245 lines
9.1 KiB
C
245 lines
9.1 KiB
C
/*
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* pixel format descriptor
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* Copyright (c) 2009 Michael Niedermayer <michaelni@gmx.at>
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#ifndef AVUTIL_PIXDESC_H
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#define AVUTIL_PIXDESC_H
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#include <inttypes.h>
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#include "pixfmt.h"
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typedef struct AVComponentDescriptor{
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uint16_t plane :2; ///< which of the 4 planes contains the component
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/**
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* Number of elements between 2 horizontally consecutive pixels minus 1.
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* Elements are bits for bitstream formats, bytes otherwise.
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*/
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uint16_t step_minus1 :3;
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/**
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* Number of elements before the component of the first pixel plus 1.
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* Elements are bits for bitstream formats, bytes otherwise.
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*/
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uint16_t offset_plus1 :3;
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uint16_t shift :3; ///< number of least significant bits that must be shifted away to get the value
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uint16_t depth_minus1 :4; ///< number of bits in the component minus 1
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}AVComponentDescriptor;
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/**
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* Descriptor that unambiguously describes how the bits of a pixel are
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* stored in the up to 4 data planes of an image. It also stores the
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* subsampling factors and number of components.
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*
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* @note This is separate of the colorspace (RGB, YCbCr, YPbPr, JPEG-style YUV
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* and all the YUV variants) AVPixFmtDescriptor just stores how values
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* are stored not what these values represent.
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*/
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typedef struct AVPixFmtDescriptor{
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const char *name;
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uint8_t nb_components; ///< The number of components each pixel has, (1-4)
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/**
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* Amount to shift the luma width right to find the chroma width.
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* For YV12 this is 1 for example.
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* chroma_width = -((-luma_width) >> log2_chroma_w)
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* The note above is needed to ensure rounding up.
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* This value only refers to the chroma components.
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*/
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uint8_t log2_chroma_w; ///< chroma_width = -((-luma_width )>>log2_chroma_w)
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/**
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* Amount to shift the luma height right to find the chroma height.
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* For YV12 this is 1 for example.
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* chroma_height= -((-luma_height) >> log2_chroma_h)
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* The note above is needed to ensure rounding up.
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* This value only refers to the chroma components.
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*/
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uint8_t log2_chroma_h;
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uint8_t flags;
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/**
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* Parameters that describe how pixels are packed.
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* If the format has 2 or 4 components, then alpha is last.
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* If the format has 1 or 2 components, then luma is 0.
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* If the format has 3 or 4 components,
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* if the RGB flag is set then 0 is red, 1 is green and 2 is blue;
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* otherwise 0 is luma, 1 is chroma-U and 2 is chroma-V.
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*/
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AVComponentDescriptor comp[4];
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}AVPixFmtDescriptor;
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#define PIX_FMT_BE 1 ///< Pixel format is big-endian.
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#define PIX_FMT_PAL 2 ///< Pixel format has a palette in data[1], values are indexes in this palette.
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#define PIX_FMT_BITSTREAM 4 ///< All values of a component are bit-wise packed end to end.
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#define PIX_FMT_HWACCEL 8 ///< Pixel format is an HW accelerated format.
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#define PIX_FMT_PLANAR 16 ///< At least one pixel component is not in the first data plane
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#define PIX_FMT_RGB 32 ///< The pixel format contains RGB-like data (as opposed to YUV/grayscale)
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/**
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* The pixel format is "pseudo-paletted". This means that FFmpeg treats it as
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* paletted internally, but the palette is generated by the decoder and is not
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* stored in the file.
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*/
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#define PIX_FMT_PSEUDOPAL 64
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#define PIX_FMT_ALPHA 128 ///< The pixel format has an alpha channel
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#if FF_API_PIX_FMT_DESC
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/**
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* The array of all the pixel format descriptors.
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*/
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extern const AVPixFmtDescriptor av_pix_fmt_descriptors[];
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#endif
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/**
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* Read a line from an image, and write the values of the
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* pixel format component c to dst.
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*
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* @param data the array containing the pointers to the planes of the image
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* @param linesize the array containing the linesizes of the image
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* @param desc the pixel format descriptor for the image
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* @param x the horizontal coordinate of the first pixel to read
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* @param y the vertical coordinate of the first pixel to read
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* @param w the width of the line to read, that is the number of
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* values to write to dst
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* @param read_pal_component if not zero and the format is a paletted
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* format writes the values corresponding to the palette
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* component c in data[1] to dst, rather than the palette indexes in
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* data[0]. The behavior is undefined if the format is not paletted.
