Move pixdesc.{h,c} from libavcodec to libavutil.
[libav.git] / libavutil / 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 AVUTIL_PIXDESC_H
23 #define AVUTIL_PIXDESC_H
24
25 #include <inttypes.h>
26
27 #include "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 #define PIX_FMT_HWACCEL 8 ///< Pixel format is an HW accelerated format.
83
84 /**
85 * The array of all the pixel format descriptors.
86 */
87 extern const AVPixFmtDescriptor av_pix_fmt_descriptors[];
88
89 /**
90 * Reads a line from an image, and writes to dst the values of the
91 * pixel format component c.
92 *
93 * @param data the array containing the pointers to the planes of the image
94 * @param linesizes the array containing the linesizes of the image
95 * @param desc the pixel format descriptor for the image
96 * @param x the horizontal coordinate of the first pixel to read
97 * @param y the vertical coordinate of the first pixel to read
98 * @param w the width of the line to read, that is the number of
99 * values to write to dst
100 * @param read_pal_component if not zero and the format is a paletted
101 * format writes to dst the values corresponding to the palette
102 * component c in data[1], rather than the palette indexes in
103 * data[0]. The behavior is undefined if the format is not paletted.
104 */
105 static inline void read_line(uint16_t *dst, const uint8_t *data[4], const int linesize[4],
106 const AVPixFmtDescriptor *desc, int x, int y, int c, int w, int read_pal_component)
107 {
108 AVComponentDescriptor comp= desc->comp[c];
109 int plane= comp.plane;
110 int depth= comp.depth_minus1+1;
111 int mask = (1<<depth)-1;
112 int shift= comp.shift;
113 int step = comp.step_minus1+1;
114 int flags= desc->flags;
115
116 if (flags & PIX_FMT_BITSTREAM){
117 int skip = x*step + comp.offset_plus1-1;
118 const uint8_t *p = data[plane] + y*linesize[plane] + (skip>>3);
119 int shift = 8 - depth - (skip&7);
120
121 while(w--){
122 int val = (*p >> shift) & mask;
123 if(read_pal_component)
124 val= data[1][4*val + c];
125 shift -= step;
126 p -= shift>>3;
127 shift &= 7;
128 *dst++= val;
129 }
130 } else {
131 const uint8_t *p = data[plane]+ y*linesize[plane] + x*step + comp.offset_plus1-1;
132
133 while(w--){
134 int val;
135 if(flags & PIX_FMT_BE) val= AV_RB16(p);
136 else val= AV_RL16(p);
137 val = (val>>shift) & mask;
138 if(read_pal_component)
139 val= data[1][4*val + c];
140 p+= step;
141 *dst++= val;
142 }
143 }
144 }
145
146 /**
147 * Writes the values from src to the pixel format component c of an
148 * image line.
149 *
150 * @param src array containing the values to write
151 * @param data the array containing the pointers to the planes of the
152 * image to write into. It is supposed to be zeroed.
153 * @param linesizes the array containing the linesizes of the image
154 * @param desc the pixel format descriptor for the image
155 * @param x the horizontal coordinate of the first pixel to write
156 * @param y the vertical coordinate of the first pixel to write
157 * @param w the width of the line to write, that is the number of
158 * values to write to the image line
159 */
160 static inline void write_line(const uint16_t *src, uint8_t *data[4], const int linesize[4],
161 const AVPixFmtDescriptor *desc, int x, int y, int c, int w)
162 {
163 AVComponentDescriptor comp = desc->comp[c];
164 int plane = comp.plane;
165 int depth = comp.depth_minus1+1;
166 int step = comp.step_minus1+1;
167 int flags = desc->flags;
168
169 if (flags & PIX_FMT_BITSTREAM) {
170 int skip = x*step + comp.offset_plus1-1;
171 uint8_t *p = data[plane] + y*linesize[plane] + (skip>>3);
172 int shift = 8 - depth - (skip&7);
173
174 while (w--) {
175 *p |= *src++ << shift;
176 shift -= step;
177 p -= shift>>3;
178 shift &= 7;
179 }
180 } else {
181 int shift = comp.shift;
182 uint8_t *p = data[plane]+ y*linesize[plane] + x*step + comp.offset_plus1-1;
183
184 while (w--) {
185 if (flags & PIX_FMT_BE) {
186 uint16_t val = AV_RB16(p) | (*src++<<shift);
187 AV_WB16(p, val);
188 } else {
189 uint16_t val = AV_RL16(p) | (*src++<<shift);
190 AV_WL16(p, val);
191 }
192 p+= step;
193 }
194 }
195 }
196
197 /**
198 * Returns the number of bits per pixel used by the pixel format
199 * described by pixdesc.
200 *
201 * The returned number of bits refers to the number of bits actually
202 * used for storing the pixel information, that is padding bits are
203 * not counted.
204 */
205 int av_get_bits_per_pixel(const AVPixFmtDescriptor *pixdesc);
206
207 #endif /* AVUTIL_PIXDESC_H */