NuppelVideo/MythTVVideo support, including rtjpeg decoder
[libav.git] / libavcodec / rtjpeg.c
1 /*
2 * RTJpeg decoding functions
3 * Copyright (c) 2006 Reimar Doeffinger
4 *
5 * This library is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU Lesser General Public
7 * License as published by the Free Software Foundation; either
8 * version 2 of the License, or (at your option) any later version.
9 *
10 * This library is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * Lesser General Public License for more details.
14 *
15 * You should have received a copy of the GNU Lesser General Public
16 * License along with this library; if not, write to the Free Software
17 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
18 */
19 #include "common.h"
20 #include "bitstream.h"
21 #include "dsputil.h"
22 #include "rtjpeg.h"
23
24 #define PUT_COEFF(c) \
25 i = scan[coeff--]; \
26 block[i] = (c) * quant[i];
27
28 //! aligns the bitstream to the give power of two
29 #define ALIGN(a) \
30 n = (-get_bits_count(gb)) & (a - 1); \
31 if (n) {skip_bits(gb, n);}
32
33 /**
34 * \brief read one block from stream
35 * \param gb contains stream data
36 * \param block where data is written to
37 * \param scan array containing the mapping stream address -> block position
38 * \param quant quantization factors
39 *
40 * Note: GetBitContext is used to make the code simpler, since all data is
41 * aligned this could be done faster in a different way, e.g. as it is done
42 * in MPlayer libmpcodecs/native/RTjpegN.c
43 */
44 static inline int get_block(GetBitContext *gb, DCTELEM *block, uint8_t *scan,
45 uint32_t *quant) {
46 int coeff, i, n;
47 int8_t ac;
48 uint8_t dc = get_bits(gb, 8);
49
50 // block not coded
51 if (dc == 255)
52 return 0;
53
54 // number of non-zero coefficients
55 coeff = get_bits(gb, 6);
56 // normally we would only need to clear the (63 - coeff) last values,
57 // but since we do not know where they are we just clear the whole block
58 memset(block, 0, 64 * sizeof(DCTELEM));
59
60 // 2 bits per coefficient
61 while (coeff) {
62 ac = get_sbits(gb, 2);
63 if (ac == -2)
64 break; // continue with more bits
65 PUT_COEFF(ac);
66 }
67
68 // 4 bits per coefficient
69 ALIGN(4);
70 while (coeff) {
71 ac = get_sbits(gb, 4);
72 if (ac == -8)
73 break; // continue with more bits
74 PUT_COEFF(ac);
75 }
76
77 // 8 bits per coefficient
78 ALIGN(8);
79 while (coeff) {
80 ac = get_sbits(gb, 8);
81 PUT_COEFF(ac);
82 }
83
84 PUT_COEFF(dc);
85 return 1;
86 }
87
88 /**
89 * \brief decode one rtjpeg YUV420 frame
90 * \param c context, must be initialized via rtjpeg_decode_init
91 * \param f AVFrame to place decoded frame into. If parts of the frame
92 * are not coded they are left unchanged, so consider initializing it
93 * \param buf buffer containing input data
94 * \param buf_size length of input data in bytes
95 * \return number of bytes consumed from the input buffer
96 */
97 int rtjpeg_decode_frame_yuv420(RTJpegContext *c, AVFrame *f,
98 uint8_t *buf, int buf_size) {
99 GetBitContext gb;
100 int w = c->w / 16, h = c->h / 16;
101 int x, y;
102 void *y1 = f->data[0], *y2 = f->data[0] + 8 * f->linesize[0];
103 void *u = f->data[1], *v = f->data[2];
104 init_get_bits(&gb, buf, buf_size * 8);
105 for (y = 0; y < h; y++) {
106 for (x = 0; x < w; x++) {
107 if (get_block(&gb, c->block, c->scan, c->lquant))
108 c->dsp->idct_put(y1, f->linesize[0], c->block);
109 y1 += 8;
110 if (get_block(&gb, c->block, c->scan, c->lquant))
111 c->dsp->idct_put(y1, f->linesize[0], c->block);
112 y1 += 8;
113 if (get_block(&gb, c->block, c->scan, c->lquant))
114 c->dsp->idct_put(y2, f->linesize[0], c->block);
115 y2 += 8;
116 if (get_block(&gb, c->block, c->scan, c->lquant))
117 c->dsp->idct_put(y2, f->linesize[0], c->block);
118 y2 += 8;
119 if (get_block(&gb, c->block, c->scan, c->cquant))
120 c->dsp->idct_put(u, f->linesize[1], c->block);
121 u += 8;
122 if (get_block(&gb, c->block, c->scan, c->cquant))
123 c->dsp->idct_put(v, f->linesize[2], c->block);
124 v += 8;
125 }
126 y1 += 2 * 8 * (f->linesize[0] - w);
127 y2 += 2 * 8 * (f->linesize[0] - w);
128 u += 8 * (f->linesize[1] - w);
129 v += 8 * (f->linesize[2] - w);
130 }
131 return get_bits_count(&gb) / 8;
132 }
133
134 /**
135 * \brief initialize an RTJpegContext, may be called multiple times
136 * \param c context to initialize
137 * \param dsp specifies the idct to use for decoding
138 * \param width width of image, will be rounded down to the nearest multiple
139 * of 16 for decoding
140 * \param height height of image, will be rounded down to the nearest multiple
141 * of 16 for decoding
142 * \param lquant luma quantization table to use
143 * \param cquant chroma quantization table to use
144 */
145 void rtjpeg_decode_init(RTJpegContext *c, DSPContext *dsp,
146 int width, int height,
147 uint32_t *lquant, uint32_t *cquant) {
148 int i;
149 c->dsp = dsp;
150 for (i = 0; i < 64; i++) {
151 int z = ff_zigzag_direct[i];
152 int p = c->dsp->idct_permutation[i];
153 z = ((z << 3) | (z >> 3)) & 63; // rtjpeg uses a transposed variant
154
155 // permute the scan and quantization tables for the chosen idct
156 c->scan[i] = c->dsp->idct_permutation[z];
157 c->lquant[p] = lquant[i];
158 c->cquant[p] = cquant[i];
159 }
160 c->w = width;
161 c->h = height;
162 }