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ffmpeg/libavcodec/dvdsubdec.c

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/*
* DVD subtitle decoding for ffmpeg
* Copyright (c) 2005 Fabrice Bellard
*
* 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 "get_bits.h"
#include "dsputil.h"
#include "libavutil/colorspace.h"
//#define DEBUG
static void yuv_a_to_rgba(const uint8_t *ycbcr, const uint8_t *alpha, uint32_t *rgba, int num_values)
{
uint8_t *cm = ff_cropTbl + MAX_NEG_CROP;
uint8_t r, g, b;
int i, y, cb, cr;
int r_add, g_add, b_add;
for (i = num_values; i > 0; i--) {
y = *ycbcr++;
cr = *ycbcr++;
cb = *ycbcr++;
YUV_TO_RGB1_CCIR(cb, cr);
YUV_TO_RGB2_CCIR(r, g, b, y);
*rgba++ = (*alpha++ << 24) | (r << 16) | (g << 8) | b;
}
}
static int decode_run_2bit(GetBitContext *gb, int *color)
{
unsigned int v, t;
v = 0;
for (t = 1; v < t && t <= 0x40; t <<= 2)
v = (v << 4) | get_bits(gb, 4);
*color = v & 3;
if (v < 4) { /* Code for fill rest of line */
return INT_MAX;
}
return v >> 2;
}
static int decode_run_8bit(GetBitContext *gb, int *color)
{
int len;
int has_run = get_bits1(gb);
if (get_bits1(gb))
*color = get_bits(gb, 8);
else
*color = get_bits(gb, 2);
if (has_run) {
if (get_bits1(gb)) {
len = get_bits(gb, 7);
if (len == 0)
len = INT_MAX;
else
len += 9;
} else
len = get_bits(gb, 3) + 2;
} else
len = 1;
return len;
}
static int decode_rle(uint8_t *bitmap, int linesize, int w, int h,
const uint8_t *buf, int start, int buf_size, int is_8bit)
{
GetBitContext gb;
int bit_len;
int x, y, len, color;
uint8_t *d;
bit_len = (buf_size - start) * 8;
init_get_bits(&gb, buf + start, bit_len);
x = 0;
y = 0;
d = bitmap;
for(;;) {
if (get_bits_count(&gb) > bit_len)
return -1;
if (is_8bit)
len = decode_run_8bit(&gb, &color);
else
len = decode_run_2bit(&gb, &color);
len = FFMIN(len, w - x);
memset(d + x, color, len);
x += len;
if (x >= w) {
y++;
if (y >= h)
break;
d += linesize;
x = 0;
/* byte align */
align_get_bits(&gb);
}
}
return 0;
}
static void guess_palette(uint32_t *rgba_palette,
uint8_t *colormap,
uint8_t *alpha,
uint32_t subtitle_color)
{
static const uint8_t level_map[4][4] = {
// this configuration (full range, lowest to highest) in tests
// seemed most common, so assume this
{0xff},
{0x00, 0xff},
{0x00, 0x80, 0xff},
{0x00, 0x55, 0xaa, 0xff},
};
uint8_t color_used[16];
int nb_opaque_colors, i, level, j, r, g, b;
for(i = 0; i < 4; i++)
rgba_palette[i] = 0;
memset(color_used, 0, 16);
nb_opaque_colors = 0;
for(i = 0; i < 4; i++) {
if (alpha[i] != 0 && !color_used[colormap[i]]) {
color_used[colormap[i]] = 1;
nb_opaque_colors++;
}
}
if (nb_opaque_colors == 0)
return;
j = 0;
memset(color_used, 0, 16);
for(i = 0; i < 4; i++) {
if (alpha[i] != 0) {
if (!color_used[colormap[i]]) {
level = level_map[nb_opaque_colors][j];
