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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 
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  uint16_t plane : 2;
35 
36  /**
37  * Number of elements between 2 horizontally consecutive pixels minus 1.
38  * Elements are bits for bitstream formats, bytes otherwise.
39  */
40  uint16_t step_minus1 : 3;
41 
42  /**
43  * Number of elements before the component of the first pixel plus 1.
44  * Elements are bits for bitstream formats, bytes otherwise.
45  */
46  uint16_t offset_plus1 : 3;
47 
48  /**
49  * Number of least significant bits that must be shifted away
50  * to get the value.
51  */
52  uint16_t shift : 3;
53 
54  /**
55  * Number of bits in the component minus 1.
56  */
57  uint16_t depth_minus1 : 4;
59 
60 /**
61  * Descriptor that unambiguously describes how the bits of a pixel are
62  * stored in the up to 4 data planes of an image. It also stores the
63  * subsampling factors and number of components.
64  *
65  * @note This is separate of the colorspace (RGB, YCbCr, YPbPr, JPEG-style YUV
66  * and all the YUV variants) AVPixFmtDescriptor just stores how values
67  * are stored not what these values represent.
68  */
69 typedef struct AVPixFmtDescriptor {
70  const char *name;
71  uint8_t nb_components; ///< The number of components each pixel has, (1-4)
72 
73  /**
74  * Amount to shift the luma width right to find the chroma width.
75  * For YV12 this is 1 for example.
76  * chroma_width = -((-luma_width) >> log2_chroma_w)
77  * The note above is needed to ensure rounding up.
78  * This value only refers to the chroma components.
79  */
80  uint8_t log2_chroma_w; ///< chroma_width = -((-luma_width )>>log2_chroma_w)
81 
82  /**
83  * Amount to shift the luma height right to find the chroma height.
84  * For YV12 this is 1 for example.
85  * chroma_height= -((-luma_height) >> log2_chroma_h)
86  * The note above is needed to ensure rounding up.
87  * This value only refers to the chroma components.
88  */
91 
92  /**
93  * Parameters that describe how pixels are packed.
94  * If the format has 2 or 4 components, then alpha is last.
95  * If the format has 1 or 2 components, then luma is 0.
96  * If the format has 3 or 4 components,
97  * if the RGB flag is set then 0 is red, 1 is green and 2 is blue;
98  * otherwise 0 is luma, 1 is chroma-U and 2 is chroma-V.
99  */
101 
102  /**
103  * Alternative comma-separated names.
104  */
105  const char *alias;
107 
108 /**
109  * Pixel format is big-endian.
110  */
111 #define AV_PIX_FMT_FLAG_BE (1 << 0)
112 /**
113  * Pixel format has a palette in data[1], values are indexes in this palette.
114  */
115 #define AV_PIX_FMT_FLAG_PAL (1 << 1)
116 /**
117  * All values of a component are bit-wise packed end to end.
118  */
119 #define AV_PIX_FMT_FLAG_BITSTREAM (1 << 2)
120 /**
121  * Pixel format is an HW accelerated format.
122  */
123 #define AV_PIX_FMT_FLAG_HWACCEL (1 << 3)
124 /**
125  * At least one pixel component is not in the first data plane.
126  */
127 #define AV_PIX_FMT_FLAG_PLANAR (1 << 4)
128 /**
129  * The pixel format contains RGB-like data (as opposed to YUV/grayscale).
130  */
131 #define AV_PIX_FMT_FLAG_RGB (1 << 5)
132 
133 /**
134  * The pixel format is "pseudo-paletted". This means that it contains a
135  * fixed palette in the 2nd plane but the palette is fixed/constant for each
136  * PIX_FMT. This allows interpreting the data as if it was PAL8, which can
137  * in some cases be simpler. Or the data can be interpreted purely based on
138  * the pixel format without using the palette.
139  * An example of a pseudo-paletted format is AV_PIX_FMT_GRAY8
140  */
141 #define AV_PIX_FMT_FLAG_PSEUDOPAL (1 << 6)
142 /**
143  * The pixel format has an alpha channel.
144  */
145 #define AV_PIX_FMT_FLAG_ALPHA (1 << 7)
146 
147 #if FF_API_PIX_FMT
148 /**
149  * @deprecated use the AV_PIX_FMT_FLAG_* flags
150  */
151 #define PIX_FMT_BE AV_PIX_FMT_FLAG_BE
152 #define PIX_FMT_PAL AV_PIX_FMT_FLAG_PAL
153 #define PIX_FMT_BITSTREAM AV_PIX_FMT_FLAG_BITSTREAM
154 #define PIX_FMT_HWACCEL AV_PIX_FMT_FLAG_HWACCEL
155 #define PIX_FMT_PLANAR AV_PIX_FMT_FLAG_PLANAR
156 #define PIX_FMT_RGB AV_PIX_FMT_FLAG_RGB
157 #define PIX_FMT_PSEUDOPAL AV_PIX_FMT_FLAG_PSEUDOPAL
158 #define PIX_FMT_ALPHA AV_PIX_FMT_FLAG_ALPHA
159 #endif
160 
161 #if FF_API_PIX_FMT_DESC
162 /**
163  * The array of all the pixel format descriptors.
