FFmpeg: libavcodec/dvdsubdec.c Source File

00001 /*
00002  * DVD subtitle decoding for ffmpeg
00003  * Copyright (c) 2005 Fabrice Bellard
00004  *
00005  * This file is part of FFmpeg.
00006  *
00007  * FFmpeg is free software; you can redistribute it and/or
00008  * modify it under the terms of the GNU Lesser General Public
00009  * License as published by the Free Software Foundation; either
00010  * version 2.1 of the License, or (at your option) any later version.
00011  *
00012  * FFmpeg is distributed in the hope that it will be useful,
00013  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00014  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00015  * Lesser General Public License for more details.
00016  *
00017  * You should have received a copy of the GNU Lesser General Public
00018  * License along with FFmpeg; if not, write to the Free Software
00019  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00020  */
00021 #include "avcodec.h"
00022 #include "get_bits.h"
00023 #include "colorspace.h"
00024 #include "dsputil.h"
00025 
00026 //#define DEBUG
00027 
00028 static void yuv_a_to_rgba(const uint8_t *ycbcr, const uint8_t *alpha, uint32_t *rgba, int num_values)
00029 {
00030     uint8_t *cm = ff_cropTbl + MAX_NEG_CROP;
00031     uint8_t r, g, b;
00032     int i, y, cb, cr;
00033     int r_add, g_add, b_add;
00034 
00035     for (i = num_values; i > 0; i--) {
00036         y = *ycbcr++;
00037         cb = *ycbcr++;
00038         cr = *ycbcr++;
00039         YUV_TO_RGB1_CCIR(cb, cr);
00040         YUV_TO_RGB2_CCIR(r, g, b, y);
00041         *rgba++ = (*alpha++ << 24) | (r << 16) | (g << 8) | b;
00042     }
00043 }
00044 
00045 static int decode_run_2bit(GetBitContext *gb, int *color)
00046 {
00047     unsigned int v, t;
00048 
00049     v = 0;
00050     for (t = 1; v < t && t <= 0x40; t <<= 2)
00051         v = (v << 4) | get_bits(gb, 4);
00052     *color = v & 3;
00053     if (v < 4) { /* Code for fill rest of line */
00054         return INT_MAX;
00055     }
00056     return v >> 2;
00057 }
00058 
00059 static int decode_run_8bit(GetBitContext *gb, int *color)
00060 {
00061     int len;
00062     int has_run = get_bits1(gb);
00063     if (get_bits1(gb))
00064         *color = get_bits(gb, 8);
00065     else
00066         *color = get_bits(gb, 2);
00067     if (has_run) {
00068         if (get_bits1(gb)) {
00069             len = get_bits(gb, 7);
00070             if (len == 0)
00071                 len = INT_MAX;
00072             else
00073                 len += 9;
00074         } else
00075             len = get_bits(gb, 3) + 2;
00076     } else
00077         len = 1;
00078     return len;
00079 }
00080 
00081 static int decode_rle(uint8_t *bitmap, int linesize, int w, int h,
00082                       const uint8_t *buf, int start, int buf_size, int is_8bit)
00083 {
00084     GetBitContext gb;
00085     int bit_len;
00086     int x, y, len, color;
00087     uint8_t *d;
00088 
00089     bit_len = (buf_size - start) * 8;
00090     init_get_bits(&gb, buf + start, bit_len);
00091 
00092     x = 0;
00093     y = 0;
00094     d = bitmap;
00095     for(;;) {
00096         if (get_bits_count(&gb) > bit_len)
00097             return -1;
00098         if (is_8bit)
00099             len = decode_run_8bit(&gb, &color);
00100         else
00101             len = decode_run_2bit(&gb, &color);
00102         len = FFMIN(len, w - x);
00103         memset(d + x, color, len);
00104         x += len;
00105         if (x >= w) {
00106             y++;
00107             if (y >= h)
00108                 break;
00109             d += linesize;
00110             x = 0;
00111             /* byte align */
00112             align_get_bits(&gb);
