FFmpeg coverage


Directory: ../../../ffmpeg/
File: src/libavcodec/mjpegenc_huffman.h
Date: 2021-09-26 18:22:30
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Lines: 3 3 100.0%
Branches: 0 0 -%

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1 /*
2 * MJPEG encoder
3 * Copyright (c) 2016 William Ma, Ted Ying, Jerry Jiang
4 *
5 * This file is part of FFmpeg.
6 *
7 * FFmpeg is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
11 *
12 * FFmpeg is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
16 *
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with FFmpeg; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20 */
21
22 /**
23 * @file
24 * Huffman table generation for MJPEG encoder.
25 */
26
27 #ifndef AVCODEC_MJPEGENC_HUFFMAN_H
28 #define AVCODEC_MJPEGENC_HUFFMAN_H
29
30 #include <stdint.h>
31
32 typedef struct MJpegEncHuffmanContext {
33 int val_count[256];
34 } MJpegEncHuffmanContext;
35
36 // Uses the package merge algorithm to compute the Huffman table.
37 void ff_mjpeg_encode_huffman_init(MJpegEncHuffmanContext *s);
38 28811107 static inline void ff_mjpeg_encode_huffman_increment(MJpegEncHuffmanContext *s,
39 uint8_t val)
40 {
41 28811107 s->val_count[val]++;
42 28811107 }
43 void ff_mjpeg_encode_huffman_close(MJpegEncHuffmanContext *s,
44 uint8_t bits[17], uint8_t val[],
45 int max_nval);
46
47
48 /**
49 * Used to assign a occurrence count or "probability" to an input value
50 */
51 typedef struct PTable {
52 int value; ///< input value
53 int prob; ///< number of occurences of this value in input
54 } PTable;
55
56 /**
57 * Used to store intermediate lists in the package merge algorithm
58 */
59 typedef struct PackageMergerList {
60 int nitems; ///< number of items in the list and probability ex. 4
61 int item_idx[515]; ///< index range for each item in items 0, 2, 5, 9, 13
62 int probability[514]; ///< probability of each item 3, 8, 18, 46
63 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
64 } PackageMergerList;
65
66 /**
67 * Used to store optimal huffman encoding results
68 */
69 typedef struct HuffTable {
70 int code; ///< code is the input value
71 int length; ///< length of the encoding
72 } HuffTable;
73
74 void ff_mjpegenc_huffman_compute_bits(PTable *prob_table, HuffTable *distincts,
75 int size, int max_length);
76 #endif /* AVCODEC_MJPEGENC_HUFFMAN_H */
77