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*/
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void av_read_image_line(uint16_t *dst, const uint8_t *data[4], const int linesize[4],
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const AVPixFmtDescriptor *desc, int x, int y, int c, int w, int read_pal_component);
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/**
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* Write the values from src to the pixel format component c of an
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* image line.
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*
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* @param src array containing the values to write
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* @param data the array containing the pointers to the planes of the
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* image to write into. It is supposed to be zeroed.
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* @param linesize the array containing the linesizes of the image
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* @param desc the pixel format descriptor for the image
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* @param x the horizontal coordinate of the first pixel to write
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* @param y the vertical coordinate of the first pixel to write
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* @param w the width of the line to write, that is the number of
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* values to write to the image line
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*/
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void av_write_image_line(const uint16_t *src, uint8_t *data[4], const int linesize[4],
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const AVPixFmtDescriptor *desc, int x, int y, int c, int w);
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/**
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* Return the pixel format corresponding to name.
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*
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* If there is no pixel format with name name, then looks for a
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* pixel format with the name corresponding to the native endian
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* format of name.
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* For example in a little-endian system, first looks for "gray16",
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* then for "gray16le".
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*
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* Finally if no pixel format has been found, returns AV_PIX_FMT_NONE.
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*/
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enum AVPixelFormat av_get_pix_fmt(const char *name);
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/**
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* Return the short name for a pixel format, NULL in case pix_fmt is
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* unknown.
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*
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* @see av_get_pix_fmt(), av_get_pix_fmt_string()
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*/
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const char *av_get_pix_fmt_name(enum AVPixelFormat pix_fmt);
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/**
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* Print in buf the string corresponding to the pixel format with
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* number pix_fmt, or an header if pix_fmt is negative.
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*
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* @param buf the buffer where to write the string
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* @param buf_size the size of buf
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* @param pix_fmt the number of the pixel format to print the
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* corresponding info string, or a negative value to print the
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* corresponding header.
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*/
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char *av_get_pix_fmt_string (char *buf, int buf_size, enum AVPixelFormat pix_fmt);
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/**
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* Return the number of bits per pixel used by the pixel format
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* described by pixdesc.
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*
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* The returned number of bits refers to the number of bits actually
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* used for storing the pixel information, that is padding bits are
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* not counted.
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*/
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int av_get_bits_per_pixel(const AVPixFmtDescriptor *pixdesc);
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/**
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* Return the number of bits per pixel for the pixel format
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* described by pixdesc, including any padding or unused bits.
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*/
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int av_get_padded_bits_per_pixel(const AVPixFmtDescriptor *pixdesc);
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/**
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* @return a pixel format descriptor for provided pixel format or NULL if
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* this pixel format is unknown.
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*/
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const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt);
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/**
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* Iterate over all pixel format descriptors known to libavutil.
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*
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* @param prev previous descriptor. NULL to get the first descriptor.
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*
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* @return next descriptor or NULL after the last descriptor
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*/
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const AVPixFmtDescriptor *av_pix_fmt_desc_next(const AVPixFmtDescriptor *prev);
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/**
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* @return an AVPixelFormat id described by desc, or AV_PIX_FMT_NONE if desc
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* is not a valid pointer to a pixel format descriptor.
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*/
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enum AVPixelFormat av_pix_fmt_desc_get_id(const AVPixFmtDescriptor *desc);
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/**
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* Utility function to access log2_chroma_w log2_chroma_h from
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* the pixel format AVPixFmtDescriptor.
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*
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* See avcodec_get_chroma_sub_sample() for a function that asserts a
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* valid pixel format instead of returning an error code.
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* Its recommanded that you use avcodec_get_chroma_sub_sample unless
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* you do check the return code!
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*
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* @param[in] pix_fmt the pixel format
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* @param[out] h_shift store log2_chroma_w
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* @param[out] v_shift store log2_chroma_h
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*
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* @return 0 on success, AVERROR(ENOSYS) on invalid or unknown pixel format
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*/
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int av_pix_fmt_get_chroma_sub_sample(enum AVPixelFormat pix_fmt,
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int *h_shift, int *v_shift);
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/**
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* @return number of planes in pix_fmt, a negative AVERROR if pix_fmt is not a
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* valid pixel format.
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*/
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int av_pix_fmt_count_planes(enum AVPixelFormat pix_fmt);
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void ff_check_pixfmt_descriptors(void);
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#endif /* AVUTIL_PIXDESC_H */
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