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https://github.com/FFmpeg/FFmpeg.git
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Merge commit '2ecfd451649c7a08cb633635df98e59f7c6e2140'
* commit '2ecfd451649c7a08cb633635df98e59f7c6e2140': Implement Snappy decompression Merged-by: Michael Niedermayer <michaelni@gmx.at>
This commit is contained in:
Michael Niedermayer
commit
9e5b0f070b
1
configure
vendored
1
configure
vendored
@ -1928,6 +1928,7 @@ CONFIG_EXTRA="
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rtpdec
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rtpenc_chain
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sinewin
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snappy
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startcode
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tpeldsp
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videodsp
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@ -103,6 +103,7 @@ RDFT-OBJS-$(CONFIG_HARDCODED_TABLES) += sin_tables.o
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OBJS-$(CONFIG_RDFT) += rdft.o $(RDFT-OBJS-yes)
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OBJS-$(CONFIG_SHARED) += log2_tab.o
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OBJS-$(CONFIG_SINEWIN) += sinewin.o
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OBJS-$(CONFIG_SNAPPY) += snappy.o
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OBJS-$(CONFIG_STARTCODE) += startcode.o
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OBJS-$(CONFIG_TPELDSP) += tpeldsp.o
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OBJS-$(CONFIG_VIDEODSP) += videodsp.o
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173
libavcodec/snappy.c
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173
libavcodec/snappy.c
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@ -0,0 +1,173 @@
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/*
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* Snappy decompression algorithm
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* Copyright (c) 2015 Luca Barbato
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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/mem.h"
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#include "bytestream.h"
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#include "snappy.h"
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enum {
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SNAPPY_LITERAL,
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SNAPPY_COPY_1,
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SNAPPY_COPY_2,
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SNAPPY_COPY_4,
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};
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static int64_t bytestream2_get_levarint(GetByteContext *gb)
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{
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uint64_t val = 0;
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int shift = 0;
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int tmp;
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do {
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tmp = bytestream2_get_byte(gb);
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val |= (tmp & 127) << shift;
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shift += 7;
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} while (tmp & 128);
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return val;
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}
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static int snappy_literal(GetByteContext *gb, uint8_t *p, int size, int val)
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{
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unsigned int len = 1;
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switch (val) {
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case 63:
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len += bytestream2_get_le32(gb);
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break;
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case 62:
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len += bytestream2_get_le24(gb);
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break;
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case 61:
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len += bytestream2_get_le16(gb);
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break;
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case 60:
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len += bytestream2_get_byte(gb);
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break;
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default: // val < 60
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len += val;
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}
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if (size < len)
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return AVERROR_INVALIDDATA;
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bytestream2_get_buffer(gb, p, len);
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return len;
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}
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static int snappy_copy(uint8_t *start, uint8_t *p, int size,
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unsigned int off, int len)
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{
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uint8_t *q;
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int i;
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if (off > p - start || size < len)
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return AVERROR_INVALIDDATA;
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q = p - off;
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for (i = 0; i < len; i++)
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p[i] = q[i];
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return len;
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}
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static int snappy_copy1(GetByteContext *gb, uint8_t *start, uint8_t *p,
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int size, int val)
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{
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int len = 4 + (val & 0x7);
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unsigned int off = bytestream2_get_byte(gb) | (val & 0x38) << 5;
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return snappy_copy(start, p, size, off, len);
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}
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static int snappy_copy2(GetByteContext *gb, uint8_t *start, uint8_t *p,
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int size, int val)
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{
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int len = 1 + val;
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unsigned int off = bytestream2_get_le16(gb);
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return snappy_copy(start, p, size, off, len);
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}
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static int snappy_copy4(GetByteContext *gb, uint8_t *start, uint8_t *p,
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int size, int val)
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{
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int len = 1 + val;
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unsigned int off = bytestream2_get_le32(gb);
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return snappy_copy(start, p, size, off, len);
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}
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static int64_t decode_len(GetByteContext *gb)
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{
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int64_t len = bytestream2_get_levarint(gb);
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if (len < 0 || len > UINT_MAX)
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return AVERROR_INVALIDDATA;
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return len;
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}
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int ff_snappy_uncompress(GetByteContext *gb, uint8_t **buf, int64_t *size)
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{
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int64_t len = decode_len(gb);
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int ret = 0;
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uint8_t *p;
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if (len < 0)
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return len;
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if ((ret = av_reallocp(buf, len)) < 0)
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return AVERROR(ENOMEM);
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*size = len;
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p = *buf;
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while (bytestream2_get_bytes_left(gb) > 0) {
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uint8_t s = bytestream2_get_byte(gb);
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int val = s >> 2;
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switch (s & 0x03) {
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case SNAPPY_LITERAL:
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ret = snappy_literal(gb, p, len, val);
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break;
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case SNAPPY_COPY_1:
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ret = snappy_copy1(gb, *buf, p, len, val);
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break;
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case SNAPPY_COPY_2:
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ret = snappy_copy2(gb, *buf, p, len, val);
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break;
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case SNAPPY_COPY_4:
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ret = snappy_copy4(gb, *buf, p, len, val);
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break;
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}
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if (ret < 0)
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return ret;
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p += ret;
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len -= ret;
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}
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return 0;
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}
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51
libavcodec/snappy.h
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51
libavcodec/snappy.h
Normal file
@ -0,0 +1,51 @@
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/*
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* Snappy module
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* Copyright (c) Luca Barbato
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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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* Snappy decompression
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*
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* Snappy is a compression/decompression algorithm that does not aim for
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* maximum compression, but rather for very high speeds and reasonable
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* compression.
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*
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* http://en.wikipedia.org/wiki/Snappy_%28software%29
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*/
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#ifndef AVCODEC_SNAPPY_H
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#define AVCODEC_SNAPPY_H
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#include <stdint.h>
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#include "bytestream.h"
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/**
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* Decompress an input buffer using Snappy algorithm. Caller is
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* responsible of freeing the memory allocated in buf.
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*
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* @param gb input GetByteContext.
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* @param buf output buffer pointer.
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* @param size output buffer size.
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* @return 0 if success, AVERROR otherwise.
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*/
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int ff_snappy_uncompress(GetByteContext *gb, uint8_t **buf, int64_t *size);
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#endif /* AVCODEC_SNAPPY_H */
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