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FFmpeg/libavcodec/srtenc.c
Clément Bœsch eb36ee1ee1 lavc/srtenc: fix invalid read in case of SubRip.
Regression since 6057de19b. The ptr-2 is used to eat the \r\n and add
the position information on the timing line. This can't be done in case
of SubRip where the timing isn't present in the payload.

Note that we can't use yet the side data to transmit the position
information since the encode subtitles API is still using buffer+size
instead AVPacket as input.
2012-10-26 21:48:27 +02:00

321 lines
9.2 KiB
C

/*
* 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 <stdarg.h>
#include "avcodec.h"
#include "libavutil/avstring.h"
#include "ass_split.h"
#include "ass.h"
#define SRT_STACK_SIZE 64
typedef struct {
AVCodecContext *avctx;
ASSSplitContext *ass_ctx;
char buffer[2048];
char *ptr;
char *end;
char *dialog_start;
int count;
char stack[SRT_STACK_SIZE];
int stack_ptr;
int alignment_applied;
} SRTContext;
#ifdef __GNUC__
__attribute__ ((__format__ (__printf__, 2, 3)))
#endif
static void srt_print(SRTContext *s, const char *str, ...)
{
va_list vargs;
va_start(vargs, str);
s->ptr += vsnprintf(s->ptr, s->end - s->ptr, 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_strlcpy(s->ptr, text, FFMIN(s->end-s->ptr, len+1));
s->ptr += 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)
{
SRTContext *s = priv;
if (s->avctx->codec->id == CODEC_ID_SRT) {
char buffer[32];
int len = snprintf(buffer, sizeof(buffer),
" X1:%03u X2:%03u Y1:%03u Y2:%03u", x1, x2, y1, y2);
if (s->end - s->ptr > len) {
memmove(s->dialog_start+len, s->dialog_start, s->ptr-s->dialog_start+1);
memcpy(s->dialog_start, buffer, len);
s->ptr += len;
}
}
}
static void srt_end_cb(void *priv)
{
srt_stack_push_pop(priv, 0, 1);
srt_print(priv, "\r\n\r\n");
}
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 int srt_encode_frame(AVCodecContext *avctx,
unsigned char *buf, int bufsize, const AVSubtitle *sub)
{
SRTContext *s = avctx->priv_data;
ASSDialog *dialog;
int i, len, num;
s->ptr = s->buffer;
s->end = s->ptr + sizeof(s->buffer);
for (i=0; i<sub->num_rects; i++) {
if (sub->rects[i]->type != SUBTITLE_ASS) {
av_log(avctx, AV_LOG_ERROR, "Only SUBTITLE_ASS type supported.\n");
return AVERROR(ENOSYS);
}
dialog = ff_ass_split_dialog(s->ass_ctx, sub->rects[i]->ass, 0, &num);
for (; dialog && num--; dialog++) {
if (avctx->codec->id == CODEC_ID_SRT) {
int sh, sm, ss, sc = 10 * dialog->start;
int eh, em, es, ec = 10 * dialog->end;
sh = sc/3600000; sc -= 3600000*sh;
sm = sc/ 60000; sc -= 60000*sm;
ss = sc/ 1000; sc -= 1000*ss;
eh = ec/3600000; ec -= 3600000*eh;
em = ec/ 60000; ec -= 60000*em;
es = ec/ 1000; ec -= 1000*es;
srt_print(s,"%d\r\n%02d:%02d:%02d,%03d --> %02d:%02d:%02d,%03d\r\n",
++s->count, sh, sm, ss, sc, eh, em, es, ec);
s->dialog_start = s->ptr - 2;
}
s->alignment_applied = 0;
srt_style_apply(s, dialog->style);
ff_ass_split_override_codes(&srt_callbacks, s, dialog->text);
}
}
if (s->ptr == s->buffer)
return 0;
len = av_strlcpy(buf, s->buffer, bufsize);
if (len > bufsize-1) {
av_log(avctx, AV_LOG_ERROR, "Buffer too small for ASS event.\n");
return -1;
}
return len;
}
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
AVCodec ff_srt_encoder = {
.name = "srt",
.long_name = NULL_IF_CONFIG_SMALL("SubRip subtitle with embedded timing"),
.type = AVMEDIA_TYPE_SUBTITLE,
.id = AV_CODEC_ID_SRT,
.priv_data_size = sizeof(SRTContext),
.init = srt_encode_init,
.encode_sub = srt_encode_frame,
.close = srt_encode_close,
};
#endif
#if CONFIG_SUBRIP_ENCODER
AVCodec ff_subrip_encoder = {
.name = "subrip",
.long_name = NULL_IF_CONFIG_SMALL("SubRip subtitle"),
.type = AVMEDIA_TYPE_SUBTITLE,
.id = AV_CODEC_ID_SUBRIP,
.priv_data_size = sizeof(SRTContext),
.init = srt_encode_init,
.encode_sub = srt_encode_frame,
.close = srt_encode_close,
};
#endif