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FFmpeg/libavcodec/dvdsubenc.c
Andreas Rheinhardt 24bc6ea28f avcodec/dvdsubenc: Mark encoder as init-threadsafe 
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
2021-05-02 03:29:55 +02:00

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/*
* DVD subtitle encoding
* Copyright (c) 2005 Wolfram Gloger
*
* 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 "bytestream.h"
#include "internal.h"
#include "libavutil/avassert.h"
#include "libavutil/bprint.h"
#include "libavutil/imgutils.h"
#include "libavutil/opt.h"
typedef struct {
AVClass *class;
uint32_t global_palette[16];
char *palette_str;
int even_rows_fix;
} DVDSubtitleContext;
// ncnt is the nibble counter
#define PUTNIBBLE(val)\
do {\
if (ncnt++ & 1)\
*q++ = bitbuf | ((val) & 0x0f);\
else\
bitbuf = (val) << 4;\
} while(0)
static void dvd_encode_rle(uint8_t **pq,
const uint8_t *bitmap, int linesize,
int w, int h,
const int cmap[256])
{
uint8_t *q;
unsigned int bitbuf = 0;
int ncnt;
int x, y, len, color;
q = *pq;
for (y = 0; y < h; ++y) {
ncnt = 0;
for(x = 0; x < w; x += len) {
color = bitmap[x];
for (len=1; x+len < w; ++len)
if (bitmap[x+len] != color)
break;
color = cmap[color];
av_assert0(color < 4);
if (len < 0x04) {
PUTNIBBLE((len << 2)|color);
} else if (len < 0x10) {
PUTNIBBLE(len >> 2);
PUTNIBBLE((len << 2)|color);
} else if (len < 0x40) {
PUTNIBBLE(0);
PUTNIBBLE(len >> 2);
PUTNIBBLE((len << 2)|color);
} else if (x+len == w) {
PUTNIBBLE(0);
PUTNIBBLE(0);
PUTNIBBLE(0);
PUTNIBBLE(color);
} else {
if (len > 0xff)
len = 0xff;
PUTNIBBLE(0);
PUTNIBBLE(len >> 6);
PUTNIBBLE(len >> 2);
PUTNIBBLE((len << 2)|color);
}
}
/* end of line */
if (ncnt & 1)
PUTNIBBLE(0);
bitmap += linesize;
}
*pq = q;
}
static int color_distance(uint32_t a, uint32_t b)
{
int r = 0, d, i;
int alpha_a = 8, alpha_b = 8;
for (i = 24; i >= 0; i -= 8) {
d = alpha_a * (int)((a >> i) & 0xFF) -
alpha_b * (int)((b >> i) & 0xFF);
r += d * d;
alpha_a = a >> 28;
alpha_b = b >> 28;
}
return r;
}
/**
* Count colors used in a rectangle, quantizing alpha and grouping by
* nearest global palette entry.
*/
static void count_colors(AVCodecContext *avctx, unsigned hits[33],
const AVSubtitleRect *r)
{
DVDSubtitleContext *dvdc = avctx->priv_data;
unsigned count[256] = { 0 };
uint32_t *palette = (uint32_t *)r->data[1];
uint32_t color;
int x, y, i, j, match, d, best_d, av_uninit(best_j);
uint8_t *p = r->data[0];
for (y = 0; y < r->h; y++) {
for (x = 0; x < r->w; x++)
count[*(p++)]++;
p += r->linesize[0] - r->w;
}
for (i = 0; i < 256; i++) {
if (!count[i]) /* avoid useless search */
continue;
color = palette[i];
/* 0: transparent, 1-16: semi-transparent, 17-33 opaque */
match = color < 0x33000000 ? 0 : color < 0xCC000000 ? 1 : 17;
if (match) {
best_d = INT_MAX;
for (j = 0; j < 16; j++) {
d = color_distance(0xFF000000 | color,
0xFF000000 | dvdc->global_palette[j]);
if (d < best_d) {
best_d = d;
best_j = j;
}
}
match += best_j;
}
hits[match] += count[i];
}
}
static void select_palette(AVCodecContext *avctx, int out_palette[4],
int out_alpha[4], unsigned hits[33])
{
DVDSubtitleContext *dvdc = avctx->priv_data;
int i, j, bright, mult;
uint32_t color;
int selected[4] = { 0 };
