1 // jpge.h - C++ class for JPEG compression. 2 // Public Domain or Apache 2.0, Richard Geldreich <richgel99@gmail.com> 3 // Alex Evans: Added RGBA support, linear memory allocator. 4 #ifndef JPEG_ENCODER_H 5 #define JPEG_ENCODER_H 6 7 namespace jpge 8 { 9 typedef unsigned char uint8; 10 typedef signed short int16; 11 typedef signed int int32; 12 typedef unsigned short uint16; 13 typedef unsigned int uint32; 14 typedef unsigned int uint; 15 16 // JPEG chroma subsampling factors. Y_ONLY (grayscale images) and H2V2 (color images) are the most common. 17 enum subsampling_t { Y_ONLY = 0, H1V1 = 1, H2V1 = 2, H2V2 = 3 }; 18 19 // JPEG compression parameters structure. 20 struct params 21 { paramsparams22 inline params() : m_quality(85), m_subsampling(H2V2), m_no_chroma_discrim_flag(false), m_two_pass_flag(false), m_use_std_tables(false) { } 23 checkparams24 inline bool check() const 25 { 26 if ((m_quality < 1) || (m_quality > 100)) return false; 27 if ((uint)m_subsampling > (uint)H2V2) return false; 28 return true; 29 } 30 31 // Quality: 1-100, higher is better. Typical values are around 50-95. 32 int m_quality; 33 34 // m_subsampling: 35 // 0 = Y (grayscale) only 36 // 1 = YCbCr, no subsampling (H1V1, YCbCr 1x1x1, 3 blocks per MCU) 37 // 2 = YCbCr, H2V1 subsampling (YCbCr 2x1x1, 4 blocks per MCU) 38 // 3 = YCbCr, H2V2 subsampling (YCbCr 4x1x1, 6 blocks per MCU-- very common) 39 subsampling_t m_subsampling; 40 41 // Disables CbCr discrimination - only intended for testing. 42 // If true, the Y quantization table is also used for the CbCr channels. 43 bool m_no_chroma_discrim_flag; 44 45 bool m_two_pass_flag; 46 47 // By default we use the same quantization tables as mozjpeg's default. 48 // Set to true to use the traditional tables from JPEG Annex K. 49 bool m_use_std_tables; 50 }; 51 52 // Writes JPEG image to a file. 53 // num_channels must be 1 (Y) or 3 (RGB), image pitch must be width*num_channels. 54 bool compress_image_to_jpeg_file(const char* pFilename, int width, int height, int num_channels, const uint8* pImage_data, const params& comp_params = params()); 55 56 // Writes JPEG image to memory buffer. 57 // On entry, buf_size is the size of the output buffer pointed at by pBuf, which should be at least ~1024 bytes. 58 // If return value is true, buf_size will be set to the size of the compressed data. 59 bool compress_image_to_jpeg_file_in_memory(void* pBuf, int& buf_size, int width, int height, int num_channels, const uint8* pImage_data, const params& comp_params = params()); 60 61 // Output stream abstract class - used by the jpeg_encoder class to write to the output stream. 62 // put_buf() is generally called with len==JPGE_OUT_BUF_SIZE bytes, but for headers it'll be called with smaller amounts. 63 class output_stream 64 { 65 public: ~output_stream()66 virtual ~output_stream() { }; 67 virtual bool put_buf(const void* Pbuf, int len) = 0; put_obj(const T & obj)68 template<class T> inline bool put_obj(const T& obj) { return put_buf(&obj, sizeof(T)); } 69 }; 70 71 // Lower level jpeg_encoder class - useful if more control is needed than the above helper functions. 72 class jpeg_encoder 73 { 74 public: 75 jpeg_encoder(); 76 ~jpeg_encoder(); 77 78 // Initializes the compressor. 79 // pStream: The stream object to use for writing compressed data. 80 // params - Compression parameters structure, defined above. 81 // width, height - Image dimensions. 