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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  uint16_t plane :2; ///< which of the 4 planes contains the component
32 
33  /**
34  * Number of elements between 2 horizontally consecutive pixels minus 1.
35  * Elements are bits for bitstream formats, bytes otherwise.
36  */
37  uint16_t step_minus1 :3;
38 
39  /**
40  * Number of elements before the component of the first pixel plus 1.
41  * Elements are bits for bitstream formats, bytes otherwise.
42  */
43  uint16_t offset_plus1 :3;
44  uint16_t shift :3; ///< number of least significant bits that must be shifted away to get the value
45  uint16_t depth_minus1 :4; ///< number of bits in the component minus 1
47 
48 /**
49  * Descriptor that unambiguously describes how the bits of a pixel are
50  * stored in the up to 4 data planes of an image. It also stores the
51  * subsampling factors and number of components.
52  *
53  * @note This is separate of the colorspace (RGB, YCbCr, YPbPr, JPEG-style YUV
54  * and all the YUV variants) AVPixFmtDescriptor just stores how values
55  * are stored not what these values represent.
56  */
57 typedef struct AVPixFmtDescriptor{
58  const char *name;
59  uint8_t nb_components; ///< The number of components each pixel has, (1-4)
60 
61  /**
62  * Amount to shift the luma width right to find the chroma width.
63  * For YV12 this is 1 for example.
64  * chroma_width = -((-luma_width) >> log2_chroma_w)
65  * The note above is needed to ensure rounding up.
66  * This value only refers to the chroma components.
67  */
68  uint8_t log2_chroma_w; ///< chroma_width = -((-luma_width )>>log2_chroma_w)
69 
70  /**
71  * Amount to shift the luma height right to find the chroma height.
72  * For YV12 this is 1 for example.
73  * chroma_height= -((-luma_height) >> log2_chroma_h)
74  * The note above is needed to ensure rounding up.
75  * This value only refers to the chroma components.
76  */
79 
80  /**
81  * Parameters that describe how pixels are packed.
82  * If the format has 2 or 4 components, then alpha is last.
83  * If the format has 1 or 2 components, then luma is 0.
84  * If the format has 3 or 4 components,
85  * if the RGB flag is set then 0 is red, 1 is green and 2 is blue;
86  * otherwise 0 is luma, 1 is chroma-U and 2 is chroma-V.
87  */
90 
91 /**
92  * Pixel format is big-endian.
93  */
94 #define AV_PIX_FMT_FLAG_BE (1 << 0)
95 /**
96  * Pixel format has a palette in data[1], values are indexes in this palette.
97  */
98 #define AV_PIX_FMT_FLAG_PAL (1 << 1)
99 /**
100  * All values of a component are bit-wise packed end to end.
101  */
102 #define AV_PIX_FMT_FLAG_BITSTREAM (1 << 2)
103 /**
104  * Pixel format is an HW accelerated format.
105  */
106 #define AV_PIX_FMT_FLAG_HWACCEL (1 << 3)
107 /**
108  * At least one pixel component is not in the first data plane.
109  */
110 #define AV_PIX_FMT_FLAG_PLANAR (1 << 4)
111 /**
112  * The pixel format contains RGB-like data (as opposed to YUV/grayscale).
113  */
114 #define AV_PIX_FMT_FLAG_RGB (1 << 5)
115 /**
116  * The pixel format is "pseudo-paletted". This means that FFmpeg treats it as
117  * paletted internally, but the palette is generated by the decoder and is not
118  * stored in the file.
119  */
120 #define AV_PIX_FMT_FLAG_PSEUDOPAL (1 << 6)
121 /**
122  * The pixel format has an alpha channel.
123  */
124 #define AV_PIX_FMT_FLAG_ALPHA (1 << 7)
125 
126 #if FF_API_PIX_FMT
127 /**
128  * @deprecated use the AV_PIX_FMT_FLAG_* flags
129  */
130 #define PIX_FMT_BE AV_PIX_FMT_FLAG_BE
131 #define PIX_FMT_PAL AV_PIX_FMT_FLAG_PAL
132 #define PIX_FMT_BITSTREAM AV_PIX_FMT_FLAG_BITSTREAM
133 #define PIX_FMT_HWACCEL AV_PIX_FMT_FLAG_HWACCEL
134 #define PIX_FMT_PLANAR AV_PIX_FMT_FLAG_PLANAR
135 #define PIX_FMT_RGB AV_PIX_FMT_FLAG_RGB
136 #define PIX_FMT_PSEUDOPAL AV_PIX_FMT_FLAG_PSEUDOPAL
137 #define PIX_FMT_ALPHA AV_PIX_FMT_FLAG_ALPHA
138 #endif
139 
140 #if FF_API_PIX_FMT_DESC
141 /**
142  * The array of all the pixel format descriptors.
