1/* SPDX-License-Identifier: GPL-2.0-only */
2/*
3 * V4L2 JPEG helpers header
4 *
5 * Copyright (C) 2019 Pengutronix, Philipp Zabel <kernel@pengutronix.de>
6 *
7 * For reference, see JPEG ITU-T.81 (ISO/IEC 10918-1)
8 */
9
10#ifndef _V4L2_JPEG_H
11#define _V4L2_JPEG_H
12
13#include <linux/v4l2-controls.h>
14
15#define V4L2_JPEG_MAX_COMPONENTS 4
16#define V4L2_JPEG_MAX_TABLES 4
17/*
18 * Prefixes used to generate huffman table class and destination identifiers as
19 * described below:
20 *
21 * V4L2_JPEG_LUM_HT | V4L2_JPEG_DC_HT : Prefix for Luma DC coefficients
22 * huffman table
23 * V4L2_JPEG_LUM_HT | V4L2_JPEG_AC_HT : Prefix for Luma AC coefficients
24 * huffman table
25 * V4L2_JPEG_CHR_HT | V4L2_JPEG_DC_HT : Prefix for Chroma DC coefficients
26 * huffman table
27 * V4L2_JPEG_CHR_HT | V4L2_JPEG_AC_HT : Prefix for Chroma AC coefficients
28 * huffman table
29 */
30#define V4L2_JPEG_LUM_HT 0x00
31#define V4L2_JPEG_CHR_HT 0x01
32#define V4L2_JPEG_DC_HT 0x00
33#define V4L2_JPEG_AC_HT 0x10
34
35/* Length of reference huffman tables as provided in Table K.3 of ITU-T.81 */
36#define V4L2_JPEG_REF_HT_AC_LEN 178
37#define V4L2_JPEG_REF_HT_DC_LEN 28
38
39/* Array size for 8x8 block of samples or DCT coefficient */
40#define V4L2_JPEG_PIXELS_IN_BLOCK 64
41
42/**
43 * struct v4l2_jpeg_reference - reference into the JPEG buffer
44 * @start: pointer to the start of the referenced segment or table
45 * @length: size of the referenced segment or table
46 *
47 * Wnen referencing marker segments, start points right after the marker code,
48 * and length is the size of the segment parameters, excluding the marker code.
49 */
50struct v4l2_jpeg_reference {
51 u8 *start;
52 size_t length;
53};
54
55/* B.2.2 Frame header syntax */
56
57/**
58 * struct v4l2_jpeg_frame_component_spec - frame component-specification
59 * @component_identifier: C[i]
60 * @horizontal_sampling_factor: H[i]
61 * @vertical_sampling_factor: V[i]
62 * @quantization_table_selector: quantization table destination selector Tq[i]
63 */
64struct v4l2_jpeg_frame_component_spec {
65 u8 component_identifier;
66 u8 horizontal_sampling_factor;
67 u8 vertical_sampling_factor;
68 u8 quantization_table_selector;
69};
70
71/**
72 * struct v4l2_jpeg_frame_header - JPEG frame header
73 * @height: Y
74 * @width: X
75 * @precision: P
76 * @num_components: Nf
77 * @component: component-specification, see v4l2_jpeg_frame_component_spec
78 * @subsampling: decoded subsampling from component-specification
79 */
80struct v4l2_jpeg_frame_header {
81 u16 height;
82 u16 width;
83 u8 precision;
84 u8 num_components;
85 struct v4l2_jpeg_frame_component_spec component[V4L2_JPEG_MAX_COMPONENTS];
86 enum v4l2_jpeg_chroma_subsampling subsampling;
87};
88
89/* B.2.3 Scan header syntax */
90
91/**
92 * struct v4l2_jpeg_scan_component_spec - scan component-specification
93 * @component_selector: Cs[j]
94 * @dc_entropy_coding_table_selector: Td[j]
95 * @ac_entropy_coding_table_selector: Ta[j]
96 */
97struct v4l2_jpeg_scan_component_spec {
98 u8 component_selector;
99 u8 dc_entropy_coding_table_selector;
100 u8 ac_entropy_coding_table_selector;
101};
102
103/**
104 * struct v4l2_jpeg_scan_header - JPEG scan header
105 * @num_components: Ns
106 * @component: component-specification, see v4l2_jpeg_scan_component_spec
107 */
108struct v4l2_jpeg_scan_header {
109 u8 num_components; /* Ns */
110 struct v4l2_jpeg_scan_component_spec component[V4L2_JPEG_MAX_COMPONENTS];
111 /* Ss, Se, Ah, and Al are not used by any driver */
112};
113
114/**
115 * enum v4l2_jpeg_app14_tf - APP14 transform flag
