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