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
7namespace 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 {
22 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
24 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:
66 virtual ~output_stream() { };
67 virtual bool put_buf(const void* Pbuf, int len) = 0;
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
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
91 uint get_total_passes() const { return m_params.m_two_pass_flag ? 2 : 1; }
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
175