Pixel Format descriptor, try #1.
[libav.git] / libavcodec / pixdesc.h
CommitLineData
9b61d838
MN
1/*
2 * Pixel Format descriptor
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
30 uint16_t shift :3; ///< number of lsb that must be shifted away to get the value
31 uint16_t depth_minus1 :4; ///< number of bits in the component minus 1
32}AVComponentDescriptor;
33
34typedef struct AVPixFmtDescriptor{
35 uint8_t nb_channels; ///< The number of components each pixel has, (1-4)
36
37 /**
38 * Amount to shift the luma width right to find the chroma width, this is for
39 * example 1 for YV12
40 * chroma_width = -((-luma_width )>>log2_chroma_w)
41 * note above is needed to ensure rounding up
42 */
43 uint8_t log2_chroma_w; ///< chroma_width = -((-luma_width )>>log2_chroma_w)
44
45 /**
46 * Amount to shift the luma height right to find the chroma height, this is for
47 * example 1 for YV12
48 * chroma_height= -((-luma_height)>>log2_chroma_h)
49 * note above is needed to ensure rounding up
50 */
51 uint8_t log2_chroma_h;
52 uint8_t flags;
53 AVComponentDescriptor comp[4]; ///< parameters that describes how pixels are packed
54}AVPixFmtDescriptor;
55
56#define PIX_FMT_BE 1 ///< Big endian
57#define PIX_FMT_PAL 2 ///< Pixel format has a palette i data[1], values are indexes in this palette
58#define PIX_FMT_BITSTREAM 4 ///< All values of a component are bitwise packed end to end
59
60
61static 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)
62{
63 AVComponentDescriptor comp= desc->comp[c];
64 int plane= comp.plane;
65 int depth= comp.depth_minus1+1;
66 int mask = (1<<depth)-1;
67 int shift= comp.shift;
68 int step = comp.step_minus1+1;
69 int flags= desc->flags;
70 const uint8_t *p= data[plane]+y*linesize[plane] + x * step + comp.offset_plus1 - 1;
71
72 //FIXME initial x in case of PIX_FMT_BITSTREAM is wrong
73
74 while(w--){
75 int val;
76 if(flags & PIX_FMT_BE) val= AV_RB16(p);
77 else val= AV_RL16(p);
78 val = (val>>shift) & mask;
79 if(flags & PIX_FMT_PAL)
80 val= data[1][4*val + c];
81 if(flags & PIX_FMT_BITSTREAM){
82 shift-=depth;
83 while(shift<0){
84 shift+=8;
85 p++;
86 }
87 }else
88 p+= step;
89 *dst++= val;
90 }
91}