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ffmpeg/libavcodec/microdvddec.c
Clément Bœsch 1f265f5205 microdvd: sanitize AVPackets. 
Current MicroDVD AVPackets contain timing information and trailing line
breaks. The data is now only composed of the markup data. Doing this
consistently between text subtitles decoders allows to use different
codec for various formats. For instance, MicroDVD markup is sometimes
found in some VPlayer files. Also, generally speaking, the subtitles
text decoders have no use of these timings (and they must not use them
since it would break any user timing adjustment).

Technically, this is a major ABI break. In practice, a mismatching
lavf/lavc will now error out for MicroDVD decoding. Supporting both
formats requires unnecessary complex and fragile code.

FATE needs update because line breaks in the ASS file were "\n" (because
that's what is used in the original file). ASS format expect "\r\n" line
breaks; this commit fixes this issue. Also note that this "\r\n"
trailing need to be moved at some point from the decoders to the ASS
muxer.
2012-12-31 00:41:35 +01:00

378 lines
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/*
* Copyright (c) 2012 Clément Bœsch
*
* 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
*/
/**
* @file
* MicroDVD subtitle decoder
*
* Based on the specifications found here:
* https://trac.videolan.org/vlc/ticket/1825#comment:6
*/
#include "libavutil/avstring.h"
#include "libavutil/parseutils.h"
#include "libavutil/bprint.h"
#include "avcodec.h"
#include "ass.h"
static int indexof(const char *s, int c)
{
char *f = strchr(s, c);
return f ? (f - s) : -1;
}
struct microdvd_tag {
char key;
int persistent;
uint32_t data1;
uint32_t data2;
char *data_string;
int data_string_len;
};
#define MICRODVD_PERSISTENT_OFF 0
#define MICRODVD_PERSISTENT_ON 1
#define MICRODVD_PERSISTENT_OPENED 2
// Color, Font, Size, cHarset, stYle, Position, cOordinate
#define MICRODVD_TAGS "cfshyYpo"
static void microdvd_set_tag(struct microdvd_tag *tags, struct microdvd_tag tag)
{
int tag_index = indexof(MICRODVD_TAGS, tag.key);
if (tag_index < 0)
return;
memcpy(&tags[tag_index], &tag, sizeof(tag));
}
// italic, bold, underline, strike-through
#define MICRODVD_STYLES "ibus"
static char *microdvd_load_tags(struct microdvd_tag *tags, char *s)
{
while (*s == '{') {
char *start = s;
char tag_char = *(s + 1);
struct microdvd_tag tag = {0};
if (!tag_char || *(s + 2) != ':')
break;
s += 3;
switch (tag_char) {
/* Style */
case 'Y':
tag.persistent = MICRODVD_PERSISTENT_ON;
case 'y':
while (*s && *s != '}') {
int style_index = indexof(MICRODVD_STYLES, *s);
if (style_index >= 0)
tag.data1 |= (1 << style_index);
s++;
}
if (*s != '}')
break;
/* We must distinguish persistent and non-persistent styles
* to handle this kind of style tags: {y:ib}{Y:us} */
tag.key = tag_char;
break;
/* Color */
case 'C':
tag.persistent = MICRODVD_PERSISTENT_ON;
case 'c':
if (*s == '$')
s++;
tag.data1 = strtol(s, &s, 16) & 0x00ffffff;
if (*s != '}')
break;
tag.key = 'c';
break;
/* Font name */
case 'F':
tag.persistent = MICRODVD_PERSISTENT_ON;
case 'f': {
int len = indexof(s, '}');
if (len < 0)
break;
tag.data_string = s;
tag.data_string_len = len;
s += len;
tag.key = 'f';
break;
}
/* Font size */
case 'S':
tag.persistent = MICRODVD_PERSISTENT_ON;
case 's':
tag.data1 = strtol(s, &s, 10);
if (*s != '}')
break;
tag.key = 's';
break;
/* Charset */
case 'H': {
//TODO: not yet handled, just parsed.
int len = indexof(s, '}');
if (len < 0)
break;
tag.data_string = s;
tag.data_string_len = len;
s += len;
tag.key = 'h';
break;
}
/* Position */
case 'P':
tag.persistent = MICRODVD_PERSISTENT_ON;
tag.data1 = (*s++ == '1');
if (*s != '}')
break;
tag.key = 'p';
break;
/* Coordinates */
case 'o':
tag.persistent = MICRODVD_PERSISTENT_ON;
tag.data1 = strtol(s, &s, 10);
if (*s != ',')
break;
s++;
tag.data2 = strtol(s, &s, 10);
if (*s != '}')
break;
tag.key = 'o';
break;
default: /* Unknown tag, we consider it's text */
break;
}
if (tag.key == 0)
return start;
microdvd_set_tag(tags, tag);
s++;
}
return s;
}
static void microdvd_open_tags(AVBPrint *new_line, struct microdvd_tag *tags)
{
int i, sidx;
for (i = 0; i < sizeof(MICRODVD_TAGS) - 1; i++) {
if (tags[i].persistent == MICRODVD_PERSISTENT_OPENED)
continue;
switch (tags[i].key) {
case 'Y':
case 'y':
for (sidx = 0; sidx < sizeof(MICRODVD_STYLES) - 1; sidx++)