uint32_t pseudopal[33] = { 0 };
uint32_t refcolor[3] = { 0x00000000, 0xFFFFFFFF, 0xFF000000 };
/* Bonus for transparent: if the rectangle fits tightly the text, the
background color can be quite rare, but it would be ugly without it */
hits[0] *= 16;
/* Bonus for bright colors */
for (i = 0; i < 16; i++) {
if (!(hits[1 + i] + hits[17 + i]))
continue; /* skip unused colors to gain time */
color = dvdc->global_palette[i];
bright = 0;
for (j = 0; j < 3; j++, color >>= 8)
bright += (color & 0xFF) < 0x40 || (color & 0xFF) >= 0xC0;
mult = 2 + FFMIN(bright, 2);
hits[ 1 + i] *= mult;
hits[17 + i] *= mult;
}
/* Select four most frequent colors */
for (i = 0; i < 4; i++) {
for (j = 0; j < 33; j++)
if (hits[j] > hits[selected[i]])
selected[i] = j;
hits[selected[i]] = 0;
}
/* Order the colors like in most DVDs:
0: background, 1: foreground, 2: outline */
for (i = 0; i < 16; i++) {
pseudopal[ 1 + i] = 0x80000000 | dvdc->global_palette[i];
pseudopal[17 + i] = 0xFF000000 | dvdc->global_palette[i];
}
for (i = 0; i < 3; i++) {
int best_d = color_distance(refcolor[i], pseudopal[selected[i]]);
for (j = i + 1; j < 4; j++) {
int d = color_distance(refcolor[i], pseudopal[selected[j]]);
if (d < best_d) {
FFSWAP(int, selected[i], selected[j]);
best_d = d;
}
}
}
/* Output */
for (i = 0; i < 4; i++) {
out_palette[i] = selected[i] ? (selected[i] - 1) & 0xF : 0;
out_alpha [i] = !selected[i] ? 0 : selected[i] < 17 ? 0x80 : 0xFF;
}
}
static void build_color_map(AVCodecContext *avctx, int cmap[],
const uint32_t palette[],
const int out_palette[], unsigned int const out_alpha[])
{
DVDSubtitleContext *dvdc = avctx->priv_data;
int i, j, d, best_d;
uint32_t pseudopal[4];
for (i = 0; i < 4; i++)
pseudopal[i] = (out_alpha[i] << 24) |
dvdc->global_palette[out_palette[i]];
for (i = 0; i < 256; i++) {
best_d = INT_MAX;
for (j = 0; j < 4; j++) {
d = color_distance(pseudopal[j], palette[i]);
if (d < best_d) {
cmap[i] = j;
best_d = d;
}
}
}
}
static void copy_rectangle(AVSubtitleRect *dst, AVSubtitleRect *src, int cmap[])
{
int x, y;
uint8_t *p, *q;
p = src->data[0];
q = dst->data[0] + (src->x - dst->x) +
(src->y - dst->y) * dst->linesize[0];
for (y = 0; y < src->h; y++) {
for (x = 0; x < src->w; x++)
*(q++) = cmap[*(p++)];
p += src->linesize[0] - src->w;
q += dst->linesize[0] - src->w;
}
}
static int encode_dvd_subtitles(AVCodecContext *avctx,
uint8_t *outbuf, int outbuf_size,
const AVSubtitle *h)
{
DVDSubtitleContext *dvdc = avctx->priv_data;
uint8_t *q, *qq;
int offset1, offset2;
int i, rects = h->num_rects, ret;
unsigned global_palette_hits[33] = { 0 };
int cmap[256];
int out_palette[4];
int out_alpha[4];
AVSubtitleRect vrect;
uint8_t *vrect_data = NULL;
int x2, y2;
int forced = 0;
if (rects == 0 || !h->rects)
return AVERROR(EINVAL);
for (i = 0; i < rects; i++)
if (h->rects[i]->type != SUBTITLE_BITMAP) {
av_log(avctx, AV_LOG_ERROR, "Bitmap subtitle required\n");
return AVERROR(EINVAL);
}
/* Mark this subtitle forced if any of the rectangles is forced. */
for (i = 0; i < rects; i++)
if ((h->rects[i]->flags & AV_SUBTITLE_FLAG_FORCED) != 0) {
forced = 1;
break;
}
vrect = *h->rects[0];
if (rects > 1) {
/* DVD subtitles can have only one rectangle: build a virtual
rectangle containing all actual rectangles.
