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pixdesc.h (9730B)

---

/*
* pixel format descriptor
* Copyright (c) 2009 Michael Niedermayer <michaelni@gmx.at>
*
* This file is part of Libav.
*
* Libav is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* Libav is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with Libav; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/

#ifndef AVUTIL_PIXDESC_H
#define AVUTIL_PIXDESC_H

#include <inttypes.h>

#include "attributes.h"
#include "pixfmt.h"

typedef struct AVComponentDescriptor{
   uint16_t plane        :2;            ///< which of the 4 planes contains the component

   /**
    * Number of elements between 2 horizontally consecutive pixels minus 1.
    * Elements are bits for bitstream formats, bytes otherwise.
    */
   uint16_t step_minus1  :3;

   /**
    * Number of elements before the component of the first pixel plus 1.
    * Elements are bits for bitstream formats, bytes otherwise.
    */
   uint16_t offset_plus1 :3;
   uint16_t shift        :3;            ///< number of least significant bits that must be shifted away to get the value
   uint16_t depth_minus1 :4;            ///< number of bits in the component minus 1
}AVComponentDescriptor;

/**
* Descriptor that unambiguously describes how the bits of a pixel are
* stored in the up to 4 data planes of an image. It also stores the
* subsampling factors and number of components.
*
* @note This is separate of the colorspace (RGB, YCbCr, YPbPr, JPEG-style YUV
*       and all the YUV variants) AVPixFmtDescriptor just stores how values
*       are stored not what these values represent.
*/
typedef struct AVPixFmtDescriptor{
   const char *name;
   uint8_t nb_components;      ///< The number of components each pixel has, (1-4)

   /**
    * Amount to shift the luma width right to find the chroma width.
    * For YV12 this is 1 for example.
    * chroma_width = -((-luma_width) >> log2_chroma_w)
    * The note above is needed to ensure rounding up.
    * This value only refers to the chroma components.
    */
   uint8_t log2_chroma_w;      ///< chroma_width = -((-luma_width )>>log2_chroma_w)

   /**
    * Amount to shift the luma height right to find the chroma height.
    * For YV12 this is 1 for example.
    * chroma_height= -((-luma_height) >> log2_chroma_h)
    * The note above is needed to ensure rounding up.
    * This value only refers to the chroma components.
    */
   uint8_t log2_chroma_h;
   uint8_t flags;

   /**
    * Parameters that describe how pixels are packed. If the format
    * has chroma components, they must be stored in comp[1] and
    * comp[2].
    */
   AVComponentDescriptor comp[4];
}AVPixFmtDescriptor;

/**
* Pixel format is big-endian.
*/
#define AV_PIX_FMT_FLAG_BE           (1 << 0)
/**
* Pixel format has a palette in data[1], values are indexes in this palette.
*/
#define AV_PIX_FMT_FLAG_PAL          (1 << 1)
/**
* All values of a component are bit-wise packed end to end.
*/
#define AV_PIX_FMT_FLAG_BITSTREAM    (1 << 2)
/**
* Pixel format is an HW accelerated format.
*/
#define AV_PIX_FMT_FLAG_HWACCEL      (1 << 3)
/**
* At least one pixel component is not in the first data plane.
*/
#define AV_PIX_FMT_FLAG_PLANAR       (1 << 4)
/**
* The pixel format contains RGB-like data (as opposed to YUV/grayscale).
*/
#define AV_PIX_FMT_FLAG_RGB          (1 << 5)
/**
* The pixel format is "pseudo-paletted". This means that Libav treats it as
* paletted internally, but the palette is generated by the decoder and is not
* stored in the file.
*/
#define AV_PIX_FMT_FLAG_PSEUDOPAL    (1 << 6)
/**
* The pixel format has an alpha channel.
*/
#define AV_PIX_FMT_FLAG_ALPHA        (1 << 7)

#if FF_API_PIX_FMT
/**
* @deprecated use the AV_PIX_FMT_FLAG_* flags
*/
#define PIX_FMT_BE        AV_PIX_FMT_FLAG_BE
#define PIX_FMT_PAL       AV_PIX_FMT_FLAG_PAL
#define PIX_FMT_BITSTREAM AV_PIX_FMT_FLAG_BITSTREAM
#define PIX_FMT_HWACCEL   AV_PIX_FMT_FLAG_HWACCEL
#define PIX_FMT_PLANAR    AV_PIX_FMT_FLAG_PLANAR
#define PIX_FMT_RGB       AV_PIX_FMT_FLAG_RGB
#define PIX_FMT_PSEUDOPAL AV_PIX_FMT_FLAG_PSEUDOPAL
#define PIX_FMT_ALPHA     AV_PIX_FMT_FLAG_ALPHA
#endif

