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 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 = AV_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, i; 57 int64_t packet_time = 0; 58 GetBitContext gb; 59 int has_alpha = avctx->codec_tag == MKTAG('D','X','S','A'); 60 61 // check that at least header fits 62 if (buf_size < 27 + 7 * 2 + 4 * 3) { 63 av_log(avctx, AV_LOG_ERROR, "coded frame size %d too small\n", buf_size); 64 return -1; 65 } 66 67 // read start and end time 68 if (buf[0] != '[' || buf[13] != '-' || buf[26] != ']') { 69 av_log(avctx, AV_LOG_ERROR, "invalid time code\n"); 70 return -1; 71 } 72 if (avpkt->pts != AV_NOPTS_VALUE) 73 packet_time = av_rescale_q(avpkt->pts, AV_TIME_BASE_Q, (AVRational){1, 1000}); 74 sub->start_display_time = parse_timecode(buf + 1, packet_time); 75 sub->end_display_time = parse_timecode(buf + 14, packet_time); 76 buf += 27; 77 78 // read header 79 w = bytestream_get_le16(&buf); 80 h = bytestream_get_le16(&buf); 81 if (av_image_check_size(w, h, 0, avctx) < 0) 82 return -1; 83 x = bytestream_get_le16(&buf); 84 y = bytestream_get_le16(&buf); 85 // skip bottom right position, it gives no new information 86 bytestream_get_le16(&buf); 87 bytestream_get_le16(&buf); 88 // The following value is supposed to indicate the start offset 89 // (relative to the palette) of the data for the second field, 90 // however there are files in which it has a bogus value and thus 91 // we just ignore it 92 bytestream_get_le16(&buf); 93 94 // allocate sub and set values 95 sub->rects = av_mallocz(sizeof(*sub->rects)); 96 sub->rects[0] = av_mallocz(sizeof(*sub->rects[0])); 97 sub->num_rects = 1; 98 sub->rects[0]->x = x; sub->rects[0]->y = y; 99 sub->rects[0]->w = w; sub->rects[0]->h = h; 100 sub->rects[0]->type = SUBTITLE_BITMAP; 101 sub->rects[0]->pict.linesize[0] = w; 102 sub->rects[0]->pict.data[0] = av_malloc(w * h); 103 sub->rects[0]->nb_colors = 4; 104 sub->rects[0]->pict.data[1] = av_mallocz(AVPALETTE_SIZE); 105 106 // read palette 107 for (i = 0; i < sub->rects[0]->nb_colors; i++) 108 ((uint32_t*)sub->rects[0]->pict.data[1])[i] = bytestream_get_be24(&buf); 109 // make all except background (first entry) non-transparent 110 for (i = 0; i < sub->rects[0]->nb_colors; i++) 111 ((uint32_t*)sub->rects[0]->pict.data[1])[i] |= (has_alpha ? *buf++ : (i ? 0xff : 0)) << 24; 112 113 // process RLE-compressed data 114 init_get_bits(&gb, buf, (buf_end - buf) * 8); 115 bitmap = sub->rects[0]->pict.data[0]; 116 for (y = 0; y < h; y++) { 117 // interlaced: do odd lines 118 if (y == (h + 1) / 2) bitmap = sub->rects[0]->pict.data[0] + w; 119 for (x = 0; x < w; ) { 120 int log2 = ff_log2_tab[show_bits(&gb, 8)]; 121 int run = get_bits(&gb, 14 - 4 * (log2 >> 1)); 122 int color = get_bits(&gb, 2); 123 run = FFMIN(run, w - x); 124 // run length 0 means till end of row 125 if (!run) run = w - x; 126 memset(bitmap, color, run); 127 bitmap += run; 128 x += run; 129 } 130 // interlaced, skip every second line 131 bitmap += w; 132 align_get_bits(&gb); 133 } 134 *data_size = 1; 135 return buf_size; 136} 137 138AVCodec ff_xsub_decoder = { 139 .name = "xsub", 140 .long_name = NULL_IF_CONFIG_SMALL("XSUB"), 141 .type = AVMEDIA_TYPE_SUBTITLE, 142 .id = AV_CODEC_ID_XSUB, 143 .init = decode_init, 144 .decode = decode_frame, 145}; 146