113 lines
3.4 KiB
C
113 lines
3.4 KiB
C
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/*
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* WebP parser
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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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/**
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* @file
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* WebP parser
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*/
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#include "libavutil/bswap.h"
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#include "libavutil/common.h"
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#include "parser.h"
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typedef struct WebPParseContext {
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ParseContext pc;
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uint32_t fsize;
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uint32_t remaining_size;
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} WebPParseContext;
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static int webp_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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WebPParseContext *ctx = s->priv_data;
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uint64_t state = ctx->pc.state64;
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int next = END_NOT_FOUND;
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int i = 0;
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*poutbuf = NULL;
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*poutbuf_size = 0;
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restart:
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if (ctx->pc.frame_start_found <= 8) {
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for (; i < buf_size; i++) {
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state = (state << 8) | buf[i];
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if (ctx->pc.frame_start_found == 0) {
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if ((state >> 32) == MKBETAG('R', 'I', 'F', 'F')) {
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ctx->fsize = av_bswap32(state);
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if (ctx->fsize > 15 && ctx->fsize <= UINT32_MAX - 10) {
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ctx->pc.frame_start_found = 1;
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ctx->fsize += 8;
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}
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}
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} else if (ctx->pc.frame_start_found == 8) {
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if ((state >> 32) != MKBETAG('W', 'E', 'B', 'P')) {
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ctx->pc.frame_start_found = 0;
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continue;
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}
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ctx->pc.frame_start_found++;
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ctx->remaining_size = ctx->fsize + i - 15;
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if (ctx->pc.index + i > 15) {
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next = i - 15;
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state = 0;
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break;
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} else {
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ctx->pc.state64 = 0;
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goto restart;
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}
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} else if (ctx->pc.frame_start_found)
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ctx->pc.frame_start_found++;
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}
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ctx->pc.state64 = state;
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} else {
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if (ctx->remaining_size) {
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i = FFMIN(ctx->remaining_size, buf_size);
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ctx->remaining_size -= i;
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if (ctx->remaining_size)
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goto flush;
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ctx->pc.frame_start_found = 0;
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goto restart;
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}
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}
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flush:
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if (ff_combine_frame(&ctx->pc, next, &buf, &buf_size) < 0)
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return buf_size;
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if (next != END_NOT_FOUND && next < 0)
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ctx->pc.frame_start_found = FFMAX(ctx->pc.frame_start_found - i - 1, 0);
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else
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ctx->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_webp_parser = {
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.codec_ids = { AV_CODEC_ID_WEBP },
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.priv_data_size = sizeof(WebPParseContext),
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.parser_parse = webp_parse,
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.parser_close = ff_parse_close,
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};
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