if (tags[i].data1 & (1 << sidx))
av_bprintf(new_line, "{\\%c1}", MICRODVD_STYLES[sidx]);
break;
case 'c':
av_bprintf(new_line, "{\\c&H%06X&}", tags[i].data1);
break;
case 'f':
av_bprintf(new_line, "{\\fn%.*s}",
tags[i].data_string_len, tags[i].data_string);
break;
case 's':
av_bprintf(new_line, "{\\fs%d}", tags[i].data1);
break;
case 'p':
if (tags[i].data1 == 0)
av_bprintf(new_line, "{\\an8}");
break;
case 'o':
av_bprintf(new_line, "{\\pos(%d,%d)}",
tags[i].data1, tags[i].data2);
break;
}
if (tags[i].persistent == MICRODVD_PERSISTENT_ON)
tags[i].persistent = MICRODVD_PERSISTENT_OPENED;
}
}
static void microdvd_close_no_persistent_tags(AVBPrint *new_line,
struct microdvd_tag *tags)
{
int i, sidx;
for (i = sizeof(MICRODVD_TAGS) - 2; i >= 0; i--) {
if (tags[i].persistent != MICRODVD_PERSISTENT_OFF)
continue;
switch (tags[i].key) {
case 'y':
for (sidx = sizeof(MICRODVD_STYLES) - 2; sidx >= 0; sidx--)
if (tags[i].data1 & (1 << sidx))
av_bprintf(new_line, "{\\%c0}", MICRODVD_STYLES[sidx]);
break;
case 'c':
av_bprintf(new_line, "{\\c}");
break;
case 'f':
av_bprintf(new_line, "{\\fn}");
break;
case 's':
av_bprintf(new_line, "{\\fs}");
break;
}
tags[i].key = 0;
}
}
static int microdvd_decode_frame(AVCodecContext *avctx,
void *data, int *got_sub_ptr, AVPacket *avpkt)
{
AVSubtitle *sub = data;
AVBPrint new_line;
char c;
char *decoded_sub;
char *line = avpkt->data;
char *end = avpkt->data + avpkt->size;
struct microdvd_tag tags[sizeof(MICRODVD_TAGS) - 1] = {{0}};
if (avpkt->size <= 0)
return avpkt->size;
/* To be removed later */
if (sscanf(line, "{%*d}{%*[0123456789]}%c", &c) == 1 &&
line[avpkt->size - 1] == '\n') {
av_log(avctx, AV_LOG_ERROR, "AVPacket is not clean (contains timing "
"information and a trailing line break). You need to upgrade "
"your libavformat or sanitize your packet.\n");
return AVERROR_INVALIDDATA;
}
av_bprint_init(&new_line, 0, 2048);
// subtitle content
while (line < end && *line) {
// parse MicroDVD tags, and open them in ASS
line = microdvd_load_tags(tags, line);
microdvd_open_tags(&new_line, tags);
// simple copy until EOL or forced carriage return
while (line < end && *line && *line != '|') {
av_bprint_chars(&new_line, *line, 1);
line++;
}
// line split
if (line < end && *line == '|') {
microdvd_close_no_persistent_tags(&new_line, tags);
av_bprintf(&new_line, "\\N");
line++;
}
}
if (new_line.len) {
av_bprintf(&new_line, "\r\n");
av_bprint_finalize(&new_line, &decoded_sub);
if (*decoded_sub) {
int64_t start = avpkt->pts;
int64_t duration = avpkt->duration;
int ts_start = av_rescale_q(start, avctx->time_base, (AVRational){1,100});
int ts_duration = duration != -1 ?
av_rescale_q(duration, avctx->time_base, (AVRational){1,100}) : -1;
ff_ass_add_rect(sub, decoded_sub, ts_start, ts_duration, 0);
}
av_free(decoded_sub);
}
*got_sub_ptr = sub->num_rects > 0;
return avpkt->size;
}
static int microdvd_init(AVCodecContext *avctx)
{
int i, sidx;
AVBPrint font_buf;
int font_size = ASS_DEFAULT_FONT_SIZE;
int color = ASS_DEFAULT_COLOR;
int bold = ASS_DEFAULT_BOLD;
int italic = ASS_DEFAULT_ITALIC;
int underline = ASS_DEFAULT_UNDERLINE;
int alignment = ASS_DEFAULT_ALIGNMENT;
struct microdvd_tag tags[sizeof(MICRODVD_TAGS) - 1] = {{0}};
av_bprint_init(&font_buf, 0, AV_BPRINT_SIZE_AUTOMATIC);
av_bprintf(&font_buf, "%s", ASS_DEFAULT_FONT);
if (avctx->extradata) {
microdvd_load_tags(tags, avctx->extradata);
for (i = 0; i < sizeof(MICRODVD_TAGS) - 1; i++) {
switch (av_tolower(tags[i].key)) {
case 'y':
for (sidx = 0; sidx < sizeof(MICRODVD_STYLES) - 1; sidx++) {
if (tags[i].data1 & (1 << sidx)) {
switch (MICRODVD_STYLES[sidx]) {
case 'i': italic = 1; break;
case 'b': bold = 1; break;
case 'u': underline = 1; break;
}
}
}
break;
case 'c': color = tags[i].data1; break;
case 's': font_size = tags[i].data1; break;
case 'p': alignment = 8; break;
case 'f':
av_bprint_clear(&font_buf);
av_bprintf(&font_buf, "%.*s",
tags[i].data_string_len, tags[i].data_string);
break;
}
}
}
return ff_ass_subtitle_header(avctx, font_buf.str, font_size, color,
ASS_DEFAULT_BACK_COLOR, bold, italic,
underline, alignment);
}
AVCodec ff_microdvd_decoder = {
.name = "microdvd",
.long_name = NULL_IF_CONFIG_SMALL("MicroDVD subtitle"),
.type = AVMEDIA_TYPE_SUBTITLE,
.id = AV_CODEC_ID_MICRODVD,
.init = microdvd_init,
.decode = microdvd_decode_frame,
};
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