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ffmpeg/libavcodec/srtenc.c

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/*
* SubRip subtitle encoder
* Copyright (c) 2010 Aurelien Jacobs <aurel@gnuage.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 "config_components.h"
#include <stdarg.h>
#include "avcodec.h"
#include "libavutil/bprint.h"
#include "ass_split.h"
#include "ass.h"
#include "codec_internal.h"
#define SRT_STACK_SIZE 64
typedef struct {
AVCodecContext *avctx;
ASSSplitContext *ass_ctx;
AVBPrint buffer;
char stack[SRT_STACK_SIZE];
int stack_ptr;
int alignment_applied;
} SRTContext;
static av_printf_format(2, 3) void srt_print(SRTContext *s, const char *str, ...)
{
va_list vargs;
va_start(vargs, str);
av_vbprintf(&s->buffer, str, vargs);
va_end(vargs);
}
static int srt_stack_push(SRTContext *s, const char c)
{
if (s->stack_ptr >= SRT_STACK_SIZE)
return -1;
s->stack[s->stack_ptr++] = c;
return 0;
}
static char srt_stack_pop(SRTContext *s)
{
if (s->stack_ptr <= 0)
return 0;
return s->stack[--s->stack_ptr];
}
static int srt_stack_find(SRTContext *s, const char c)
{
int i;
for (i = s->stack_ptr-1; i >= 0; i--)
if (s->stack[i] == c)
break;
return i;
}
static void srt_close_tag(SRTContext *s, char tag)
{
srt_print(s, "</%c%s>", tag, tag == 'f' ? "ont" : "");
}
static void srt_stack_push_pop(SRTContext *s, const char c, int close)
{
if (close) {
int i = c ? srt_stack_find(s, c) : 0;
if (i < 0)
return;
while (s->stack_ptr != i)
srt_close_tag(s, srt_stack_pop(s));
} else if (srt_stack_push(s, c) < 0)
av_log(s->avctx, AV_LOG_ERROR, "tag stack overflow\n");
}
static void srt_style_apply(SRTContext *s, const char *style)
{
ASSStyle *st = ff_ass_style_get(s->ass_ctx, style);
if (st) {
int c = st->primary_color & 0xFFFFFF;
if (st->font_name && strcmp(st->font_name, ASS_DEFAULT_FONT) ||
st->font_size != ASS_DEFAULT_FONT_SIZE ||
c != ASS_DEFAULT_COLOR) {
srt_print(s, "<font");
if (st->font_name && strcmp(st->font_name, ASS_DEFAULT_FONT))
srt_print(s, " face=\"%s\"", st->font_name);
if (st->font_size != ASS_DEFAULT_FONT_SIZE)
srt_print(s, " size=\"%d\"", st->font_size);
if (c != ASS_DEFAULT_COLOR)
srt_print(s, " color=\"#%06x\"",
(c & 0xFF0000) >> 16 | c & 0xFF00 | (c & 0xFF) << 16);
srt_print(s, ">");
srt_stack_push(s, 'f');
}
if (st->bold != ASS_DEFAULT_BOLD) {
srt_print(s, "<b>");
srt_stack_push(s, 'b');
}
if (st->italic != ASS_DEFAULT_ITALIC) {
srt_print(s, "<i>");
srt_stack_push(s, 'i');
}
if (st->underline != ASS_DEFAULT_UNDERLINE) {
srt_print(s, "<u>");
srt_stack_push(s, 'u');
}
if (st->alignment != ASS_DEFAULT_ALIGNMENT) {
srt_print(s, "{\\an%d}", st->alignment);
s->alignment_applied = 1;
}
}
}
static av_cold int srt_encode_init(AVCodecContext *avctx)
{
SRTContext *s = avctx->priv_data;
s->avctx = avctx;
s->ass_ctx = ff_ass_split(avctx->subtitle_header);
return s->ass_ctx ? 0 : AVERROR_INVALIDDATA;
}
static void srt_text_cb(void *priv, const char *text, int len)
{
SRTContext *s = priv;
av_bprint_append_data(&s->buffer, text, len);
}
static void srt_new_line_cb(void *priv, int forced)
{
srt_print(priv, "\r\n");
}
static void srt_style_cb(void *priv, char style, int close)
{
srt_stack_push_pop(priv, style, close);
if (!close)
srt_print(priv, "<%c>", style);
}
static void srt_color_cb(void *priv, unsigned int color, unsigned int color_id)
{
if (color_id > 1)
return;
srt_stack_push_pop(priv, 'f', color == 0xFFFFFFFF);
if (color != 0xFFFFFFFF)
srt_print(priv, "<font color=\"#%06x\">",
(color & 0xFF0000) >> 16 | color & 0xFF00 | (color & 0xFF) << 16);
}
static void srt_font_name_cb(void *priv, const char *name)
{
srt_stack_push_pop(priv, 'f', !name);
if (name)
srt_print(priv, "<font face=\"%s\">", name);
}
static void srt_font_size_cb(void *priv, int size)
{
srt_stack_push_pop(priv, 'f', size < 0);
if (size >= 0)
srt_print(priv, "<font size=\"%d\">", size);
}
static void srt_alignment_cb(void *priv, int alignment)
{
SRTContext *s = priv;
if (!s->alignment_applied && alignment >= 0) {
srt_print(s, "{\\an%d}", alignment);
s->alignment_applied = 1;
}
}
static void srt_cancel_overrides_cb(void *priv, const char *style)
{
srt_stack_push_pop(priv, 0, 1);
srt_style_apply(priv, style);
}
static void srt_move_cb(void *priv, int x1, int y1, int x2, int y2,
int t1, int t2)
{
// TODO: add a AV_PKT_DATA_SUBTITLE_POSITION side data when a new subtitles
// encoding API passing the AVPacket is available.