82 // channels - May be 1, or 3. 1 indicates grayscale, 3 indicates RGB source data. 83 // Returns false on out of memory or if a stream write fails. 84 bool init(output_stream* pStream, int width, int height, int src_channels, const params& comp_params = params()); 85 get_params()86 const params& get_params() const { return m_params; } 87 88 // Deinitializes the compressor, freeing any allocated memory. May be called at any time. 89 void deinit(); 90 get_total_passes()91 uint get_total_passes() const { return m_params.m_two_pass_flag ? 2 : 1; } get_cur_pass()92 inline uint get_cur_pass() { return m_pass_num; } 93 94 // Call this method with each source scanline. 95 // width * src_channels bytes per scanline is expected (RGB or Y format). 96 // You must call with NULL after all scanlines are processed to finish compression. 97 // Returns false on out of memory or if a stream write fails. 98 bool process_scanline(const void* pScanline); 99 100 private: 101 jpeg_encoder(const jpeg_encoder&); 102 jpeg_encoder& operator =(const jpeg_encoder&); 103 104 typedef int32 sample_array_t; 105 106 output_stream* m_pStream; 107 params m_params; 108 uint8 m_num_components; 109 uint8 m_comp_h_samp[3], m_comp_v_samp[3]; 110 int m_image_x, m_image_y, m_image_bpp, m_image_bpl; 111 int m_image_x_mcu, m_image_y_mcu; 112 int m_image_bpl_xlt, m_image_bpl_mcu; 113 int m_mcus_per_row; 114 int m_mcu_x, m_mcu_y; 115 uint8* m_mcu_lines[16]; 116 uint8 m_mcu_y_ofs; 117 sample_array_t m_sample_array[64]; 118 int16 m_coefficient_array[64]; 119 int32 m_quantization_tables[2][64]; 120 uint m_huff_codes[4][256]; 121 uint8 m_huff_code_sizes[4][256]; 122 uint8 m_huff_bits[4][17]; 123 uint8 m_huff_val[4][256]; 124 uint32 m_huff_count[4][256]; 125 int m_last_dc_val[3]; 126 enum { JPGE_OUT_BUF_SIZE = 2048 }; 127 uint8 m_out_buf[JPGE_OUT_BUF_SIZE]; 128 uint8* m_pOut_buf; 129 uint m_out_buf_left; 130 uint32 m_bit_buffer; 131 uint m_bits_in; 132 uint8 m_pass_num; 133 bool m_all_stream_writes_succeeded; 134 135 void optimize_huffman_table(int table_num, int table_len); 136 void emit_byte(uint8 i); 137 void emit_word(uint i); 138 void emit_marker(int marker); 139 void emit_jfif_app0(); 140 void emit_dqt(); 141 void emit_sof(); 142 void emit_dht(uint8* bits, uint8* val, int index, bool ac_flag); 143 void emit_dhts(); 144 void emit_sos(); 145 void emit_markers(); 146 void compute_huffman_table(uint* codes, uint8* code_sizes, uint8* bits, uint8* val); 147 void compute_quant_table(int32* dst, int16* src); 148 void adjust_quant_table(int32* dst, int32* src); 149 void first_pass_init(); 150 bool second_pass_init(); 151 bool jpg_open(int p_x_res, int p_y_res, int src_channels); 152 void load_block_8_8_grey(int x); 153 void load_block_8_8(int x, int y, int c); 154 void load_block_16_8(int x, int c); 155 void load_block_16_8_8(int x, int c); 156 void load_quantized_coefficients(int component_num); 157 void flush_output_buffer(); 158 void put_bits(uint bits, uint len); 159 void code_coefficients_pass_one(int component_num); 160 void code_coefficients_pass_two(int component_num); 161 void code_block(int component_num); 162 void process_mcu_row(); 163 bool terminate_pass_one(); 164 bool terminate_pass_two(); 165 bool process_end_of_image(); 166 void load_mcu(const void* src); 167 void clear(); 168 void init(); 169 }; 170 171 } // namespace jpge 172 173 #endif // JPEG_ENCODER 174