164  */
166 #endif
167 
168 /**
169  * Read a line from an image, and write the values of the
170  * pixel format component c to dst.
171  *
172  * @param data the array containing the pointers to the planes of the image
173  * @param linesize the array containing the linesizes of the image
174  * @param desc the pixel format descriptor for the image
175  * @param x the horizontal coordinate of the first pixel to read
176  * @param y the vertical coordinate of the first pixel to read
177  * @param w the width of the line to read, that is the number of
178  * values to write to dst
179  * @param read_pal_component if not zero and the format is a paletted
180  * format writes the values corresponding to the palette
181  * component c in data[1] to dst, rather than the palette indexes in
182  * data[0]. The behavior is undefined if the format is not paletted.
183  */
184 void av_read_image_line(uint16_t *dst, const uint8_t *data[4],
185  const int linesize[4], const AVPixFmtDescriptor *desc,
186  int x, int y, int c, int w, int read_pal_component);
187 
188 /**
189  * Write the values from src to the pixel format component c of an
190  * image line.
191  *
192  * @param src array containing the values to write
193  * @param data the array containing the pointers to the planes of the
194  * image to write into. It is supposed to be zeroed.
195  * @param linesize the array containing the linesizes of the image
196  * @param desc the pixel format descriptor for the image
197  * @param x the horizontal coordinate of the first pixel to write
198  * @param y the vertical coordinate of the first pixel to write
199  * @param w the width of the line to write, that is the number of
200  * values to write to the image line
201  */
202 void av_write_image_line(const uint16_t *src, uint8_t *data[4],
203  const int linesize[4], const AVPixFmtDescriptor *desc,
204  int x, int y, int c, int w);
205 
206 /**
207  * Return the pixel format corresponding to name.
208  *
209  * If there is no pixel format with name name, then looks for a
210  * pixel format with the name corresponding to the native endian
211  * format of name.
212  * For example in a little-endian system, first looks for "gray16",
213  * then for "gray16le".
214  *
215  * Finally if no pixel format has been found, returns AV_PIX_FMT_NONE.
216  */
217 enum AVPixelFormat av_get_pix_fmt(const char *name);
218 
219 /**
220  * Return the short name for a pixel format, NULL in case pix_fmt is
221  * unknown.
222  *
223  * @see av_get_pix_fmt(), av_get_pix_fmt_string()
224  */
225 const char *av_get_pix_fmt_name(enum AVPixelFormat pix_fmt);
226 
227 /**
228  * Print in buf the string corresponding to the pixel format with
229  * number pix_fmt, or a header if pix_fmt is negative.
230  *
231  * @param buf the buffer where to write the string
232  * @param buf_size the size of buf
233  * @param pix_fmt the number of the pixel format to print the
234  * corresponding info string, or a negative value to print the
235  * corresponding header.
236  */
237 char *av_get_pix_fmt_string(char *buf, int buf_size,
238  enum AVPixelFormat pix_fmt);
239 
240 /**
241  * Return the number of bits per pixel used by the pixel format
242  * described by pixdesc. Note that this is not the same as the number
243  * of bits per sample.
244  *
245  * The returned number of bits refers to the number of bits actually
246  * used for storing the pixel information, that is padding bits are
247  * not counted.
248  */
249 int av_get_bits_per_pixel(const AVPixFmtDescriptor *pixdesc);
250 
251 /**
252  * Return the number of bits per pixel for the pixel format
253  * described by pixdesc, including any padding or unused bits.
254  */
256 
257 /**
258  * @return a pixel format descriptor for provided pixel format or NULL if
259  * this pixel format is unknown.
260  */
262 
263 /**
264  * Iterate over all pixel format descriptors known to libavutil.
265  *
266  * @param prev previous descriptor. NULL to get the first descriptor.
267  *
268  * @return next descriptor or NULL after the last descriptor
269  */
271 
272 /**
273  * @return an AVPixelFormat id described by desc, or AV_PIX_FMT_NONE if desc
274  * is not a valid pointer to a pixel format descriptor.
275  */
277 
278 /**
279  * Utility function to access log2_chroma_w log2_chroma_h from
280  * the pixel format AVPixFmtDescriptor.
281  *
282  * See av_get_chroma_sub_sample() for a function that asserts a
283  * valid pixel format instead of returning an error code.