143  */
145 #endif
146 
147 /**
148  * Read a line from an image, and write the values of the
149  * pixel format component c to dst.
150  *
151  * @param data the array containing the pointers to the planes of the image
152  * @param linesize 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 read
155  * @param y the vertical coordinate of the first pixel to read
156  * @param w the width of the line to read, that is the number of
157  * values to write to dst
158  * @param read_pal_component if not zero and the format is a paletted
159  * format writes the values corresponding to the palette
160  * component c in data[1] to dst, rather than the palette indexes in
161  * data[0]. The behavior is undefined if the format is not paletted.
162  */
163 void av_read_image_line(uint16_t *dst, const uint8_t *data[4], const int linesize[4],
164  const AVPixFmtDescriptor *desc, int x, int y, int c, int w, int read_pal_component);
165 
166 /**
167  * Write the values from src to the pixel format component c of an
168  * image line.
169  *
170  * @param src array containing the values to write
171  * @param data the array containing the pointers to the planes of the
172  * image to write into. It is supposed to be zeroed.
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 write
176  * @param y the vertical coordinate of the first pixel to write
177  * @param w the width of the line to write, that is the number of
178  * values to write to the image line
179  */
180 void av_write_image_line(const uint16_t *src, uint8_t *data[4], const int linesize[4],
181  const AVPixFmtDescriptor *desc, int x, int y, int c, int w);
182 
183 /**
184  * Return the pixel format corresponding to name.
185  *
186  * If there is no pixel format with name name, then looks for a
187  * pixel format with the name corresponding to the native endian
188  * format of name.
189  * For example in a little-endian system, first looks for "gray16",
190  * then for "gray16le".
191  *
192  * Finally if no pixel format has been found, returns AV_PIX_FMT_NONE.
193  */
194 enum AVPixelFormat av_get_pix_fmt(const char *name);
195 
196 /**
197  * Return the short name for a pixel format, NULL in case pix_fmt is
198  * unknown.
199  *
200  * @see av_get_pix_fmt(), av_get_pix_fmt_string()
201  */
202 const char *av_get_pix_fmt_name(enum AVPixelFormat pix_fmt);
203 
204 /**
205  * Print in buf the string corresponding to the pixel format with
206  * number pix_fmt, or a header if pix_fmt is negative.
207  *
208  * @param buf the buffer where to write the string
209  * @param buf_size the size of buf
210  * @param pix_fmt the number of the pixel format to print the
211  * corresponding info string, or a negative value to print the
212  * corresponding header.
213  */
214 char *av_get_pix_fmt_string (char *buf, int buf_size, enum AVPixelFormat pix_fmt);
215 
216 /**
217  * Return the number of bits per pixel used by the pixel format
218  * described by pixdesc. Note that this is not the same as the number
219  * of bits per sample.
220  *
221  * The returned number of bits refers to the number of bits actually
222  * used for storing the pixel information, that is padding bits are
223  * not counted.
224  */
225 int av_get_bits_per_pixel(const AVPixFmtDescriptor *pixdesc);
226 
227 /**
228  * Return the number of bits per pixel for the pixel format
229  * described by pixdesc, including any padding or unused bits.
230  */
232 
233 /**
234  * @return a pixel format descriptor for provided pixel format or NULL if
235  * this pixel format is unknown.
236  */
238 
239 /**
240  * Iterate over all pixel format descriptors known to libavutil.
241  *
242  * @param prev previous descriptor. NULL to get the first descriptor.
243  *
244  * @return next descriptor or NULL after the last descriptor
245  */
247 
248 /**
249  * @return an AVPixelFormat id described by desc, or AV_PIX_FMT_NONE if desc
250  * is not a valid pointer to a pixel format descriptor.
