1/* 2 * XSUB subtitle decoder 3 * Copyright (c) 2007 Reimar D��ffinger 4 * 5 * This file is part of FFmpeg. 6 * 7 * FFmpeg is free software; you can redistribute it and/or 8 * modify it under the terms of the GNU Lesser General Public 9 * License as published by the Free Software Foundation; either 10 * version 2.1 of the License, or (at your option) any later version. 11 * 12 * FFmpeg is distributed in the hope that it will be useful, 13 * but WITHOUT ANY WARRANTY; without even the implied warranty of 14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 15 * Lesser General Public License for more details. 16 * 17 * You should have received a copy of the GNU Lesser General Public 18 * License along with FFmpeg; if not, write to the Free Software 19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 20 */ 21#include "avcodec.h" 22#include "bitstream.h" 23#include "bytestream.h" 24 25static av_cold int decode_init(AVCodecContext *avctx) { 26 avctx->pix_fmt = PIX_FMT_PAL8; 27 return 0; 28} 29 30static const uint8_t tc_offsets[9] = { 0, 1, 3, 4, 6, 7, 9, 10, 11 }; 31static const uint8_t tc_muls[9] = { 10, 6, 10, 6, 10, 10, 10, 10, 1 }; 32 33static uint64_t parse_timecode(const uint8_t *buf) { 34 int i; 35 int64_t ms = 0; 36 if (buf[2] != ':' || buf[5] != ':' || buf[8] != '.') 37 return AV_NOPTS_VALUE; 38 for (i = 0; i < sizeof(tc_offsets); i++) { 39 uint8_t c = buf[tc_offsets[i]] - '0'; 40 if (c > 9) return AV_NOPTS_VALUE; 41 ms = (ms + c) * tc_muls[i]; 42 } 43 return ms; 44} 45 46static int decode_frame(AVCodecContext *avctx, void *data, int *data_size, 47 const uint8_t *buf, int buf_size) { 48 AVSubtitle *sub = data; 49 const uint8_t *buf_end = buf + buf_size; 50 uint8_t *bitmap; 51 int w, h, x, y, rlelen, i; 52 GetBitContext gb; 53 54 sub->format = 0; 55 56 // check that at least header fits 57 if (buf_size < 27 + 7 * 2 + 4 * 3) { 58 av_log(avctx, AV_LOG_ERROR, "coded frame too small\n"); 59 return -1; 60 } 61 62 // read start and end time 63 if (buf[0] != '[' || buf[13] != '-' || buf[26] != ']') { 64 av_log(avctx, AV_LOG_ERROR, "invalid time code\n"); 65 return -1; 66 } 67 sub->start_display_time = parse_timecode(buf + 1); 68 sub->end_display_time = parse_timecode(buf + 14); 69 buf += 27; 70 71 // read header 72 w = bytestream_get_le16(&buf); 73 h = bytestream_get_le16(&buf); 74 if (avcodec_check_dimensions(avctx, w, h) < 0) 75 return -1; 76 x = bytestream_get_le16(&buf); 77 y = bytestream_get_le16(&buf); 78 // skip bottom right position, it gives no new information 79 bytestream_get_le16(&buf); 80 bytestream_get_le16(&buf); 81 rlelen = bytestream_get_le16(&buf); 82 83 // allocate sub and set values 84 if (!sub->rects) { 85 sub->rects = av_mallocz(sizeof(*sub->rects)); 86 sub->rects[0] = av_mallocz(sizeof(*sub->rects[0])); 87 sub->num_rects = 1; 88 } 89 av_freep(&sub->rects[0]->pict.data[0]); 90 sub->rects[0]->x = x; sub->rects[0]->y = y; 91 sub->rects[0]->w = w; sub->rects[0]->h = h; 92 sub->rects[0]->pict.linesize[0] = w; 93 sub->rects[0]->pict.data[0] = av_malloc(w * h); 94 sub->rects[0]->nb_colors = 4; 95 sub->rects[0]->pict.data[1] = av_malloc(sub->rects[0]->nb_colors * 4); 96 97 // read palette 98 for (i = 0; i < sub->rects[0]->nb_colors; i++) 99 ((uint32_t*)sub->rects[0]->pict.data[1])[i] = bytestream_get_be24(&buf); 100 // make all except background (first entry) non-transparent 101 for (i = 1; i < sub->rects[0]->nb_colors; i++) 102 ((uint32_t*)sub->rects[0]->pict.data[1])[i] |= 0xff000000; 103 104 // process RLE-compressed data 105 rlelen = FFMIN(rlelen, buf_end - buf); 106 init_get_bits(&gb, buf, rlelen * 8); 107 bitmap = sub->rects[0]->pict.data[0]; 108 for (y = 0; y < h; y++) { 109 // interlaced: do odd lines 110 if (y == (h + 1) / 2) bitmap = sub->rects[0]->pict.data[0] + w; 111 for (x = 0; x < w; ) { 112 int log2 = ff_log2_tab[show_bits(&gb, 8)]; 113 int run = get_bits(&gb, 14 - 4 * (log2 >> 1)); 114 int color = get_bits(&gb, 2); 115 run = FFMIN(run, w - x); 116 // run length 0 means till end of row 117 if (!run) run = w - x; 118 memset(bitmap, color, run); 119 bitmap += run; 120 x += run; 121 } 122 // interlaced, skip every second line 123 bitmap += w; 124 align_get_bits(&gb); 125 } 126 *data_size = 1; 127 return buf_size; 128} 129 130AVCodec xsub_decoder = { 131 "xsub", 132 CODEC_TYPE_SUBTITLE, 133 CODEC_ID_XSUB, 134 0, 135 decode_init, 136 NULL, 137 NULL, 138 decode_frame, 139 .long_name = NULL_IF_CONFIG_SMALL("XSUB"), 140}; 141