284  * Its recommended that you use avcodec_get_chroma_sub_sample unless
285  * you do check the return code!
286  *
287  * @param[in] pix_fmt the pixel format
288  * @param[out] h_shift store log2_chroma_w
289  * @param[out] v_shift store log2_chroma_h
290  *
291  * @return 0 on success, AVERROR(ENOSYS) on invalid or unknown pixel format
292  */
294  int *h_shift, int *v_shift);
295 
296 /**
297  * @return number of planes in pix_fmt, a negative AVERROR if pix_fmt is not a
298  * valid pixel format.
299  */
301 
302 void ff_check_pixfmt_descriptors(void);
303 
304 /**
305  * Utility function to swap the endianness of a pixel format.
306  *
307  * @param[in] pix_fmt the pixel format
308  *
309  * @return pixel format with swapped endianness if it exists,
310  * otherwise AV_PIX_FMT_NONE
311  */
313 
314 #define FF_LOSS_RESOLUTION 0x0001 /**< loss due to resolution change */
315 #define FF_LOSS_DEPTH 0x0002 /**< loss due to color depth change */
316 #define FF_LOSS_COLORSPACE 0x0004 /**< loss due to color space conversion */
317 #define FF_LOSS_ALPHA 0x0008 /**< loss of alpha bits */
318 #define FF_LOSS_COLORQUANT 0x0010 /**< loss due to color quantization */
319 #define FF_LOSS_CHROMA 0x0020 /**< loss of chroma (e.g. RGB to gray conversion) */
320 
321 /**
322  * Compute what kind of losses will occur when converting from one specific
323  * pixel format to another.
324  * When converting from one pixel format to another, information loss may occur.
325  * For example, when converting from RGB24 to GRAY, the color information will
326  * be lost. Similarly, other losses occur when converting from some formats to
327  * other formats. These losses can involve loss of chroma, but also loss of
328  * resolution, loss of color depth, loss due to the color space conversion, loss
329  * of the alpha bits or loss due to color quantization.
330  * av_get_fix_fmt_loss() informs you about the various types of losses
331  * which will occur when converting from one pixel format to another.
332  *
333  * @param[in] dst_pix_fmt destination pixel format
334  * @param[in] src_pix_fmt source pixel format
335  * @param[in] has_alpha Whether the source pixel format alpha channel is used.
336  * @return Combination of flags informing you what kind of losses will occur
337  * (maximum loss for an invalid dst_pix_fmt).
338  */
339 int av_get_pix_fmt_loss(enum AVPixelFormat dst_pix_fmt,
340  enum AVPixelFormat src_pix_fmt,
341  int has_alpha);
342 
343 /**
344  * Compute what kind of losses will occur when converting from one specific
345  * pixel format to another.
346  * When converting from one pixel format to another, information loss may occur.
347  * For example, when converting from RGB24 to GRAY, the color information will
348  * be lost. Similarly, other losses occur when converting from some formats to
349  * other formats. These losses can involve loss of chroma, but also loss of
350  * resolution, loss of color depth, loss due to the color space conversion, loss
351  * of the alpha bits or loss due to color quantization.
352  * av_get_fix_fmt_loss() informs you about the various types of losses
353  * which will occur when converting from one pixel format to another.
354  *
355  * @param[in] dst_pix_fmt destination pixel format
356  * @param[in] src_pix_fmt source pixel format
357  * @param[in] has_alpha Whether the source pixel format alpha channel is used.
358  * @return Combination of flags informing you what kind of losses will occur
359  * (maximum loss for an invalid dst_pix_fmt).
360  */
361 enum AVPixelFormat av_find_best_pix_fmt_of_2(enum AVPixelFormat dst_pix_fmt1, enum AVPixelFormat dst_pix_fmt2,
362  enum AVPixelFormat src_pix_fmt, int has_alpha, int *loss_ptr);
363 
364 /**
365  * @return the name for provided color range or NULL if unknown.
366  */
367 const char *av_color_range_name(enum AVColorRange range);
368 
369 /**
370  * @return the name for provided color primaries or NULL if unknown.
371  */
372 const char *av_color_primaries_name(enum AVColorPrimaries primaries);
373 
374 /**
375  * @return the name for provided color transfer or NULL if unknown.
376  */
377 const char *av_color_transfer_name(enum AVColorTransferCharacteristic transfer);
378 
379 /**
380  * @return the name for provided color space or NULL if unknown.
381  */
382 const char *av_color_space_name(enum AVColorSpace space);
383 
384 /**
385  * @return the name for provided chroma location or NULL if unknown.
386  */
387 const char *av_chroma_location_name(enum AVChromaLocation location);
388 
389 #endif /* AVUTIL_PIXDESC_H */