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https://github.com/xenia-project/FFmpeg.git
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3b4621acbb
Do not use rlelen for buffer size in init_get_bits, it is only the size of the data for the first field. Since it is not reliable, just use the size of the whole buffer. Additional comments add removal of unused rlelen variable by Reimar Döffinger.
147 lines
5.0 KiB
C
147 lines
5.0 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 FFmpeg.
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*
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* FFmpeg 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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* FFmpeg 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 FFmpeg; 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/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, i;
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int64_t packet_time = 0;
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GetBitContext gb;
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int has_alpha = avctx->codec_tag == MKTAG('D','X','S','A');
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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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// The following value is supposed to indicate the start offset
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// (relative to the palette) of the data for the second field,
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// however there are files where it has a bogus value and thus
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// we just ignore it
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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 = 0; i < sub->rects[0]->nb_colors; i++)
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((uint32_t*)sub->rects[0]->pict.data[1])[i] |= (has_alpha ? *buf++ : (i ? 0xff : 0)) << 24;
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// process RLE-compressed data
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init_get_bits(&gb, buf, (buf_end - buf) * 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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"xsub",
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AVMEDIA_TYPE_SUBTITLE,
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CODEC_ID_XSUB,
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0,
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decode_init,
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NULL,
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NULL,
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decode_frame,
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.long_name = NULL_IF_CONFIG_SMALL("XSUB"),
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};
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