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 #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

    44 }AVComponentDescriptor;

    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      */

    75     uint8_t log2_chroma_h;

    76     uint8_t flags;

    77 

    78     /**

    79      * Parameters that describe how pixels are packed. If the format

    80      * has chroma components, they must be stored in comp[1] and

    81      * comp[2].

    82      */

    83     AVComponentDescriptor comp[4];

    84 }AVPixFmtDescriptor;

    85 

    86 #define PIX_FMT_BE        1 ///< Pixel format is big-endian.

    87 #define PIX_FMT_PAL       2 ///< Pixel format has a palette in data[1], values are indexes in this palette.

    88 #define PIX_FMT_BITSTREAM 4 ///< All values of a component are bit-wise packed end to end.

    89 #define PIX_FMT_HWACCEL   8 ///< Pixel format is an HW accelerated format.

    90 #define PIX_FMT_PLANAR   16 ///< At least one pixel component is not in the first data plane

    91 #define PIX_FMT_RGB      32 ///< The pixel format contains RGB-like data (as opposed to YUV/grayscale)

    92 /**

    93  * The pixel format is "pseudo-paletted". This means that Libav treats it as

    94  * paletted internally, but the palette is generated by the decoder and is not

    95  * stored in the file.

    96  */

    97 #define PIX_FMT_PSEUDOPAL 64

    98 

    99 #if FF_API_PIX_FMT_DESC

   100 /**

   101  * The array of all the pixel format descriptors.

   102  */

   103 extern const AVPixFmtDescriptor av_pix_fmt_descriptors[];

   104 #endif

   105 

   106 /**

   107  * Read a line from an image, and write the values of the

   108  * pixel format component c to dst.

   109  *

   110  * @param data the array containing the pointers to the planes of the image

   111  * @param linesize the array containing the linesizes of the image

   112  * @param desc the pixel format descriptor for the image

   113  * @param x the horizontal coordinate of the first pixel to read

   114  * @param y the vertical coordinate of the first pixel to read

   115  * @param w the width of the line to read, that is the number of

   116  * values to write to dst

   117  * @param read_pal_component if not zero and the format is a paletted

   118  * format writes the values corresponding to the palette

   119  * component c in data[1] to dst, rather than the palette indexes in

   120  * data[0]. The behavior is undefined if the format is not paletted.

   121  */

   122 void av_read_image_line(uint16_t *dst, const uint8_t *data[4], const int linesize[4],

   123                         const AVPixFmtDescriptor *desc, int x, int y, int c, int w, int read_pal_component);

   124 

   125 /**

   126  * Write the values from src to the pixel format component c of an

   127  * image line.

   128  *

   129  * @param src array containing the values to write

   130  * @param data the array containing the pointers to the planes of the

   131  * image to write into. It is supposed to be zeroed.

   132  * @param linesize the array containing the linesizes of the image

   133  * @param desc the pixel format descriptor for the image

   134  * @param x the horizontal coordinate of the first pixel to write

   135  * @param y the vertical coordinate of the first pixel to write

   136  * @param w the width of the line to write, that is the number of

   137  * values to write to the image line

   138  */

   139 void av_write_image_line(const uint16_t *src, uint8_t *data[4], const int linesize[4],

   140                          const AVPixFmtDescriptor *desc, int x, int y, int c, int w);

   141 

   142 /**

   143  * Return the pixel format corresponding to name.

   144  *

   145  * If there is no pixel format with name name, then looks for a

   146  * pixel format with the name corresponding to the native endian

   147  * format of name.

   148  * For example in a little-endian system, first looks for "gray16",

   149  * then for "gray16le".

   150  *

   151  * Finally if no pixel format has been found, returns PIX_FMT_NONE.

   152  */

   153 enum AVPixelFormat av_get_pix_fmt(const char *name);

   154 

   155 /**

   156  * Return the short name for a pixel format, NULL in case pix_fmt is

   157  * unknown.

   158  *

   159  * @see av_get_pix_fmt(), av_get_pix_fmt_string()

   160  */

   161 const char *av_get_pix_fmt_name(enum AVPixelFormat pix_fmt);

   162 

   163 /**

   164  * Print in buf the string corresponding to the pixel format with

   165  * number pix_fmt, or an header if pix_fmt is negative.

   166  *

   167  * @param buf the buffer where to write the string

   168  * @param buf_size the size of buf

   169  * @param pix_fmt the number of the pixel format to print the

   170  * corresponding info string, or a negative value to print the

   171  * corresponding header.

   172  */

   173 char *av_get_pix_fmt_string (char *buf, int buf_size, enum AVPixelFormat pix_fmt);

   174 

   175 /**

   176  * Return the number of bits per pixel used by the pixel format

   177  * described by pixdesc.

   178  *

   179  * The returned number of bits refers to the number of bits actually

   180  * used for storing the pixel information, that is padding bits are

   181  * not counted.

   182  */

   183 int av_get_bits_per_pixel(const AVPixFmtDescriptor *pixdesc);

   184 

   185 /**

   186  * @return a pixel format descriptor for provided pixel format or NULL if

   187  * this pixel format is unknown.

   188  */

   189 const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt);

   190 

   191 /**

   192  * Iterate over all pixel format descriptors known to libavutil.

   193  *

   194  * @param prev previous descriptor. NULL to get the first descriptor.

   195  *

   196  * @return next descriptor or NULL after the last descriptor

   197  */

   198 const AVPixFmtDescriptor *av_pix_fmt_desc_next(const AVPixFmtDescriptor *prev);

   199 

   200 /**

   201  * @return an AVPixelFormat id described by desc, or AV_PIX_FMT_NONE if desc

   202  * is not a valid pointer to a pixel format descriptor.

   203  */

   204 enum AVPixelFormat av_pix_fmt_desc_get_id(const AVPixFmtDescriptor *desc);

   205 

   206 #endif /* AVUTIL_PIXDESC_H */