/* 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 … #define V4L2_JPEG_MAX_TABLES … /* * Prefixes used to generate huffman table class and destination identifiers as * described below: * * V4L2_JPEG_LUM_HT | V4L2_JPEG_DC_HT : Prefix for Luma DC coefficients * huffman table * V4L2_JPEG_LUM_HT | V4L2_JPEG_AC_HT : Prefix for Luma AC coefficients * huffman table * V4L2_JPEG_CHR_HT | V4L2_JPEG_DC_HT : Prefix for Chroma DC coefficients * huffman table * V4L2_JPEG_CHR_HT | V4L2_JPEG_AC_HT : Prefix for Chroma AC coefficients * huffman table */ #define V4L2_JPEG_LUM_HT … #define V4L2_JPEG_CHR_HT … #define V4L2_JPEG_DC_HT … #define V4L2_JPEG_AC_HT … /* Length of reference huffman tables as provided in Table K.3 of ITU-T.81 */ #define V4L2_JPEG_REF_HT_AC_LEN … #define V4L2_JPEG_REF_HT_DC_LEN … /* Array size for 8x8 block of samples or DCT coefficient */ #define V4L2_JPEG_PIXELS_IN_BLOCK … /** * 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 { … }; /* 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 { … }; /** * 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 { … }; /* 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 { … }; /** * 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 { … }; /** * 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 { … }; /** * 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 { … }; 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); extern const u8 v4l2_jpeg_zigzag_scan_index[V4L2_JPEG_PIXELS_IN_BLOCK]; extern const u8 v4l2_jpeg_ref_table_luma_qt[V4L2_JPEG_PIXELS_IN_BLOCK]; extern const u8 v4l2_jpeg_ref_table_chroma_qt[V4L2_JPEG_PIXELS_IN_BLOCK]; extern const u8 v4l2_jpeg_ref_table_luma_dc_ht[V4L2_JPEG_REF_HT_DC_LEN]; extern const u8 v4l2_jpeg_ref_table_luma_ac_ht[V4L2_JPEG_REF_HT_AC_LEN]; extern const u8 v4l2_jpeg_ref_table_chroma_dc_ht[V4L2_JPEG_REF_HT_DC_LEN]; extern const u8 v4l2_jpeg_ref_table_chroma_ac_ht[V4L2_JPEG_REF_HT_AC_LEN]; #endif
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