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FFmpeg/libavcodec/movtextenc.c
Andreas Rheinhardt acdfc4bdfb avcodec/movtextenc: Simplify writing a single char 
Reviewed-by: Philip Langdale <philipl@overt.org>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
2021-12-02 07:31:43 +01:00

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/*
* 3GPP TS 26.245 Timed Text encoder
* 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 <stdarg.h>
#include "avcodec.h"
#include "libavutil/opt.h"
#include "libavutil/avstring.h"
#include "libavutil/intreadwrite.h"
#include "libavutil/mem.h"
#include "libavutil/common.h"
#include "ass_split.h"
#include "ass.h"
#include "bytestream.h"
#include "internal.h"
#define STYLE_FLAG_BOLD (1<<0)
#define STYLE_FLAG_ITALIC (1<<1)
#define STYLE_FLAG_UNDERLINE (1<<2)
#define STYLE_RECORD_SIZE 12
#define SIZE_ADD 10
#define STYL_BOX (1<<0)
#define HLIT_BOX (1<<1)
#define HCLR_BOX (1<<2)
#define DEFAULT_STYLE_FONT_ID 0x01
#define DEFAULT_STYLE_FONTSIZE 0x12
#define DEFAULT_STYLE_COLOR 0xffffffff
#define DEFAULT_STYLE_FLAG 0x00
#define BGR_TO_RGB(c) (((c) & 0xff) << 16 | ((c) & 0xff00) | (((uint32_t)(c) >> 16) & 0xff))
#define FONTSIZE_SCALE(s,fs) ((fs) * (s)->font_scale_factor + 0.5)
#define av_bprint_append_any(buf, data, size) av_bprint_append_data(buf, ((const char*)data), size)
typedef struct {
uint16_t style_start;
uint16_t style_end;
uint8_t style_flag;
uint16_t style_fontID;
uint8_t style_fontsize;
uint32_t style_color;
} StyleBox;
typedef struct {
uint16_t start;
uint16_t end;
} HighlightBox;
typedef struct {
uint32_t color;
} HilightcolorBox;
typedef struct {
AVClass *class;
AVCodecContext *avctx;
ASSSplitContext *ass_ctx;
ASSStyle *ass_dialog_style;
StyleBox *style_attributes;
unsigned count;
unsigned style_attributes_bytes_allocated;
StyleBox style_attributes_temp;
AVBPrint buffer;
HighlightBox hlit;
HilightcolorBox hclr;
uint8_t box_flags;
StyleBox d;
uint16_t text_pos;
char **fonts;
int font_count;
double font_scale_factor;
int frame_height;
} MovTextContext;
typedef struct {
void (*encode)(MovTextContext *s);
} Box;
static void mov_text_cleanup(MovTextContext *s)
{
s->count = 0;
s->style_attributes_temp = s->d;
}
static void encode_styl(MovTextContext *s)
{
if ((s->box_flags & STYL_BOX) && s->count) {
uint8_t buf[12], *p = buf;
bytestream_put_be32(&p, s->count * STYLE_RECORD_SIZE + SIZE_ADD);
bytestream_put_be32(&p, MKBETAG('s','t','y','l'));
bytestream_put_be16(&p, s->count);
/*The above three attributes are hard coded for now
but will come from ASS style in the future*/
av_bprint_append_any(&s->buffer, buf, 10);
for (unsigned j = 0; j < s->count; j++) {
const StyleBox *style = &s->style_attributes[j];
p = buf;
bytestream_put_be16(&p, style->style_start);
bytestream_put_be16(&p, style->style_end);
bytestream_put_be16(&p, style->style_fontID);
bytestream_put_byte(&p, style->style_flag);
bytestream_put_byte(&p, style->style_fontsize);
bytestream_put_be32(&p, style->style_color);
av_bprint_append_any(&s->buffer, buf, 12);
}
}
mov_text_cleanup(s);
}
static void encode_hlit(MovTextContext *s)
{
if (s->box_flags & HLIT_BOX) {
uint8_t buf[12], *p = buf;
bytestream_put_be32(&p, 12);
bytestream_put_be32(&p, MKBETAG('h','l','i','t'));
bytestream_put_be16(&p, s->hlit.start);
bytestream_put_be16(&p, s->hlit.end);
av_bprint_append_any(&s->buffer, buf, 12);
}
}
static void encode_hclr(MovTextContext *s)
{
if (s->box_flags & HCLR_BOX) {
uint8_t buf[12], *p = buf;
bytestream_put_be32(&p, 12);
bytestream_put_be32(&p, MKBETAG('h','c','l','r'));
bytestream_put_be32(&p, s->hclr.color);
av_bprint_append_any(&s->buffer, buf, 12);
}
}
