_record(&m->d.style, &tx3g_ptr);
// FontRecord
// FontRecord Size
tx3g_ptr += 4;
// ftab
tx3g_ptr += 4;
// In case of broken header, init default font
m->d.font = ASS_DEFAULT_FONT;
ftab_entries = bytestream_get_be16(&tx3g_ptr);
if (!ftab_entries)
return 0;
remaining -= 3 * ftab_entries;
if (remaining < 0)
return AVERROR_INVALIDDATA;
m->ftab = av_calloc(ftab_entries, sizeof(*m->ftab));
if (!m->ftab)
return AVERROR(ENOMEM);
m->ftab_entries = ftab_entries;
for (i = 0; i < m->ftab_entries; i++) {
m->ftab[i].font_id = bytestream_get_be16(&tx3g_ptr);
if (m->ftab[i].font_id == m->d.style.font_id)
j = i;
font_length = bytestream_get_byte(&tx3g_ptr);
remaining -= font_length;
if (remaining < 0) {
mov_text_cleanup_ftab(m);
return -1;
}
m->ftab[i].font = av_malloc(font_length + 1);
if (!m->ftab[i].font) {
mov_text_cleanup_ftab(m);
return AVERROR(ENOMEM);
}
bytestream_get_buffer(&tx3g_ptr, m->ftab[i].font, font_length);
m->ftab[i].font[font_length] = '\0';
}
if (j >= 0)
m->d.font = m->ftab[j].font;
return 0;
}
static int decode_twrp(const uint8_t *tsmb, MovTextContext *m, uint64_t size)
{
m->box_flags |= TWRP_BOX;
m->w.wrap_flag = bytestream_get_byte(&tsmb);
return 0;
}
static int decode_hlit(const uint8_t *tsmb, MovTextContext *m, uint64_t size)
{
m->box_flags |= HLIT_BOX;
m->h.hlit_start = bytestream_get_be16(&tsmb);
m->h.hlit_end = bytestream_get_be16(&tsmb);
return 0;
}
static int decode_hclr(const uint8_t *tsmb, MovTextContext *m, uint64_t size)
{
m->box_flags |= HCLR_BOX;
bytestream_get_buffer(&tsmb, m->c.hlit_color, 4);
return 0;
}
static int styles_equivalent(const StyleBox *a, const StyleBox *b)
{
#define CMP(field) ((a)->field == (b)->field)
return CMP(bold) && CMP(italic) && CMP(underline) && CMP(color) &&
CMP(alpha) && CMP(fontsize) && CMP(font_id);
#undef CMP
}
static int decode_styl(const uint8_t *tsmb, MovTextContext *m, uint64_t size)
{
int i;
int style_entries = bytestream_get_be16(&tsmb);
StyleBox *tmp;
// A single style record is of length 12 bytes.
if (2 + style_entries * 12 > size)
return -1;
tmp = av_realloc_array(m->s, style_entries, sizeof(*m->s));
if (!tmp)
return AVERROR(ENOMEM);
m->s = tmp;
m->style_entries = style_entries;
m->box_flags |= STYL_BOX;
for(i = 0; i < m->style_entries; i++) {
StyleBox *style = &m->s[i];
style->start = bytestream_get_be16(&tsmb);
style->end = bytestream_get_be16(&tsmb);
if (style->end < style->start ||
(i && style->start < m->s[i - 1].end)) {
mov_text_cleanup(m);
return AVERROR_INVALIDDATA;
}
if (style->start == style->end) {
/* Skip this style as it applies to no character */
tsmb += 8;
m->style_entries--;
i--;
continue;
}
mov_text_parse_style_record(style, &tsmb);
if (styles_equivalent(style, &m->d.style)) {
/* Skip this style as it is equivalent to the default style */
m->style_entries--;
i--;
continue;
} else if (i && style->start == style[-1].end &&
styles_equivalent(style, &style[-1])) {
/* Merge the two adjacent styles */
style[-1].end = style->end;
m->style_entries--;
i--;
continue;
}
}
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 },
{ MKBETAG('t','w','r','p'), 1, decode_twrp }
};
const static size_t box_count = FF_ARRAY_ELEMS(box_types);
// Return byte length of the UTF-8 sequence starting at text[0]. 0 on error.
