- unsigned max_samp_h = 2, max_samp_v = 2;
-
- unsigned nw0 = nominal_w * samp_h0 / max_samp_h, nh0 = nominal_h * samp_v0 / max_samp_v;
- unsigned nw1 = nominal_w * samp_h1 / max_samp_h, nh1 = nominal_h * samp_v1 / max_samp_v;
- unsigned nw2 = nominal_w * samp_h2 / max_samp_h, nh2 = nominal_h * samp_v2 / max_samp_v;
-
- unsigned stride0 = (nw0 + DCTSIZE-1) & ~(DCTSIZE-1);
- unsigned stride1 = (nw1 + DCTSIZE-1) & ~(DCTSIZE-1);
- unsigned stride2 = (nw2 + DCTSIZE-1) & ~(DCTSIZE-1);
-
- struct jpeg_decompress_struct dinfo;
- struct jpeg_error_mgr jerr;
- dinfo.err = jpeg_std_error(&jerr);
- jpeg_create_decompress(&dinfo);
- jpeg_stdio_src(&dinfo, stdin);
- jpeg_read_header(&dinfo, TRUE);
- dinfo.raw_data_out = TRUE;
- jpeg_start_decompress(&dinfo);
-
- fprintf(stderr, "Scaling using Lanczos filter:\n");
- fprintf(stderr, " Y component: %ux%u -> %ux%u\n", dinfo.comp_info[0].width_in_blocks * DCTSIZE, dinfo.comp_info[0].height_in_blocks * DCTSIZE, nw0, nh0);
- fprintf(stderr, " Cb component: %ux%u -> %ux%u\n", dinfo.comp_info[1].width_in_blocks * DCTSIZE, dinfo.comp_info[1].height_in_blocks * DCTSIZE, nw1, nh1);
- fprintf(stderr, " Cr component: %ux%u -> %ux%u\n", dinfo.comp_info[2].width_in_blocks * DCTSIZE, dinfo.comp_info[2].height_in_blocks * DCTSIZE, nw2, nh2);
-
- JSAMPLE *data_y = (JSAMPLE*)malloc(dinfo.comp_info[0].height_in_blocks * dinfo.comp_info[0].width_in_blocks * DCTSIZE * DCTSIZE);
- JSAMPLE *data_cb = (JSAMPLE*)malloc(dinfo.comp_info[1].height_in_blocks * dinfo.comp_info[1].width_in_blocks * DCTSIZE * DCTSIZE);
- JSAMPLE *data_cr = (JSAMPLE*)malloc(dinfo.comp_info[2].height_in_blocks * dinfo.comp_info[2].width_in_blocks * DCTSIZE * DCTSIZE);
- JSAMPLE *data_ny, *data_ncb, *data_ncr;
-
- int total_lines = 0, blocks = 0;
- while (total_lines < dinfo.comp_info[0].height_in_blocks * DCTSIZE) {
- unsigned max_lines = dinfo.max_v_samp_factor * DCTSIZE;
-
- JSAMPROW y_row_ptrs[max_lines];
- JSAMPROW cb_row_ptrs[max_lines];
- JSAMPROW cr_row_ptrs[max_lines];
- JSAMPROW* ptrs[] = { y_row_ptrs, cb_row_ptrs, cr_row_ptrs };
- int i;
-
- for (i = 0; i < max_lines; ++i) {
- y_row_ptrs[i] = data_y + (i+blocks*DCTSIZE*dinfo.comp_info[0].v_samp_factor) * dinfo.comp_info[0].width_in_blocks * DCTSIZE;
- cb_row_ptrs[i] = data_cb + (i+blocks*DCTSIZE*dinfo.comp_info[1].v_samp_factor) * dinfo.comp_info[1].width_in_blocks * DCTSIZE;
- cr_row_ptrs[i] = data_cr + (i+blocks*DCTSIZE*dinfo.comp_info[2].v_samp_factor) * dinfo.comp_info[2].width_in_blocks * DCTSIZE;
- }
-
- total_lines += max_lines;
- ++blocks;
-
- if (jpeg_read_raw_data(&dinfo, ptrs, max_lines) == 0)
- break;
- }
-
- {
- float *npix = (float*)malloc(dinfo.comp_info[0].width_in_blocks * DCTSIZE * nh0 * sizeof(float));
