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
34/**
35 * Descriptor that unambiguously describes how the bits of a pixel are
36 * stored in the up to 4 data planes of an image. It also stores the
37 * subsampling factors and number of components.
38 *
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.
42 */
43typedef struct AVPixFmtDescriptor{
44    uint8_t nb_channels;        ///< The number of components each pixel has, (1-4)
45
46    /**
47     * Amount to shift the luma width right to find the chroma width.
48     * For YV12 this is 1 for example.
49     * chroma_width = -((-luma_width) >> log2_chroma_w)
50     * The note above is needed to ensure rounding up.
51     */
52    uint8_t log2_chroma_w;      ///< chroma_width = -((-luma_width )>>log2_chroma_w)
53
54    /**
55     * Amount to shift the luma height right to find the chroma height.
56     * For YV12 this is 1 for example.
57     * chroma_height= -((-luma_height) >> log2_chroma_h)
58     * The note above is needed to ensure rounding up.
59     */
60    uint8_t log2_chroma_h;
61    uint8_t flags;
62    AVComponentDescriptor comp[4]; ///< parameters that describe how pixels are packed
63}AVPixFmtDescriptor;
64
65#define PIX_FMT_BE        1 ///< big-endian
66#define PIX_FMT_PAL       2 ///< Pixel format has a palette i data[1], values are indexes in this palette.
67#define PIX_FMT_BITSTREAM 4 ///< All values of a component are bit-wise packed end to end.
68
69
70static 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)
71{
72    AVComponentDescriptor comp= desc->comp[c];
73    int plane= comp.plane;
74    int depth= comp.depth_minus1+1;
75    int mask = (1<<depth)-1;
76    int shift= comp.shift;
77    int step = comp.step_minus1+1;
78    int flags= desc->flags;
79    const uint8_t *p= data[plane]+y*linesize[plane] + x * step + comp.offset_plus1 - 1;
80
81    //FIXME initial x in case of PIX_FMT_BITSTREAM is wrong
82
83    while(w--){
84        int val;
85        if(flags & PIX_FMT_BE) val= AV_RB16(p);
86        else                   val= AV_RL16(p);
87        val = (val>>shift) & mask;
88        if(flags & PIX_FMT_PAL)
89            val= data[1][4*val + c];
90        if(flags & PIX_FMT_BITSTREAM){
91            shift-=depth;
92            while(shift<0){
93                shift+=8;
94                p++;
95            }
96        }else
97            p+= step;
98        *dst++= val;
99    }
100}
101