yading@10: /*
yading@10:  * XSUB subtitle decoder
yading@10:  * Copyright (c) 2007 Reimar Döffinger
yading@10:  *
yading@10:  * This file is part of FFmpeg.
yading@10:  *
yading@10:  * FFmpeg is free software; you can redistribute it and/or
yading@10:  * modify it under the terms of the GNU Lesser General Public
yading@10:  * License as published by the Free Software Foundation; either
yading@10:  * version 2.1 of the License, or (at your option) any later version.
yading@10:  *
yading@10:  * FFmpeg is distributed in the hope that it will be useful,
yading@10:  * but WITHOUT ANY WARRANTY; without even the implied warranty of
yading@10:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
yading@10:  * Lesser General Public License for more details.
yading@10:  *
yading@10:  * You should have received a copy of the GNU Lesser General Public
yading@10:  * License along with FFmpeg; if not, write to the Free Software
yading@10:  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
yading@10:  */
yading@10: 
yading@10: #include "libavutil/mathematics.h"
yading@10: #include "libavutil/imgutils.h"
yading@10: #include "avcodec.h"
yading@10: #include "get_bits.h"
yading@10: #include "bytestream.h"
yading@10: 
yading@10: static av_cold int decode_init(AVCodecContext *avctx) {
yading@10:     avctx->pix_fmt = AV_PIX_FMT_PAL8;
yading@10:     return 0;
yading@10: }
yading@10: 
yading@10: static const uint8_t tc_offsets[9] = { 0, 1, 3, 4, 6, 7, 9, 10, 11 };
yading@10: static const uint8_t tc_muls[9] = { 10, 6, 10, 6, 10, 10, 10, 10, 1 };
yading@10: 
yading@10: static int64_t parse_timecode(const uint8_t *buf, int64_t packet_time) {
yading@10:     int i;
yading@10:     int64_t ms = 0;
yading@10:     if (buf[2] != ':' || buf[5] != ':' || buf[8] != '.')
yading@10:         return AV_NOPTS_VALUE;
yading@10:     for (i = 0; i < sizeof(tc_offsets); i++) {
yading@10:         uint8_t c = buf[tc_offsets[i]] - '0';
yading@10:         if (c > 9) return AV_NOPTS_VALUE;
yading@10:         ms = (ms + c) * tc_muls[i];
yading@10:     }
yading@10:     return ms - packet_time;
yading@10: }
yading@10: 
yading@10: static int decode_frame(AVCodecContext *avctx, void *data, int *data_size,
yading@10:                         AVPacket *avpkt) {
yading@10:     const uint8_t *buf = avpkt->data;
yading@10:     int buf_size = avpkt->size;
yading@10:     AVSubtitle *sub = data;
yading@10:     const uint8_t *buf_end = buf + buf_size;
yading@10:     uint8_t *bitmap;
yading@10:     int w, h, x, y, i;
yading@10:     int64_t packet_time = 0;
yading@10:     GetBitContext gb;
yading@10:     int has_alpha = avctx->codec_tag == MKTAG('D','X','S','A');
yading@10: 
yading@10:     // check that at least header fits
yading@10:     if (buf_size < 27 + 7 * 2 + 4 * 3) {
yading@10:         av_log(avctx, AV_LOG_ERROR, "coded frame size %d too small\n", buf_size);
yading@10:         return -1;
yading@10:     }
yading@10: 
yading@10:     // read start and end time
yading@10:     if (buf[0] != '[' || buf[13] != '-' || buf[26] != ']') {
yading@10:         av_log(avctx, AV_LOG_ERROR, "invalid time code\n");
yading@10:         return -1;
yading@10:     }
yading@10:     if (avpkt->pts != AV_NOPTS_VALUE)
yading@10:         packet_time = av_rescale_q(avpkt->pts, AV_TIME_BASE_Q, (AVRational){1, 1000});
yading@10:     sub->start_display_time = parse_timecode(buf +  1, packet_time);
