mirror of https://git.ffmpeg.org/ffmpeg.git
125 lines
3.7 KiB
C
125 lines
3.7 KiB
C
/*
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* PNG parser
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* Copyright (c) 2009 Peter Holik
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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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/**
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* @file
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* PNG parser
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*/
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#include "libavutil/intreadwrite.h"
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#include "libavutil/common.h"
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#include "parser.h"
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#define PNG_SIGNATURE UINT64_C(0x89504e470d0a1a0a)
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#define MNG_SIGNATURE UINT64_C(0x8a4d4e470d0a1a0a)
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typedef struct PNGParseContext {
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ParseContext pc;
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int chunk_pos; ///< position inside current chunk
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uint32_t chunk_length; ///< length of the current chunk
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int remaining_size; ///< remaining size of the current chunk
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} PNGParseContext;
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static int png_parse(AVCodecParserContext *s, AVCodecContext *avctx,
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const uint8_t **poutbuf, int *poutbuf_size,
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const uint8_t *buf, int buf_size)
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{
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PNGParseContext *ppc = s->priv_data;
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int next = END_NOT_FOUND;
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int i = 0;
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*poutbuf_size = 0;
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if (buf_size == 0)
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return 0;
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if (!ppc->pc.frame_start_found) {
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uint64_t state64 = ppc->pc.state64;
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for (; i < buf_size; i++) {
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state64 = (state64 << 8) | buf[i];
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if (state64 == PNG_SIGNATURE ||
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state64 == MNG_SIGNATURE) {
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i++;
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ppc->pc.frame_start_found = 1;
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break;
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}
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}
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ppc->pc.state64 = state64;
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} else if (ppc->remaining_size) {
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i = FFMIN(ppc->remaining_size, buf_size);
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ppc->remaining_size -= i;
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if (ppc->remaining_size)
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goto flush;
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if (ppc->chunk_pos == -1) {
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next = i;
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goto flush;
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}
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}
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for (; ppc->pc.frame_start_found && i < buf_size; i++) {
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ppc->pc.state = (ppc->pc.state << 8) | buf[i];
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if (ppc->chunk_pos == 3) {
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ppc->chunk_length = ppc->pc.state;
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if (ppc->chunk_length > 0x7fffffff) {
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ppc->chunk_pos = ppc->pc.frame_start_found = 0;
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goto flush;
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}
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ppc->chunk_length += 4;
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} else if (ppc->chunk_pos == 7) {
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if (ppc->chunk_length >= buf_size - i)
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ppc->remaining_size = ppc->chunk_length - buf_size + i + 1;
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if (ppc->pc.state == MKBETAG('I', 'E', 'N', 'D')) {
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if (ppc->remaining_size)
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ppc->chunk_pos = -1;
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else
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next = ppc->chunk_length + i + 1;
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break;
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} else {
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ppc->chunk_pos = 0;
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if (ppc->remaining_size)
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break;
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else
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i += ppc->chunk_length;
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continue;
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}
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}
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ppc->chunk_pos++;
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}
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flush:
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if (ff_combine_frame(&ppc->pc, next, &buf, &buf_size) < 0)
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return buf_size;
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ppc->chunk_pos = ppc->pc.frame_start_found = 0;
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*poutbuf = buf;
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*poutbuf_size = buf_size;
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return next;
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}
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AVCodecParser ff_png_parser = {
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.codec_ids = { AV_CODEC_ID_PNG },
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.priv_data_size = sizeof(PNGParseContext),
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.parser_parse = png_parse,
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.parser_close = ff_parse_close,
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};
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