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