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FFmpeg/libavcodec/movtextdec.c
Andreas Rheinhardt 74bffc00c5 avcodec: Constify some AVPackets 
Reviewed-by: James Almer <jamrial@gmail.com>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
2021-03-09 13:41:22 +01:00

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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"
#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 fontID;
const char *font;
uint8_t fontsize;
int color;
uint8_t alpha;
int back_color;
uint8_t back_alpha;
uint8_t bold;
uint8_t italic;
uint8_t underline;
int alignment;
} MovTextDefault;
typedef struct {
uint16_t fontID;
char *font;
} FontRecord;
typedef struct {
uint16_t style_start;
uint16_t style_end;
uint8_t style_flag;
uint8_t bold;
uint8_t italic;
uint8_t underline;
int color;
uint8_t alpha;
uint8_t fontsize;
uint16_t style_fontID;
} StyleBox;
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;
uint64_t tracksize;
int size_var;
int readorder;
int frame_width;
int frame_height;
} MovTextContext;
typedef struct {
uint32_t type;
size_t base_size;
int (*decode)(const uint8_t *tsmb, MovTextContext *m, const AVPacket *avpkt);
} 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 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;
StyleBox s_default;
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_alpha = bytestream_get_byte(&tx3g_ptr);
// BoxRecord
tx3g_ptr += 8;
// StyleRecord
tx3g_ptr += 4;
// fontID
m->d.fontID = bytestream_get_be16(&tx3g_ptr);
// face-style-flags
s_default.style_flag = bytestream_get_byte(&tx3g_ptr);
m->d.bold = !!(s_default.style_flag & STYLE_FLAG_BOLD);
m->d.italic = !!(s_default.style_flag & STYLE_FLAG_ITALIC);
m->d.underline = !!(s_default.style_flag & STYLE_FLAG_UNDERLINE);
// fontsize
m->d.fontsize = bytestream_get_byte(&tx3g_ptr);
// Primary color
m->d.color = bytestream_get_be24(&tx3g_ptr);
m->d.alpha = bytestream_get_byte(&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].fontID = bytestream_get_be16(&tx3g_ptr);
if (m->ftab[i].fontID == m->d.fontID)
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, const AVPacket *avpkt)
{
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, const AVPacket *avpkt)
{
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, const AVPacket *avpkt)
{
m->box_flags |= HCLR_BOX;
bytestream_get_buffer(&tsmb, m->c.hlit_color, 4);
return 0;
}
static int decode_styl(const uint8_t *tsmb, MovTextContext *m, const AVPacket *avpkt)
{
int i;
int style_entries = bytestream_get_be16(&tsmb);
StyleBox *tmp;
// A single style record is of length 12 bytes.
if (m->tracksize + m->size_var + 2 + style_entries * 12 > avpkt->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->style_start = bytestream_get_be16(&tsmb);
style->style_end = bytestream_get_be16(&tsmb);
if ( style->style_end < style->style_start
|| (i && style->style_start < m->s[i - 1].style_end)) {
mov_text_cleanup(m);
return AVERROR(ENOMEM);
}
if (style->style_start == style->style_end) {
/* Skip this style as it applies to no character */
tsmb += 8;
m->style_entries--;
i--;
continue;
}
style->style_fontID = bytestream_get_be16(&tsmb);
style->style_flag = bytestream_get_byte(&tsmb);
style->bold = !!(style->style_flag & STYLE_FLAG_BOLD);
style->italic = !!(style->style_flag & STYLE_FLAG_ITALIC);
style->underline = !!(style->style_flag & STYLE_FLAG_UNDERLINE);
style->fontsize = bytestream_get_byte(&tsmb);
style->color = bytestream_get_be24(&tsmb);
style->alpha = bytestream_get_byte(&tsmb);
}
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;
int i = 0;
int text_pos = 0;
int entry = 0;
int color = m->d.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->style_end) {
av_bprintf(buf, "{\\r}");
color = m->d.color;
entry++;
style++;
}
if (entry < m->style_entries && text_pos == style->style_start) {
if (style->bold ^ m->d.bold)
av_bprintf(buf, "{\\b%d}", style->bold);
if (style->italic ^ m->d.italic)
av_bprintf(buf, "{\\i%d}", style->italic);
if (style->underline ^ m->d.underline)
av_bprintf(buf, "{\\u%d}", style->underline);
if (style->fontsize != m->d.fontsize)
av_bprintf(buf, "{\\fs%d}", style->fontsize);
if (style->style_fontID != m->d.fontID)
for (i = 0; i < m->ftab_entries; i++) {
if (style->style_fontID == m->ftab[i].fontID)
av_bprintf(buf, "{\\fn%s}", m->ftab[i].font);
}
if (m->d.color != style->color) {
color = style->color;
av_bprintf(buf, "{\\1c&H%X&}", RGB_TO_BGR(color));
}
if (m->d.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&}", RGB_TO_BGR(m->d.color));
} else {
av_bprintf(buf, "{\\1c&H%X&}{\\2c&H%X&}",
RGB_TO_BGR(color), RGB_TO_BGR(m->d.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) {
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, m->d.fontsize,
(255U - m->d.alpha) << 24 | RGB_TO_BGR(m->d.color),
(255U - m->d.alpha) << 24 | RGB_TO_BGR(m->d.color),
(255U - m->d.back_alpha) << 24 | RGB_TO_BGR(m->d.back_color),
(255U - m->d.back_alpha) << 24 | RGB_TO_BGR(m->d.back_color),
m->d.bold, m->d.italic, m->d.underline,
ASS_DEFAULT_BORDERSTYLE, m->d.alignment);
} else
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;
AVBPrint buf;
char *ptr = avpkt->data;
char *end;
int text_length, tsmb_type, ret_tsmb;
uint64_t tsmb_size;
const uint8_t *tsmb;
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);
tsmb_size = 0;
m->tracksize = 2 + text_length;
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) {
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 (tsmb_size == 0) {
av_log(avctx, AV_LOG_ERROR, "tsmb_size is 0\n");
return AVERROR_INVALIDDATA;
}
if (tsmb_size > avpkt->size - m->tracksize)
break;
for (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, 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",
.item_name = av_default_item_name,
.option = options,
.version = LIBAVUTIL_VERSION_INT,
};
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),
.priv_class = &mov_text_decoder_class,
.init = mov_text_init,
.decode = mov_text_decode_frame,
.close = mov_text_decode_close,
.flush = mov_text_flush,
};
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