0a2acab7199488b3afa147d58c0245b1332bdb7b
[libav.git] / libavcodec / pixdesc.h
1 /*
2 * pixel format descriptor
3 * Copyright (c) 2009 Michael Niedermayer <michaelni@gmx.at>
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 #ifndef AVCODEC_PIXDESC_H
23 #define AVCODEC_PIXDESC_H
24
25 #include <inttypes.h>
26
27 #include "libavutil/intreadwrite.h"
28
29 typedef struct AVComponentDescriptor{
30 uint16_t plane :2; ///< which of the 4 planes contains the component
31
32 /**
33 * Number of elements between 2 horizontally consecutive pixels minus 1.
34 * Elements are bits for bitstream formats, bytes otherwise.
35 */
36 uint16_t step_minus1 :3;
37
38 /**
39 * Number of elements before the component of the first pixel plus 1.
40 * Elements are bits for bitstream formats, bytes otherwise.
41 */
42 uint16_t offset_plus1 :3;
43 uint16_t shift :3; ///< number of least significant bits that must be shifted away to get the value
44 uint16_t depth_minus1 :4; ///< number of bits in the component minus 1
45 }AVComponentDescriptor;
46
47 /**
48 * Descriptor that unambiguously describes how the bits of a pixel are
49 * stored in the up to 4 data planes of an image. It also stores the
50 * subsampling factors and number of components.
51 *
52 * @note This is separate of the colorspace (RGB, YCbCr, YPbPr, JPEG-style YUV
53 * and all the YUV variants) AVPixFmtDescriptor just stores how values
54 * are stored not what these values represent.
55 */
56 typedef struct AVPixFmtDescriptor{
57 const char *name;
58 uint8_t nb_channels; ///< The number of components each pixel has, (1-4)
59
60 /**
61 * Amount to shift the luma width right to find the chroma width.
62 * For YV12 this is 1 for example.
63 * chroma_width = -((-luma_width) >> log2_chroma_w)
64 * The note above is needed to ensure rounding up.
65 */
66 uint8_t log2_chroma_w; ///< chroma_width = -((-luma_width )>>log2_chroma_w)
67
68 /**
69 * Amount to shift the luma height right to find the chroma height.
70 * For YV12 this is 1 for example.
71 * chroma_height= -((-luma_height) >> log2_chroma_h)
72 * The note above is needed to ensure rounding up.
73 */
74 uint8_t log2_chroma_h;
75 uint8_t flags;
76 AVComponentDescriptor comp[4]; ///< parameters that describe how pixels are packed
77 }AVPixFmtDescriptor;
78
79 #define PIX_FMT_BE 1 ///< big-endian
80 #define PIX_FMT_PAL 2 ///< Pixel format has a palette in data[1], values are indexes in this palette.
81 #define PIX_FMT_BITSTREAM 4 ///< All values of a component are bit-wise packed end to end.
82
83 /**
84 * The array of all the pixel format descriptors.
85 */
86 extern const AVPixFmtDescriptor av_pix_fmt_descriptors[];
87
88 /**
89 * Reads a line from an image, and writes to \p dst the values of the
90 * pixel format component \p c.
91 *
92 * @param data the array containing the pointers to the planes of the image
93 * @param linesizes the array containing the linesizes of the image
94 * @param desc the pixel format descriptor for the image
95 * @param x the horizontal coordinate of the first pixel to read
96 * @param y the vertical coordinate of the first pixel to read
97 * @param w the width of the line to read, that is the number of
98 * values to write to \p dst
99 * @param read_pal_component if not zero and the format is a paletted
100 * format writes to \p dst the values corresponding to the palette
101 * component \p c in data[1], rather than the palette indexes in
102 * data[0]. The behavior is undefined if the format is not paletted.
103 */
104 static inline void read_line(uint16_t *dst, const uint8_t *data[4], const int linesize[4],
105 const AVPixFmtDescriptor *desc, int x, int y, int c, int w, int read_pal_component)
106 {
107 AVComponentDescriptor comp= desc->comp[c];
108 int plane= comp.plane;
109 int depth= comp.depth_minus1+1;
110 int mask = (1<<depth)-1;
111 int shift= comp.shift;
112 int step = comp.step_minus1+1;
113 int flags= desc->flags;
114
115 if (flags & PIX_FMT_BITSTREAM){
116 int skip = x*step + comp.offset_plus1-1;
117 const uint8_t *p = data[plane] + y*linesize[plane] + (skip>>3);
118 int shift = 8 - depth - (skip&7);
119
120 while(w--){
121 int val = (*p >> shift) & mask;
122 if(read_pal_component)
123 val= data[1][4*val + c];
124 shift -= step;
125 p -= shift>>3;
126 shift &= 7;
127 *dst++= val;
128 }
129 } else {
130 const uint8_t *p = data[plane]+ y*linesize[plane] + x*step + comp.offset_plus1-1;
131
132 while(w--){
133 int val;
134 if(flags & PIX_FMT_BE) val= AV_RB16(p);
135 else val= AV_RL16(p);
136 val = (val>>shift) & mask;
137 if(read_pal_component)
138 val= data[1][4*val + c];
139 p+= step;
140 *dst++= val;
141 }
142 }
143 }
144
145 /**
146 * Writes the values from src to the pixel format component c of an
147 * image line.
148 *
149 * @param src array containing the values to write
150 * @param data the array containing the pointers to the planes of the
151 * image to write into. It is supposed to be zeroed.
152 * @param linesizes the array containing the linesizes of the image
153 * @param desc the pixel format descriptor for the image
154 * @param x the horizontal coordinate of the first pixel to write
155 * @param y the vertical coordinate of the first pixel to write
156 * @param w the width of the line to write, that is the number of
157 * values to write to the image line
158 */
159 static inline void write_line(const uint16_t *src, uint8_t *data[4], const int linesize[4],
160 const AVPixFmtDescriptor *desc, int x, int y, int c, int w)
161 {
162 AVComponentDescriptor comp = desc->comp[c];
163 int plane = comp.plane;
164 int depth = comp.depth_minus1+1;
165 int step = comp.step_minus1+1;
166 int flags = desc->flags;
167
168 if (flags & PIX_FMT_BITSTREAM) {
169 int skip = x*step + comp.offset_plus1-1;
170 uint8_t *p = data[plane] + y*linesize[plane] + (skip>>3);
171 int shift = 8 - depth - (skip&7);
172
173 while (w--) {
174 *p |= *src++ << shift;
175 shift -= step;
176 p -= shift>>3;
177 shift &= 7;
178 }
179 } else {
180 int shift = comp.shift;
181 uint8_t *p = data[plane]+ y*linesize[plane] + x*step + comp.offset_plus1-1;
182
183 while (w--) {
184 if (flags & PIX_FMT_BE) {
185 uint16_t val = AV_RB16(p) | (*src++<<shift);
186 AV_WB16(p, val);
187 } else {
188 uint16_t val = AV_RL16(p) | (*src++<<shift);
189 AV_WL16(p, val);
190 }
191 p+= step;
192 }
193 }
194 }
195
196 /**
197 * Returns the number of bits per pixel used by the pixel format
198 * described by pixdesc.
199 *
200 * The returned number of bits refers to the number of bits actually
201 * used for storing the pixel information, that is padding bits are
202 * not counted.
203 */
204 int av_get_bits_per_pixel(const AVPixFmtDescriptor *pixdesc);
205
206 #endif /* AVCODEC_PIXDESC_H */