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v4l2-jpeg.h
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v4l2-jpeg.h
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/* SPDX-License-Identifier: GPL-2.0-only */
/*
* V4L2 JPEG helpers header
*
* Copyright (C) 2019 Pengutronix, Philipp Zabel <[email protected]>
*
* For reference, see JPEG ITU-T.81 (ISO/IEC 10918-1)
*/
#ifndef _V4L2_JPEG_H
#define _V4L2_JPEG_H
#include <linux/v4l2-controls.h>
#define V4L2_JPEG_MAX_COMPONENTS 4
#define V4L2_JPEG_MAX_TABLES 4
/**
* struct v4l2_jpeg_reference - reference into the JPEG buffer
* @start: pointer to the start of the referenced segment or table
* @length: size of the referenced segment or table
*
* Wnen referencing marker segments, start points right after the marker code,
* and length is the size of the segment parameters, excluding the marker code.
*/
struct v4l2_jpeg_reference {
u8 *start;
size_t length;
};
/* B.2.2 Frame header syntax */
/**
* struct v4l2_jpeg_frame_component_spec - frame component-specification
* @component_identifier: C[i]
* @horizontal_sampling_factor: H[i]
* @vertical_sampling_factor: V[i]
* @quantization_table_selector: quantization table destination selector Tq[i]
*/
struct v4l2_jpeg_frame_component_spec {
u8 component_identifier;
u8 horizontal_sampling_factor;
u8 vertical_sampling_factor;
u8 quantization_table_selector;
};
/**
* struct v4l2_jpeg_frame_header - JPEG frame header
* @height: Y
* @width: X
* @precision: P
* @num_components: Nf
* @component: component-specification, see v4l2_jpeg_frame_component_spec
* @subsampling: decoded subsampling from component-specification
*/
struct v4l2_jpeg_frame_header {
u16 height;
u16 width;
u8 precision;
u8 num_components;
struct v4l2_jpeg_frame_component_spec component[V4L2_JPEG_MAX_COMPONENTS];
enum v4l2_jpeg_chroma_subsampling subsampling;
};
/* B.2.3 Scan header syntax */
/**
* struct v4l2_jpeg_scan_component_spec - scan component-specification
* @component_selector: Cs[j]
* @dc_entropy_coding_table_selector: Td[j]
* @ac_entropy_coding_table_selector: Ta[j]
*/
struct v4l2_jpeg_scan_component_spec {
u8 component_selector;
u8 dc_entropy_coding_table_selector;
u8 ac_entropy_coding_table_selector;
};
/**
* struct v4l2_jpeg_scan_header - JPEG scan header
* @num_components: Ns
* @component: component-specification, see v4l2_jpeg_scan_component_spec
*/
struct v4l2_jpeg_scan_header {
u8 num_components; /* Ns */
struct v4l2_jpeg_scan_component_spec component[V4L2_JPEG_MAX_COMPONENTS];
/* Ss, Se, Ah, and Al are not used by any driver */
};
/**
* enum v4l2_jpeg_app14_tf - APP14 transform flag
* According to Rec. ITU-T T.872 (06/2012) 6.5.3
* APP14 segment is for color encoding, it contains a transform flag,
* which may have values of 0, 1 and 2 and are interpreted as follows:
* @V4L2_JPEG_APP14_TF_CMYK_RGB: CMYK for images encoded with four components
* RGB for images encoded with three components
* @V4L2_JPEG_APP14_TF_YCBCR: an image encoded with three components using YCbCr
* @V4L2_JPEG_APP14_TF_YCCK: an image encoded with four components using YCCK
* @V4L2_JPEG_APP14_TF_UNKNOWN: indicate app14 is not present
*/
enum v4l2_jpeg_app14_tf {
V4L2_JPEG_APP14_TF_CMYK_RGB = 0,
V4L2_JPEG_APP14_TF_YCBCR = 1,
V4L2_JPEG_APP14_TF_YCCK = 2,
V4L2_JPEG_APP14_TF_UNKNOWN = -1,
};
/**
* struct v4l2_jpeg_header - parsed JPEG header
* @sof: pointer to frame header and size
* @sos: pointer to scan header and size
* @num_dht: number of entries in @dht
* @dht: pointers to huffman tables and sizes
* @num_dqt: number of entries in @dqt
* @dqt: pointers to quantization tables and sizes
* @frame: parsed frame header
* @scan: pointer to parsed scan header, optional
* @quantization_tables: references to four quantization tables, optional
* @huffman_tables: references to four Huffman tables in DC0, DC1, AC0, AC1
* order, optional
* @restart_interval: number of MCU per restart interval, Ri
* @ecs_offset: buffer offset in bytes to the entropy coded segment
* @app14_tf: transform flag from app14 data
*
* When this structure is passed to v4l2_jpeg_parse_header, the optional scan,
* quantization_tables, and huffman_tables pointers must be initialized to NULL
* or point at valid memory.
*/
struct v4l2_jpeg_header {
struct v4l2_jpeg_reference sof;
struct v4l2_jpeg_reference sos;
unsigned int num_dht;
struct v4l2_jpeg_reference dht[V4L2_JPEG_MAX_TABLES];
unsigned int num_dqt;
struct v4l2_jpeg_reference dqt[V4L2_JPEG_MAX_TABLES];
struct v4l2_jpeg_frame_header frame;
struct v4l2_jpeg_scan_header *scan;
struct v4l2_jpeg_reference *quantization_tables;
struct v4l2_jpeg_reference *huffman_tables;
u16 restart_interval;
size_t ecs_offset;
enum v4l2_jpeg_app14_tf app14_tf;
};
int v4l2_jpeg_parse_header(void *buf, size_t len, struct v4l2_jpeg_header *out);
int v4l2_jpeg_parse_frame_header(void *buf, size_t len,
struct v4l2_jpeg_frame_header *frame_header);
int v4l2_jpeg_parse_scan_header(void *buf, size_t len,
struct v4l2_jpeg_scan_header *scan_header);
int v4l2_jpeg_parse_quantization_tables(void *buf, size_t len, u8 precision,
struct v4l2_jpeg_reference *q_tables);
int v4l2_jpeg_parse_huffman_tables(void *buf, size_t len,
struct v4l2_jpeg_reference *huffman_tables);
#endif