5 #include "bytesource.h"
13 ssize_t stdio_read(void* userdata, uint8_t* buf, size_t count)
15 return fread(buf, 1, count, (FILE*)userdata);
18 void read_dqt(struct byte_source* source, struct jpeg_image* image)
20 unsigned len = read_uint16(byte_source_input_func, source);
22 uint8_t precision_table = read_uint8(byte_source_input_func, source);
23 int precision = precision_table >> 4; // 0 = 8 bits, otherwise 16 bits.
24 int table = precision_table & 0x0f;
26 if (image->idct_data[table] != NULL) {
27 idct_choice_free(image->idct_data[table]);
32 fprintf(stderr, "Quantization table %u: 16 bits/entry\n", table);
35 fprintf(stderr, "Quantization table %u: 8 bits/entry\n", table);
38 for (unsigned i = 0; i < 64; ++i) {
40 image->qvalues[table][unzigzag[i]] =
41 read_uint16(byte_source_input_func, source);
43 image->qvalues[table][unzigzag[i]] =
44 read_uint8(byte_source_input_func, source);
48 image->idct_data[table] = idct_choice_alloc(image->qvalues[table]);
51 void read_sof(struct byte_source* source, struct jpeg_image* image)
53 unsigned len = read_uint16(byte_source_input_func, source);
55 image->precision = read_uint8(byte_source_input_func, source);
56 assert(image->precision == 8);
57 image->height = read_uint16(byte_source_input_func, source);
58 image->width = read_uint16(byte_source_input_func, source);
59 image->num_components = read_uint8(byte_source_input_func, source);
62 fprintf(stderr, "%u-bit %ux%u JPEG with %u components\n",
63 image->precision, image->width, image->height, image->num_components);
65 for (unsigned i = 0; i < image->num_components; ++i) {
67 unsigned c = read_uint8(byte_source_input_func, source);
68 unsigned sampling_factors = read_uint8(byte_source_input_func, source);
69 image->hsample[c] = sampling_factors >> 4;
70 image->vsample[c] = sampling_factors & 0x0f;
71 image->qtable[c] = read_uint8(byte_source_input_func, source);
74 if (image->hsample[c] > image->max_hsample) {
75 image->max_hsample = image->hsample[c];
77 if (image->vsample[c] > image->max_vsample) {
78 image->max_vsample = image->vsample[c];
81 fprintf(stderr, "Component %u: sampling factors %u x %x, quantization table %u\n",
82 c, image->hsample[c], image->vsample[c], image->qtable[c]);
85 image->num_blocks_horizontal = (image->width + image->max_hsample * DCTSIZE - 1) / (image->max_hsample * DCTSIZE);
86 image->num_blocks_vertical = (image->height + image->max_vsample * DCTSIZE - 1) / (image->max_vsample * DCTSIZE);
88 for (unsigned c = 0; c < 256; ++c) {
89 if (image->hsample[c] == 0) {
93 unsigned width = image->num_blocks_horizontal * image->hsample[c] * DCTSIZE;
94 unsigned height = image->num_blocks_vertical * image->vsample[c] * DCTSIZE;
95 image->stride[c] = width;
96 image->pixel_data[c] = (uint8_t*)malloc(width * height);
97 assert(image->pixel_data[c] != NULL);
98 image->pixel_write_pointer[c] = image->pixel_data[c];
100 fprintf(stderr, "Component %u: allocating %d x %d\n", c, width, height);
104 void decode_ac_coefficients(const struct huffman_table* tbl, struct bit_source* bits, int16_t* coeff)
106 possibly_refill(bits, DEHUF_AC_TABLE_BITS);
107 for (unsigned i = 0; i < DCTSIZE2 - 1; ) {
108 unsigned lookup = peek_bits(bits, DEHUF_AC_TABLE_BITS);
109 int code = tbl->ac_table_codes[lookup];
110 unsigned length = tbl->ac_table_length[lookup];
111 unsigned r = tbl->ac_table_skip[lookup];
113 if (code == AC_DEHUF_SLOW_PATH) {
114 unsigned rs = read_huffman_symbol_no_refill(tbl, bits);
120 unsigned r = rs >> 4;
121 unsigned s = rs & 0xf;
123 possibly_refill(bits, s);
124 coeff[unzigzag[i]] = extend(read_bits(bits, s), s);
125 possibly_refill(bits, DEHUF_AC_TABLE_BITS);
127 assert(bits->bits_available >= length);
128 read_bits(bits, length);
129 possibly_refill(bits, DEHUF_AC_TABLE_BITS);
133 coeff[unzigzag[i]] = code;
138 void read_scan(struct byte_source* source, struct jpeg_image* image, huffman_tables_t* tables)
