Libav 0.7.1
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00001 /* 00002 * XSUB subtitle decoder 00003 * Copyright (c) 2007 Reimar Döffinger 00004 * 00005 * This file is part of Libav. 00006 * 00007 * Libav 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 * Libav 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 Libav; if not, write to the Free Software 00019 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 00020 */ 00021 #include "libavutil/imgutils.h" 00022 #include "avcodec.h" 00023 #include "get_bits.h" 00024 #include "bytestream.h" 00025 00026 static av_cold int decode_init(AVCodecContext *avctx) { 00027 avctx->pix_fmt = PIX_FMT_PAL8; 00028 return 0; 00029 } 00030 00031 static const uint8_t tc_offsets[9] = { 0, 1, 3, 4, 6, 7, 9, 10, 11 }; 00032 static const uint8_t tc_muls[9] = { 10, 6, 10, 6, 10, 10, 10, 10, 1 }; 00033 00034 static int64_t parse_timecode(const uint8_t *buf, int64_t packet_time) { 00035 int i; 00036 int64_t ms = 0; 00037 if (buf[2] != ':' || buf[5] != ':' || buf[8] != '.') 00038 return AV_NOPTS_VALUE; 00039 for (i = 0; i < sizeof(tc_offsets); i++) { 00040 uint8_t c = buf[tc_offsets[i]] - '0'; 00041 if (c > 9) return AV_NOPTS_VALUE; 00042 ms = (ms + c) * tc_muls[i]; 00043 } 00044 return ms - packet_time; 00045 } 00046 00047 static int decode_frame(AVCodecContext *avctx, void *data, int *data_size, 00048 AVPacket *avpkt) { 00049 const uint8_t *buf = avpkt->data; 00050 int buf_size = avpkt->size; 00051 AVSubtitle *sub = data; 00052 const uint8_t *buf_end = buf + buf_size; 00053 uint8_t *bitmap; 00054 int w, h, x, y, rlelen, i; 00055 int64_t packet_time = 0; 00056 GetBitContext gb; 00057 00058 memset(sub, 0, sizeof(*sub)); 00059 00060 // check that at least header fits 00061 if (buf_size < 27 + 7 * 2 + 4 * 3) { 00062 av_log(avctx, AV_LOG_ERROR, "coded frame too small\n"); 00063 return -1; 00064 } 00065 00066 // read start and end time 00067 if (buf[0] != '[' || buf[13] != '-' || buf[26] != ']') { 00068 av_log(avctx, AV_LOG_ERROR, "invalid time code\n"); 00069 return -1; 00070 } 00071 if (avpkt->pts != AV_NOPTS_VALUE) 00072 packet_time = av_rescale_q(avpkt->pts, AV_TIME_BASE_Q, (AVRational){1, 1000}); 00073 sub->start_display_time = parse_timecode(buf + 1, packet_time); 00074 sub->end_display_time = parse_timecode(buf + 14, packet_time); 00075 buf += 27; 00076 00077 // read header 00078 w = bytestream_get_le16(&buf); 00079 h = bytestream_get_le16(&buf); 00080 if (av_image_check_size(w, h, 0, avctx) < 0) 00081 return -1; 00082 x = bytestream_get_le16(&buf); 00083 y = bytestream_get_le16(&buf); 00084 // skip bottom right position, it gives no new information 00085 bytestream_get_le16(&buf); 00086 bytestream_get_le16(&buf); 00087 rlelen = bytestream_get_le16(&buf); 00088 00089 // allocate sub and set values 00090 sub->rects = av_mallocz(sizeof(*sub->rects)); 00091 sub->rects[0] = av_mallocz(sizeof(*sub->rects[0])); 00092 sub->num_rects = 1; 00093 sub->rects[0]->x = x; sub->rects[0]->y = y; 00094 sub->rects[0]->w = w; sub->rects[0]->h = h; 00095 sub->rects[0]->type = SUBTITLE_BITMAP; 00096 sub->rects[0]->pict.linesize[0] = w; 00097 sub->rects[0]->pict.data[0] = av_malloc(w * h); 00098 sub->rects[0]->nb_colors = 4; 00099 sub->rects[0]->pict.data[1] = av_mallocz(AVPALETTE_SIZE); 00100 00101 // read palette 00102 for (i = 0; i < sub->rects[0]->nb_colors; i++) 00103 ((uint32_t*)sub->rects[0]->pict.data[1])[i] = bytestream_get_be24(&buf); 00104 // make all except background (first entry) non-transparent 00105 for (i = 1; i < sub->rects[0]->nb_colors; i++) 00106 ((uint32_t*)sub->rects[0]->pict.data[1])[i] |= 0xff000000; 00107 00108 // process RLE-compressed data 00109 rlelen = FFMIN(rlelen, buf_end - buf); 00110 init_get_bits(&gb, buf, rlelen * 8); 00111 bitmap = sub->rects[0]->pict.data[0]; 00112 for (y = 0; y < h; y++) { 00113 // interlaced: do odd lines 00114 if (y == (h + 1) / 2) bitmap = sub->rects[0]->pict.data[0] + w; 00115 for (x = 0; x < w; ) { 00116 int log2 = ff_log2_tab[show_bits(&gb, 8)]; 00117 int run = get_bits(&gb, 14 - 4 * (log2 >> 1)); 00118 int color = get_bits(&gb, 2); 00119 run = FFMIN(run, w - x); 00120 // run length 0 means till end of row 00121 if (!run) run = w - x; 00122 memset(bitmap, color, run); 00123 bitmap += run; 00124 x += run; 00125 } 00126 // interlaced, skip every second line 00127 bitmap += w; 00128 align_get_bits(&gb); 00129 } 00130 *data_size = 1; 00131 return buf_size; 00132 } 00133 00134 AVCodec ff_xsub_decoder = { 00135 "xsub", 00136 AVMEDIA_TYPE_SUBTITLE, 00137 CODEC_ID_XSUB, 00138 0, 00139 decode_init, 00140 NULL, 00141 NULL, 00142 decode_frame, 00143 .long_name = NULL_IF_CONFIG_SMALL("XSUB"), 00144 };