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FFmpeg/libavcodec/movtextdec.c
Andreas Rheinhardt 20f9727018 avcodec/codec_internal: Add FFCodec, hide internal part of AVCodec 
Up until now, codec.h contains both public and private parts
of AVCodec. This exposes the internals of AVCodec to users
and leads them into the temptation of actually using them
and forces us to forward-declare structures and types that
users can't use at all.

This commit changes this by adding a new structure FFCodec to
codec_internal.h that extends AVCodec, i.e. contains the public
AVCodec as first member; the private fields of AVCodec are moved
to this structure, leaving codec.h clean.

Reviewed-by: Anton Khirnov <anton@khirnov.net>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
2022-03-21 01:33:09 +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"
#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,
void *data, int *got_sub_ptr, AVPacket *avpkt)
{
AVSubtitle *sub = data;
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",
.item_name = av_default_item_name,
.option = options,
.version = LIBAVUTIL_VERSION_INT,
};
const FFCodec ff_movtext_decoder = {
.p.name = "mov_text",
.p.long_name = NULL_IF_CONFIG_SMALL("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,
.decode = mov_text_decode_frame,
.close = mov_text_decode_close,
.flush = mov_text_flush,
.caps_internal = FF_CODEC_CAP_INIT_THREADSAFE,
};
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