1/* 2 * XSUB subtitle decoder 3 * Copyright (c) 2007 Reimar D��ffinger 4 * 5 * This file is part of Libav. 6 * 7 * Libav 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 * Libav 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 Libav; if not, write to the Free Software 19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 20 */ 21 22#include "libavutil/mathematics.h" 23#include "libavutil/imgutils.h" 24#include "avcodec.h" 25#include "get_bits.h" 26#include "bytestream.h" 27 28static av_cold int decode_init(AVCodecContext *avctx) { 29 avctx->pix_fmt = PIX_FMT_PAL8; 30 return 0; 31} 32 33static const uint8_t tc_offsets[9] = { 0, 1, 3, 4, 6, 7, 9, 10, 11 }; 34static const uint8_t tc_muls[9] = { 10, 6, 10, 6, 10, 10, 10, 10, 1 }; 35 36static int64_t parse_timecode(const uint8_t *buf, int64_t packet_time) { 37 int i; 38 int64_t ms = 0; 39 if (buf[2] != ':' || buf[5] != ':' || buf[8] != '.') 40 return AV_NOPTS_VALUE; 41 for (i = 0; i < sizeof(tc_offsets); i++) { 42 uint8_t c = buf[tc_offsets[i]] - '0'; 43 if (c > 9) return AV_NOPTS_VALUE; 44 ms = (ms + c) * tc_muls[i]; 45 } 46 return ms - packet_time; 47} 48 49static int decode_frame(AVCodecContext *avctx, void *data, int *data_size, 50 AVPacket *avpkt) { 51 const uint8_t *buf = avpkt->data; 52 int buf_size = avpkt->size; 53 AVSubtitle *sub = data; 54 const uint8_t *buf_end = buf + buf_size; 55 uint8_t *bitmap; 56 int w, h, x, y, rlelen, i; 57 int64_t packet_time = 0; 58 GetBitContext gb; 59 60 memset(sub, 0, sizeof(*sub)); 61 62 // check that at least header fits 63 if (buf_size < 27 + 7 * 2 + 4 * 3) { 64 av_log(avctx, AV_LOG_ERROR, "coded frame too small\n"); 65 return -1; 66 } 67 68 // read start and end time 69 if (buf[0] != '[' || buf[13] != '-' || buf[26] != ']') { 70 av_log(avctx, AV_LOG_ERROR, "invalid time code\n"); 71 return -1; 72 } 73 if (avpkt->pts != AV_NOPTS_VALUE) 74 packet_time = av_rescale_q(avpkt->pts, AV_TIME_BASE_Q, (AVRational){1, 1000}); 75 sub->start_display_time = parse_timecode(buf + 1, packet_time); 76 sub->end_display_time = parse_timecode(buf + 14, packet_time); 77 buf += 27; 78 79 // read header 80 w = bytestream_get_le16(&buf); 81 h = bytestream_get_le16(&buf); 82 if (av_image_check_size(w, h, 0, avctx) < 0) 83 return -1; 84 x = bytestream_get_le16(&buf); 85 y = bytestream_get_le16(&buf); 86 // skip bottom right position, it gives no new information 87 bytestream_get_le16(&buf); 88 bytestream_get_le16(&buf); 89 rlelen = bytestream_get_le16(&buf); 90 91 // allocate sub and set values 92 sub->rects = av_mallocz(sizeof(*sub->rects)); 93 sub->rects[0] = av_mallocz(sizeof(*sub->rects[0])); 94 sub->num_rects = 1; 95 sub->rects[0]->x = x; sub->rects[0]->y = y; 96 sub->rects[0]->w = w; sub->rects[0]->h = h; 97 sub->rects[0]->type = SUBTITLE_BITMAP; 98 sub->rects[0]->pict.linesize[0] = w; 99 sub->rects[0]->pict.data[0] = av_malloc(w * h); 100 sub->rects[0]->nb_colors = 4; 101 sub->rects[0]->pict.data[1] = av_mallocz(AVPALETTE_SIZE); 102 103 // read palette 104 for (i = 0; i < sub->rects[0]->nb_colors; i++) 105 ((uint32_t*)sub->rects[0]->pict.data[1])[i] = bytestream_get_be24(&buf); 106 // make all except background (first entry) non-transparent 107 for (i = 1; i < sub->rects[0]->nb_colors; i++) 108 ((uint32_t*)sub->rects[0]->pict.data[1])[i] |= 0xff000000; 109 110 // process RLE-compressed data 111 rlelen = FFMIN(rlelen, buf_end - buf); 112 init_get_bits(&gb, buf, rlelen * 8); 113 bitmap = sub->rects[0]->pict.data[0]; 114 for (y = 0; y < h; y++) { 115 // interlaced: do odd lines 116 if (y == (h + 1) / 2) bitmap = sub->rects[0]->pict.data[0] + w; 117 for (x = 0; x < w; ) { 118 int log2 = ff_log2_tab[show_bits(&gb, 8)]; 119 int run = get_bits(&gb, 14 - 4 * (log2 >> 1)); 120 int color = get_bits(&gb, 2); 121 run = FFMIN(run, w - x); 122 // run length 0 means till end of row 123 if (!run) run = w - x; 124 memset(bitmap, color, run); 125 bitmap += run; 126 x += run; 127 } 128 // interlaced, skip every second line 129 bitmap += w; 130 align_get_bits(&gb); 131 } 132 *data_size = 1; 133 return buf_size; 134} 135 136AVCodec ff_xsub_decoder = { 137 .name = "xsub", 138 .type = AVMEDIA_TYPE_SUBTITLE, 139 .id = CODEC_ID_XSUB, 140 .init = decode_init, 141 .decode = decode_frame, 142 .long_name = NULL_IF_CONFIG_SMALL("XSUB"), 143}; 144