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* 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
* 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.
#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)
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);