116 * According to Rec. ITU-T T.872 (06/2012) 6.5.3
117 * APP14 segment is for color encoding, it contains a transform flag,
118 * which may have values of 0, 1 and 2 and are interpreted as follows:
119 * @V4L2_JPEG_APP14_TF_CMYK_RGB: CMYK for images encoded with four components
120 * RGB for images encoded with three components
121 * @V4L2_JPEG_APP14_TF_YCBCR: an image encoded with three components using YCbCr
122 * @V4L2_JPEG_APP14_TF_YCCK: an image encoded with four components using YCCK
123 * @V4L2_JPEG_APP14_TF_UNKNOWN: indicate app14 is not present
124 */
125enum v4l2_jpeg_app14_tf {
126 V4L2_JPEG_APP14_TF_CMYK_RGB = 0,
127 V4L2_JPEG_APP14_TF_YCBCR = 1,
128 V4L2_JPEG_APP14_TF_YCCK = 2,
129 V4L2_JPEG_APP14_TF_UNKNOWN = -1,
130};
131
132/**
133 * struct v4l2_jpeg_header - parsed JPEG header
134 * @sof: pointer to frame header and size
135 * @sos: pointer to scan header and size
136 * @num_dht: number of entries in @dht
137 * @dht: pointers to huffman tables and sizes
138 * @num_dqt: number of entries in @dqt
139 * @dqt: pointers to quantization tables and sizes
140 * @frame: parsed frame header
141 * @scan: pointer to parsed scan header, optional
142 * @quantization_tables: references to four quantization tables, optional
143 * @huffman_tables: references to four Huffman tables in DC0, DC1, AC0, AC1
144 * order, optional
145 * @restart_interval: number of MCU per restart interval, Ri
146 * @ecs_offset: buffer offset in bytes to the entropy coded segment
147 * @app14_tf: transform flag from app14 data
148 *
149 * When this structure is passed to v4l2_jpeg_parse_header, the optional scan,
150 * quantization_tables, and huffman_tables pointers must be initialized to NULL
151 * or point at valid memory.
152 */
153struct v4l2_jpeg_header {
154 struct v4l2_jpeg_reference sof;
155 struct v4l2_jpeg_reference sos;
156 unsigned int num_dht;
157 struct v4l2_jpeg_reference dht[V4L2_JPEG_MAX_TABLES];
158 unsigned int num_dqt;
159 struct v4l2_jpeg_reference dqt[V4L2_JPEG_MAX_TABLES];
160
161 struct v4l2_jpeg_frame_header frame;
162 struct v4l2_jpeg_scan_header *scan;
163 struct v4l2_jpeg_reference *quantization_tables;
164 struct v4l2_jpeg_reference *huffman_tables;
165 u16 restart_interval;
166 size_t ecs_offset;
167 enum v4l2_jpeg_app14_tf app14_tf;
168};
169
170int v4l2_jpeg_parse_header(void *buf, size_t len, struct v4l2_jpeg_header *out);
171
172int v4l2_jpeg_parse_frame_header(void *buf, size_t len,
173 struct v4l2_jpeg_frame_header *frame_header);
174int v4l2_jpeg_parse_scan_header(void *buf, size_t len,
175 struct v4l2_jpeg_scan_header *scan_header);
176int v4l2_jpeg_parse_quantization_tables(void *buf, size_t len, u8 precision,
177 struct v4l2_jpeg_reference *q_tables);
178int v4l2_jpeg_parse_huffman_tables(void *buf, size_t len,
179 struct v4l2_jpeg_reference *huffman_tables);
180
181extern const u8 v4l2_jpeg_zigzag_scan_index[V4L2_JPEG_PIXELS_IN_BLOCK];
182extern const u8 v4l2_jpeg_ref_table_luma_qt[V4L2_JPEG_PIXELS_IN_BLOCK];
183extern const u8 v4l2_jpeg_ref_table_chroma_qt[V4L2_JPEG_PIXELS_IN_BLOCK];
184extern const u8 v4l2_jpeg_ref_table_luma_dc_ht[V4L2_JPEG_REF_HT_DC_LEN];
185extern const u8 v4l2_jpeg_ref_table_luma_ac_ht[V4L2_JPEG_REF_HT_AC_LEN];
186extern const u8 v4l2_jpeg_ref_table_chroma_dc_ht[V4L2_JPEG_REF_HT_DC_LEN];
187extern const u8 v4l2_jpeg_ref_table_chroma_ac_ht[V4L2_JPEG_REF_HT_AC_LEN];
188
189#endif
190

Provided by KDAB

Privacy Policy
Improve your Profiling and Debugging skills
Find out more

source code of linux/include/media/v4l2-jpeg.h