- vscale(data_y, npix, dinfo.comp_info[0].width_in_blocks * DCTSIZE, dinfo.comp_info[0].height_in_blocks * DCTSIZE, nh0, dinfo.comp_info[0].width_in_blocks * DCTSIZE);
- data_ny = (unsigned char *)malloc(nw0 * stride0);
- hscale(npix, data_ny, dinfo.comp_info[0].width_in_blocks * DCTSIZE, nh0, nw0, stride0);
- free(npix);
- }
- {
- float *npix = (float*)malloc(dinfo.comp_info[1].width_in_blocks * DCTSIZE * nh1 * sizeof(float));
- vscale(data_cr, npix, dinfo.comp_info[1].width_in_blocks * DCTSIZE, dinfo.comp_info[1].height_in_blocks * DCTSIZE, nh1, dinfo.comp_info[1].width_in_blocks * DCTSIZE);
- data_ncr = (unsigned char *)malloc(nw1 * stride1);
- hscale(npix, data_ncr, dinfo.comp_info[1].width_in_blocks * DCTSIZE, nh1, nw1, stride1);
- free(npix);
- }
- {
- float *npix = (float*)malloc(dinfo.comp_info[2].width_in_blocks * DCTSIZE * nh2 * sizeof(float));
- vscale(data_cb, npix, dinfo.comp_info[2].width_in_blocks * DCTSIZE, dinfo.comp_info[2].height_in_blocks * DCTSIZE, nh2, dinfo.comp_info[2].width_in_blocks * DCTSIZE);
- data_ncb = (unsigned char *)malloc(nw2 * stride2);
- hscale(npix, data_ncb, dinfo.comp_info[2].width_in_blocks * DCTSIZE, nh2, nw2, stride2);
- free(npix);
- }
- jpeg_destroy_decompress(&dinfo);
-
- struct jpeg_compress_struct cinfo;
- cinfo.err = jpeg_std_error(&jerr);
- jpeg_create_compress(&cinfo);
- jpeg_stdio_dest(&cinfo, stdout);
- cinfo.input_components = 3;
- jpeg_set_defaults(&cinfo);
- jpeg_set_quality(&cinfo, 85, FALSE);
- cinfo.image_width = nominal_w;
- cinfo.image_height = nominal_h;
- cinfo.raw_data_in = TRUE;
- jpeg_set_colorspace(&cinfo, JCS_YCbCr);
- cinfo.comp_info[0].h_samp_factor = samp_h0;
- cinfo.comp_info[0].v_samp_factor = samp_v0;
- cinfo.comp_info[1].h_samp_factor = samp_h1;
- cinfo.comp_info[1].v_samp_factor = samp_v1;
- cinfo.comp_info[2].h_samp_factor = samp_h2;
- cinfo.comp_info[2].v_samp_factor = samp_v2;
- jpeg_start_compress(&cinfo, TRUE);
-
- total_lines = 0;
- blocks = 0;
- while (total_lines < cinfo.comp_info[0].height_in_blocks * DCTSIZE) {
- unsigned max_lines = cinfo.max_v_samp_factor * DCTSIZE;
-
- JSAMPROW y_row_ptrs[max_lines];
- JSAMPROW cb_row_ptrs[max_lines];
- JSAMPROW cr_row_ptrs[max_lines];
- JSAMPROW* ptrs[] = { y_row_ptrs, cb_row_ptrs, cr_row_ptrs };
- int i;
-
- for (i = 0; i < max_lines; ++i) {
- // simple edge extension
- int yline = i + blocks*DCTSIZE*cinfo.comp_info[0].v_samp_factor;
- if (yline > nh0 - 1)
- yline = nh0 - 1;
-
- int cbline = i + blocks*DCTSIZE*cinfo.comp_info[1].v_samp_factor;
- if (cbline > nh1 - 1)
- cbline = nh1 - 1;
-
- int crline = i + blocks*DCTSIZE*cinfo.comp_info[2].v_samp_factor;
- if (crline > nh2 - 1)
- crline = nh2 - 1;
-
- y_row_ptrs[i] = data_ny + yline * stride0;
- cb_row_ptrs[i] = data_ncb + cbline * stride1;
- cr_row_ptrs[i] = data_ncr + crline * stride2;
- }
-
- total_lines += max_lines;
- ++blocks;