include/media/v4l2-jpeg.h

   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