2 * pixel format descriptor
3 * Copyright (c) 2009 Michael Niedermayer <michaelni@gmx.at>
5 * This file is part of FFmpeg.
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.
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.
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
22 #ifndef AVUTIL_PIXDESC_H
23 #define AVUTIL_PIXDESC_H
28 typedef struct AVComponentDescriptor{
29 uint16_t plane :2; ///< which of the 4 planes contains the component
32 * Number of elements between 2 horizontally consecutive pixels minus 1.
33 * Elements are bits for bitstream formats, bytes otherwise.
35 uint16_t step_minus1 :3;
38 * Number of elements before the component of the first pixel plus 1.
39 * Elements are bits for bitstream formats, bytes otherwise.
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
44 }AVComponentDescriptor;
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.
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.
55 typedef struct AVPixFmtDescriptor{
57 uint8_t nb_components; ///< The number of components each pixel has, (1-4)
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.
66 uint8_t log2_chroma_w; ///< chroma_width = -((-luma_width )>>log2_chroma_w)
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.
75 uint8_t log2_chroma_h;
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.
86 AVComponentDescriptor comp[4];
89 #define PIX_FMT_BE 1 ///< Pixel format is big-endian.
90 #define PIX_FMT_PAL 2 ///< Pixel format has a palette in data[1], values are indexes in this palette.
91 #define PIX_FMT_BITSTREAM 4 ///< All values of a component are bit-wise packed end to end.
92 #define PIX_FMT_HWACCEL 8 ///< Pixel format is an HW accelerated format.
93 #define PIX_FMT_PLANAR 16 ///< At least one pixel component is not in the first data plane
94 #define PIX_FMT_RGB 32 ///< The pixel format contains RGB-like data (as opposed to YUV/grayscale)
96 * The pixel format is "pseudo-paletted". This means that FFmpeg treats it as
97 * paletted internally, but the palette is generated by the decoder and is not
100 #define PIX_FMT_PSEUDOPAL 64
102 #if FF_API_PIX_FMT_DESC
104 * The array of all the pixel format descriptors.
106 extern const AVPixFmtDescriptor av_pix_fmt_descriptors[];
110 * Read a line from an image, and write the values of the
111 * pixel format component c to dst.
113 * @param data the array containing the pointers to the planes of the image
114 * @param linesize the array containing the linesizes of the image
115 * @param desc the pixel format descriptor for the image
116 * @param x the horizontal coordinate of the first pixel to read
117 * @param y the vertical coordinate of the first pixel to read
118 * @param w the width of the line to read, that is the number of
119 * values to write to dst
120 * @param read_pal_component if not zero and the format is a paletted
121 * format writes the values corresponding to the palette
122 * component c in data[1] to dst, rather than the palette indexes in
123 * data[0]. The behavior is undefined if the format is not paletted.
125 void av_read_image_line(uint16_t *dst, const uint8_t *data[4], const int linesize[4],
126 const AVPixFmtDescriptor *desc, int x, int y, int c, int w, int read_pal_component);
129 * Write the values from src to the pixel format component c of an
132 * @param src array containing the values to write
133 * @param data the array containing the pointers to the planes of the
134 * image to write into. It is supposed to be zeroed.
135 * @param linesize the array containing the linesizes of the image
136 * @param desc the pixel format descriptor for the image
137 * @param x the horizontal coordinate of the first pixel to write
138 * @param y the vertical coordinate of the first pixel to write
139 * @param w the width of the line to write, that is the number of
140 * values to write to the image line
142 void av_write_image_line(const uint16_t *src, uint8_t *data[4], const int linesize[4],
143 const AVPixFmtDescriptor *desc, int x, int y, int c, int w);
146 * Return the pixel format corresponding to name.
148 * If there is no pixel format with name name, then looks for a
149 * pixel format with the name corresponding to the native endian
151 * For example in a little-endian system, first looks for "gray16",
152 * then for "gray16le".
154 * Finally if no pixel format has been found, returns AV_PIX_FMT_NONE.
156 enum AVPixelFormat av_get_pix_fmt(const char *name);
159 * Return the short name for a pixel format, NULL in case pix_fmt is
162 * @see av_get_pix_fmt(), av_get_pix_fmt_string()
164 const char *av_get_pix_fmt_name(enum AVPixelFormat pix_fmt);
167 * Print in buf the string corresponding to the pixel format with
168 * number pix_fmt, or an header if pix_fmt is negative.
170 * @param buf the buffer where to write the string
171 * @param buf_size the size of buf
172 * @param pix_fmt the number of the pixel format to print the
173 * corresponding info string, or a negative value to print the
174 * corresponding header.
176 char *av_get_pix_fmt_string (char *buf, int buf_size, enum AVPixelFormat pix_fmt);
179 * Return the number of bits per pixel used by the pixel format
180 * described by pixdesc.
182 * The returned number of bits refers to the number of bits actually
183 * used for storing the pixel information, that is padding bits are
186 int av_get_bits_per_pixel(const AVPixFmtDescriptor *pixdesc);
189 * @return a pixel format descriptor for provided pixel format or NULL if
190 * this pixel format is unknown.
192 const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt);
195 * Iterate over all pixel format descriptors known to libavutil.
197 * @param prev previous descriptor. NULL to get the first descriptor.
199 * @return next descriptor or NULL after the last descriptor
201 const AVPixFmtDescriptor *av_pix_fmt_desc_next(const AVPixFmtDescriptor *prev);
204 * @return an AVPixelFormat id described by desc, or AV_PIX_FMT_NONE if desc
205 * is not a valid pointer to a pixel format descriptor.
207 enum AVPixelFormat av_pix_fmt_desc_get_id(const AVPixFmtDescriptor *desc);
210 * Utility function to access log2_chroma_w log2_chroma_h from
211 * the pixel format AVPixFmtDescriptor.
213 * See avcodec_get_chroma_sub_sample() for a function that asserts a
214 * valid pixel format instead of returning an error code.
215 * Its recommanded that you use avcodec_get_chroma_sub_sample unless
216 * you do check the return code!
218 * @param[in] pix_fmt the pixel format
219 * @param[out] h_shift store log2_chroma_h
220 * @param[out] v_shift store log2_chroma_w
222 * @return 0 on success, AVERROR(ENOSYS) on invalid or unknown pixel format
224 int av_pix_fmt_get_chroma_sub_sample(enum AVPixelFormat pix_fmt,
225 int *h_shift, int *v_shift);
228 #endif /* AVUTIL_PIXDESC_H */