00113         }
00114     }
00115     return 0;
00116 }
00117 
00118 static void guess_palette(uint32_t *rgba_palette,
00119                           uint8_t *colormap,
00120                           uint8_t *alpha,
00121                           uint32_t subtitle_color)
00122 {
00123     uint8_t color_used[16];
00124     int nb_opaque_colors, i, level, j, r, g, b;
00125 
00126     for(i = 0; i < 4; i++)
00127         rgba_palette[i] = 0;
00128 
00129     memset(color_used, 0, 16);
00130     nb_opaque_colors = 0;
00131     for(i = 0; i < 4; i++) {
00132         if (alpha[i] != 0 && !color_used[colormap[i]]) {
00133             color_used[colormap[i]] = 1;
00134             nb_opaque_colors++;
00135         }
00136     }
00137 
00138     if (nb_opaque_colors == 0)
00139         return;
00140 
00141     j = nb_opaque_colors;
00142     memset(color_used, 0, 16);
00143     for(i = 0; i < 4; i++) {
00144         if (alpha[i] != 0) {
00145             if (!color_used[colormap[i]])  {
00146                 level = (0xff * j) / nb_opaque_colors;
00147                 r = (((subtitle_color >> 16) & 0xff) * level) >> 8;
00148                 g = (((subtitle_color >> 8) & 0xff) * level) >> 8;
00149                 b = (((subtitle_color >> 0) & 0xff) * level) >> 8;
00150                 rgba_palette[i] = b | (g << 8) | (r << 16) | ((alpha[i] * 17) << 24);
00151                 color_used[colormap[i]] = (i + 1);
00152                 j--;
00153             } else {
00154                 rgba_palette[i] = (rgba_palette[color_used[colormap[i]] - 1] & 0x00ffffff) |
00155                                     ((alpha[i] * 17) << 24);
00156             }
00157         }
00158     }
00159 }
00160 
00161 #define READ_OFFSET(a) (big_offsets ? AV_RB32(a) : AV_RB16(a))
00162 
00163 static int decode_dvd_subtitles(AVSubtitle *sub_header,
00164                                 const uint8_t *buf, int buf_size)
00165 {
00166     int cmd_pos, pos, cmd, x1, y1, x2, y2, offset1, offset2, next_cmd_pos;
00167     int big_offsets, offset_size, is_8bit = 0;
00168     const uint8_t *yuv_palette = 0;
00169     uint8_t colormap[4], alpha[256];
00170     int date;
00171     int i;
00172     int is_menu = 0;
00173 
00174     if (buf_size < 10)
00175         return -1;
00176     memset(sub_header, 0, sizeof(*sub_header));
00177 
00178     if (AV_RB16(buf) == 0) {   /* HD subpicture with 4-byte offsets */
00179         big_offsets = 1;
00180         offset_size = 4;
00181         cmd_pos = 6;
00182     } else {
00183         big_offsets = 0;
00184         offset_size = 2;
00185         cmd_pos = 2;
00186     }
00187 
00188     cmd_pos = READ_OFFSET(buf + cmd_pos);
00189 
00190     while (cmd_pos > 0 && cmd_pos < buf_size - 2 - offset_size) {
00191         date = AV_RB16(buf + cmd_pos);
00192         next_cmd_pos = READ_OFFSET(buf + cmd_pos + 2);
00193         dprintf(NULL, "cmd_pos=0x%04x next=0x%04x date=%d\n",
00194                 cmd_pos, next_cmd_pos, date);
00195         pos = cmd_pos + 2 + offset_size;
00196         offset1 = -1;
00197         offset2 = -1;
00198         x1 = y1 = x2 = y2 = 0;
00199         while (pos < buf_size) {
00200             cmd = buf[pos++];
00201             dprintf(NULL, "cmd=%02x\n", cmd);
00202             switch(cmd) {
00203             case 0x00:
00204                 /* menu subpicture */
00205                 is_menu = 1;
00206                 break;
00207             case 0x01:
00208                 /* set start date */
00209                 sub_header->start_display_time = (date << 10) / 90;
00210                 break;
00211             case 0x02:
00212                 /* set end date */
00213                 sub_header->end_display_time = (date << 10) / 90;