static const Box box_types[] = {
{ encode_styl },
{ encode_hlit },
{ encode_hclr },
};
const static size_t box_count = FF_ARRAY_ELEMS(box_types);
static int mov_text_encode_close(AVCodecContext *avctx)
{
MovTextContext *s = avctx->priv_data;
ff_ass_split_free(s->ass_ctx);
av_freep(&s->style_attributes);
av_freep(&s->fonts);
av_bprint_finalize(&s->buffer, NULL);
return 0;
}
static int encode_sample_description(AVCodecContext *avctx)
{
ASS *ass;
ASSStyle *style;
int i, j;
uint32_t back_color = 0;
int font_names_total_len = 0;
MovTextContext *s = avctx->priv_data;
uint8_t buf[30], *p = buf;
// 0x00, 0x00, 0x00, 0x00, // uint32_t displayFlags
// 0x01, // int8_t horizontal-justification
// 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
// };
// StyleRecord {
// 0x00, 0x00, // uint16_t startChar
// 0x00, 0x00, // uint16_t endChar
// 0x00, 0x01, // uint16_t font-ID
// 0x00, // uint8_t face-style-flags
// 0x12, // uint8_t font-size
// 0xFF, 0xFF, 0xFF, 0xFF, // uint8_t text-color-rgba[4]
// };
// FontTableBox {
// 0x00, 0x00, 0x00, 0x12, // uint32_t size
// 'f', 't', 'a', 'b', // uint8_t name[4]
// 0x00, 0x01, // uint16_t entry-count
// FontRecord {
// 0x00, 0x01, // uint16_t font-ID
// 0x05, // uint8_t font-name-length
// 'S', 'e', 'r', 'i', 'f',// uint8_t font[font-name-length]
// };
// };
// Populate sample description from ASS header
ass = (ASS*)s->ass_ctx;
// Compute font scaling factor based on (optionally) provided
// output video height and ASS script play_res_y
if (s->frame_height && ass->script_info.play_res_y)
s->font_scale_factor = (double)s->frame_height / ass->script_info.play_res_y;
else
s->font_scale_factor = 1;
style = ff_ass_style_get(s->ass_ctx, "Default");
if (!style && ass->styles_count) {
style = &ass->styles[0];
}
s->d.style_fontID = DEFAULT_STYLE_FONT_ID;
s->d.style_fontsize = DEFAULT_STYLE_FONTSIZE;
s->d.style_color = DEFAULT_STYLE_COLOR;
s->d.style_flag = DEFAULT_STYLE_FLAG;
if (style) {
s->d.style_fontsize = FONTSIZE_SCALE(s, style->font_size);
s->d.style_color = BGR_TO_RGB(style->primary_color & 0xffffff) << 8 |
255 - ((uint32_t)style->primary_color >> 24);
s->d.style_flag = (!!style->bold * STYLE_FLAG_BOLD) |
(!!style->italic * STYLE_FLAG_ITALIC) |
(!!style->underline * STYLE_FLAG_UNDERLINE);
back_color = (BGR_TO_RGB(style->back_color & 0xffffff) << 8) |
(255 - ((uint32_t)style->back_color >> 24));
}
bytestream_put_be32(&p, 0); // displayFlags
bytestream_put_be16(&p, 0x01FF); // horizontal/vertical justification (2x int8_t)
bytestream_put_be32(&p, back_color);
bytestream_put_be64(&p, 0); // BoxRecord - 4xint16_t: top, left, bottom, right
// StyleRecord {
bytestream_put_be16(&p, s->d.style_start);
bytestream_put_be16(&p, s->d.style_end);
bytestream_put_be16(&p, s->d.style_fontID);
bytestream_put_byte(&p, s->d.style_flag);
bytestream_put_byte(&p, s->d.style_fontsize);
bytestream_put_be32(&p, s->d.style_color);
// };
av_bprint_append_any(&s->buffer, buf, 30);
// Build font table
// We can't build a complete font table since that would require
// scanning all dialogs first. But we can at least fill in what
// is avaiable in the ASS header
if (style && ass->styles_count) {
// Find unique font names
if (style->font_name) {
av_dynarray_add(&s->fonts, &s->font_count, style->font_name);
font_names_total_len += strlen(style->font_name);
}
for (i = 0; i < ass->styles_count; i++) {
int found = 0;
if (!ass->styles[i].font_name)
continue;
for (j = 0; j < s->font_count; j++) {
if (!strcmp(s->fonts[j], ass->styles[i].font_name)) {
found = 1;
break;
}
}
if (!found) {
av_dynarray_add(&s->fonts, &s->font_count,
ass->styles[i].font_name);
font_names_total_len += strlen(ass->styles[i].font_name);
