09c2d08c
 Hu Chunming
arm交付版
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/*
* WebP parser
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/**
* @file
* WebP parser
*/
#include "libavutil/bswap.h"
#include "libavutil/common.h"
#include "parser.h"
typedef struct WebPParseContext {
ParseContext pc;
uint32_t fsize;
uint32_t remaining_size;
} WebPParseContext;
static int webp_parse(AVCodecParserContext *s, AVCodecContext *avctx,
const uint8_t **poutbuf, int *poutbuf_size,
const uint8_t *buf, int buf_size)
{
WebPParseContext *ctx = s->priv_data;
uint64_t state = ctx->pc.state64;
int next = END_NOT_FOUND;
int i = 0;
*poutbuf = NULL;
*poutbuf_size = 0;
restart:
if (ctx->pc.frame_start_found <= 8) {
for (; i < buf_size; i++) {
state = (state << 8) | buf[i];
if (ctx->pc.frame_start_found == 0) {
if ((state >> 32) == MKBETAG('R', 'I', 'F', 'F')) {
ctx->fsize = av_bswap32(state);
if (ctx->fsize > 15 && ctx->fsize <= UINT32_MAX - 10) {
ctx->pc.frame_start_found = 1;
ctx->fsize += 8;
}
}
} else if (ctx->pc.frame_start_found == 8) {
if ((state >> 32) != MKBETAG('W', 'E', 'B', 'P')) {
ctx->pc.frame_start_found = 0;
continue;
}
ctx->pc.frame_start_found++;
ctx->remaining_size = ctx->fsize + i - 15;
if (ctx->pc.index + i > 15) {
next = i - 15;
state = 0;
break;
} else {
ctx->pc.state64 = 0;
goto restart;
}
} else if (ctx->pc.frame_start_found)
ctx->pc.frame_start_found++;
}
ctx->pc.state64 = state;
} else {
if (ctx->remaining_size) {
i = FFMIN(ctx->remaining_size, buf_size);
ctx->remaining_size -= i;
if (ctx->remaining_size)
goto flush;
ctx->pc.frame_start_found = 0;
goto restart;
}
}
flush:
if (ff_combine_frame(&ctx->pc, next, &buf, &buf_size) < 0)
return buf_size;
if (next != END_NOT_FOUND && next < 0)
ctx->pc.frame_start_found = FFMAX(ctx->pc.frame_start_found - i - 1, 0);
else
ctx->pc.frame_start_found = 0;
*poutbuf = buf;
*poutbuf_size = buf_size;
return next;
}
AVCodecParser ff_webp_parser = {
.codec_ids = { AV_CODEC_ID_WEBP },
.priv_data_size = sizeof(WebPParseContext),
.parser_parse = webp_parse,
.parser_close = ff_parse_close,
};
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