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2dedd8f496
DVD subtitles packets can only encode a single rectangle: if there are several, copy them into a big transparent one. DVD subtitles rely on an external 16-colors palette: use a reasonable default one, stored in the private context, and encode it into the extradata, as specified by Matroska. TODO: allow to change the palette with an option. Each packet can use four colors out of the global palette. The old logic was to map transparent colors to the color 0 and all other colors to 3, 2, 1, cyclically in descending frequency order, completely disregarding the original color. Select the "best" four colors from the global palette, according to heuristics based on frequency, opacity and brightness, and arrange them in standard DVD order: background, foreground, outline, other. TODO: select the alpha value more finely; see if CHG_COLCON can allow more than 4 colors per packet. Reference: http://dvd.sourceforge.net/dvdinfo/spu.html With these changes, dvdsubenc can be used to transcode DVB subtitles and get a very decent result.
433 lines
14 KiB
C
433 lines
14 KiB
C
/*
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* DVD subtitle encoding
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* Copyright (c) 2005 Wolfram Gloger
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include "avcodec.h"
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#include "bytestream.h"
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#include "libavutil/avassert.h"
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#include "libavutil/bprint.h"
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#include "libavutil/imgutils.h"
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typedef struct {
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uint32_t global_palette[16];
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} DVDSubtitleContext;
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// ncnt is the nibble counter
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#define PUTNIBBLE(val)\
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do {\
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if (ncnt++ & 1)\
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*q++ = bitbuf | ((val) & 0x0f);\
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else\
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bitbuf = (val) << 4;\
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} while(0)
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static void dvd_encode_rle(uint8_t **pq,
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const uint8_t *bitmap, int linesize,
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int w, int h,
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const int cmap[256])
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{
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uint8_t *q;
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unsigned int bitbuf = 0;
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int ncnt;
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int x, y, len, color;
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q = *pq;
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for (y = 0; y < h; ++y) {
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ncnt = 0;
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for(x = 0; x < w; x += len) {
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color = bitmap[x];
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for (len=1; x+len < w; ++len)
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if (bitmap[x+len] != color)
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break;
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color = cmap[color];
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av_assert0(color < 4);
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if (len < 0x04) {
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PUTNIBBLE((len << 2)|color);
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} else if (len < 0x10) {
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PUTNIBBLE(len >> 2);
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PUTNIBBLE((len << 2)|color);
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} else if (len < 0x40) {
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PUTNIBBLE(0);
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PUTNIBBLE(len >> 2);
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PUTNIBBLE((len << 2)|color);
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} else if (x+len == w) {
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PUTNIBBLE(0);
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PUTNIBBLE(0);
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PUTNIBBLE(0);
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PUTNIBBLE(color);
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} else {
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if (len > 0xff)
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len = 0xff;
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PUTNIBBLE(0);
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PUTNIBBLE(len >> 6);
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PUTNIBBLE(len >> 2);
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PUTNIBBLE((len << 2)|color);
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}
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}
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/* end of line */
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if (ncnt & 1)
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PUTNIBBLE(0);
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bitmap += linesize;
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}
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*pq = q;
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}
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static int color_distance(uint32_t a, uint32_t b)
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{
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int r = 0, d, i;
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for (i = 0; i < 32; i += 8) {
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d = ((a >> i) & 0xFF) - ((b >> i) & 0xFF);
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r += d * d;
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}
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return r;
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}
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/**
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* Count colors used in a rectangle, quantizing alpha and grouping by
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* nearest global palette entry.