251  */
253 
254 /**
255  * Utility function to access log2_chroma_w log2_chroma_h from
256  * the pixel format AVPixFmtDescriptor.
257  *
258  * See av_get_chroma_sub_sample() for a function that asserts a
259  * valid pixel format instead of returning an error code.
260  * Its recommended that you use avcodec_get_chroma_sub_sample unless
261  * you do check the return code!
262  *
263  * @param[in] pix_fmt the pixel format
264  * @param[out] h_shift store log2_chroma_w
265  * @param[out] v_shift store log2_chroma_h
266  *
267  * @return 0 on success, AVERROR(ENOSYS) on invalid or unknown pixel format
268  */
270  int *h_shift, int *v_shift);
271 
272 /**
273  * @return number of planes in pix_fmt, a negative AVERROR if pix_fmt is not a
274  * valid pixel format.
275  */
277 
278 void ff_check_pixfmt_descriptors(void);
279 
280 /**
281  * Utility function to swap the endianness of a pixel format.
282  *
283  * @param[in] pix_fmt the pixel format
284  *
285  * @return pixel format with swapped endianness if it exists,
286  * otherwise AV_PIX_FMT_NONE
287  */
289 
290 #define FF_LOSS_RESOLUTION 0x0001 /**< loss due to resolution change */
291 #define FF_LOSS_DEPTH 0x0002 /**< loss due to color depth change */
292 #define FF_LOSS_COLORSPACE 0x0004 /**< loss due to color space conversion */
293 #define FF_LOSS_ALPHA 0x0008 /**< loss of alpha bits */
294 #define FF_LOSS_COLORQUANT 0x0010 /**< loss due to color quantization */
295 #define FF_LOSS_CHROMA 0x0020 /**< loss of chroma (e.g. RGB to gray conversion) */
296 
297 /**
298  * Compute what kind of losses will occur when converting from one specific
299  * pixel format to another.
300  * When converting from one pixel format to another, information loss may occur.
301  * For example, when converting from RGB24 to GRAY, the color information will
302  * be lost. Similarly, other losses occur when converting from some formats to
303  * other formats. These losses can involve loss of chroma, but also loss of
304  * resolution, loss of color depth, loss due to the color space conversion, loss
305  * of the alpha bits or loss due to color quantization.
306  * av_get_fix_fmt_loss() informs you about the various types of losses
307  * which will occur when converting from one pixel format to another.
308  *
309  * @param[in] dst_pix_fmt destination pixel format
310  * @param[in] src_pix_fmt source pixel format
311  * @param[in] has_alpha Whether the source pixel format alpha channel is used.
312  * @return Combination of flags informing you what kind of losses will occur
313  * (maximum loss for an invalid dst_pix_fmt).
314  */
315 int av_get_pix_fmt_loss(enum AVPixelFormat dst_pix_fmt,
316  enum AVPixelFormat src_pix_fmt,
317  int has_alpha);
318 
319 /**
320  * Compute what kind of losses will occur when converting from one specific
321  * pixel format to another.
322  * When converting from one pixel format to another, information loss may occur.
323  * For example, when converting from RGB24 to GRAY, the color information will
324  * be lost. Similarly, other losses occur when converting from some formats to
325  * other formats. These losses can involve loss of chroma, but also loss of
326  * resolution, loss of color depth, loss due to the color space conversion, loss
327  * of the alpha bits or loss due to color quantization.
328  * av_get_fix_fmt_loss() informs you about the various types of losses
329  * which will occur when converting from one pixel format to another.
330  *
331  * @param[in] dst_pix_fmt destination pixel format
332  * @param[in] src_pix_fmt source pixel format
333  * @param[in] has_alpha Whether the source pixel format alpha channel is used.
334  * @return Combination of flags informing you what kind of losses will occur
335  * (maximum loss for an invalid dst_pix_fmt).
336  */
337 enum AVPixelFormat av_find_best_pix_fmt_of_2(enum AVPixelFormat dst_pix_fmt1, enum AVPixelFormat dst_pix_fmt2,
338  enum AVPixelFormat src_pix_fmt, int has_alpha, int *loss_ptr);
339 #endif /* AVUTIL_PIXDESC_H */