}
}
} else
av_dynarray_add(&s->fonts, &s->font_count, (char*)"Serif");
// FontTableBox {
p = buf;
bytestream_put_be32(&p, SIZE_ADD + 3 * s->font_count + font_names_total_len); // Size
bytestream_put_be32(&p, MKBETAG('f','t','a','b'));
bytestream_put_be16(&p, s->font_count);
av_bprint_append_any(&s->buffer, buf, 10);
// FontRecord {
for (i = 0; i < s->font_count; i++) {
size_t len = strlen(s->fonts[i]);
p = buf;
bytestream_put_be16(&p, i + 1); //fontID
bytestream_put_byte(&p, len);
av_bprint_append_any(&s->buffer, buf, 3);
av_bprint_append_any(&s->buffer, s->fonts[i], len);
}
// };
// };
if (!av_bprint_is_complete(&s->buffer)) {
return AVERROR(ENOMEM);
}
avctx->extradata_size = s->buffer.len;
avctx->extradata = av_mallocz(avctx->extradata_size + AV_INPUT_BUFFER_PADDING_SIZE);
if (!avctx->extradata) {
return AVERROR(ENOMEM);
}
memcpy(avctx->extradata, s->buffer.str, avctx->extradata_size);
av_bprint_clear(&s->buffer);
return 0;
}
static av_cold int mov_text_encode_init(AVCodecContext *avctx)
{
int ret;
MovTextContext *s = avctx->priv_data;
s->avctx = avctx;
av_bprint_init(&s->buffer, 0, AV_BPRINT_SIZE_UNLIMITED);
s->ass_ctx = ff_ass_split(avctx->subtitle_header);
if (!s->ass_ctx)
return AVERROR_INVALIDDATA;
ret = encode_sample_description(avctx);
if (ret < 0)
return ret;
return 0;
}
// Start a new style box if needed
static int mov_text_style_start(MovTextContext *s)
{
// there's an existing style entry
if (s->style_attributes_temp.style_start == s->text_pos)
// Still at same text pos, use same entry
return 1;
if (s->style_attributes_temp.style_flag != s->d.style_flag ||
s->style_attributes_temp.style_color != s->d.style_color ||
s->style_attributes_temp.style_fontID != s->d.style_fontID ||
s->style_attributes_temp.style_fontsize != s->d.style_fontsize) {
StyleBox *tmp;
// last style != defaults, end the style entry and start a new one
if (s->count + 1 > FFMIN(SIZE_MAX / sizeof(*s->style_attributes), UINT16_MAX) ||
!(tmp = av_fast_realloc(s->style_attributes,
&s->style_attributes_bytes_allocated,
(s->count + 1) * sizeof(*s->style_attributes)))) {
mov_text_cleanup(s);
av_bprint_clear(&s->buffer);
s->box_flags &= ~STYL_BOX;
return 0;
}
s->style_attributes = tmp;
s->style_attributes_temp.style_end = s->text_pos;
s->style_attributes[s->count++] = s->style_attributes_temp;
s->box_flags |= STYL_BOX;
s->style_attributes_temp = s->d;
s->style_attributes_temp.style_start = s->text_pos;
} else { // style entry matches defaults, drop entry
s->style_attributes_temp = s->d;
s->style_attributes_temp.style_start = s->text_pos;
}
return 1;
}
static uint8_t mov_text_style_to_flag(const char style)
{
uint8_t style_flag = 0;
switch (style){
case 'b':
style_flag = STYLE_FLAG_BOLD;
break;
case 'i':
style_flag = STYLE_FLAG_ITALIC;
break;
case 'u':
style_flag = STYLE_FLAG_UNDERLINE;
break;
}
return style_flag;
}
static void mov_text_style_set(MovTextContext *s, uint8_t style_flags)
{
if (!((s->style_attributes_temp.style_flag & style_flags) ^ style_flags)) {
// setting flags that that are already set
return;
}
if (mov_text_style_start(s))
s->style_attributes_temp.style_flag |= style_flags;
}
static void mov_text_style_cb(void *priv, const char style, int close)
{
MovTextContext *s = priv;
uint8_t style_flag = mov_text_style_to_flag(style);
if (!!(s->style_attributes_temp.style_flag & style_flag) != close) {
// setting flag that is already set
return;
}
if (mov_text_style_start(s)) {
if (!close)
s->style_attributes_temp.style_flag |= style_flag;
else
s->style_attributes_temp.style_flag &= ~style_flag;
}
}
static void mov_text_color_set(MovTextContext *s, uint32_t color)
{
