| 1 | /* |
| 2 | * XSUB subtitle decoder |
| 3 | * Copyright (c) 2007 Reimar Döffinger |
| 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 | |
| 28 | static av_cold int decode_init(AVCodecContext *avctx) { |
| 29 | avctx->pix_fmt = AV_PIX_FMT_PAL8; |
| 30 | return 0; |
| 31 | } |
| 32 | |
| 33 | static const uint8_t tc_offsets[9] = { 0, 1, 3, 4, 6, 7, 9, 10, 11 }; |
| 34 | static const uint8_t tc_muls[9] = { 10, 6, 10, 6, 10, 10, 10, 10, 1 }; |
| 35 | |
| 36 | static 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 | |
| 49 | static 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 | |
| 138 | AVCodec 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 | }; |