r = (((subtitle_color >> 16) & 0xff) * level) >> 8;
g = (((subtitle_color >> 8) & 0xff) * level) >> 8;
b = (((subtitle_color >> 0) & 0xff) * level) >> 8;
rgba_palette[i] = b | (g << 8) | (r << 16) | ((alpha[i] * 17) << 24);
color_used[colormap[i]] = (i + 1);
j++;
} else {
rgba_palette[i] = (rgba_palette[color_used[colormap[i]] - 1] & 0x00ffffff) |
((alpha[i] * 17) << 24);
}
}
}
}
#define READ_OFFSET(a) (big_offsets ? AV_RB32(a) : AV_RB16(a))
static int decode_dvd_subtitles(AVSubtitle *sub_header,
const uint8_t *buf, int buf_size)
{
int cmd_pos, pos, cmd, x1, y1, x2, y2, offset1, offset2, next_cmd_pos;
int big_offsets, offset_size, is_8bit = 0;
const uint8_t *yuv_palette = 0;
uint8_t colormap[4], alpha[256];
int date;
int i;
int is_menu = 0;
if (buf_size < 10)
return -1;
if (AV_RB16(buf) == 0) { /* HD subpicture with 4-byte offsets */
big_offsets = 1;
offset_size = 4;
cmd_pos = 6;
} else {
big_offsets = 0;
offset_size = 2;
cmd_pos = 2;
}
cmd_pos = READ_OFFSET(buf + cmd_pos);
while (cmd_pos > 0 && cmd_pos < buf_size - 2 - offset_size) {
date = AV_RB16(buf + cmd_pos);
next_cmd_pos = READ_OFFSET(buf + cmd_pos + 2);
av_dlog(NULL, "cmd_pos=0x%04x next=0x%04x date=%d\n",
cmd_pos, next_cmd_pos, date);
pos = cmd_pos + 2 + offset_size;
offset1 = -1;
offset2 = -1;
x1 = y1 = x2 = y2 = 0;
while (pos < buf_size) {
cmd = buf[pos++];
av_dlog(NULL, "cmd=%02x\n", cmd);
switch(cmd) {
case 0x00:
/* menu subpicture */
is_menu = 1;
break;
case 0x01:
/* set start date */
sub_header->start_display_time = (date << 10) / 90;
break;
case 0x02:
/* set end date */
sub_header->end_display_time = (date << 10) / 90;
break;
case 0x03:
/* set colormap */
if ((buf_size - pos) < 2)
goto fail;
colormap[3] = buf[pos] >> 4;
colormap[2] = buf[pos] & 0x0f;
colormap[1] = buf[pos + 1] >> 4;
colormap[0] = buf[pos + 1] & 0x0f;
pos += 2;
break;
case 0x04:
/* set alpha */
if ((buf_size - pos) < 2)
goto fail;
alpha[3] = buf[pos] >> 4;
alpha[2] = buf[pos] & 0x0f;
alpha[1] = buf[pos + 1] >> 4;
alpha[0] = buf[pos + 1] & 0x0f;
pos += 2;
av_dlog(NULL, "alpha=%x%x%x%x\n", alpha[0],alpha[1],alpha[2],alpha[3]);
break;
case 0x05:
case 0x85:
if ((buf_size - pos) < 6)
goto fail;
x1 = (buf[pos] << 4) | (buf[pos + 1] >> 4);
x2 = ((buf[pos + 1] & 0x0f) << 8) | buf[pos + 2];
y1 = (buf[pos + 3] << 4) | (buf[pos + 4] >> 4);
y2 = ((buf[pos + 4] & 0x0f) << 8) | buf[pos + 5];
if (cmd & 0x80)
is_8bit = 1;
av_dlog(NULL, "x1=%d x2=%d y1=%d y2=%d\n", x1, x2, y1, y2);
pos += 6;
break;
case 0x06:
if ((buf_size - pos) < 4)
goto fail;
offset1 = AV_RB16(buf + pos);
offset2 = AV_RB16(buf + pos + 2);
av_dlog(NULL, "offset1=0x%04x offset2=0x%04x\n", offset1, offset2);
pos += 4;
break;
case 0x86:
if ((buf_size - pos) < 8)
goto fail;
offset1 = AV_RB32(buf + pos);
offset2 = AV_RB32(buf + pos + 4);
