]> git.sesse.net Git - qscale/blobdiff - libqscale.c
Link with LD=gcc; fixes a problem with missing reference to __stack_chk_fail_local.
[qscale] / libqscale.c
index b744a9b5f3b98e1a1da8182e15f9eaefc991f694..1ce7e891fdf0564c70a070bc0555a935a4e45e19 100644 (file)
@@ -1,9 +1,54 @@
+/*
+ * qscale: Quick, high-quality JPEG-to-JPEG scaler.
+ * Copyright (C) 2008 Steinar H. Gunderson <sgunderson@bigfoot.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA
+ */
+
+#include <math.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 #include <malloc.h>
 
 #include "libqscale.h"
 
+/* The number of pixels to process at a time when scaling vertically. */
+#define CACHE_LINE_FACTOR 16
+
+/* Whether to use SSE for horizontal scaling or not (requires SSE3). */
+#define USE_HORIZONTAL_SSE 1
+
+/* Whether to use SSE for vertical scaling or not (requires only SSE1). */
+#define USE_VERTICAL_SSE 1
+
+#if USE_VERTICAL_SSE
+#undef CACHE_LINE_FACTOR
+#define CACHE_LINE_FACTOR 16
+#endif
+
+#ifndef M_PI
+#define M_PI 3.14159265358979323846264
+#endif
+
+#if USE_VERTICAL_SSE || USE_HORIZONTAL_SSE
+typedef float v4sf __attribute__((vector_size(16)));
+typedef int v4si __attribute__((vector_size(16)));
+typedef short v8hi __attribute__((vector_size(16)));
+typedef char v16qi __attribute__((vector_size(16)));
+#endif
+
 qscale_img *qscale_load_jpeg(const char *filename)
 {
        FILE *file = fopen(filename, "rb");
@@ -32,16 +77,16 @@ qscale_img *qscale_load_jpeg_from_stdio(FILE *file)
        struct jpeg_error_mgr jerr;
        dinfo.err = jpeg_std_error(&jerr);
        jpeg_create_decompress(&dinfo);
-       jpeg_stdio_src(&dinfo, stdin);
+       jpeg_stdio_src(&dinfo, file);
        jpeg_read_header(&dinfo, TRUE);
        dinfo.raw_data_out = TRUE;
        jpeg_start_decompress(&dinfo);
        
-       /* We do not handle anything but YCbCr images (yet?). */
-       if (dinfo.num_components != 3) {
+       if (dinfo.num_components != 1 && dinfo.num_components != 3) {
                qscale_destroy(img);
                return NULL;
        }
+       img->num_components = dinfo.num_components;
 
        img->width = dinfo.image_width;
        img->height = dinfo.image_height;
@@ -49,21 +94,40 @@ qscale_img *qscale_load_jpeg_from_stdio(FILE *file)
        img->w0 = dinfo.image_width * dinfo.comp_info[0].h_samp_factor / dinfo.max_h_samp_factor;
        img->h0 = dinfo.image_height * dinfo.comp_info[0].v_samp_factor / dinfo.max_v_samp_factor;
 
-       img->w1 = dinfo.image_width * dinfo.comp_info[1].h_samp_factor / dinfo.max_h_samp_factor;
-       img->h1 = dinfo.image_height * dinfo.comp_info[1].v_samp_factor / dinfo.max_v_samp_factor;
+       if (img->num_components == 3) {
+               img->w1 = dinfo.image_width * dinfo.comp_info[1].h_samp_factor / dinfo.max_h_samp_factor;
+               img->h1 = dinfo.image_height * dinfo.comp_info[1].v_samp_factor / dinfo.max_v_samp_factor;
 
-       img->w2 = dinfo.image_width * dinfo.comp_info[2].h_samp_factor / dinfo.max_h_samp_factor;
-       img->h2 = dinfo.image_height * dinfo.comp_info[2].v_samp_factor / dinfo.max_v_samp_factor;
+               img->w2 = dinfo.image_width * dinfo.comp_info[2].h_samp_factor / dinfo.max_h_samp_factor;
+               img->h2 = dinfo.image_height * dinfo.comp_info[2].v_samp_factor / dinfo.max_v_samp_factor;
+       }
 
-       img->data_y  = (JSAMPLE*)memalign(16, dinfo.comp_info[0].height_in_blocks * dinfo.comp_info[0].width_in_blocks * DCTSIZE * DCTSIZE);
-       img->data_cb = (JSAMPLE*)memalign(16, dinfo.comp_info[1].height_in_blocks * dinfo.comp_info[1].width_in_blocks * DCTSIZE * DCTSIZE);
-       img->data_cr = (JSAMPLE*)memalign(16, dinfo.comp_info[2].height_in_blocks * dinfo.comp_info[2].width_in_blocks * DCTSIZE * DCTSIZE);
+       img->samp_h0 = dinfo.comp_info[0].h_samp_factor;
+       img->samp_v0 = dinfo.comp_info[0].v_samp_factor;
+
+       if (img->num_components == 3) {
+               img->samp_h1 = dinfo.comp_info[1].h_samp_factor;
+               img->samp_v1 = dinfo.comp_info[1].v_samp_factor;
 