00214                 break;
00215             case 0x03:
00216                 /* set colormap */
00217                 if ((buf_size - pos) < 2)
00218                     goto fail;
00219                 colormap[3] = buf[pos] >> 4;
00220                 colormap[2] = buf[pos] & 0x0f;
00221                 colormap[1] = buf[pos + 1] >> 4;
00222                 colormap[0] = buf[pos + 1] & 0x0f;
00223                 pos += 2;
00224                 break;
00225             case 0x04:
00226                 /* set alpha */
00227                 if ((buf_size - pos) < 2)
00228                     goto fail;
00229                 alpha[3] = buf[pos] >> 4;
00230                 alpha[2] = buf[pos] & 0x0f;
00231                 alpha[1] = buf[pos + 1] >> 4;
00232                 alpha[0] = buf[pos + 1] & 0x0f;
00233                 pos += 2;
00234             dprintf(NULL, "alpha=%x%x%x%x\n", alpha[0],alpha[1],alpha[2],alpha[3]);
00235                 break;
00236             case 0x05:
00237             case 0x85:
00238                 if ((buf_size - pos) < 6)
00239                     goto fail;
00240                 x1 = (buf[pos] << 4) | (buf[pos + 1] >> 4);
00241                 x2 = ((buf[pos + 1] & 0x0f) << 8) | buf[pos + 2];
00242                 y1 = (buf[pos + 3] << 4) | (buf[pos + 4] >> 4);
00243                 y2 = ((buf[pos + 4] & 0x0f) << 8) | buf[pos + 5];
00244                 if (cmd & 0x80)
00245                     is_8bit = 1;
00246                 dprintf(NULL, "x1=%d x2=%d y1=%d y2=%d\n", x1, x2, y1, y2);
00247                 pos += 6;
00248                 break;
00249             case 0x06:
00250                 if ((buf_size - pos) < 4)
00251                     goto fail;
00252                 offset1 = AV_RB16(buf + pos);
00253                 offset2 = AV_RB16(buf + pos + 2);
00254                 dprintf(NULL, "offset1=0x%04x offset2=0x%04x\n", offset1, offset2);
00255                 pos += 4;
00256                 break;
00257             case 0x86:
00258                 if ((buf_size - pos) < 8)
00259                     goto fail;
00260                 offset1 = AV_RB32(buf + pos);
00261                 offset2 = AV_RB32(buf + pos + 4);
00262                 dprintf(NULL, "offset1=0x%04x offset2=0x%04x\n", offset1, offset2);
00263                 pos += 8;
00264                 break;
00265 
00266             case 0x83:
00267                 /* HD set palette */
00268                 if ((buf_size - pos) < 768)
00269                     goto fail;
00270                 yuv_palette = buf + pos;
00271                 pos += 768;
00272                 break;
00273             case 0x84:
00274                 /* HD set contrast (alpha) */
00275                 if ((buf_size - pos) < 256)
00276                     goto fail;
00277                 for (i = 0; i < 256; i++)
00278                     alpha[i] = 0xFF - buf[pos+i];
00279                 pos += 256;
00280                 break;
00281 
00282             case 0xff:
00283                 goto the_end;
00284             default:
00285                 dprintf(NULL, "unrecognised subpicture command 0x%x\n", cmd);
00286                 goto the_end;
00287             }
00288         }
00289     the_end:
00290         if (offset1 >= 0) {
00291             int w, h;
00292             uint8_t *bitmap;
00293 
00294             /* decode the bitmap */
00295             w = x2 - x1 + 1;
00296             if (w < 0)
00297                 w = 0;
00298             h = y2 - y1;
00299             if (h < 0)
00300                 h = 0;
00301             if (w > 0 && h > 0) {
00302                 if (sub_header->rects != NULL) {
00303                     for (i = 0; i < sub_header->num_rects; i++) {