static int get_utf8_length_at(const char *text, const char *text_end)
{
const char *start = text;
int err = 0;
uint32_t c;
GET_UTF8(c, text < text_end ? (uint8_t)*text++ : (err = 1, 0), goto error;);
if (err)
goto error;
return text - start;
error:
return 0;
}
static int text_to_ass(AVBPrint *buf, const char *text, const char *text_end,
AVCodecContext *avctx)
{
MovTextContext *m = avctx->priv_data;
const StyleBox *const default_style = &m->d.style;
int i = 0;
int text_pos = 0;
int entry = 0;
int color = default_style->color;
if (text < text_end && m->box_flags & TWRP_BOX) {
if (m->w.wrap_flag == 1) {
av_bprintf(buf, "{\\q1}"); /* End of line wrap */
} else {
av_bprintf(buf, "{\\q2}"); /* No wrap */
}
}
while (text < text_end) {
int len;
if ((m->box_flags & STYL_BOX) && entry < m->style_entries) {
const StyleBox *style = &m->s[entry];
if (text_pos == style->end) {
av_bprintf(buf, "{\\r}");
color = default_style->color;
entry++;
style++;
}
if (entry < m->style_entries && text_pos == style->start) {
if (style->bold ^ default_style->bold)
av_bprintf(buf, "{\\b%d}", style->bold);
if (style->italic ^ default_style->italic)
av_bprintf(buf, "{\\i%d}", style->italic);
if (style->underline ^ default_style->underline)
av_bprintf(buf, "{\\u%d}", style->underline);
if (style->fontsize != default_style->fontsize)
av_bprintf(buf, "{\\fs%d}", style->fontsize);
if (style->font_id != default_style->font_id)
for (i = 0; i < m->ftab_entries; i++) {
if (style->font_id == m->ftab[i].font_id)
av_bprintf(buf, "{\\fn%s}", m->ftab[i].font);
}
if (default_style->color != style->color) {
color = style->color;
av_bprintf(buf, "{\\1c&H%X&}", color);
}
if (default_style->alpha != style->alpha)
av_bprintf(buf, "{\\1a&H%02X&}", 255 - style->alpha);
}
}
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&H%X&}", default_style->color);
} else {
av_bprintf(buf, "{\\1c&H%X&}{\\2c&H%X&}",
color, default_style->color);
}
}
}
len = get_utf8_length_at(text, text_end);
if (len < 1) {
av_log(avctx, AV_LOG_ERROR, "invalid UTF-8 byte in subtitle\n");
len = 1;
}
switch (*text) {
case '\r':
break;
case '\n':
av_bprintf(buf, "\\N");
break;
default:
av_bprint_append_data(buf, text, len);
break;
}
text += len;
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.
*/
int ret;
MovTextContext *m = avctx->priv_data;
ret = mov_text_tx3g(avctx, m);
if (ret == 0) {
const StyleBox *const default_style = &m->d.style;
if (!m->frame_width || !m->frame_height) {
m->frame_width = ASS_DEFAULT_PLAYRESX;
m->frame_height = ASS_DEFAULT_PLAYRESY;
}
return ff_ass_subtitle_header_full(avctx,
m->frame_width, m->frame_height,
m->d.font, default_style->fontsize,
(255U - default_style->alpha) << 24 | default_style->color,
(255U - default_style->alpha) << 24 | default_style->color,
(255U - m->d.back_alpha) << 24 | m->d.back_color,
(255U - m->d.back_alpha) << 24 | m->d.back_color,
default_style->bold, default_style->italic, default_style->underline,
ASS_DEFAULT_BORDERSTYLE, m->d.alignment);
} else
return ff_ass_subtitle_header_default(avctx);
}
static int mov_text_decode_frame(AVCodecContext *avctx, AVSubtitle *sub,
int *got_sub_ptr, const AVPacket *avpkt)
{
MovTextContext *m = avctx->priv_data;
int ret;
AVBPrint buf;
const char *ptr = avpkt->data, *end;
int text_length;
size_t i;
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;
mov_text_cleanup(m);
m->style_entries = 0;
m->box_flags = 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) {
const uint8_t *tsmb = end;
const uint8_t *const tsmb_end = avpkt->data + avpkt->size;
// A box is a minimum of 8 bytes.