av_dlog(NULL, "offset1=0x%04x offset2=0x%04x\n", offset1, offset2);
pos += 8;
break;
case 0x83:
/* HD set palette */
if ((buf_size - pos) < 768)
goto fail;
yuv_palette = buf + pos;
pos += 768;
break;
case 0x84:
/* HD set contrast (alpha) */
if ((buf_size - pos) < 256)
goto fail;
for (i = 0; i < 256; i++)
alpha[i] = 0xFF - buf[pos+i];
pos += 256;
break;
case 0xff:
goto the_end;
default:
av_dlog(NULL, "unrecognised subpicture command 0x%x\n", cmd);
goto the_end;
}
}
the_end:
if (offset1 >= 0) {
int w, h;
uint8_t *bitmap;
/* decode the bitmap */
w = x2 - x1 + 1;
if (w < 0)
w = 0;
h = y2 - y1;
if (h < 0)
h = 0;
if (w > 0 && h > 0) {
if (sub_header->rects != NULL) {
for (i = 0; i < sub_header->num_rects; i++) {
av_freep(&sub_header->rects[i]->pict.data[0]);
av_freep(&sub_header->rects[i]->pict.data[1]);
av_freep(&sub_header->rects[i]);
}
av_freep(&sub_header->rects);
sub_header->num_rects = 0;
}
bitmap = av_malloc(w * h);
sub_header->rects = av_mallocz(sizeof(*sub_header->rects));
sub_header->rects[0] = av_mallocz(sizeof(AVSubtitleRect));
sub_header->num_rects = 1;
sub_header->rects[0]->pict.data[0] = bitmap;
decode_rle(bitmap, w * 2, w, (h + 1) / 2,
buf, offset1, buf_size, is_8bit);
decode_rle(bitmap + w, w * 2, w, h / 2,
buf, offset2, buf_size, is_8bit);
sub_header->rects[0]->pict.data[1] = av_mallocz(AVPALETTE_SIZE);
if (is_8bit) {
if (yuv_palette == 0)
goto fail;
sub_header->rects[0]->nb_colors = 256;
yuv_a_to_rgba(yuv_palette, alpha, (uint32_t*)sub_header->rects[0]->pict.data[1], 256);
} else {
sub_header->rects[0]->nb_colors = 4;
guess_palette((uint32_t*)sub_header->rects[0]->pict.data[1],
colormap, alpha, 0xffff00);
}
sub_header->rects[0]->x = x1;
sub_header->rects[0]->y = y1;
sub_header->rects[0]->w = w;
sub_header->rects[0]->h = h;
sub_header->rects[0]->type = SUBTITLE_BITMAP;
sub_header->rects[0]->pict.linesize[0] = w;
}
}
if (next_cmd_pos < cmd_pos) {
av_log(NULL, AV_LOG_ERROR, "Invalid command offset\n");
break;
}
if (next_cmd_pos == cmd_pos)
break;
cmd_pos = next_cmd_pos;
}
if (sub_header->num_rects > 0)
return is_menu;
fail:
if (sub_header->rects != NULL) {
for (i = 0; i < sub_header->num_rects; i++) {
av_freep(&sub_header->rects[i]->pict.data[0]);
av_freep(&sub_header->rects[i]->pict.data[1]);
av_freep(&sub_header->rects[i]);
}
av_freep(&sub_header->rects);
sub_header->num_rects = 0;
}
return -1;
}
static int is_transp(const uint8_t *buf, int pitch, int n,
const uint8_t *transp_color)
{
int i;
for(i = 0; i < n; i++) {
if (!transp_color[*buf])
return 0;
buf += pitch;
}
return 1;
}
/* return 0 if empty rectangle, 1 if non empty */
static int find_smallest_bounding_rectangle(AVSubtitle *s)
{
uint8_t transp_color[256];
int y1, y2, x1, x2, y, w, h, i;
uint8_t *bitmap;