yading@10:     sub->end_display_time   = parse_timecode(buf + 14, packet_time);
yading@10:     buf += 27;
yading@10: 
yading@10:     // read header
yading@10:     w = bytestream_get_le16(&buf);
yading@10:     h = bytestream_get_le16(&buf);
yading@10:     if (av_image_check_size(w, h, 0, avctx) < 0)
yading@10:         return -1;
yading@10:     x = bytestream_get_le16(&buf);
yading@10:     y = bytestream_get_le16(&buf);
yading@10:     // skip bottom right position, it gives no new information
yading@10:     bytestream_get_le16(&buf);
yading@10:     bytestream_get_le16(&buf);
yading@10:     // The following value is supposed to indicate the start offset
yading@10:     // (relative to the palette) of the data for the second field,
yading@10:     // however there are files in which it has a bogus value and thus
yading@10:     // we just ignore it
yading@10:     bytestream_get_le16(&buf);
yading@10: 
yading@10:     // allocate sub and set values
yading@10:     sub->rects =  av_mallocz(sizeof(*sub->rects));
yading@10:     sub->rects[0] = av_mallocz(sizeof(*sub->rects[0]));
yading@10:     sub->num_rects = 1;
yading@10:     sub->rects[0]->x = x; sub->rects[0]->y = y;
yading@10:     sub->rects[0]->w = w; sub->rects[0]->h = h;
yading@10:     sub->rects[0]->type = SUBTITLE_BITMAP;
yading@10:     sub->rects[0]->pict.linesize[0] = w;
yading@10:     sub->rects[0]->pict.data[0] = av_malloc(w * h);
yading@10:     sub->rects[0]->nb_colors = 4;
yading@10:     sub->rects[0]->pict.data[1] = av_mallocz(AVPALETTE_SIZE);
yading@10: 
yading@10:     // read palette
yading@10:     for (i = 0; i < sub->rects[0]->nb_colors; i++)
yading@10:         ((uint32_t*)sub->rects[0]->pict.data[1])[i] = bytestream_get_be24(&buf);
yading@10:     // make all except background (first entry) non-transparent
yading@10:     for (i = 0; i < sub->rects[0]->nb_colors; i++)
yading@10:         ((uint32_t*)sub->rects[0]->pict.data[1])[i] |= (has_alpha ? *buf++ : (i ? 0xff : 0)) << 24;
yading@10: 
yading@10:     // process RLE-compressed data
yading@10:     init_get_bits(&gb, buf, (buf_end - buf) * 8);
yading@10:     bitmap = sub->rects[0]->pict.data[0];
yading@10:     for (y = 0; y < h; y++) {
yading@10:         // interlaced: do odd lines
yading@10:         if (y == (h + 1) / 2) bitmap = sub->rects[0]->pict.data[0] + w;
yading@10:         for (x = 0; x < w; ) {
yading@10:             int log2 = ff_log2_tab[show_bits(&gb, 8)];
yading@10:             int run = get_bits(&gb, 14 - 4 * (log2 >> 1));
yading@10:             int color = get_bits(&gb, 2);
yading@10:             run = FFMIN(run, w - x);
yading@10:             // run length 0 means till end of row
yading@10:             if (!run) run = w - x;
yading@10:             memset(bitmap, color, run);
yading@10:             bitmap += run;
yading@10:             x += run;
yading@10:         }
yading@10:         // interlaced, skip every second line
yading@10:         bitmap += w;
yading@10:         align_get_bits(&gb);
yading@10:     }
yading@10:     *data_size = 1;
yading@10:     return buf_size;
yading@10: }
yading@10: 
yading@10: AVCodec ff_xsub_decoder = {
yading@10:     .name      = "xsub",
yading@10:     .type      = AVMEDIA_TYPE_SUBTITLE,
yading@10:     .id        = AV_CODEC_ID_XSUB,
yading@10:     .init      = decode_init,
yading@10:     .decode    = decode_frame,
yading@10:     .long_name = NULL_IF_CONFIG_SMALL("XSUB"),
yading@10: };