while (tsmb_end - tsmb >= 8) {
uint64_t tsmb_size = bytestream_get_be32(&tsmb);
uint32_t tsmb_type = bytestream_get_be32(&tsmb);
int size_var, ret_tsmb;
if (tsmb_size == 1) {
if (tsmb_end - tsmb < 8)
break;
tsmb_size = bytestream_get_be64(&tsmb);
size_var = 16;
} else
size_var = 8;
//size_var is equal to 8 or 16 depending on the size of box
if (tsmb_size < size_var) {
av_log(avctx, AV_LOG_ERROR, "tsmb_size invalid\n");
return AVERROR_INVALIDDATA;
}
tsmb_size -= size_var;
if (tsmb_end - tsmb < tsmb_size)
break;
for (i = 0; i < box_count; i++) {
if (tsmb_type == box_types[i].type) {
if (tsmb_size < box_types[i].base_size)
break;
ret_tsmb = box_types[i].decode(tsmb, m, tsmb_size);
if (ret_tsmb == -1)
break;
}
}
tsmb += tsmb_size;
}
text_to_ass(&buf, ptr, end, avctx);
mov_text_cleanup(m);
} else
text_to_ass(&buf, ptr, end, avctx);
ret = ff_ass_add_rect(sub, buf.str, m->readorder++, 0, NULL, NULL);
av_bprint_finalize(&buf, NULL);
if (ret < 0)
return ret;
*got_sub_ptr = sub->num_rects > 0;
return avpkt->size;
}
static int mov_text_decode_close(AVCodecContext *avctx)
{
MovTextContext *m = avctx->priv_data;
mov_text_cleanup_ftab(m);
mov_text_cleanup(m);
return 0;
}
static void mov_text_flush(AVCodecContext *avctx)
{
MovTextContext *m = avctx->priv_data;
if (!(avctx->flags2 & AV_CODEC_FLAG2_RO_FLUSH_NOOP))
m->readorder = 0;
}
#define OFFSET(x) offsetof(MovTextContext, x)
#define FLAGS AV_OPT_FLAG_DECODING_PARAM | AV_OPT_FLAG_SUBTITLE_PARAM
static const AVOption options[] = {
{ "width", "Frame width, usually video width", OFFSET(frame_width), AV_OPT_TYPE_INT, {.i64=0}, 0, INT_MAX, FLAGS },
{ "height", "Frame height, usually video height", OFFSET(frame_height), AV_OPT_TYPE_INT, {.i64=0}, 0, INT_MAX, FLAGS },
{ NULL },
};
static const AVClass mov_text_decoder_class = {
.class_name = "MOV text decoder",
.option = options,
.version = LIBAVUTIL_VERSION_INT,
};
const FFCodec ff_movtext_decoder = {
.p.name = "mov_text",
CODEC_LONG_NAME("3GPP Timed Text subtitle"),
.p.type = AVMEDIA_TYPE_SUBTITLE,
.p.id = AV_CODEC_ID_MOV_TEXT,
.priv_data_size = sizeof(MovTextContext),
.p.priv_class = &mov_text_decoder_class,
.init = mov_text_init,
FF_CODEC_DECODE_SUB_CB(mov_text_decode_frame),
.close = mov_text_decode_close,
.flush = mov_text_flush,
};