00304                         av_freep(&sub_header->rects[i]->pict.data[0]);
00305                         av_freep(&sub_header->rects[i]->pict.data[1]);
00306                         av_freep(&sub_header->rects[i]);
00307                     }
00308                     av_freep(&sub_header->rects);
00309                     sub_header->num_rects = 0;
00310                 }
00311 
00312                 bitmap = av_malloc(w * h);
00313                 sub_header->rects = av_mallocz(sizeof(*sub_header->rects));
00314                 sub_header->rects[0] = av_mallocz(sizeof(AVSubtitleRect));
00315                 sub_header->num_rects = 1;
00316                 sub_header->rects[0]->pict.data[0] = bitmap;
00317                 decode_rle(bitmap, w * 2, w, (h + 1) / 2,
00318                            buf, offset1, buf_size, is_8bit);
00319                 decode_rle(bitmap + w, w * 2, w, h / 2,
00320                            buf, offset2, buf_size, is_8bit);
00321                 sub_header->rects[0]->pict.data[1] = av_mallocz(AVPALETTE_SIZE);
00322                 if (is_8bit) {
00323                     if (yuv_palette == 0)
00324                         goto fail;
00325                     sub_header->rects[0]->nb_colors = 256;
00326                     yuv_a_to_rgba(yuv_palette, alpha, (uint32_t*)sub_header->rects[0]->pict.data[1], 256);
00327                 } else {
00328                     sub_header->rects[0]->nb_colors = 4;
00329                     guess_palette((uint32_t*)sub_header->rects[0]->pict.data[1],
00330                                   colormap, alpha, 0xffff00);
00331                 }
00332                 sub_header->rects[0]->x = x1;
00333                 sub_header->rects[0]->y = y1;
00334                 sub_header->rects[0]->w = w;
00335                 sub_header->rects[0]->h = h;
00336                 sub_header->rects[0]->type = SUBTITLE_BITMAP;
00337                 sub_header->rects[0]->pict.linesize[0] = w;
00338             }
00339         }
00340         if (next_cmd_pos == cmd_pos)
00341             break;
00342         cmd_pos = next_cmd_pos;
00343     }
00344     if (sub_header->num_rects > 0)
00345         return is_menu;
00346  fail:
00347     if (sub_header->rects != NULL) {
00348         for (i = 0; i < sub_header->num_rects; i++) {
00349             av_freep(&sub_header->rects[i]->pict.data[0]);
00350             av_freep(&sub_header->rects[i]->pict.data[1]);
00351             av_freep(&sub_header->rects[i]);
00352         }
00353         av_freep(&sub_header->rects);
00354         sub_header->num_rects = 0;
00355     }
00356     return -1;
00357 }
00358 
00359 static int is_transp(const uint8_t *buf, int pitch, int n,
00360                      const uint8_t *transp_color)
00361 {
00362     int i;
00363     for(i = 0; i < n; i++) {
00364         if (!transp_color[*buf])
00365             return 0;
00366         buf += pitch;
00367     }
00368     return 1;
00369 }
00370 
00371 /* return 0 if empty rectangle, 1 if non empty */
00372 static int find_smallest_bounding_rectangle(AVSubtitle *s)
00373 {
00374     uint8_t transp_color[256];
00375     int y1, y2, x1, x2, y, w, h, i;
00376     uint8_t *bitmap;
00377 
00378     if (s->num_rects == 0 || s->rects == NULL || s->rects[0]->w <= 0 || s->rects[0]->h <= 0)
00379         return 0;
00380 
00381     memset(transp_color, 0, 256);
00382     for(i = 0; i < s->rects[0]->nb_colors; i++) {
00383         if ((((uint32_t*)s->rects[0]->pict.data[1])[i] >> 24) == 0)
00384             transp_color[i] = 1;
00385     }
00386     y1 = 0;
00387     while (y1 < s->rects[0]->h && is_transp(s->rects[0]->pict.data[0] + y1 * s->rects[0]->pict.linesize[0],
