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101 lines
3.9 KiB
C
101 lines
3.9 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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#include <inttypes.h>
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#include "libavutil/intreadwrite.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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uint16_t step_minus1 :3; ///< number of bytes between 2 horizontally consecutive pixels minus 1
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uint16_t offset_plus1 :3; ///< number of bytes before the component of the first pixel plus 1
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uint16_t shift :3; ///< number of lsb 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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uint8_t nb_channels; ///< 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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*/
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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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*/
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uint8_t log2_chroma_h;
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uint8_t flags;
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AVComponentDescriptor comp[4]; ///< parameters that describe how pixels are packed
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}AVPixFmtDescriptor;
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#define PIX_FMT_BE 1 ///< 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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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)
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{
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AVComponentDescriptor comp= desc->comp[c];
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int plane= comp.plane;
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int depth= comp.depth_minus1+1;
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int mask = (1<<depth)-1;
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int shift= comp.shift;
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int step = comp.step_minus1+1;
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int flags= desc->flags;
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const uint8_t *p= data[plane]+y*linesize[plane] + x * step + comp.offset_plus1 - 1;
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//FIXME initial x in case of PIX_FMT_BITSTREAM is wrong
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while(w--){
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int val;
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if(flags & PIX_FMT_BE) val= AV_RB16(p);
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else val= AV_RL16(p);
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val = (val>>shift) & mask;
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if(flags & PIX_FMT_PAL)
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val= data[1][4*val + c];
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if(flags & PIX_FMT_BITSTREAM){
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shift-=depth;
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while(shift<0){
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shift+=8;
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p++;
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}
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}else
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p+= step;
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*dst++= val;
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}
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}
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