if ((s->style_attributes_temp.style_color & 0xffffff00) == color) {
// color hasn't changed
return;
}
if (mov_text_style_start(s))
s->style_attributes_temp.style_color = (color & 0xffffff00) |
(s->style_attributes_temp.style_color & 0xff);
}
static void mov_text_color_cb(void *priv, unsigned int color, unsigned int color_id)
{
MovTextContext *s = priv;
color = BGR_TO_RGB(color) << 8;
if (color_id == 1) { //primary color changes
mov_text_color_set(s, color);
} else if (color_id == 2) { //secondary color changes
if (!(s->box_flags & HCLR_BOX))
// Highlight alpha not set yet, use current primary alpha
s->hclr.color = s->style_attributes_temp.style_color;
if (!(s->box_flags & HLIT_BOX) || s->hlit.start == s->text_pos) {
s->box_flags |= HCLR_BOX;
s->box_flags |= HLIT_BOX;
s->hlit.start = s->text_pos;
s->hclr.color = color | (s->hclr.color & 0xFF);
}
else //close tag
s->hlit.end = s->text_pos;
/* If there are more than one secondary color changes in ASS,
take start of first section and end of last section. Movtext
allows only one highlight box per sample.
*/
}
// Movtext does not support changes to other color_id (outline, background)
}
static void mov_text_alpha_set(MovTextContext *s, uint8_t alpha)
{
if ((s->style_attributes_temp.style_color & 0xff) == alpha) {
// color hasn't changed
return;
}
if (mov_text_style_start(s))
s->style_attributes_temp.style_color =
(s->style_attributes_temp.style_color & 0xffffff00) | alpha;
}
static void mov_text_alpha_cb(void *priv, int alpha, int alpha_id)
{
MovTextContext *s = priv;
alpha = 255 - alpha;
if (alpha_id == 1) // primary alpha changes
mov_text_alpha_set(s, alpha);
else if (alpha_id == 2) { //secondary alpha changes
if (!(s->box_flags & HCLR_BOX))
// Highlight color not set yet, use current primary color
s->hclr.color = s->style_attributes_temp.style_color;
if (!(s->box_flags & HLIT_BOX) || s->hlit.start == s->text_pos) {
s->box_flags |= HCLR_BOX;
s->box_flags |= HLIT_BOX;
s->hlit.start = s->text_pos;
s->hclr.color = (s->hclr.color & 0xffffff00) | alpha;
}
else //close tag
s->hlit.end = s->text_pos;
}
// Movtext does not support changes to other alpha_id (outline, background)
}
static uint16_t find_font_id(MovTextContext *s, const char *name)
{
int i;
for (i = 0; i < s->font_count; i++) {
if (!strcmp(name, s->fonts[i]))
return i + 1;
}
return 1;
}
static void mov_text_font_name_set(MovTextContext *s, const char *name)
{
int fontID = find_font_id(s, name);
if (s->style_attributes_temp.style_fontID == fontID) {
// color hasn't changed
return;
}
if (mov_text_style_start(s))
s->style_attributes_temp.style_fontID = fontID;
}
static void mov_text_font_name_cb(void *priv, const char *name)
{
mov_text_font_name_set((MovTextContext*)priv, name);
}
static void mov_text_font_size_set(MovTextContext *s, int size)
{
size = FONTSIZE_SCALE(s, size);
if (s->style_attributes_temp.style_fontsize == size) {
// color hasn't changed
return;
}
if (mov_text_style_start(s))
s->style_attributes_temp.style_fontsize = size;
}
static void mov_text_font_size_cb(void *priv, int size)
{
mov_text_font_size_set((MovTextContext*)priv, size);
}
static void mov_text_end_cb(void *priv)
{
// End of text, close any open style record
mov_text_style_start((MovTextContext*)priv);
}
static void mov_text_ass_style_set(MovTextContext *s, ASSStyle *style)
{
uint8_t style_flags, alpha;
uint32_t color;
if (style) {
style_flags = (!!style->bold * STYLE_FLAG_BOLD) |
(!!style->italic * STYLE_FLAG_ITALIC) |
(!!style->underline * STYLE_FLAG_UNDERLINE);
mov_text_style_set(s, style_flags);
color = BGR_TO_RGB(style->primary_color & 0xffffff) << 8;
mov_text_color_set(s, color);
