pixdesc: Document the component order
[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 Libav.
6 *
7 * Libav 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 * Libav 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 Libav; 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 "attributes.h"
28 #include "pixfmt.h"
29
30 typedef struct AVComponentDescriptor {
31 /**
32 * Which of the 4 planes contains the component.
33 */
34 int plane;
35
36 /**
37 * Number of elements between 2 horizontally consecutive pixels.
38 * Elements are bits for bitstream formats, bytes otherwise.
39 */
40 int step;
41
42 /**
43 * Number of elements before the component of the first pixel.
44 * Elements are bits for bitstream formats, bytes otherwise.
45 */
46 int offset;
47
48 /**
49 * Number of least significant bits that must be shifted away
50 * to get the value.
51 */
52 int shift;
53
54 /**
55 * Number of bits in the component.
56 */
57 int depth;
58
59 #if FF_API_PLUS1_MINUS1
60 /** deprecated, use step instead */
61 attribute_deprecated int step_minus1;
62
63 /** deprecated, use depth instead */
64 attribute_deprecated int depth_minus1;
65
66 /** deprecated, use offset instead */
67 attribute_deprecated int offset_plus1;
68 #endif
69 } AVComponentDescriptor;
70
71 /**
72 * Descriptor that unambiguously describes how the bits of a pixel are
73 * stored in the up to 4 data planes of an image. It also stores the
74 * subsampling factors and number of components.
75 *
76 * @note This is separate of the colorspace (RGB, YCbCr, YPbPr, JPEG-style YUV
77 * and all the YUV variants) AVPixFmtDescriptor just stores how values
78 * are stored not what these values represent.
79 */
80 typedef struct AVPixFmtDescriptor {
81 const char *name;
82 uint8_t nb_components; ///< The number of components each pixel has, (1-4)
83
84 /**
85 * Amount to shift the luma width right to find the chroma width.
86 * For YV12 this is 1 for example.
87 * chroma_width = -((-luma_width) >> log2_chroma_w)
88 * The note above is needed to ensure rounding up.
89 * This value only refers to the chroma components.
90 */
91 uint8_t log2_chroma_w; ///< chroma_width = -((-luma_width )>>log2_chroma_w)
92
93 /**
94 * Amount to shift the luma height right to find the chroma height.
95 * For YV12 this is 1 for example.
96 * chroma_height= -((-luma_height) >> log2_chroma_h)
97 * The note above is needed to ensure rounding up.
98 * This value only refers to the chroma components.
99 */
100 uint8_t log2_chroma_h;
101
102 /**
103 * Combination of AV_PIX_FMT_FLAG_... flags.
104 */
105 uint64_t flags;
106
107 /**
108 * Parameters that describe how pixels are packed. If the format
109 * has chroma components, they must be stored in comp[1] and
110 * comp[2].
111 * If the format is RGB-like, the first component is R, followed
112 * by G and B.
113 *
114 * If the format is YUV-like, the first component is Y, followed
115 * by U and V.
116 *
117 * If present, the Alpha channel is always the last component.
118 */
119 AVComponentDescriptor comp[4];
120
121 /**
122 * Alternative comma-separated names.
123 */
124 const char *alias;
125 } AVPixFmtDescriptor;
126
127 /**
128 * Pixel format is big-endian.
129 */
130 #define AV_PIX_FMT_FLAG_BE (1 << 0)
131 /**
132 * Pixel format has a palette in data[1], values are indexes in this palette.
133 */
134 #define AV_PIX_FMT_FLAG_PAL (1 << 1)
135 /**
136 * All values of a component are bit-wise packed end to end.
137 */
138 #define AV_PIX_FMT_FLAG_BITSTREAM (1 << 2)
139 /**
140 * Pixel format is an HW accelerated format.
141 */
142 #define AV_PIX_FMT_FLAG_HWACCEL (1 << 3)
143 /**
144 * At least one pixel component is not in the first data plane.
145 */
146 #define AV_PIX_FMT_FLAG_PLANAR (1 << 4)
147 /**
148 * The pixel format contains RGB-like data (as opposed to YUV/grayscale).
149 */
150 #define AV_PIX_FMT_FLAG_RGB (1 << 5)
151 /**
152 * The pixel format is "pseudo-paletted". This means that Libav treats it as
153 * paletted internally, but the palette is generated by the decoder and is not
154 * stored in the file.
155 */
156 #define AV_PIX_FMT_FLAG_PSEUDOPAL (1 << 6)
157 /**
158 * The pixel format has an alpha channel.
159 */
160 #define AV_PIX_FMT_FLAG_ALPHA (1 << 7)
161
162 /**
163 * Read a line from an image, and write the values of the
164 * pixel format component c to dst.
165 *
166 * @param data the array containing the pointers to the planes of the image
167 * @param linesize the array containing the linesizes of the image
168 * @param desc the pixel format descriptor for the image
169 * @param x the horizontal coordinate of the first pixel to read
170 * @param y the vertical coordinate of the first pixel to read
171 * @param w the width of the line to read, that is the number of
172 * values to write to dst
173 * @param read_pal_component if not zero and the format is a paletted
174 * format writes the values corresponding to the palette
175 * component c in data[1] to dst, rather than the palette indexes in
176 * data[0]. The behavior is undefined if the format is not paletted.