00388                                   1, s->rects[0]->w, transp_color))
00389         y1++;
00390     if (y1 == s->rects[0]->h) {
00391         av_freep(&s->rects[0]->pict.data[0]);
00392         s->rects[0]->w = s->rects[0]->h = 0;
00393         return 0;
00394     }
00395 
00396     y2 = s->rects[0]->h - 1;
00397     while (y2 > 0 && is_transp(s->rects[0]->pict.data[0] + y2 * s->rects[0]->pict.linesize[0], 1,
00398                                s->rects[0]->w, transp_color))
00399         y2--;
00400     x1 = 0;
00401     while (x1 < (s->rects[0]->w - 1) && is_transp(s->rects[0]->pict.data[0] + x1, s->rects[0]->pict.linesize[0],
00402                                         s->rects[0]->h, transp_color))
00403         x1++;
00404     x2 = s->rects[0]->w - 1;
00405     while (x2 > 0 && is_transp(s->rects[0]->pict.data[0] + x2, s->rects[0]->pict.linesize[0], s->rects[0]->h,
00406                                   transp_color))
00407         x2--;
00408     w = x2 - x1 + 1;
00409     h = y2 - y1 + 1;
00410     bitmap = av_malloc(w * h);
00411     if (!bitmap)
00412         return 1;
00413     for(y = 0; y < h; y++) {
00414         memcpy(bitmap + w * y, s->rects[0]->pict.data[0] + x1 + (y1 + y) * s->rects[0]->pict.linesize[0], w);
00415     }
00416     av_freep(&s->rects[0]->pict.data[0]);
00417     s->rects[0]->pict.data[0] = bitmap;
00418     s->rects[0]->pict.linesize[0] = w;
00419     s->rects[0]->w = w;
00420     s->rects[0]->h = h;
00421     s->rects[0]->x += x1;
00422     s->rects[0]->y += y1;
00423     return 1;
00424 }
00425 
00426 #ifdef DEBUG
00427 #undef fprintf
00428 #undef perror
00429 #undef exit
00430 static void ppm_save(const char *filename, uint8_t *bitmap, int w, int h,
00431                      uint32_t *rgba_palette)
00432 {
00433     int x, y, v;
00434     FILE *f;
00435 
00436     f = fopen(filename, "w");
00437     if (!f) {
00438         perror(filename);
00439         exit(1);
00440     }
00441     fprintf(f, "P6\n"
00442             "%d %d\n"
00443             "%d\n",
00444             w, h, 255);
00445     for(y = 0; y < h; y++) {
00446         for(x = 0; x < w; x++) {
00447             v = rgba_palette[bitmap[y * w + x]];
00448             putc((v >> 16) & 0xff, f);
00449             putc((v >> 8) & 0xff, f);
00450             putc((v >> 0) & 0xff, f);
00451         }
00452     }
00453     fclose(f);
00454 }
00455 #endif
00456 
00457 static int dvdsub_decode(AVCodecContext *avctx,
00458                          void *data, int *data_size,
00459                          AVPacket *avpkt)
00460 {
00461     const uint8_t *buf = avpkt->data;
00462     int buf_size = avpkt->size;
00463     AVSubtitle *sub = (void *)data;
00464     int is_menu;
00465 
00466     is_menu = decode_dvd_subtitles(sub, buf, buf_size);
00467 
00468     if (is_menu < 0) {
00469     no_subtitle:
00470         *data_size = 0;
00471 
00472         return buf_size;
00473     }
00474     if (!is_menu && find_smallest_bounding_rectangle(sub) == 0)
00475         goto no_subtitle;
00476 
00477 #if defined(DEBUG)
00478     dprintf(NULL, "start=%d ms end =%d ms\n",
00479             sub->start_display_time,
00480             sub->end_display_time);
00481     ppm_save("/tmp/a.ppm", sub->rects[0]->pict.data[0],
00482              sub->rects[0]->w, sub->rects[0]->h, sub->rects[0]->pict.data[1]);
00483 #endif
00484 
00485     *data_size = 1;
00486     return buf_size;
00487 }
00488 
00489 AVCodec dvdsub_decoder = {
00490     "dvdsub",
00491     AVMEDIA_TYPE_SUBTITLE,
00492     CODEC_ID_DVD_SUBTITLE,
00493     0,
00494     NULL,
00495     NULL,
00496     NULL,
00497     dvdsub_decode,
00498     .long_name = NULL_IF_CONFIG_SMALL("DVD subtitles"),
00499 };