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pixdesc.h
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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 #include "pixfmt.h"
27 
28 typedef struct AVComponentDescriptor{
29  uint16_t plane :2; ///< which of the 4 planes contains the component
30 
31  /**
32  * Number of elements between 2 horizontally consecutive pixels minus 1.
33  * Elements are bits for bitstream formats, bytes otherwise.
34  */
35  uint16_t step_minus1 :3;
36 
37  /**
38  * Number of elements before the component of the first pixel plus 1.
39  * Elements are bits for bitstream formats, bytes otherwise.
40  */
41  uint16_t offset_plus1 :3;
42  uint16_t shift :3; ///< number of least significant bits that must be shifted away to get the value
43  uint16_t depth_minus1 :4; ///< number of bits in the component minus 1
45 
46 /**
47  * Descriptor that unambiguously describes how the bits of a pixel are
48  * stored in the up to 4 data planes of an image. It also stores the
49  * subsampling factors and number of components.
50  *
51  * @note This is separate of the colorspace (RGB, YCbCr, YPbPr, JPEG-style YUV
52  * and all the YUV variants) AVPixFmtDescriptor just stores how values
53  * are stored not what these values represent.
54  */
55 typedef struct AVPixFmtDescriptor{
56  const char *name;
57  uint8_t nb_components; ///< The number of components each pixel has, (1-4)
58 
59  /**
60  * Amount to shift the luma width right to find the chroma width.
61  * For YV12 this is 1 for example.
62  * chroma_width = -((-luma_width) >> log2_chroma_w)
63  * The note above is needed to ensure rounding up.
64  * This value only refers to the chroma components.
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  * This value only refers to the chroma components.
74  */
77 
78  /**
79  * Parameters that describe how pixels are packed.
80  * If the format has 2 or 4 components, then alpha is last.
81  * If the format has 1 or 2 components, then luma is 0.
82  * If the format has 3 or 4 components,
83  * if the RGB flag is set then 0 is red, 1 is green and 2 is blue;
84  * otherwise 0 is luma, 1 is chroma-U and 2 is chroma-V.
85  */
88 
89 /**
90  * Pixel format is big-endian.
91  */
92 #define AV_PIX_FMT_FLAG_BE (1 << 0)
93 /**
94  * Pixel format has a palette in data[1], values are indexes in this palette.
95  */
96 #define AV_PIX_FMT_FLAG_PAL (1 << 1)
97 /**
98  * All values of a component are bit-wise packed end to end.
99  */
100 #define AV_PIX_FMT_FLAG_BITSTREAM (1 << 2)
101 /**
102  * Pixel format is an HW accelerated format.
103  */
104 #define AV_PIX_FMT_FLAG_HWACCEL (1 << 3)
105 /**
106  * At least one pixel component is not in the first data plane.
107  */
108 #define AV_PIX_FMT_FLAG_PLANAR (1 << 4)
109 /**
110  * The pixel format contains RGB-like data (as opposed to YUV/grayscale).
111  */
112 #define AV_PIX_FMT_FLAG_RGB (1 << 5)
113 /**
114  * The pixel format is "pseudo-paletted". This means that FFmpeg treats it as
115  * paletted internally, but the palette is generated by the decoder and is not
116  * stored in the file.
117  */
118 #define AV_PIX_FMT_FLAG_PSEUDOPAL (1 << 6)
119 /**
120  * The pixel format has an alpha channel.
121  */
122 #define AV_PIX_FMT_FLAG_ALPHA (1 << 7)
123 
124 #if FF_API_PIX_FMT
125 /**
126  * @deprecate use the AV_PIX_FMT_FLAG_* flags
127  */
128 #define PIX_FMT_BE AV_PIX_FMT_FLAG_BE
129 #define PIX_FMT_PAL AV_PIX_FMT_FLAG_PAL
130 #define PIX_FMT_BITSTREAM AV_PIX_FMT_FLAG_BITSTREAM
131 #define PIX_FMT_HWACCEL AV_PIX_FMT_FLAG_HWACCEL
132 #define PIX_FMT_PLANAR AV_PIX_FMT_FLAG_PLANAR
133 #define PIX_FMT_RGB AV_PIX_FMT_FLAG_RGB
134 #define PIX_FMT_PSEUDOPAL AV_PIX_FMT_FLAG_PSEUDOPAL
135 #define PIX_FMT_ALPHA AV_PIX_FMT_FLAG_ALPHA
136 #endif
137 
138 #if FF_API_PIX_FMT_DESC
139 /**
140  * The array of all the pixel format descriptors.
141  */
143 #endif
144 
145 /**
146  * Read a line from an image, and write the values of the
147  * pixel format component c to dst.
