// jpge.h - C++ class for JPEG compression. // Public domain, Rich Geldreich // Alex Evans: Added RGBA support, linear memory allocator. #ifndef JPEG_ENCODER_H #define JPEG_ENCODER_H #include namespace jpge { typedef unsigned char uint8; typedef signed short int16; typedef signed int int32; typedef unsigned short uint16; typedef unsigned int uint32; typedef unsigned int uint; // JPEG chroma subsampling factors. Y_ONLY (grayscale images) and H2V2 (color images) are the most common. enum subsampling_t { Y_ONLY = 0, H1V1 = 1, H2V1 = 2, H2V2 = 3 }; // JPEG compression parameters structure. struct params { inline params() : m_quality(85), m_subsampling(H2V2), m_no_chroma_discrim_flag(false), m_two_pass_flag(false) { } inline bool check_valid() const { if ((m_quality < 1) || (m_quality > 100)) return false; if ((uint)m_subsampling > (uint)H2V2) return false; return true; } // Quality: 1-100, higher is better. Typical values are around 50-95. int m_quality; // m_subsampling: // 0 = Y (grayscale) only // 1 = YCbCr, no subsampling (H1V1, YCbCr 1x1x1, 3 blocks per MCU) // 2 = YCbCr, H2V1 subsampling (YCbCr 2x1x1, 4 blocks per MCU) // 3 = YCbCr, H2V2 subsampling (YCbCr 4x1x1, 6 blocks per MCU-- very common) subsampling_t m_subsampling; // Disables CbCr discrimination - only intended for testing. // If true, the Y quantization table is also used for the CbCr channels. bool m_no_chroma_discrim_flag; bool m_two_pass_flag; }; // Writes JPEG image to a file. // num_channels must be 1 (Y) or 3 (RGB), image pitch must be width*num_channels. bool compress_image_to_jpeg_file(const char *pFilename, int64_t width, int64_t height, int64_t num_channels, const uint8 *pImage_data, const params &comp_params = params()); // Writes JPEG image to memory buffer. // On entry, buf_size is the size of the output buffer pointed at by pBuf, which should be at least ~1024 bytes. // If return value is true, buf_size will be set to the size of the compressed data. bool compress_image_to_jpeg_file_in_memory(void *pBuf, int64_t &buf_size, int64_t width, int64_t height, int64_t num_channels, const uint8 *pImage_data, const params &comp_params = params()); // Output stream abstract class - used by the jpeg_encoder class to write to the output stream. // put_buf() is generally called with len==JPGE_OUT_BUF_SIZE bytes, but for headers it'll be called with smaller amounts. class output_stream { public: virtual ~output_stream() { }; virtual bool put_buf(const void* Pbuf, int64_t len) = 0; template inline bool put_obj(const T& obj) { return put_buf(&obj, sizeof(T)); } }; // Lower level jpeg_encoder class - useful if more control is needed than the above helper functions. class jpeg_encoder { public: jpeg_encoder(); ~jpeg_encoder(); // Initializes the compressor. // pStream: The stream object to use for writing compressed data. // params - Compression parameters structure, defined above. // width, height - Image dimensions. // channels - May be 1, or 3. 1 indicates grayscale, 3 indicates RGB source data. // Returns false on out of memory or if a stream write fails. bool init(output_stream *pStream, int64_t width, int64_t height, int64_t src_channels, const params &comp_params = params()); const params &get_params() const { return m_params; } // Deinitializes the compressor, freeing any allocated memory. May be called at any time. void deinit(); uint get_total_passes() const { return m_params.m_two_pass_flag ? 2 : 1; } inline uint get_cur_pass() { return m_pass_num; } // Call this method with each source scanline. // width * src_channels bytes per scanline is expected (RGB or Y format). // You must call with NULL after all scanlines are processed to finish compression. // Returns false on out of memory or if a stream write fails. bool process_scanline(const void* pScanline); private: jpeg_encoder(const jpeg_encoder &); jpeg_encoder &operator =(const jpeg_encoder &); typedef int32 sample_array_t; output_stream *m_pStream; params m_params; uint8 m_num_components; uint8 m_comp_h_samp[3], m_comp_v_samp[3]; int m_image_x, m_image_y, m_image_bpp, m_image_bpl; int m_image_x_mcu, m_image_y_mcu; int m_image_bpl_xlt, m_image_bpl_mcu; int m_mcus_per_row; int m_mcu_x, m_mcu_y; uint8 *m_mcu_lines[16]; uint8 m_mcu_y_ofs; sample_array_t m_sample_array[64]; int16 m_coefficient_array[64]; int32 m_quantization_tables[2][64]; uint m_huff_codes[4][256]; uint8 m_huff_code_sizes[4][256]; uint8 m_huff_bits[4][17]; uint8 m_huff_val[4][256]; uint32 m_huff_count[4][256]; int m_last_dc_val[3]; enum { JPGE_OUT_BUF_SIZE = 2048 }; uint8 m_out_buf[JPGE_OUT_BUF_SIZE]; uint8 *m_pOut_buf; uint m_out_buf_left; uint32 m_bit_buffer; uint m_bits_in; uint8 m_pass_num; bool m_all_stream_writes_succeeded; void optimize_huffman_table(int table_num, int table_len); void emit_byte(uint8 i); void emit_word(uint i); void emit_marker(int marker); void emit_jfif_app0(); void emit_dqt(); void emit_sof(); void emit_dht(uint8 *bits, uint8 *val, int index, bool ac_flag); void emit_dhts(); void emit_sos(); void emit_markers(); void compute_huffman_table(uint *codes, uint8 *code_sizes, uint8 *bits, uint8 *val); void compute_quant_table(int32 *dst, int16 *src); void adjust_quant_table(int32 *dst, int32 *src); void first_pass_init(); bool second_pass_init(); bool jpg_open(int p_x_res, int p_y_res, int src_channels); void load_block_8_8_grey(int x); void load_block_8_8(int x, int y, int c); void load_block_16_8(int x, int c); void load_block_16_8_8(int x, int c); void load_quantized_coefficients(int component_num); void flush_output_buffer(); void put_bits(uint bits, uint len); void code_coefficients_pass_one(int component_num); void code_coefficients_pass_two(int component_num); void code_block(int component_num); void process_mcu_row(); bool terminate_pass_one(); bool terminate_pass_two(); bool process_end_of_image(); void load_mcu(const void* src); void clear(); void init(); }; } // namespace jpge #endif // JPEG_ENCODER