Add a notice telling that the behavior of skip_put_bits() is undefined
[libav.git] / libavcodec / pixdesc.h
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9b61d838 1/*
e0cffbe7 2 * pixel format descriptor
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3 * Copyright (c) 2009 Michael Niedermayer <michaelni@gmx.at>
4 *
5 * This file is part of FFmpeg.
6 *
7 * FFmpeg is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
11 *
12 * FFmpeg is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
16 *
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with FFmpeg; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20 */
21
22#include <inttypes.h>
23
24#include "libavutil/intreadwrite.h"
25
26typedef struct AVComponentDescriptor{
27 uint16_t plane :2; ///< which of the 4 planes contains the component
28 uint16_t step_minus1 :3; ///< number of bytes between 2 horizontally consecutive pixels minus 1
29 uint16_t offset_plus1 :3; ///< number of bytes before the component of the first pixel plus 1
78679783 30 uint16_t shift :3; ///< number of least significant bits that must be shifted away to get the value
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31 uint16_t depth_minus1 :4; ///< number of bits in the component minus 1
32}AVComponentDescriptor;
33
d3bcbf57 34/**
e0cffbe7 35 * Descriptor that unambiguously describes how the bits of a pixel are
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36 * stored in the up to 4 data planes of an image. It also stores the
37 * subsampling factors and number of components.
38 *
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39 * @note This is separate of the colorspace (RGB, YCbCr, YPbPr, JPEG-style YUV
40 * and all the YUV variants) AVPixFmtDescriptor just stores how values
41 * are stored not what these values represent.
d3bcbf57 42 */
9b61d838 43typedef struct AVPixFmtDescriptor{
1e896640 44 const char *name;
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45 uint8_t nb_channels; ///< The number of components each pixel has, (1-4)
46
47 /**
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48 * Amount to shift the luma width right to find the chroma width.
49 * For YV12 this is 1 for example.
50 * chroma_width = -((-luma_width) >> log2_chroma_w)
51 * The note above is needed to ensure rounding up.
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52 */
53 uint8_t log2_chroma_w; ///< chroma_width = -((-luma_width )>>log2_chroma_w)
54
55 /**
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56 * Amount to shift the luma height right to find the chroma height.
57 * For YV12 this is 1 for example.
58 * chroma_height= -((-luma_height) >> log2_chroma_h)
59 * The note above is needed to ensure rounding up.
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60 */
61 uint8_t log2_chroma_h;
62 uint8_t flags;
e0cffbe7 63 AVComponentDescriptor comp[4]; ///< parameters that describe how pixels are packed
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64}AVPixFmtDescriptor;
65
e0cffbe7 66#define PIX_FMT_BE 1 ///< big-endian
d3f76612 67#define PIX_FMT_PAL 2 ///< Pixel format has a palette in data[1], values are indexes in this palette.
e0cffbe7 68#define PIX_FMT_BITSTREAM 4 ///< All values of a component are bit-wise packed end to end.
9b61d838 69
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70/**
71 * The array of all the pixel format descriptors.
72 */
73extern const AVPixFmtDescriptor av_pix_fmt_descriptors[];
9b61d838 74
30266c92 75static inline void read_line(uint16_t *dst, const uint8_t *data[4], const int linesize[4], const AVPixFmtDescriptor *desc, int x, int y, int c, int w)
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76{
77 AVComponentDescriptor comp= desc->comp[c];
78 int plane= comp.plane;
79 int depth= comp.depth_minus1+1;
80 int mask = (1<<depth)-1;
81 int shift= comp.shift;
82 int step = comp.step_minus1+1;
83 int flags= desc->flags;
84 const uint8_t *p= data[plane]+y*linesize[plane] + x * step + comp.offset_plus1 - 1;
85
86 //FIXME initial x in case of PIX_FMT_BITSTREAM is wrong
87
88 while(w--){
89 int val;
90 if(flags & PIX_FMT_BE) val= AV_RB16(p);
91 else val= AV_RL16(p);
92 val = (val>>shift) & mask;
93 if(flags & PIX_FMT_PAL)
94 val= data[1][4*val + c];
95 if(flags & PIX_FMT_BITSTREAM){
96 shift-=depth;
97 while(shift<0){
98 shift+=8;
99 p++;
100 }
101 }else
102 p+= step;
103 *dst++= val;
104 }
105}