#if FF_API_PIX_FMT_DESC
/**
* The array of all the pixel format descriptors.
*/
extern attribute_deprecated const AVPixFmtDescriptor av_pix_fmt_descriptors[];
#endif

/**
* Read a line from an image, and write the values of the
* pixel format component c to dst.
*
* @param data the array containing the pointers to the planes of the image
* @param linesize the array containing the linesizes of the image
* @param desc the pixel format descriptor for the image
* @param x the horizontal coordinate of the first pixel to read
* @param y the vertical coordinate of the first pixel to read
* @param w the width of the line to read, that is the number of
* values to write to dst
* @param read_pal_component if not zero and the format is a paletted
* format writes the values corresponding to the palette
* component c in data[1] to dst, rather than the palette indexes in
* data[0]. The behavior is undefined if the format is not paletted.
*/
void av_read_image_line(uint16_t *dst, const uint8_t *data[4], const int linesize[4],
                       const AVPixFmtDescriptor *desc, int x, int y, int c, int w, int read_pal_component);

/**
* Write the values from src to the pixel format component c of an
* image line.
*
* @param src array containing the values to write
* @param data the array containing the pointers to the planes of the
* image to write into. It is supposed to be zeroed.
* @param linesize the array containing the linesizes of the image
* @param desc the pixel format descriptor for the image
* @param x the horizontal coordinate of the first pixel to write
* @param y the vertical coordinate of the first pixel to write
* @param w the width of the line to write, that is the number of
* values to write to the image line
*/
void av_write_image_line(const uint16_t *src, uint8_t *data[4], const int linesize[4],
                        const AVPixFmtDescriptor *desc, int x, int y, int c, int w);

/**
* Return the pixel format corresponding to name.
*
* If there is no pixel format with name name, then looks for a
* pixel format with the name corresponding to the native endian
* format of name.
* For example in a little-endian system, first looks for "gray16",
* then for "gray16le".
*
* Finally if no pixel format has been found, returns PIX_FMT_NONE.
*/
enum AVPixelFormat av_get_pix_fmt(const char *name);

/**
* Return the short name for a pixel format, NULL in case pix_fmt is
* unknown.
*
* @see av_get_pix_fmt(), av_get_pix_fmt_string()
*/
const char *av_get_pix_fmt_name(enum AVPixelFormat pix_fmt);

/**
* Print in buf the string corresponding to the pixel format with
* number pix_fmt, or an header if pix_fmt is negative.
*
* @param buf the buffer where to write the string
* @param buf_size the size of buf
* @param pix_fmt the number of the pixel format to print the
* corresponding info string, or a negative value to print the
* corresponding header.
*/
char *av_get_pix_fmt_string (char *buf, int buf_size, enum AVPixelFormat pix_fmt);

/**
* Return the number of bits per pixel used by the pixel format
* described by pixdesc. Note that this is not the same as the number
* of bits per sample.
*
* The returned number of bits refers to the number of bits actually
* used for storing the pixel information, that is padding bits are
* not counted.
*/
int av_get_bits_per_pixel(const AVPixFmtDescriptor *pixdesc);

/**
* @return a pixel format descriptor for provided pixel format or NULL if
* this pixel format is unknown.
*/
const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt);

/**
* Iterate over all pixel format descriptors known to libavutil.
*
* @param prev previous descriptor. NULL to get the first descriptor.
*
* @return next descriptor or NULL after the last descriptor
*/
const AVPixFmtDescriptor *av_pix_fmt_desc_next(const AVPixFmtDescriptor *prev);

/**
* @return an AVPixelFormat id described by desc, or AV_PIX_FMT_NONE if desc
* is not a valid pointer to a pixel format descriptor.
*/
enum AVPixelFormat av_pix_fmt_desc_get_id(const AVPixFmtDescriptor *desc);

/**
* Utility function to access log2_chroma_w log2_chroma_h from
* the pixel format AVPixFmtDescriptor.
*
* @param[in]  pix_fmt the pixel format
* @param[out] h_shift store log2_chroma_h
* @param[out] v_shift store log2_chroma_w
*
* @return 0 on success, AVERROR(ENOSYS) on invalid or unknown pixel format
*/
int av_pix_fmt_get_chroma_sub_sample(enum AVPixelFormat pix_fmt,
                                    int *h_shift, int *v_shift);

/**
* @return number of planes in pix_fmt, a negative AVERROR if pix_fmt is not a
* valid pixel format.
*/
int av_pix_fmt_count_planes(enum AVPixelFormat pix_fmt);


/**
* Utility function to swap the endianness of a pixel format.
*
* @param[in]  pix_fmt the pixel format
*
* @return pixel format with swapped endianness if it exists,
* otherwise AV_PIX_FMT_NONE
*/
enum AVPixelFormat av_pix_fmt_swap_endianness(enum AVPixelFormat pix_fmt);


#endif /* AVUTIL_PIXDESC_H */