140 unsigned len = read_uint16(byte_source_input_func, source);
145 unsigned num_components = read_uint8(byte_source_input_func, source);
148 unsigned component_num[256];
149 unsigned dc_huffman_table[256], ac_huffman_table[256];
150 unsigned ss, se, ah_al;
153 for (unsigned i = 0; i < num_components; ++i) {
156 component_num[i] = read_uint8(byte_source_input_func, source);
157 td_ta = read_uint8(byte_source_input_func, source);
159 dc_huffman_table[i] = td_ta >> 4;
160 ac_huffman_table[i] = td_ta & 0x0f;
165 ss = read_uint8(byte_source_input_func, source);
166 se = read_uint8(byte_source_input_func, source);
167 ah_al = read_uint8(byte_source_input_func, source);
171 fprintf(stderr, "Error: %u unused bytes at end of SOS segment\n", len);
174 struct bit_source bits;
175 init_bit_source(&bits, byte_source_input_func, 8, source);
177 unsigned mcu_x = 0, mcu_y = 0;
179 while (!bits.source_eof) {
180 for (unsigned c = 0; c < num_components; ++c) {
181 unsigned cn = component_num[c];
182 assert(image->idct_data[image->qtable[cn]] != NULL);
184 uint8_t* pixel_write_pointer_y = image->pixel_write_pointer[cn];
185 for (unsigned local_yb = 0; local_yb < image->vsample[cn]; ++local_yb, pixel_write_pointer_y += image->stride[cn] * DCTSIZE) {
186 uint8_t* pixel_write_pointer = pixel_write_pointer_y;
187 for (unsigned local_xb = 0; local_xb < image->hsample[cn]; ++local_xb, pixel_write_pointer += DCTSIZE) {
188 const struct huffman_table* dc_table = &((*tables)[DC_CLASS][dc_huffman_table[c]]);
189 const struct huffman_table* ac_table = &((*tables)[AC_CLASS][ac_huffman_table[c]]);
191 // decode DC component
192 unsigned dc_category = read_huffman_symbol(dc_table, &bits);
193 possibly_refill(&bits, dc_category);
194 last_dc[c] += extend(read_bits(&bits, dc_category), dc_category);
196 int16_t coeff[DCTSIZE2] = { 0 };
197 coeff[0] = last_dc[c];
198 decode_ac_coefficients(ac_table, &bits, coeff);
200 uint8_t pixdata[DCTSIZE2];
201 idct_choice(coeff, image->idct_data[image->qtable[cn]], pixdata);
203 uint8_t* dest_pixdata = pixel_write_pointer;
204 for (unsigned y = 0; y < DCTSIZE; ++y, dest_pixdata += image->stride[cn]) {
205 memcpy(dest_pixdata, pixdata + y * DCTSIZE, DCTSIZE);
209 image->pixel_write_pointer[cn] += DCTSIZE * image->hsample[cn];
212 if (++mcu_x == image->num_blocks_horizontal) {
216 for (unsigned c = 0; c < num_components; ++c) {
217 unsigned cn = component_num[c];
218 image->pixel_write_pointer[cn] += (image->vsample[cn] * DCTSIZE - 1) * image->stride[cn];
220 if (mcu_y == image->num_blocks_vertical) {
226 fprintf(stderr, "Error: %u unused bytes at end of SOS segment\n", len);
230 void skip_segment(struct byte_source* source)
234 ssize_t ret = byte_source_input_func(source, buf, 4096);
236 fprintf(stderr, "Input error!\n");
245 void read_jpeg(struct jpeg_image* jpeg, FILE *input)
247 memset(jpeg, 0, sizeof(*jpeg));
249 struct byte_source source;
250 init_byte_source(&source, stdio_read, input);
252 huffman_tables_t tables;
255 uint8_t m2 = byte_source_read_marker(&source);
258 fprintf(stderr, "Marker 0x%02x, at position %ld\n", m2, ftell(stdin) - source.bytes_available);
277 /* APP0 through APPF */
279 /* some EXIF stuff */
284 skip_segment(&source);
288 read_dqt(&source, jpeg);
291 /* SOF0 (baseline DCT, Huffman encoded) */
292 read_sof(&source, jpeg);
301 /* DHT (define Huffman tables) */
302 read_huffman_tables(&tables, byte_source_input_func, &source);
305 /* SOS (start of scan) */
306 read_scan(&source, jpeg, &tables);
309 fprintf(stderr, "Error: Unknown marker 0x%02x\n", m2);
319 struct jpeg_image jpeg;
320 read_jpeg(&jpeg, stdin);
324 unsigned stride = jpeg.num_blocks_horizontal * jpeg.hsample[c] * DCTSIZE;
325 unsigned height = jpeg.num_blocks_vertical * jpeg.vsample[c] * DCTSIZE;
326 printf("P5\n%u %u\n255\n", stride, height);
327 fwrite(jpeg.pixel_data[c], stride * height, 1, stdout);