| /* |
| * 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 */ |