FFmpeg/libavutil/pixdesc.h
Anton Khirnov d2fcb356ca pixdesc: add functions for accessing pixel format descriptors.
Make av_pix_fmt_descriptors table static on next major bump.

Making the table public is dangerous, since the caller has no way to
know how large it actually is. It also prevents adding new fields to
AVPixFmtDescriptor without a major bump.
2012-10-12 12:45:25 +02:00

207 lines
7.8 KiB
C

/*
* 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 "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;
#define PIX_FMT_BE 1 ///< Pixel format is big-endian.
#define PIX_FMT_PAL 2 ///< Pixel format has a palette in data[1], values are indexes in this palette.
#define PIX_FMT_BITSTREAM 4 ///< All values of a component are bit-wise packed end to end.
#define PIX_FMT_HWACCEL 8 ///< Pixel format is an HW accelerated format.
#define PIX_FMT_PLANAR 16 ///< At least one pixel component is not in the first data plane
#define PIX_FMT_RGB 32 ///< The pixel format contains RGB-like data (as opposed to YUV/grayscale)
/**
* 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 PIX_FMT_PSEUDOPAL 64
#if FF_API_PIX_FMT_DESC
/**
* The array of all the pixel format descriptors.
*/
extern 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.
*
* 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);
#endif /* AVUTIL_PIXDESC_H */