The data of the rectangles will be copied later, when the palette
is decided, because the rectangles may have different palettes. */
int xmin = h->rects[0]->x, xmax = xmin + h->rects[0]->w;
int ymin = h->rects[0]->y, ymax = ymin + h->rects[0]->h;
for (i = 1; i < rects; i++) {
xmin = FFMIN(xmin, h->rects[i]->x);
ymin = FFMIN(ymin, h->rects[i]->y);
xmax = FFMAX(xmax, h->rects[i]->x + h->rects[i]->w);
ymax = FFMAX(ymax, h->rects[i]->y + h->rects[i]->h);
}
vrect.x = xmin;
vrect.y = ymin;
vrect.w = xmax - xmin;
vrect.h = ymax - ymin;
if ((ret = av_image_check_size(vrect.w, vrect.h, 0, avctx)) < 0)
return ret;
/* Count pixels outside the virtual rectangle as transparent */
global_palette_hits[0] = vrect.w * vrect.h;
for (i = 0; i < rects; i++)
global_palette_hits[0] -= h->rects[i]->w * h->rects[i]->h;
}
for (i = 0; i < rects; i++)
count_colors(avctx, global_palette_hits, h->rects[i]);
select_palette(avctx, out_palette, out_alpha, global_palette_hits);
if (rects > 1) {
if (!(vrect_data = av_calloc(vrect.w, vrect.h)))
return AVERROR(ENOMEM);
vrect.data [0] = vrect_data;
vrect.linesize[0] = vrect.w;
for (i = 0; i < rects; i++) {
build_color_map(avctx, cmap, (uint32_t *)h->rects[i]->data[1],
out_palette, out_alpha);
copy_rectangle(&vrect, h->rects[i], cmap);
}
for (i = 0; i < 4; i++)
cmap[i] = i;
} else {
build_color_map(avctx, cmap, (uint32_t *)h->rects[0]->data[1],
out_palette, out_alpha);
}
av_log(avctx, AV_LOG_DEBUG, "Selected palette:");
for (i = 0; i < 4; i++)
av_log(avctx, AV_LOG_DEBUG, " 0x%06"PRIx32"@@%02x (0x%x,0x%x)",
dvdc->global_palette[out_palette[i]], out_alpha[i],
out_palette[i], out_alpha[i] >> 4);
av_log(avctx, AV_LOG_DEBUG, "\n");
// encode data block
q = outbuf + 4;
offset1 = q - outbuf;
// worst case memory requirement: 1 nibble per pixel..
if ((q - outbuf) + vrect.w * vrect.h / 2 + 17 + 21 > outbuf_size) {
av_log(NULL, AV_LOG_ERROR, "dvd_subtitle too big\n");
ret = AVERROR_BUFFER_TOO_SMALL;
goto fail;
}
dvd_encode_rle(&q, vrect.data[0], vrect.w * 2,
vrect.w, (vrect.h + 1) >> 1, cmap);
offset2 = q - outbuf;
dvd_encode_rle(&q, vrect.data[0] + vrect.w, vrect.w * 2,
vrect.w, vrect.h >> 1, cmap);
if (dvdc->even_rows_fix && (vrect.h & 1)) {
// Work-around for some players that want the height to be even.
vrect.h++;
*q++ = 0x00; // 0x00 0x00 == empty row, i.e. fully transparent
*q++ = 0x00;
}
// set data packet size
qq = outbuf + 2;
bytestream_put_be16(&qq, q - outbuf);
// send start display command
bytestream_put_be16(&q, (h->start_display_time*90) >> 10);
bytestream_put_be16(&q, (q - outbuf) /*- 2 */ + 8 + 12 + 2);
*q++ = 0x03; // palette - 4 nibbles
*q++ = (out_palette[3] << 4) | out_palette[2];
*q++ = (out_palette[1] << 4) | out_palette[0];
*q++ = 0x04; // alpha - 4 nibbles
*q++ = (out_alpha[3] & 0xF0) | (out_alpha[2] >> 4);
*q++ = (out_alpha[1] & 0xF0) | (out_alpha[0] >> 4);
// 12 bytes per rect
x2 = vrect.x + vrect.w - 1;
y2 = vrect.y + vrect.h - 1;
*q++ = 0x05;
// x1 x2 -> 6 nibbles
*q++ = vrect.x >> 4;
*q++ = (vrect.x << 4) | ((x2 >> 8) & 0xf);
*q++ = x2;
// y1 y2 -> 6 nibbles
*q++ = vrect.y >> 4;
*q++ = (vrect.y << 4) | ((y2 >> 8) & 0xf);
*q++ = y2;
*q++ = 0x06;
// offset1, offset2
bytestream_put_be16(&q, offset1);
bytestream_put_be16(&q, offset2);
*q++ = forced ? 0x00 : 0x01; // start command
