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 /** 19 * struct v4l2_jpeg_reference - reference into the JPEG buffer 20 * @start: pointer to the start of the referenced segment or table 21 * @length: size of the referenced segment or table 22 * 23 * Wnen referencing marker segments, start points right after the marker code, 24 * and length is the size of the segment parameters, excluding the marker code. 25 */ 26 struct v4l2_jpeg_reference { 27 u8 *start; 28 size_t length; 29 }; 30 31 /* B.2.2 Frame header syntax */ 32 33 /** 34 * struct v4l2_jpeg_frame_component_spec - frame component-specification 35 * @component_identifier: C[i] 36 * @horizontal_sampling_factor: H[i] 37 * @vertical_sampling_factor: V[i] 38 * @quantization_table_selector: quantization table destination selector Tq[i] 39 */ 40 struct v4l2_jpeg_frame_component_spec { 41 u8 component_identifier; 42 u8 horizontal_sampling_factor; 43 u8 vertical_sampling_factor; 44 u8 quantization_table_selector; 45 }; 46 47 /** 48 * struct v4l2_jpeg_frame_header - JPEG frame header 49 * @height: Y 50 * @width: X 51 * @precision: P 52 * @num_components: Nf 53 * @component: component-specification, see v4l2_jpeg_frame_component_spec 54 * @subsampling: decoded subsampling from component-specification 55 */ 56 struct v4l2_jpeg_frame_header { 57 u16 height; 58 u16 width; 59 u8 precision; 60 u8 num_components; 61 struct v4l2_jpeg_frame_component_spec component[V4L2_JPEG_MAX_COMPONENTS]; 62 enum v4l2_jpeg_chroma_subsampling subsampling; 63 }; 64 65 /* B.2.3 Scan header syntax */ 66 67 /** 68 * struct v4l2_jpeg_scan_component_spec - scan component-specification 69 * @component_selector: Cs[j] 70 * @dc_entropy_coding_table_selector: Td[j] 71 * @ac_entropy_coding_table_selector: Ta[j] 72 */ 73 struct v4l2_jpeg_scan_component_spec { 74 u8 component_selector; 75 u8 dc_entropy_coding_table_selector; 76 u8 ac_entropy_coding_table_selector; 77 }; 78 79 /** 80 * struct v4l2_jpeg_scan_header - JPEG scan header 81 * @num_components: Ns 82 * @component: component-specification, see v4l2_jpeg_scan_component_spec 83 */ 84 struct v4l2_jpeg_scan_header { 85 u8 num_components; /* Ns */ 86 struct v4l2_jpeg_scan_component_spec component[V4L2_JPEG_MAX_COMPONENTS]; 87 /* Ss, Se, Ah, and Al are not used by any driver */ 88 }; 89 90 /** 91 * struct v4l2_jpeg_header - parsed JPEG header 92 * @sof: pointer to frame header and size 93 * @sos: pointer to scan header and size 94 * @dht: pointers to huffman tables and sizes 95 * @dqt: pointers to quantization tables and sizes 96 * @frame: parsed frame header 97 * @scan: pointer to parsed scan header, optional 98 * @quantization_tables: references to four quantization tables, optional 99 * @huffman_tables: references to four Huffman tables in DC0, DC1, AC0, AC1 100 * order, optional 101 * @restart_interval: number of MCU per restart interval, Ri 102 * @ecs_offset: buffer offset in bytes to the entropy coded segment 103 * 104 * When this structure is passed to v4l2_jpeg_parse_header, the optional scan, 105 * quantization_tables, and huffman_tables pointers must be initialized to NULL 106 * or point at valid memory. 107 */ 108 struct v4l2_jpeg_header { 109 struct v4l2_jpeg_reference sof; 110 struct v4l2_jpeg_reference sos; 111 unsigned int num_dht; 112 struct v4l2_jpeg_reference dht[V4L2_JPEG_MAX_TABLES]; 113 unsigned int num_dqt; 114 struct v4l2_jpeg_reference dqt[V4L2_JPEG_MAX_TABLES]; 115 116 struct v4l2_jpeg_frame_header frame; 117 struct v4l2_jpeg_scan_header *scan; 118 struct v4l2_jpeg_reference *quantization_tables; 119 struct v4l2_jpeg_reference *huffman_tables; 120 u16 restart_interval; 121 size_t ecs_offset; 122 }; 123 124 int v4l2_jpeg_parse_header(void *buf, size_t len, struct v4l2_jpeg_header *out); 125 126 int v4l2_jpeg_parse_frame_header(void *buf, size_t len, 127 struct v4l2_jpeg_frame_header *frame_header); 128 int v4l2_jpeg_parse_scan_header(void *buf, size_t len, 129 struct v4l2_jpeg_scan_header *scan_header); 130 int v4l2_jpeg_parse_quantization_tables(void *buf, size_t len, u8 precision, 131 struct v4l2_jpeg_reference *q_tables); 132 int v4l2_jpeg_parse_huffman_tables(void *buf, size_t len, 133 struct v4l2_jpeg_reference *huffman_tables); 134 135 #endif 136