libavcodec/dvdsubdec.c - third_party/ffmpeg - Git at Google

 /*
  * DVD subtitle decoding
  * 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

 typedef struct DVDSubContext
 {
   uint32_t palette[16];
   int      has_palette;
   uint8_t  colormap[4];
   uint8_t  alpha[256];
 } DVDSubContext;

 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,
                           DVDSubContext* ctx,
                           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;
     uint8_t *colormap = ctx->colormap, *alpha = ctx->alpha;

     if(ctx->has_palette) {
         for(i = 0; i < 4; i++)
             rgba_palette[i] = (ctx->palette[colormap[i]] & 0x00ffffff)
                               | ((alpha[i] * 17) << 24);
         return;
     }

     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(DVDSubContext *ctx, 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 = ctx->colormap, *alpha = ctx->alpha;
     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], ctx,
                                   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)
 {
     DVDSubContext *ctx = (DVDSubContext*) avctx->priv_data;
     const uint8_t *buf = avpkt->data;
     int buf_size = avpkt->size;
     AVSubtitle *sub = data;
     int is_menu;

     is_menu = decode_dvd_subtitles(ctx, 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;
 }

 static int dvdsub_init(AVCodecContext *avctx)
 {
     DVDSubContext *ctx = (DVDSubContext*) avctx->priv_data;
     char *dataorig, *data;

     if (!avctx->extradata || !avctx->extradata_size)
         return 1;

     dataorig = data = av_malloc(avctx->extradata_size+1);
     if (!data)
         return AVERROR(ENOMEM);
     memcpy(data, avctx->extradata, avctx->extradata_size);
     data[avctx->extradata_size] = '\0';

     for(;;) {
         int pos = strcspn(data, "\n\r");
         if (pos==0 && *data==0)
             break;

         if (strncmp("palette:", data, 8) == 0) {
             int i;
             char *p = data+8;
             ctx->has_palette = 1;
             for(i=0;i<16;i++) {
                 ctx->palette[i] = strtoul(p, &p, 16);
                 while(*p == ',' || isspace(*p))
                     p++;
             }
         }

         data += pos;
         data += strspn(data, "\n\r");
     }

     if (ctx->has_palette) {
         int i;
         av_log(avctx, AV_LOG_DEBUG, "palette:");
         for(i=0;i<16;i++)
             av_log(avctx, AV_LOG_DEBUG, " 0x%06x", ctx->palette[i]);
         av_log(avctx, AV_LOG_DEBUG, "\n");
     }

     av_free(dataorig);
     return 1;
 }

 AVCodec ff_dvdsub_decoder = {
     .name           = "dvdsub",
     .type           = AVMEDIA_TYPE_SUBTITLE,
     .id             = CODEC_ID_DVD_SUBTITLE,
     .priv_data_size = sizeof(DVDSubContext),
     .init           = dvdsub_init,
     .decode         = dvdsub_decode,
     .long_name = NULL_IF_CONFIG_SMALL("DVD subtitles"),
 };
	/*
	* DVD subtitle decoding
	* 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

	typedef struct DVDSubContext
	{
	uint32_t palette[16];
	int has_palette;
	uint8_t colormap[4];
	uint8_t alpha[256];
	} DVDSubContext;

	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,
	DVDSubContext* ctx,
	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;
	uint8_t colormap = ctx->colormap, alpha = ctx->alpha;

	if(ctx->has_palette) {
	for(i = 0; i < 4; i++)
	rgba_palette[i] = (ctx->palette[colormap[i]] & 0x00ffffff)
	\| ((alpha[i] * 17) << 24);
	return;
	}

	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(DVDSubContext ctx, 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 = ctx->colormap, alpha = ctx->alpha;
	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], ctx,
	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)
	{
	DVDSubContext ctx = (DVDSubContext) avctx->priv_data;
	const uint8_t *buf = avpkt->data;
	int buf_size = avpkt->size;
	AVSubtitle *sub = data;
	int is_menu;

	is_menu = decode_dvd_subtitles(ctx, 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;
	}

	static int dvdsub_init(AVCodecContext *avctx)
	{
	DVDSubContext ctx = (DVDSubContext) avctx->priv_data;
	char dataorig, data;

	if (!avctx->extradata \|\| !avctx->extradata_size)
	return 1;

	dataorig = data = av_malloc(avctx->extradata_size+1);
	if (!data)
	return AVERROR(ENOMEM);
	memcpy(data, avctx->extradata, avctx->extradata_size);
	data[avctx->extradata_size] = '\0';

	for(;;) {
	int pos = strcspn(data, "\n\r");
	if (pos==0 && *data==0)
	break;

	if (strncmp("palette:", data, 8) == 0) {
	int i;
	char *p = data+8;
	ctx->has_palette = 1;
	for(i=0;i<16;i++) {
	ctx->palette[i] = strtoul(p, &p, 16);
	while(p == ',' \|\| isspace(p))
	p++;
	}
	}

	data += pos;
	data += strspn(data, "\n\r");
	}

	if (ctx->has_palette) {
	int i;
	av_log(avctx, AV_LOG_DEBUG, "palette:");
	for(i=0;i<16;i++)
	av_log(avctx, AV_LOG_DEBUG, " 0x%06x", ctx->palette[i]);
	av_log(avctx, AV_LOG_DEBUG, "\n");
	}

	av_free(dataorig);
	return 1;
	}

	AVCodec ff_dvdsub_decoder = {
	.name = "dvdsub",
	.type = AVMEDIA_TYPE_SUBTITLE,
	.id = CODEC_ID_DVD_SUBTITLE,
	.priv_data_size = sizeof(DVDSubContext),
	.init = dvdsub_init,
	.decode = dvdsub_decode,
	.long_name = NULL_IF_CONFIG_SMALL("DVD subtitles"),
	};