jpeg_reader.h

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#ifndef UTILS_JPEG_READER_H_
#define UTILS_JPEG_READER_H_
 
#ifndef __cplusplus
#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
#else
#include <cstddef>
#include <cstdint>
#endif
 
enum jpeg_color_spec {
        JPEG_COLOR_SPEC_NONE = 0,
        JPEG_COLOR_SPEC_YCBCR,
        JPEG_COLOR_SPEC_RGB,
        JPEG_COLOR_SPEC_CMYK,
        JPEG_COLOR_SPEC_YCCK
};
 
enum {
        JPEG_MAX_COMPONENT_COUNT = 4,
};
 
struct jpeg_info {
        int width, height, comp_count;
        enum jpeg_color_spec color_spec;
        bool interleaved;
        int sampling_factor_v[JPEG_MAX_COMPONENT_COUNT];
        int sampling_factor_h[JPEG_MAX_COMPONENT_COUNT];
        int restart_interval; // content of DRI marker
        uint8_t *quantization_tables[JPEG_MAX_COMPONENT_COUNT];
        int comp_table_quantization_map[JPEG_MAX_COMPONENT_COUNT];
        uint8_t *data; // entropy-coded segment start
        char com[65536 - 2 + 1]; // comment (COM marker)
        uint8_t huff_lum_dc[16 + 256]; // if first byte is 255, table was not defined
        uint8_t huff_lum_ac[16 + 256];
        uint8_t huff_chm_dc[16 + 256];
        uint8_t huff_chm_ac[16 + 256];
};
 
struct jpeg_rtp_data {
        int width, height;
        int type; // RTP JPEG type
        int q; // either 0..100 or 255 (dynamic QT - included in quantization_tables)
        int restart_interval; // content of DRI marker
        uint8_t *quantization_tables[2]; // assuming 8-bit tables
        uint8_t *data; // entropy-coded data start
};
 
#ifdef __cplusplus
extern "C" {
#endif // defined __cplusplus
 
int jpeg_read_info(uint8_t *image, int len, struct jpeg_info *info);
bool jpeg_get_rtp_hdr_data(uint8_t *jpeg_data, int len, struct jpeg_rtp_data *hdr_data);
 
// for writer
struct huffman_table {
        const uint8_t *bits; // 16 items
        const uint8_t *bufval;
};
enum huff_type { 
        LUM_DC = 0,
        LUM_AC = 1,
        CHR_DC = 2,
        CHR_AC = 3,
};
extern const struct huffman_table default_huffman_tables[4];
 
#ifdef __cplusplus
}
#endif // defined __cplusplus
 
#endif// UTILS_JPEG_READER_H_