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*/
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static void count_colors(AVCodecContext *avctx, unsigned hits[33],
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const AVSubtitleRect *r)
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{
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DVDSubtitleContext *dvdc = avctx->priv_data;
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unsigned count[256] = { 0 };
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uint32_t *palette = (uint32_t *)r->pict.data[1];
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uint32_t color;
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int x, y, i, j, match, d, best_d, av_uninit(best_j);
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uint8_t *p = r->pict.data[0];
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for (y = 0; y < r->h; y++) {
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for (x = 0; x < r->w; x++)
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count[*(p++)]++;
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p += r->pict.linesize[0] - r->w;
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}
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for (i = 0; i < 256; i++) {
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if (!count[i]) /* avoid useless search */
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continue;
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color = palette[i];
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/* 0: transparent, 1-16: semi-transparent, 17-33 opaque */
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match = color < 0x33000000 ? 0 : color < 0xCC000000 ? 1 : 17;
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if (match) {
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best_d = INT_MAX;
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for (j = 0; j < 16; j++) {
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d = color_distance(color & 0xFFFFFF, dvdc->global_palette[j]);
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if (d < best_d) {
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best_d = d;
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best_j = j;
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}
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}
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match += best_j;
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}
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hits[match] += count[i];
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}
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}
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static void select_palette(AVCodecContext *avctx, int out_palette[4],
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int out_alpha[4], unsigned hits[33])
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{
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DVDSubtitleContext *dvdc = avctx->priv_data;
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int i, j, bright, mult;
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uint32_t color;
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int selected[4] = { 0 };
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uint32_t pseudopal[33] = { 0 };
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uint32_t refcolor[3] = { 0x00000000, 0xFFFFFFFF, 0xFF000000 };
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/* Bonus for transparent: if the rectangle fits tightly the text, the
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background color can be quite rare, but it would be ugly without it */
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hits[0] *= 16;
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/* Bonus for bright colors */
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for (i = 0; i < 16; i++) {
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if (!(hits[1 + i] + hits[17 + i]))
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continue; /* skip unused colors to gain time */
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color = dvdc->global_palette[i];
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bright = 0;
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for (j = 0; j < 3; j++, color >>= 8)
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bright += (color & 0xFF) < 0x40 || (color & 0xFF) >= 0xC0;
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mult = 2 + FFMIN(bright, 2);
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hits[ 1 + i] *= mult;
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hits[17 + i] *= mult;
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}
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/* Select four most frequent colors */
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for (i = 0; i < 4; i++) {
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for (j = 0; j < 33; j++)
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if (hits[j] > hits[selected[i]])
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selected[i] = j;
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hits[selected[i]] = 0;
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}
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/* Order the colors like in most DVDs:
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0: background, 1: foreground, 2: outline */
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for (i = 0; i < 16; i++) {
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pseudopal[ 1 + i] = 0x80000000 | dvdc->global_palette[i];
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pseudopal[17 + i] = 0xFF000000 | dvdc->global_palette[i];
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}
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for (i = 0; i < 3; i++) {
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int best_d = color_distance(refcolor[i], pseudopal[selected[i]]);
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for (j = i + 1; j < 4; j++) {
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int d = color_distance(refcolor[i], pseudopal[selected[j]]);
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if (d < best_d) {
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FFSWAP(int, selected[i], selected[j]);
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best_d = d;
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}
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}
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}
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/* Output */
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for (i = 0; i < 4; i++) {
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out_palette[i] = selected[i] ? (selected[i] - 1) & 0xF : 0;
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out_alpha [i] = !selected[i] ? 0 : selected[i] < 17 ? 0x80 : 0xFF;
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}
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}
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static void build_color_map(AVCodecContext *avctx, int cmap[],
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const uint32_t palette[],
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const int out_palette[], int const out_alpha[])
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{
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DVDSubtitleContext *dvdc = avctx->priv_data;
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int i, j, d, best_d;
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uint32_t pseudopal[4];
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for (i = 0; i < 4; i++)
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pseudopal[i] = (out_alpha[i] << 24) |
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dvdc->global_palette[out_palette[i]];
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for (i = 0; i < 256; i++) {
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best_d = INT_MAX;
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for (j = 0; j < 4; j++) {
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d = color_distance(pseudopal[j], palette[i]);
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if (d < best_d) {
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cmap[i] = j;
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best_d = d;
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}
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}
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}
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}
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static void copy_rectangle(AVSubtitleRect *dst, AVSubtitleRect *src, int cmap[])
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{
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int x, y;
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uint8_t *p, *q;
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p = src->pict.data[0];
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q = dst->pict.data[0] + (src->x - dst->x) +
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(src->y - dst->y) * dst->pict.linesize[0];
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for (y = 0; y < src->h; y++) {
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for (x = 0; x < src->w; x++)
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*(q++) = cmap[*(p++)];
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p += src->pict.linesize[0] - src->w;
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q += dst->pict.linesize[0] - src->w;
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}
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}
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static int encode_dvd_subtitles(AVCodecContext *avctx,
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uint8_t *outbuf, int outbuf_size,
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const AVSubtitle *h)
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{
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DVDSubtitleContext *dvdc = avctx->priv_data;
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uint8_t *q, *qq;
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int offset1, offset2;
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int i, rects = h->num_rects, ret;
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unsigned global_palette_hits[33] = { 0 };
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int cmap[256];
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int out_palette[4];
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int out_alpha[4];
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AVSubtitleRect vrect;
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uint8_t *vrect_data = NULL;
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int x2, y2;
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if (rects == 0 || h->rects == NULL)
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return AVERROR(EINVAL);
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vrect = *h->rects[0];
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if (rects > 1) {
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/* DVD subtitles can have only one rectangle: build a virtual
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rectangle containing all actual rectangles.
