144 lines
4.8 KiB
C
144 lines
4.8 KiB
C
/*
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* XSUB subtitle decoder
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* Copyright (c) 2007 Reimar Döffinger
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*
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* This file is part of Libav.
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*
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* Libav is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* Libav is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with Libav; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include "libavutil/mathematics.h"
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#include "libavutil/imgutils.h"
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#include "avcodec.h"
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#include "get_bits.h"
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#include "bytestream.h"
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static av_cold int decode_init(AVCodecContext *avctx) {
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avctx->pix_fmt = PIX_FMT_PAL8;
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return 0;
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}
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static const uint8_t tc_offsets[9] = { 0, 1, 3, 4, 6, 7, 9, 10, 11 };
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static const uint8_t tc_muls[9] = { 10, 6, 10, 6, 10, 10, 10, 10, 1 };
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static int64_t parse_timecode(const uint8_t *buf, int64_t packet_time) {
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int i;
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int64_t ms = 0;
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if (buf[2] != ':' || buf[5] != ':' || buf[8] != '.')
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return AV_NOPTS_VALUE;
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for (i = 0; i < sizeof(tc_offsets); i++) {
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uint8_t c = buf[tc_offsets[i]] - '0';
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if (c > 9) return AV_NOPTS_VALUE;
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ms = (ms + c) * tc_muls[i];
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}
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return ms - packet_time;
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}
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static int decode_frame(AVCodecContext *avctx, void *data, int *data_size,
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AVPacket *avpkt) {
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const uint8_t *buf = avpkt->data;
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int buf_size = avpkt->size;
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AVSubtitle *sub = data;
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const uint8_t *buf_end = buf + buf_size;
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uint8_t *bitmap;
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int w, h, x, y, rlelen, i;
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int64_t packet_time = 0;
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GetBitContext gb;
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memset(sub, 0, sizeof(*sub));
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// check that at least header fits
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if (buf_size < 27 + 7 * 2 + 4 * 3) {
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av_log(avctx, AV_LOG_ERROR, "coded frame too small\n");
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return -1;
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}
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// read start and end time
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if (buf[0] != '[' || buf[13] != '-' || buf[26] != ']') {
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av_log(avctx, AV_LOG_ERROR, "invalid time code\n");
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return -1;
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}
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if (avpkt->pts != AV_NOPTS_VALUE)
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packet_time = av_rescale_q(avpkt->pts, AV_TIME_BASE_Q, (AVRational){1, 1000});
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sub->start_display_time = parse_timecode(buf + 1, packet_time);
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sub->end_display_time = parse_timecode(buf + 14, packet_time);
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buf += 27;
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// read header
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w = bytestream_get_le16(&buf);
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h = bytestream_get_le16(&buf);
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if (av_image_check_size(w, h, 0, avctx) < 0)
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return -1;
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x = bytestream_get_le16(&buf);
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y = bytestream_get_le16(&buf);
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// skip bottom right position, it gives no new information
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bytestream_get_le16(&buf);
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bytestream_get_le16(&buf);
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rlelen = bytestream_get_le16(&buf);
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// allocate sub and set values
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sub->rects = av_mallocz(sizeof(*sub->rects));
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sub->rects[0] = av_mallocz(sizeof(*sub->rects[0]));
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sub->num_rects = 1;
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sub->rects[0]->x = x; sub->rects[0]->y = y;
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sub->rects[0]->w = w; sub->rects[0]->h = h;
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sub->rects[0]->type = SUBTITLE_BITMAP;
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sub->rects[0]->pict.linesize[0] = w;
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sub->rects[0]->pict.data[0] = av_malloc(w * h);
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sub->rects[0]->nb_colors = 4;
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sub->rects[0]->pict.data[1] = av_mallocz(AVPALETTE_SIZE);
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// read palette
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for (i = 0; i < sub->rects[0]->nb_colors; i++)
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((uint32_t*)sub->rects[0]->pict.data[1])[i] = bytestream_get_be24(&buf);
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// make all except background (first entry) non-transparent
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for (i = 1; i < sub->rects[0]->nb_colors; i++)
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((uint32_t*)sub->rects[0]->pict.data[1])[i] |= 0xff000000;
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// process RLE-compressed data
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rlelen = FFMIN(rlelen, buf_end - buf);
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init_get_bits(&gb, buf, rlelen * 8);
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bitmap = sub->rects[0]->pict.data[0];
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for (y = 0; y < h; y++) {
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// interlaced: do odd lines
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if (y == (h + 1) / 2) bitmap = sub->rects[0]->pict.data[0] + w;
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for (x = 0; x < w; ) {
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int log2 = ff_log2_tab[show_bits(&gb, 8)];
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int run = get_bits(&gb, 14 - 4 * (log2 >> 1));
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int color = get_bits(&gb, 2);
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run = FFMIN(run, w - x);
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// run length 0 means till end of row
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if (!run) run = w - x;
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memset(bitmap, color, run);
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bitmap += run;
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x += run;
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}
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// interlaced, skip every second line
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bitmap += w;
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align_get_bits(&gb);
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}
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*data_size = 1;
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return buf_size;
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}
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AVCodec ff_xsub_decoder = {
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.name = "xsub",
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.type = AVMEDIA_TYPE_SUBTITLE,
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.id = CODEC_ID_XSUB,
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.init = decode_init,
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.decode = decode_frame,
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.long_name = NULL_IF_CONFIG_SMALL("XSUB"),
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};
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