*q++ = 0xff; // terminating command
// send stop display command last
bytestream_put_be16(&q, (h->end_display_time*90) >> 10);
bytestream_put_be16(&q, (q - outbuf) - 2 /*+ 4*/);
*q++ = 0x02; // set end
*q++ = 0xff; // terminating command
qq = outbuf;
bytestream_put_be16(&qq, q - outbuf);
av_log(NULL, AV_LOG_DEBUG, "subtitle_packet size=%"PTRDIFF_SPECIFIER"\n", q - outbuf);
ret = q - outbuf;
fail:
av_free(vrect_data);
return ret;
}
static int bprint_to_extradata(AVCodecContext *avctx, struct AVBPrint *buf)
{
int ret;
char *str;
ret = av_bprint_finalize(buf, &str);
if (ret < 0)
return ret;
if (!av_bprint_is_complete(buf)) {
av_free(str);
return AVERROR(ENOMEM);
}
avctx->extradata = str;
/* Note: the string is NUL terminated (so extradata can be read as a
* string), but the ending character is not accounted in the size (in
* binary formats you are likely not supposed to mux that character). When
* extradata is copied, it is also padded with AV_INPUT_BUFFER_PADDING_SIZE
* zeros. */
avctx->extradata_size = buf->len;
return 0;
}
static int dvdsub_init(AVCodecContext *avctx)
{
DVDSubtitleContext *dvdc = avctx->priv_data;
static const uint32_t default_palette[16] = {
0x000000, 0x0000FF, 0x00FF00, 0xFF0000,
0xFFFF00, 0xFF00FF, 0x00FFFF, 0xFFFFFF,
0x808000, 0x8080FF, 0x800080, 0x80FF80,
0x008080, 0xFF8080, 0x555555, 0xAAAAAA,
};
AVBPrint extradata;
int i, ret;
av_assert0(sizeof(dvdc->global_palette) == sizeof(default_palette));
if (dvdc->palette_str) {
ff_dvdsub_parse_palette(dvdc->global_palette, dvdc->palette_str);
} else {
memcpy(dvdc->global_palette, default_palette, sizeof(dvdc->global_palette));
}
av_bprint_init(&extradata, 0, AV_BPRINT_SIZE_AUTOMATIC);
if (avctx->width && avctx->height)
av_bprintf(&extradata, "size: %dx%d\n", avctx->width, avctx->height);
av_bprintf(&extradata, "palette:");
for (i = 0; i < 16; i++)
av_bprintf(&extradata, " %06"PRIx32"%c",
dvdc->global_palette[i] & 0xFFFFFF, i < 15 ? ',' : '\n');
ret = bprint_to_extradata(avctx, &extradata);
if (ret < 0)
return ret;
return 0;
}
static int dvdsub_encode(AVCodecContext *avctx,
unsigned char *buf, int buf_size,
const AVSubtitle *sub)
{
//DVDSubtitleContext *s = avctx->priv_data;
int ret;
ret = encode_dvd_subtitles(avctx, buf, buf_size, sub);
return ret;
}
#define OFFSET(x) offsetof(DVDSubtitleContext, x)
#define SE AV_OPT_FLAG_SUBTITLE_PARAM | AV_OPT_FLAG_ENCODING_PARAM
static const AVOption options[] = {
{"palette", "set the global palette", OFFSET(palette_str), AV_OPT_TYPE_STRING, { .str = NULL }, 0, 0, SE },
{"even_rows_fix", "Make number of rows even (workaround for some players)", OFFSET(even_rows_fix), AV_OPT_TYPE_BOOL, {.i64 = 0}, 0, 1, SE},
{ NULL },
};
static const AVClass dvdsubenc_class = {
.class_name = "VOBSUB subtitle encoder",
.item_name = av_default_item_name,
.option = options,
.version = LIBAVUTIL_VERSION_INT,
};
const AVCodec ff_dvdsub_encoder = {
.name = "dvdsub",
.long_name = NULL_IF_CONFIG_SMALL("DVD subtitles"),
.type = AVMEDIA_TYPE_SUBTITLE,
.id = AV_CODEC_ID_DVD_SUBTITLE,
.init = dvdsub_init,
.encode_sub = dvdsub_encode,
.priv_class = &dvdsubenc_class,
.priv_data_size = sizeof(DVDSubtitleContext),
.caps_internal = FF_CODEC_CAP_INIT_THREADSAFE,
};
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