148  *
149  * @param data the array containing the pointers to the planes of the image
150  * @param linesize the array containing the linesizes of the image
151  * @param desc the pixel format descriptor for the image
152  * @param x the horizontal coordinate of the first pixel to read
153  * @param y the vertical coordinate of the first pixel to read
154  * @param w the width of the line to read, that is the number of
155  * values to write to dst
156  * @param read_pal_component if not zero and the format is a paletted
157  * format writes the values corresponding to the palette
158  * component c in data[1] to dst, rather than the palette indexes in
159  * data[0]. The behavior is undefined if the format is not paletted.
160  */
161 void av_read_image_line(uint16_t *dst, const uint8_t *data[4], const int linesize[4],
162  const AVPixFmtDescriptor *desc, int x, int y, int c, int w, int read_pal_component);
163 
164 /**
165  * Write the values from src to the pixel format component c of an
166  * image line.
167  *
168  * @param src array containing the values to write
169  * @param data the array containing the pointers to the planes of the
170  * image to write into. It is supposed to be zeroed.
171  * @param linesize the array containing the linesizes of the image
172  * @param desc the pixel format descriptor for the image
173  * @param x the horizontal coordinate of the first pixel to write
174  * @param y the vertical coordinate of the first pixel to write
175  * @param w the width of the line to write, that is the number of
176  * values to write to the image line
177  */
178 void av_write_image_line(const uint16_t *src, uint8_t *data[4], const int linesize[4],
179  const AVPixFmtDescriptor *desc, int x, int y, int c, int w);
180 
181 /**
182  * Return the pixel format corresponding to name.
183  *
184  * If there is no pixel format with name name, then looks for a
185  * pixel format with the name corresponding to the native endian
186  * format of name.
187  * For example in a little-endian system, first looks for "gray16",
188  * then for "gray16le".
189  *
190  * Finally if no pixel format has been found, returns AV_PIX_FMT_NONE.
191  */
192 enum AVPixelFormat av_get_pix_fmt(const char *name);
193 
194 /**
195  * Return the short name for a pixel format, NULL in case pix_fmt is
196  * unknown.
197  *
198  * @see av_get_pix_fmt(), av_get_pix_fmt_string()
199  */
200 const char *av_get_pix_fmt_name(enum AVPixelFormat pix_fmt);
201 
202 /**
203  * Print in buf the string corresponding to the pixel format with
204  * number pix_fmt, or an header if pix_fmt is negative.
205  *
206  * @param buf the buffer where to write the string
207  * @param buf_size the size of buf
208  * @param pix_fmt the number of the pixel format to print the
209  * corresponding info string, or a negative value to print the
210  * corresponding header.
211  */
212 char *av_get_pix_fmt_string (char *buf, int buf_size, enum AVPixelFormat pix_fmt);
213 
214 /**
215  * Return the number of bits per pixel used by the pixel format
216  * described by pixdesc. Note that this is not the same as the number
217  * of bits per sample.
218  *
219  * The returned number of bits refers to the number of bits actually
220  * used for storing the pixel information, that is padding bits are
221  * not counted.
222  */
223 int av_get_bits_per_pixel(const AVPixFmtDescriptor *pixdesc);
224 
225 /**
226  * Return the number of bits per pixel for the pixel format
227  * described by pixdesc, including any padding or unused bits.
228  */
230 
231 /**
232  * @return a pixel format descriptor for provided pixel format or NULL if
233  * this pixel format is unknown.
234  */
236 
237 /**
238  * Iterate over all pixel format descriptors known to libavutil.
239  *
240  * @param prev previous descriptor. NULL to get the first descriptor.
241  *
242  * @return next descriptor or NULL after the last descriptor
243  */
245 
246 /**
247  * @return an AVPixelFormat id described by desc, or AV_PIX_FMT_NONE if desc
248  * is not a valid pointer to a pixel format descriptor.
249  */
251 
252 /**
253  * Utility function to access log2_chroma_w log2_chroma_h from
254  * the pixel format AVPixFmtDescriptor.
255  *
256  * See avcodec_get_chroma_sub_sample() for a function that asserts a
257  * valid pixel format instead of returning an error code.
258  * Its recommanded that you use avcodec_get_chroma_sub_sample unless
259  * you do check the return code!
260  *
261  * @param[in] pix_fmt the pixel format
262  * @param[out] h_shift store log2_chroma_w
263  * @param[out] v_shift store log2_chroma_h
264  *
265  * @return 0 on success, AVERROR(ENOSYS) on invalid or unknown pixel format
266  */
268  int *h_shift, int *v_shift);
269 
270 /**
271  * @return number of planes in pix_fmt, a negative AVERROR if pix_fmt is not a
272  * valid pixel format.
273  */
275 
276 void ff_check_pixfmt_descriptors(void);
277 
278 /**
279  * Utility function to swap the endianness of a pixel format.
280  *
281  * @param[in] pix_fmt the pixel format
282  *
283  * @return pixel format with swapped endianness if it exists,
284  * otherwise AV_PIX_FMT_NONE
285  */
287 
288 
289 #endif /* AVUTIL_PIXDESC_H */