77 lines
2.6 KiB
C
77 lines
2.6 KiB
C
|
/*
|
||
|
|
* MJPEG encoder
|
||
|
|
* Copyright (c) 2016 William Ma, Ted Ying, Jerry Jiang
|
||
|
|
*
|
||
|
|
* 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
|
||
|
|
* Huffman table generation for MJPEG encoder.
|
||
|
|
*/
|
||
|
|
|
||
|
|
#ifndef AVCODEC_MJPEGENC_HUFFMAN_H
|
||
|
|
#define AVCODEC_MJPEGENC_HUFFMAN_H
|
||
|
|
|
||
|
|
#include <stdint.h>
|
||
|
|
|
||
|
|
typedef struct MJpegEncHuffmanContext {
|
||
|
|
int val_count[256];
|
||
|
|
} MJpegEncHuffmanContext;
|
||
|
|
|
||
|
|
// Uses the package merge algorithm to compute the Huffman table.
|
||
|
|
void ff_mjpeg_encode_huffman_init(MJpegEncHuffmanContext *s);
|
||
|
|
static inline void ff_mjpeg_encode_huffman_increment(MJpegEncHuffmanContext *s,
|
||
|
|
uint8_t val)
|
||
|
|
{
|
||
|
|
s->val_count[val]++;
|
||
|
|
}
|
||
|
|
void ff_mjpeg_encode_huffman_close(MJpegEncHuffmanContext *s,
|
||
|
|
uint8_t bits[17], uint8_t val[],
|
||
|
|
int max_nval);
|
||
|
|
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Used to assign a occurrence count or "probability" to an input value
|
||
|
|
*/
|
||
|
|
typedef struct PTable {
|
||
|
|
int value; ///< input value
|
||
|
|
int prob; ///< number of occurences of this value in input
|
||
|
|
} PTable;
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Used to store intermediate lists in the package merge algorithm
|
||
|
|
*/
|
||
|
|
typedef struct PackageMergerList {
|
||
|
|
int nitems; ///< number of items in the list and probability ex. 4
|
||
|
|
int item_idx[515]; ///< index range for each item in items 0, 2, 5, 9, 13
|
||
|
|
int probability[514]; ///< probability of each item 3, 8, 18, 46
|
||
|
|
int items[257 * 16]; ///< chain of all individual values that make up items A, B, A, B, C, A, B, C, D, C, D, D, E
|
||
|
|
} PackageMergerList;
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Used to store optimal huffman encoding results
|
||
|
|
*/
|
||
|
|
typedef struct HuffTable {
|
||
|
|
int code; ///< code is the input value
|
||
|
|
int length; ///< length of the encoding
|
||
|
|
} HuffTable;
|
||
|
|
|
||
|
|
void ff_mjpegenc_huffman_compute_bits(PTable *prob_table, HuffTable *distincts,
|
||
|
|
int size, int max_length);
|
||
|
|
#endif /* AVCODEC_MJPEGENC_HUFFMAN_H */
|