177 */
178 void av_read_image_line(uint16_t *dst, const uint8_t *data[4],
179 const int linesize[4], const AVPixFmtDescriptor *desc,
180 int x, int y, int c, int w, int read_pal_component);
181
182 /**
183 * Write the values from src to the pixel format component c of an
184 * image line.
185 *
186 * @param src array containing the values to write
187 * @param data the array containing the pointers to the planes of the
188 * image to write into. It is supposed to be zeroed.
189 * @param linesize the array containing the linesizes of the image
190 * @param desc the pixel format descriptor for the image
191 * @param x the horizontal coordinate of the first pixel to write
192 * @param y the vertical coordinate of the first pixel to write
193 * @param w the width of the line to write, that is the number of
194 * values to write to the image line
195 */
196 void av_write_image_line(const uint16_t *src, uint8_t *data[4],
197 const int linesize[4], const AVPixFmtDescriptor *desc,
198 int x, int y, int c, int w);
199
200 /**
201 * Return the pixel format corresponding to name.
202 *
203 * If there is no pixel format with name name, then looks for a
204 * pixel format with the name corresponding to the native endian
205 * format of name.
206 * For example in a little-endian system, first looks for "gray16",
207 * then for "gray16le".
208 *
209 * Finally if no pixel format has been found, returns PIX_FMT_NONE.
210 */
211 enum AVPixelFormat av_get_pix_fmt(const char *name);
212
213 /**
214 * Return the short name for a pixel format, NULL in case pix_fmt is
215 * unknown.
216 *
217 * @see av_get_pix_fmt(), av_get_pix_fmt_string()
218 */
219 const char *av_get_pix_fmt_name(enum AVPixelFormat pix_fmt);
220
221 /**
222 * Print in buf the string corresponding to the pixel format with
223 * number pix_fmt, or an header if pix_fmt is negative.
224 *
225 * @param buf the buffer where to write the string
226 * @param buf_size the size of buf
227 * @param pix_fmt the number of the pixel format to print the
228 * corresponding info string, or a negative value to print the
229 * corresponding header.
230 */
231 char *av_get_pix_fmt_string(char *buf, int buf_size,
232 enum AVPixelFormat pix_fmt);
233
234 /**
235 * Return the number of bits per pixel used by the pixel format
236 * described by pixdesc. Note that this is not the same as the number
237 * of bits per sample.
238 *
239 * The returned number of bits refers to the number of bits actually
240 * used for storing the pixel information, that is padding bits are
241 * not counted.
242 */
243 int av_get_bits_per_pixel(const AVPixFmtDescriptor *pixdesc);
244
245 /**
246 * @return a pixel format descriptor for provided pixel format or NULL if
247 * this pixel format is unknown.
248 */
249 const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt);
250
251 /**
252 * Iterate over all pixel format descriptors known to libavutil.
253 *
254 * @param prev previous descriptor. NULL to get the first descriptor.
255 *
256 * @return next descriptor or NULL after the last descriptor
257 */
258 const AVPixFmtDescriptor *av_pix_fmt_desc_next(const AVPixFmtDescriptor *prev);
259
260 /**
261 * @return an AVPixelFormat id described by desc, or AV_PIX_FMT_NONE if desc
262 * is not a valid pointer to a pixel format descriptor.
263 */
264 enum AVPixelFormat av_pix_fmt_desc_get_id(const AVPixFmtDescriptor *desc);
265
266 /**
267 * Utility function to access log2_chroma_w log2_chroma_h from
268 * the pixel format AVPixFmtDescriptor.
269 *
270 * @param[in] pix_fmt the pixel format
271 * @param[out] h_shift store log2_chroma_h
272 * @param[out] v_shift store log2_chroma_w
273 *
274 * @return 0 on success, AVERROR(ENOSYS) on invalid or unknown pixel format
275 */
276 int av_pix_fmt_get_chroma_sub_sample(enum AVPixelFormat pix_fmt,
277 int *h_shift, int *v_shift);
278
279 /**
280 * @return number of planes in pix_fmt, a negative AVERROR if pix_fmt is not a
281 * valid pixel format.
282 */
283 int av_pix_fmt_count_planes(enum AVPixelFormat pix_fmt);
284
285 /**
286 * Utility function to swap the endianness of a pixel format.
287 *
288 * @param[in] pix_fmt the pixel format
289 *
290 * @return pixel format with swapped endianness if it exists,
291 * otherwise AV_PIX_FMT_NONE
292 */
293 enum AVPixelFormat av_pix_fmt_swap_endianness(enum AVPixelFormat pix_fmt);
294
295 /**
296 * @return the name for provided color range or NULL if unknown.
297 */
298 const char *av_color_range_name(enum AVColorRange range);
299
300 /**
301 * @return the name for provided color primaries or NULL if unknown.
302 */
303 const char *av_color_primaries_name(enum AVColorPrimaries primaries);
304
305 /**
306 * @return the name for provided color transfer or NULL if unknown.
307 */
308 const char *av_color_transfer_name(enum AVColorTransferCharacteristic transfer);
309
310 /**
311 * @return the name for provided color space or NULL if unknown.
312 */
313 const char *av_color_space_name(enum AVColorSpace space);
314
315 /**
316 * @return the name for provided chroma location or NULL if unknown.
317 */
318 const char *av_chroma_location_name(enum AVChromaLocation location);
319
320 #endif /* AVUTIL_PIXDESC_H */