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The data of the rectangles will be copied later, when the palette
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is decided, because the rectangles may have different palettes. */
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int xmin = h->rects[0]->x, xmax = xmin + h->rects[0]->w;
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int ymin = h->rects[0]->y, ymax = ymin + h->rects[0]->h;
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for (i = 1; i < rects; i++) {
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xmin = FFMIN(xmin, h->rects[i]->x);
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ymin = FFMIN(ymin, h->rects[i]->y);
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xmax = FFMAX(xmax, h->rects[i]->x + h->rects[i]->w);
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ymax = FFMAX(ymax, h->rects[i]->y + h->rects[i]->h);
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}
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vrect.x = xmin;
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vrect.y = ymin;
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vrect.w = xmax - xmin;
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vrect.h = ymax - ymin;
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if ((ret = av_image_check_size(vrect.w, vrect.h, 0, avctx)) < 0)
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return ret;
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/* Count pixels outside the virtual rectangle as transparent */
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global_palette_hits[0] = vrect.w * vrect.h;
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for (i = 0; i < rects; i++)
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global_palette_hits[0] -= h->rects[i]->w * h->rects[i]->h;
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}
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for (i = 0; i < rects; i++)
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count_colors(avctx, global_palette_hits, h->rects[i]);
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select_palette(avctx, out_palette, out_alpha, global_palette_hits);
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if (rects > 1) {
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if (!(vrect_data = av_calloc(vrect.w, vrect.h)))
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return AVERROR(ENOMEM);
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vrect.pict.data [0] = vrect_data;
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vrect.pict.linesize[0] = vrect.w;
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for (i = 0; i < rects; i++) {
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build_color_map(avctx, cmap, (uint32_t *)h->rects[i]->pict.data[1],
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out_palette, out_alpha);
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copy_rectangle(&vrect, h->rects[i], cmap);
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}
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for (i = 0; i < 4; i++)
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cmap[i] = i;
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} else {
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build_color_map(avctx, cmap, (uint32_t *)h->rects[0]->pict.data[1],
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out_palette, out_alpha);
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}
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av_log(avctx, AV_LOG_DEBUG, "Selected palette:");
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for (i = 0; i < 4; i++)
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av_log(avctx, AV_LOG_DEBUG, " 0x%06x@@%02x (0x%x,0x%x)",
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dvdc->global_palette[out_palette[i]], out_alpha[i],
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out_palette[i], out_alpha[i] >> 4);
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av_log(avctx, AV_LOG_DEBUG, "\n");
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// encode data block
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q = outbuf + 4;
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/* TODO reindent */
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offset1 = q - outbuf;
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// worst case memory requirement: 1 nibble per pixel..
