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* pixel format descriptor
* Copyright (c) 2009 Michael Niedermayer <>
* 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
* 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
#include <inttypes.h>
#include "libavutil/intreadwrite.h"
typedef struct AVComponentDescriptor{
uint16_t plane :2; ///< which of the 4 planes contains the component
uint16_t step_minus1 :3; ///< number of bytes between 2 horizontally consecutive pixels minus 1
uint16_t offset_plus1 :3; ///< number of bytes before the component of the first pixel plus 1
uint16_t shift :3; ///< number of lsb that must be shifted away to get the value
uint16_t depth_minus1 :4; ///< number of bits in the component minus 1
* 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{
uint8_t nb_channels; ///< 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.
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.
uint8_t log2_chroma_h;
uint8_t flags;
AVComponentDescriptor comp[4]; ///< parameters that describe how pixels are packed
#define PIX_FMT_BE 1 ///< big-endian
#define PIX_FMT_PAL 2 ///< Pixel format has a palette i 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.
static inline void read_line(uint16_t *dst, const uint8_t *data[4], const int linesize[4], AVPixFmtDescriptor *desc, int x, int y, int c, int w)
AVComponentDescriptor comp= desc->comp[c];
int plane= comp.plane;
int depth= comp.depth_minus1+1;
int mask = (1<<depth)-1;
int shift= comp.shift;
int step = comp.step_minus1+1;
int flags= desc->flags;
const uint8_t *p= data[plane]+y*linesize[plane] + x * step + comp.offset_plus1 - 1;
//FIXME initial x in case of PIX_FMT_BITSTREAM is wrong
int val;
if(flags & PIX_FMT_BE) val= AV_RB16(p);
else val= AV_RL16(p);
val = (val>>shift) & mask;
if(flags & PIX_FMT_PAL)
val= data[1][4*val + c];
if(flags & PIX_FMT_BITSTREAM){
p+= step;
*dst++= val;