alpha = 255 - ((uint32_t)style->primary_color >> 24);
mov_text_alpha_set(s, alpha);
mov_text_font_size_set(s, style->font_size);
mov_text_font_name_set(s, style->font_name);
} else {
// End current style record, go back to defaults
mov_text_style_start(s);
}
}
static void mov_text_dialog(MovTextContext *s, ASSDialog *dialog)
{
ASSStyle *style = ff_ass_style_get(s->ass_ctx, dialog->style);
s->ass_dialog_style = style;
mov_text_ass_style_set(s, style);
}
static void mov_text_cancel_overrides_cb(void *priv, const char *style_name)
{
MovTextContext *s = priv;
ASSStyle *style;
if (!style_name || !*style_name)
style = s->ass_dialog_style;
else
style= ff_ass_style_get(s->ass_ctx, style_name);
mov_text_ass_style_set(s, style);
}
static unsigned utf8_strlen(const char *text, int len)
{
unsigned i = 0, ret = 0;
while (i < len) {
char c = text[i];
if ((c & 0x80) == 0)
i += 1;
else if ((c & 0xE0) == 0xC0)
i += 2;
else if ((c & 0xF0) == 0xE0)
i += 3;
else if ((c & 0xF8) == 0xF0)
i += 4;
else
return 0;
ret++;
}
return ret;
}
static void mov_text_text_cb(void *priv, const char *text, int len)
{
unsigned utf8_len = utf8_strlen(text, len);
MovTextContext *s = priv;
av_bprint_append_data(&s->buffer, text, len);
// If it's not utf-8, just use the byte length
s->text_pos += utf8_len ? utf8_len : len;
}
static void mov_text_new_line_cb(void *priv, int forced)
{
MovTextContext *s = priv;
s->text_pos += 1;
av_bprint_chars(&s->buffer, '\n', 1);
}
static const ASSCodesCallbacks mov_text_callbacks = {
.text = mov_text_text_cb,
.new_line = mov_text_new_line_cb,
.style = mov_text_style_cb,
.color = mov_text_color_cb,
.alpha = mov_text_alpha_cb,
.font_name = mov_text_font_name_cb,
.font_size = mov_text_font_size_cb,
.cancel_overrides = mov_text_cancel_overrides_cb,
.end = mov_text_end_cb,
};
static int mov_text_encode_frame(AVCodecContext *avctx, unsigned char *buf,
int bufsize, const AVSubtitle *sub)
{
MovTextContext *s = avctx->priv_data;
ASSDialog *dialog;
int i, length;
s->text_pos = 0;
s->count = 0;
s->box_flags = 0;
av_bprint_clear(&s->buffer);
for (i = 0; i < sub->num_rects; i++) {
const char *ass = sub->rects[i]->ass;
if (sub->rects[i]->type != SUBTITLE_ASS) {
av_log(avctx, AV_LOG_ERROR, "Only SUBTITLE_ASS type supported.\n");
return AVERROR(EINVAL);
}
dialog = ff_ass_split_dialog(s->ass_ctx, ass);
if (!dialog)
return AVERROR(ENOMEM);
mov_text_dialog(s, dialog);
ff_ass_split_override_codes(&mov_text_callbacks, s, dialog->text);
ff_ass_free_dialog(&dialog);
}
if (s->buffer.len > UINT16_MAX)
return AVERROR(ERANGE);
AV_WB16(buf, s->buffer.len);
buf += 2;
for (size_t j = 0; j < box_count; j++)
box_types[j].encode(s);
if (!av_bprint_is_complete(&s->buffer))
return AVERROR(ENOMEM);
if (!s->buffer.len)
return 0;
if (s->buffer.len > bufsize - 3) {
av_log(avctx, AV_LOG_ERROR, "Buffer too small for ASS event.\n");
return AVERROR_BUFFER_TOO_SMALL;
}
memcpy(buf, s->buffer.str, s->buffer.len);
length = s->buffer.len + 2;
return length;
}
#define OFFSET(x) offsetof(MovTextContext, x)
#define FLAGS AV_OPT_FLAG_ENCODING_PARAM | AV_OPT_FLAG_SUBTITLE_PARAM
static const AVOption options[] = {
{ "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_encoder_class = {
.class_name = "MOV text enoder",
.item_name = av_default_item_name,
.option = options,
.version = LIBAVUTIL_VERSION_INT,
};
const AVCodec ff_movtext_encoder = {
.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_encoder_class,
.init = mov_text_encode_init,
.encode_sub = mov_text_encode_frame,
.close = mov_text_encode_close,
.caps_internal = FF_CODEC_CAP_INIT_THREADSAFE | FF_CODEC_CAP_INIT_CLEANUP,
};
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