text: /*
   * pixel format descriptor
   * Copyright (c) 2009 Michael Niedermayer <michaelni@gmx.at>
   *
   * This file is part of FFmpeg.
   *
   * FFmpeg 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.
   *
   * FFmpeg 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 FFmpeg; 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"
  #include "version.h"
  
  typedef struct AVComponentDescriptor {
      /**
       * Which of the 4 planes contains the component.
       */
      int plane;
  
      /**
       * Number of elements between 2 horizontally consecutive pixels.
       * Elements are bits for bitstream formats, bytes otherwise.
       */
      int step;
  
      /**
       * Number of elements before the component of the first pixel.
       * Elements are bits for bitstream formats, bytes otherwise.
       */
      int offset;
  
      /**
       * Number of least significant bits that must be shifted away
       * to get the value.
       */
      int shift;
  
      /**
       * Number of bits in the component.
       */
      int depth;
  
  #if FF_API_PLUS1_MINUS1
      /** deprecated, use step instead */
      attribute_deprecated int step_minus1;
  
      /** deprecated, use depth instead */
      attribute_deprecated int depth_minus1;
  
      /** deprecated, use offset instead */
      attribute_deprecated int offset_plus1;
  #endif
  } 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 = AV_CEIL_RSHIFT(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;
  
      /**
       * Amount to shift the luma height right to find the chroma height.
       * For YV12 this is 1 for example.
       * chroma_height= AV_CEIL_RSHIFT(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;
  
      /**
       * Combination of AV_PIX_FMT_FLAG_... flags.
       */
      uint64_t flags;
  
      /**
       * Parameters that describe how pixels are packed.
       * If the format has 1 or 2 components, then luma is 0.
       * If the format has 3 or 4 components:
       *   if the RGB flag is set then 0 is red, 1 is green and 2 is blue;
       *   otherwise 0 is luma, 1 is chroma-U and 2 is chroma-V.
       *
       * If present, the Alpha channel is always the last component.
       */
      AVComponentDescriptor comp[4];
  
      /**
       * Alternative comma-separated names.
       */
      const char *alias;
  } 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 it contains a
   * fixed palette in the 2nd plane but the palette is fixed/constant for each
   * PIX_FMT. This allows interpreting the data as if it was PAL8, which can
   * in some cases be simpler. Or the data can be interpreted purely based on
   * the pixel format without using the palette.
   * An example of a pseudo-paletted format is AV_PIX_FMT_GRAY8
   */
  #define AV_PIX_FMT_FLAG_PSEUDOPAL    (1 << 6)
  
  /**
   * The pixel format has an alpha channel. This is set on all formats that
   * support alpha in some way. The exception is AV_PIX_FMT_PAL8, which can
   * carry alpha as part of the palette. Details are explained in the
   * AVPixelFormat enum, and are also encoded in the corresponding
   * AVPixFmtDescriptor.
   *
   * The alpha is always straight, never pre-multiplied.
   *
   * If a codec or a filter does not support alpha, it should set all alpha to
   * opaque, or use the equivalent pixel formats without alpha component, e.g.
   * AV_PIX_FMT_RGB0 (or AV_PIX_FMT_RGB24 etc.) instead of AV_PIX_FMT_RGBA.
   */
  #define AV_PIX_FMT_FLAG_ALPHA        (1 << 7)
  
  /**
   * The pixel format is following a Bayer pattern
   */
  #define AV_PIX_FMT_FLAG_BAYER        (1 << 8)
  
  /**
   * The pixel format contains IEEE-754 floating point values. Precision (double,
   * single, or half) should be determined by the pixel size (64, 32, or 16 bits).
   */
  #define AV_PIX_FMT_FLAG_FLOAT        (1 << 9)
  
  /**
   * 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 the number of bits per pixel for the pixel format
   * described by pixdesc, including any padding or unused bits.
   */
  int av_get_padded_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.
   *
   * See av_get_chroma_sub_sample() for a function that asserts a
   * valid pixel format instead of returning an error code.
   * Its recommended that you use avcodec_get_chroma_sub_sample unless
   * you do check the return code!
   *
   * @param[in]  pix_fmt the pixel format
   * @param[out] h_shift store log2_chroma_w (horizontal/width shift)
   * @param[out] v_shift store log2_chroma_h (vertical/height shift)
   *
   * @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);
  