if (s->num_rects == 0 || s->rects == NULL || s->rects[0]->w <= 0 || s->rects[0]->h <= 0)
return 0;
memset(transp_color, 0, 256);
for(i = 0; i < s->rects[0]->nb_colors; i++) {
if ((((uint32_t*)s->rects[0]->pict.data[1])[i] >> 24) == 0)
transp_color[i] = 1;
}
y1 = 0;
while (y1 < s->rects[0]->h && is_transp(s->rects[0]->pict.data[0] + y1 * s->rects[0]->pict.linesize[0],
1, s->rects[0]->w, transp_color))
y1++;
if (y1 == s->rects[0]->h) {
av_freep(&s->rects[0]->pict.data[0]);
s->rects[0]->w = s->rects[0]->h = 0;
return 0;
}
y2 = s->rects[0]->h - 1;
while (y2 > 0 && is_transp(s->rects[0]->pict.data[0] + y2 * s->rects[0]->pict.linesize[0], 1,
s->rects[0]->w, transp_color))
y2--;
x1 = 0;
while (x1 < (s->rects[0]->w - 1) && is_transp(s->rects[0]->pict.data[0] + x1, s->rects[0]->pict.linesize[0],
s->rects[0]->h, transp_color))
x1++;
x2 = s->rects[0]->w - 1;
while (x2 > 0 && is_transp(s->rects[0]->pict.data[0] + x2, s->rects[0]->pict.linesize[0], s->rects[0]->h,
transp_color))
x2--;
w = x2 - x1 + 1;
h = y2 - y1 + 1;
bitmap = av_malloc(w * h);
if (!bitmap)
return 1;
for(y = 0; y < h; y++) {
memcpy(bitmap + w * y, s->rects[0]->pict.data[0] + x1 + (y1 + y) * s->rects[0]->pict.linesize[0], w);
}
av_freep(&s->rects[0]->pict.data[0]);
s->rects[0]->pict.data[0] = bitmap;
s->rects[0]->pict.linesize[0] = w;
s->rects[0]->w = w;
s->rects[0]->h = h;
s->rects[0]->x += x1;
s->rects[0]->y += y1;
return 1;
}
#ifdef DEBUG
#undef fprintf
#undef perror
#undef exit
static void ppm_save(const char *filename, uint8_t *bitmap, int w, int h,
uint32_t *rgba_palette)
{
int x, y, v;
FILE *f;
f = fopen(filename, "w");
if (!f) {
perror(filename);
exit(1);
}
fprintf(f, "P6\n"
"%d %d\n"
"%d\n",
w, h, 255);
for(y = 0; y < h; y++) {
for(x = 0; x < w; x++) {
v = rgba_palette[bitmap[y * w + x]];
putc((v >> 16) & 0xff, f);
putc((v >> 8) & 0xff, f);
putc((v >> 0) & 0xff, f);
}
}
fclose(f);
}
#endif
static int dvdsub_decode(AVCodecContext *avctx,
void *data, int *data_size,
AVPacket *avpkt)
{
const uint8_t *buf = avpkt->data;
int buf_size = avpkt->size;
AVSubtitle *sub = data;
int is_menu;
is_menu = decode_dvd_subtitles(sub, buf, buf_size);
if (is_menu < 0) {
no_subtitle:
*data_size = 0;
return buf_size;
}
if (!is_menu && find_smallest_bounding_rectangle(sub) == 0)
goto no_subtitle;
#if defined(DEBUG)
av_dlog(NULL, "start=%d ms end =%d ms\n",
sub->start_display_time,
sub->end_display_time);
ppm_save("/tmp/a.ppm", sub->rects[0]->pict.data[0],
sub->rects[0]->w, sub->rects[0]->h, sub->rects[0]->pict.data[1]);
#endif
*data_size = 1;
return buf_size;
}
AVCodec ff_dvdsub_decoder = {
.name = "dvdsub",
.type = AVMEDIA_TYPE_SUBTITLE,
.id = CODEC_ID_DVD_SUBTITLE,
.decode = dvdsub_decode,
.long_name = NULL_IF_CONFIG_SMALL("DVD subtitles"),
};
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