blob: 8e02bce2e85642a1e2b55a5b6217f6d1b31c88db
1 | /* |
2 | * RTJpeg decoding functions |
3 | * Copyright (c) 2006 Reimar Doeffinger |
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 | #include "libavutil/common.h" |
22 | #include "get_bits.h" |
23 | #include "rtjpeg.h" |
24 | |
25 | #define PUT_COEFF(c) \ |
26 | i = scan[coeff--]; \ |
27 | block[i] = (c) * quant[i]; |
28 | |
29 | /// aligns the bitstream to the given power of two |
30 | #define ALIGN(a) \ |
31 | n = (-get_bits_count(gb)) & (a - 1); \ |
32 | if (n) {skip_bits(gb, n);} |
33 | |
34 | /** |
35 | * @brief read one block from stream |
36 | * @param gb contains stream data |
37 | * @param block where data is written to |
38 | * @param scan array containing the mapping stream address -> block position |
39 | * @param quant quantization factors |
40 | * @return 0 means the block is not coded, < 0 means an error occurred. |
41 | * |
42 | * Note: GetBitContext is used to make the code simpler, since all data is |
43 | * aligned this could be done faster in a different way, e.g. as it is done |
44 | * in MPlayer libmpcodecs/native/rtjpegn.c. |
45 | */ |
46 | static inline int get_block(GetBitContext *gb, int16_t *block, const uint8_t *scan, |
47 | const uint32_t *quant) { |
48 | int coeff, i, n; |
49 | int8_t ac; |
50 | uint8_t dc = get_bits(gb, 8); |
51 | |
52 | // block not coded |
53 | if (dc == 255) |
54 | return 0; |
55 | |
56 | // number of non-zero coefficients |
57 | coeff = get_bits(gb, 6); |
58 | if (get_bits_left(gb) < (coeff << 1)) |
59 | return AVERROR_INVALIDDATA; |
60 | |
61 | // normally we would only need to clear the (63 - coeff) last values, |
62 | // but since we do not know where they are we just clear the whole block |
63 | memset(block, 0, 64 * sizeof(int16_t)); |
64 | |
65 | // 2 bits per coefficient |
66 | while (coeff) { |
67 | ac = get_sbits(gb, 2); |
68 | if (ac == -2) |
69 | break; // continue with more bits |
70 | PUT_COEFF(ac); |
71 | } |
72 | |
73 | // 4 bits per coefficient |
74 | ALIGN(4); |
75 | if (get_bits_left(gb) < (coeff << 2)) |
76 | return AVERROR_INVALIDDATA; |
77 | while (coeff) { |
78 | ac = get_sbits(gb, 4); |
79 | if (ac == -8) |
80 | break; // continue with more bits |
81 | PUT_COEFF(ac); |
82 | } |
83 | |
84 | // 8 bits per coefficient |
85 | ALIGN(8); |
86 | if (get_bits_left(gb) < (coeff << 3)) |
87 | return AVERROR_INVALIDDATA; |
88 | while (coeff) { |
89 | ac = get_sbits(gb, 8); |
90 | PUT_COEFF(ac); |
91 | } |
92 | |
93 | PUT_COEFF(dc); |
94 | return 1; |
95 | } |
96 | |
97 | /** |
98 | * @brief decode one rtjpeg YUV420 frame |
99 | * @param c context, must be initialized via ff_rtjpeg_decode_init |
100 | * @param f AVFrame to place decoded frame into. If parts of the frame |
101 | * are not coded they are left unchanged, so consider initializing it |
102 | * @param buf buffer containing input data |
103 | * @param buf_size length of input data in bytes |
104 | * @return number of bytes consumed from the input buffer |
105 | */ |
106 | int ff_rtjpeg_decode_frame_yuv420(RTJpegContext *c, AVFrame *f, |
107 | const uint8_t *buf, int buf_size) { |
108 | GetBitContext gb; |
109 | int w = c->w / 16, h = c->h / 16; |
110 | int x, y, ret; |
111 | uint8_t *y1 = f->data[0], *y2 = f->data[0] + 8 * f->linesize[0]; |
112 | uint8_t *u = f->data[1], *v = f->data[2]; |
113 | |
114 | if ((ret = init_get_bits8(&gb, buf, buf_size)) < 0) |
115 | return ret; |
116 | |
117 | for (y = 0; y < h; y++) { |
118 | for (x = 0; x < w; x++) { |
119 | #define BLOCK(quant, dst, stride) do { \ |
120 | int res = get_block(&gb, block, c->scan, quant); \ |
121 | if (res < 0) \ |
122 | return res; \ |
123 | if (res > 0) \ |
124 | c->idsp.idct_put(dst, stride, block); \ |
125 | } while (0) |
126 | int16_t *block = c->block; |
127 | BLOCK(c->lquant, y1, f->linesize[0]); |
128 | y1 += 8; |
129 | BLOCK(c->lquant, y1, f->linesize[0]); |
130 | y1 += 8; |
131 | BLOCK(c->lquant, y2, f->linesize[0]); |
132 | y2 += 8; |
133 | BLOCK(c->lquant, y2, f->linesize[0]); |
134 | y2 += 8; |
135 | BLOCK(c->cquant, u, f->linesize[1]); |
136 | u += 8; |
137 | BLOCK(c->cquant, v, f->linesize[2]); |
138 | v += 8; |
139 | } |
140 | y1 += 2 * 8 * (f->linesize[0] - w); |
141 | y2 += 2 * 8 * (f->linesize[0] - w); |
142 | u += 8 * (f->linesize[1] - w); |
143 | v += 8 * (f->linesize[2] - w); |
144 | } |
145 | return get_bits_count(&gb) / 8; |
146 | } |
147 | |
148 | /** |
149 | * @brief initialize an RTJpegContext, may be called multiple times |
150 | * @param c context to initialize |
151 | * @param width width of image, will be rounded down to the nearest multiple |
152 | * of 16 for decoding |
153 | * @param height height of image, will be rounded down to the nearest multiple |
154 | * of 16 for decoding |
155 | * @param lquant luma quantization table to use |
156 | * @param cquant chroma quantization table to use |
157 | */ |
158 | void ff_rtjpeg_decode_init(RTJpegContext *c, int width, int height, |
159 | const uint32_t *lquant, const uint32_t *cquant) { |
160 | int i; |
161 | for (i = 0; i < 64; i++) { |
162 | int p = c->idsp.idct_permutation[i]; |
163 | c->lquant[p] = lquant[i]; |
164 | c->cquant[p] = cquant[i]; |
165 | } |
166 | c->w = width; |
167 | c->h = height; |
168 | } |
169 | |
170 | void ff_rtjpeg_init(RTJpegContext *c, AVCodecContext *avctx) |
171 | { |
172 | int i; |
173 | |
174 | ff_idctdsp_init(&c->idsp, avctx); |
175 | |
176 | for (i = 0; i < 64; i++) { |
177 | int z = ff_zigzag_direct[i]; |
178 | z = ((z << 3) | (z >> 3)) & 63; // rtjpeg uses a transposed variant |
179 | |
180 | // permute the scan and quantization tables for the chosen idct |
181 | c->scan[i] = c->idsp.idct_permutation[z]; |
182 | } |
183 | } |
184 |