linux/include/media/v4l2-jpeg.h
Philipp Zabel 50733b5b91 media: add v4l2 JPEG helpers
Add helpers for JPEG header parsing. They allow both scanning for marker
segment positions and later parsing the segments individually, as
required by s5p-jpeg, as well as parsing all headers in one go, as
required by coda-vpu. The frame header is always parsed, as basically
all decoders are interested in width, height, and number of components.
For convenience, the JPEG chroma subsampling factors are decoded into a
v4l2_jpeg_chroma_subsampling enum.

Only baseline and extended sequential DCT encoded JPEGs with 8-bit or
12-bit precision with up to four components are supported.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
2020-04-14 11:47:47 +02:00

136 lines
4.2 KiB
C

/* SPDX-License-Identifier: GPL-2.0-only */
/*
* V4L2 JPEG helpers header
*
* Copyright (C) 2019 Pengutronix, Philipp Zabel <kernel@pengutronix.de>
*
* 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 */
};
/**
* struct v4l2_jpeg_header - parsed JPEG header
* @sof: pointer to frame header and size
* @sos: pointer to scan header and size
* @dht: pointers to huffman tables and sizes
* @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
*
* 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;
};
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