}
static void srt_end_cb(void *priv)
{
srt_stack_push_pop(priv, 0, 1);
}
static const ASSCodesCallbacks srt_callbacks = {
.text = srt_text_cb,
.new_line = srt_new_line_cb,
.style = srt_style_cb,
.color = srt_color_cb,
.font_name = srt_font_name_cb,
.font_size = srt_font_size_cb,
.alignment = srt_alignment_cb,
.cancel_overrides = srt_cancel_overrides_cb,
.move = srt_move_cb,
.end = srt_end_cb,
};
static const ASSCodesCallbacks text_callbacks = {
.text = srt_text_cb,
.new_line = srt_new_line_cb,
};
static int encode_frame(AVCodecContext *avctx,
unsigned char *buf, int bufsize, const AVSubtitle *sub,
const ASSCodesCallbacks *cb)
{
SRTContext *s = avctx->priv_data;
ASSDialog *dialog;
int i;
av_bprint_init_for_buffer(&s->buffer, buf, bufsize);
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);
s->alignment_applied = 0;
if (avctx->codec_id == AV_CODEC_ID_SUBRIP)
srt_style_apply(s, dialog->style);
ff_ass_split_override_codes(cb, s, dialog->text);
ff_ass_free_dialog(&dialog);
}
if (!s->buffer.len)
return 0;
if (!av_bprint_is_complete(&s->buffer)) {
av_log(avctx, AV_LOG_ERROR, "Buffer too small for ASS event.\n");
return AVERROR_BUFFER_TOO_SMALL;
}
return s->buffer.len;
}
static int srt_encode_frame(AVCodecContext *avctx,
unsigned char *buf, int bufsize, const AVSubtitle *sub)
{
return encode_frame(avctx, buf, bufsize, sub, &srt_callbacks);
}
static int text_encode_frame(AVCodecContext *avctx,
unsigned char *buf, int bufsize, const AVSubtitle *sub)
{
return encode_frame(avctx, buf, bufsize, sub, &text_callbacks);
}
static int srt_encode_close(AVCodecContext *avctx)
{
SRTContext *s = avctx->priv_data;
ff_ass_split_free(s->ass_ctx);
return 0;
}
#if CONFIG_SRT_ENCODER
/* deprecated encoder */
const FFCodec ff_srt_encoder = {
.p.name = "srt",
CODEC_LONG_NAME("SubRip subtitle"),
.p.type = AVMEDIA_TYPE_SUBTITLE,
.p.id = AV_CODEC_ID_SUBRIP,
.priv_data_size = sizeof(SRTContext),
.init = srt_encode_init,
FF_CODEC_ENCODE_SUB_CB(srt_encode_frame),
.close = srt_encode_close,
};
#endif
#if CONFIG_SUBRIP_ENCODER
const FFCodec ff_subrip_encoder = {
.p.name = "subrip",
CODEC_LONG_NAME("SubRip subtitle"),
.p.type = AVMEDIA_TYPE_SUBTITLE,
.p.id = AV_CODEC_ID_SUBRIP,
.priv_data_size = sizeof(SRTContext),
.init = srt_encode_init,
FF_CODEC_ENCODE_SUB_CB(srt_encode_frame),
.close = srt_encode_close,
};
#endif
#if CONFIG_TEXT_ENCODER
const FFCodec ff_text_encoder = {
.p.name = "text",
CODEC_LONG_NAME("Raw text subtitle"),
.p.type = AVMEDIA_TYPE_SUBTITLE,
.p.id = AV_CODEC_ID_TEXT,
.priv_data_size = sizeof(SRTContext),
.init = srt_encode_init,
FF_CODEC_ENCODE_SUB_CB(text_encode_frame),
.close = srt_encode_close,
};
#endif
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