  /**
   * @return the name for provided color range or NULL if unknown.
   */
  const char *av_color_range_name(enum AVColorRange range);
  
  /**
   * @return the AVColorRange value for name or an AVError if not found.
   */
  int av_color_range_from_name(const char *name);
  
  /**
   * @return the name for provided color primaries or NULL if unknown.
   */
  const char *av_color_primaries_name(enum AVColorPrimaries primaries);
  
  /**
   * @return the AVColorPrimaries value for name or an AVError if not found.
   */
  int av_color_primaries_from_name(const char *name);
  
  /**
   * @return the name for provided color transfer or NULL if unknown.
   */
  const char *av_color_transfer_name(enum AVColorTransferCharacteristic transfer);
  
  /**
   * @return the AVColorTransferCharacteristic value for name or an AVError if not found.
   */
  int av_color_transfer_from_name(const char *name);
  
  /**
   * @return the name for provided color space or NULL if unknown.
   */
  const char *av_color_space_name(enum AVColorSpace space);
  
  /**
   * @return the AVColorSpace value for name or an AVError if not found.
   */
  int av_color_space_from_name(const char *name);
  
  /**
   * @return the name for provided chroma location or NULL if unknown.
   */
  const char *av_chroma_location_name(enum AVChromaLocation location);
  
  /**
   * @return the AVChromaLocation value for name or an AVError if not found.
   */
  int av_chroma_location_from_name(const char *name);
  
  /**
   * 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 AV_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 a 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);
  
  /**
   * 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);
  
  /**
   * 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);
  
  #define FF_LOSS_RESOLUTION  0x0001 /**< loss due to resolution change */
  #define FF_LOSS_DEPTH       0x0002 /**< loss due to color depth change */
  #define FF_LOSS_COLORSPACE  0x0004 /**< loss due to color space conversion */
  #define FF_LOSS_ALPHA       0x0008 /**< loss of alpha bits */
  #define FF_LOSS_COLORQUANT  0x0010 /**< loss due to color quantization */
  #define FF_LOSS_CHROMA      0x0020 /**< loss of chroma (e.g. RGB to gray conversion) */
  
  /**
   * Compute what kind of losses will occur when converting from one specific
   * pixel format to another.
   * When converting from one pixel format to another, information loss may occur.
   * For example, when converting from RGB24 to GRAY, the color information will
   * be lost. Similarly, other losses occur when converting from some formats to
   * other formats. These losses can involve loss of chroma, but also loss of
   * resolution, loss of color depth, loss due to the color space conversion, loss
   * of the alpha bits or loss due to color quantization.
   * av_get_fix_fmt_loss() informs you about the various types of losses
   * which will occur when converting from one pixel format to another.
   *
   * @param[in] dst_pix_fmt destination pixel format
   * @param[in] src_pix_fmt source pixel format
   * @param[in] has_alpha Whether the source pixel format alpha channel is used.
   * @return Combination of flags informing you what kind of losses will occur
   * (maximum loss for an invalid dst_pix_fmt).
   */
  int av_get_pix_fmt_loss(enum AVPixelFormat dst_pix_fmt,
                          enum AVPixelFormat src_pix_fmt,
                          int has_alpha);
  
  /**
   * Compute what kind of losses will occur when converting from one specific
   * pixel format to another.
   * When converting from one pixel format to another, information loss may occur.
   * For example, when converting from RGB24 to GRAY, the color information will
   * be lost. Similarly, other losses occur when converting from some formats to
   * other formats. These losses can involve loss of chroma, but also loss of
   * resolution, loss of color depth, loss due to the color space conversion, loss
   * of the alpha bits or loss due to color quantization.
   * av_get_fix_fmt_loss() informs you about the various types of losses
   * which will occur when converting from one pixel format to another.
   *
   * @param[in] dst_pix_fmt destination pixel format
   * @param[in] src_pix_fmt source pixel format
   * @param[in] has_alpha Whether the source pixel format alpha channel is used.
   * @return Combination of flags informing you what kind of losses will occur
   * (maximum loss for an invalid dst_pix_fmt).
   */
  enum AVPixelFormat av_find_best_pix_fmt_of_2(enum AVPixelFormat dst_pix_fmt1, enum AVPixelFormat dst_pix_fmt2,
                                               enum AVPixelFormat src_pix_fmt, int has_alpha, int *loss_ptr);
  
  #endif /* AVUTIL_PIXDESC_H */
  