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if ((q - outbuf) + vrect.w * vrect.h / 2 + 17 + 21 > outbuf_size) {
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av_log(NULL, AV_LOG_ERROR, "dvd_subtitle too big\n");
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ret = AVERROR_BUFFER_TOO_SMALL;
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goto fail;
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}
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dvd_encode_rle(&q, vrect.pict.data[0], vrect.w * 2,
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vrect.w, (vrect.h + 1) >> 1, cmap);
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offset2 = q - outbuf;
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dvd_encode_rle(&q, vrect.pict.data[0] + vrect.w, vrect.w * 2,
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vrect.w, vrect.h >> 1, cmap);
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// set data packet size
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qq = outbuf + 2;
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bytestream_put_be16(&qq, q - outbuf);
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// send start display command
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bytestream_put_be16(&q, (h->start_display_time*90) >> 10);
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bytestream_put_be16(&q, (q - outbuf) /*- 2 */ + 8 + 12 + 2);
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*q++ = 0x03; // palette - 4 nibbles
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*q++ = (out_palette[3] << 4) | out_palette[2];
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*q++ = (out_palette[1] << 4) | out_palette[0];
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*q++ = 0x04; // alpha - 4 nibbles
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*q++ = (out_alpha[3] & 0xF0) | (out_alpha[2] >> 4);
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*q++ = (out_alpha[1] & 0xF0) | (out_alpha[0] >> 4);
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// 12 bytes per rect
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/* TODO reindent */
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x2 = vrect.x + vrect.w - 1;
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y2 = vrect.y + vrect.h - 1;
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*q++ = 0x05;
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// x1 x2 -> 6 nibbles
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*q++ = vrect.x >> 4;
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*q++ = (vrect.x << 4) | ((x2 >> 8) & 0xf);
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*q++ = x2;
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// y1 y2 -> 6 nibbles
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*q++ = vrect.y >> 4;
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*q++ = (vrect.y << 4) | ((y2 >> 8) & 0xf);
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*q++ = y2;
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*q++ = 0x06;
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// offset1, offset2
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bytestream_put_be16(&q, offset1);
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bytestream_put_be16(&q, offset2);
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*q++ = 0x01; // start command
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*q++ = 0xff; // terminating command
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// send stop display command last
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bytestream_put_be16(&q, (h->end_display_time*90) >> 10);
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bytestream_put_be16(&q, (q - outbuf) - 2 /*+ 4*/);
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*q++ = 0x02; // set end
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*q++ = 0xff; // terminating command
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qq = outbuf;
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bytestream_put_be16(&qq, q - outbuf);
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av_log(NULL, AV_LOG_DEBUG, "subtitle_packet size=%td\n", q - outbuf);
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ret = q - outbuf;
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fail:
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av_free(vrect_data);
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return ret;
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}
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static int dvdsub_init(AVCodecContext *avctx)
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{
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DVDSubtitleContext *dvdc = avctx->priv_data;
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static const uint32_t default_palette[16] = {
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0x000000, 0x0000FF, 0x00FF00, 0xFF0000,
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0xFFFF00, 0xFF00FF, 0x00FFFF, 0xFFFFFF,
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0x808000, 0x8080FF, 0x800080, 0x80FF80,
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0x008080, 0xFF8080, 0x555555, 0xAAAAAA,
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};
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AVBPrint extradata;
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int i, ret;
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av_assert0(sizeof(dvdc->global_palette) == sizeof(default_palette));
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memcpy(dvdc->global_palette, default_palette, sizeof(dvdc->global_palette));
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av_bprint_init(&extradata, 0, 1);
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av_bprintf(&extradata, "palette:");
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for (i = 0; i < 16; i++)
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av_bprintf(&extradata, " %06"PRIx32"%c",
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dvdc->global_palette[i] & 0xFFFFFF, i < 15 ? ',' : '\n');
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if ((ret = av_bprint_finalize(&extradata, (char **)&avctx->extradata)) < 0)
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return ret;
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avctx->extradata_size = extradata.len;
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return 0;
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}
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static int dvdsub_encode(AVCodecContext *avctx,
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unsigned char *buf, int buf_size, void *data)
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{
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//DVDSubtitleContext *s = avctx->priv_data;
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AVSubtitle *sub = data;
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int ret;
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ret = encode_dvd_subtitles(avctx, buf, buf_size, sub);
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return ret;
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}
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AVCodec ff_dvdsub_encoder = {
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.name = "dvdsub",
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.type = AVMEDIA_TYPE_SUBTITLE,
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.id = AV_CODEC_ID_DVD_SUBTITLE,
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.init = dvdsub_init,
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.encode = dvdsub_encode,
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.long_name = NULL_IF_CONFIG_SMALL("DVD subtitles"),
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.priv_data_size = sizeof(DVDSubtitleContext),
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};
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