-       if (img->data_y == NULL || img->data_cb == NULL || img->data_cr == NULL) {
+               img->samp_h2 = dinfo.comp_info[2].h_samp_factor;
+               img->samp_v2 = dinfo.comp_info[2].v_samp_factor;
+       }
+
+       img->data_y  = (JSAMPLE*)memalign(16, dinfo.comp_info[0].height_in_blocks * dinfo.comp_info[0].width_in_blocks * DCTSIZE * DCTSIZE);
+       if (img->data_y == NULL) {
                qscale_destroy(img);
                return NULL;
        }
 
+       if (img->num_components == 3) {
+               img->data_cb = (JSAMPLE*)memalign(16, dinfo.comp_info[1].height_in_blocks * dinfo.comp_info[1].width_in_blocks * DCTSIZE * DCTSIZE);
+               img->data_cr = (JSAMPLE*)memalign(16, dinfo.comp_info[2].height_in_blocks * dinfo.comp_info[2].width_in_blocks * DCTSIZE * DCTSIZE);
+               if (img->data_cb == NULL || img->data_cr == NULL) {
+                       qscale_destroy(img);
+                       return NULL;
+               }
+       }
+
        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;
@@ -76,8 +140,10 @@ qscale_img *qscale_load_jpeg_from_stdio(FILE *file)
                int i;
                 for (i = 0; i < max_lines; ++i) {
                         y_row_ptrs[i]  = img->data_y  + (i+blocks*DCTSIZE*dinfo.comp_info[0].v_samp_factor) * dinfo.comp_info[0].width_in_blocks * DCTSIZE;
-                        cb_row_ptrs[i] = img->data_cb + (i+blocks*DCTSIZE*dinfo.comp_info[1].v_samp_factor) * dinfo.comp_info[1].width_in_blocks * DCTSIZE;
-                        cr_row_ptrs[i] = img->data_cr + (i+blocks*DCTSIZE*dinfo.comp_info[2].v_samp_factor) * dinfo.comp_info[2].width_in_blocks * DCTSIZE;
+                       if (img->num_components == 3) {
+                               cb_row_ptrs[i] = img->data_cb + (i+blocks*DCTSIZE*dinfo.comp_info[1].v_samp_factor) * dinfo.comp_info[1].width_in_blocks * DCTSIZE;
+                               cr_row_ptrs[i] = img->data_cr + (i+blocks*DCTSIZE*dinfo.comp_info[2].v_samp_factor) * dinfo.comp_info[2].width_in_blocks * DCTSIZE;
+                       }
                 }
 
                 total_lines += max_lines;
@@ -98,3 +164,550 @@ void qscale_destroy(qscale_img *img)
        free(img->data_cr);
        free(img);
 }
+
+
+static double sinc(double x)
+{
+       static const double cutoff = 1.220703668e-4;  /* sqrt(sqrt(eps)) */
+
+       if (abs(x) < cutoff) {
+               /* For small |x|, use Taylor series instead */
+               const double x2 = x * x;
+               const double x4 = x2 * x2;
+
+               return 1.0 - x2 / 6.0 + x4 / 120.0;
+       } else {
+               return sin(x) / x;
+       }
+}
+
+static double lanczos_tap(double x)
+{
+       if (x < -3.0 || x > 3.0)
+               return 0.0;
+       if (x < 0.0)
+               return sinc(-x*M_PI) * sinc(-x*M_PI / 3.0);
+       else
+               return sinc(x*M_PI) * sinc(x*M_PI / 3.0);
+}
+
+static double mitchell_tap(double x)
+{
+       const double b = 1.0 / 3.0;
+       const double c = 1.0 / 3.0;
+       const double p0 = (  6.0 -  2.0*b         ) / 6.0;
+       const double p2 = (-18.0 + 12.0*b +  6.0*c) / 6.0;
+       const double p3 = ( 12.0 -  9.0*b -  6.0*c) / 6.0;
+       const double q0 = (         8.0*b + 24.0*c) / 6.0;
+       const double q1 = (      - 12.0*b - 48.0*c) / 6.0;
+       const double q2 = (         6.0*b + 30.0*c) / 6.0;
+       const double q3 = (      -      b -  6.0*c) / 6.0;
+
+       if (x < -2.0) {
+               return 0.0;
+       } else if (x < -1.0) {
+               return q0 - x * (q1 - x * (q2 - x * q3));
+       } else if (x < 0.0) {
+               return p0 + x * x * (p2 - x * p3);
+       } else if (x < 1.0) {
+               return p0 + x * x * (p2 + x * p3);
+       } else if (x < 2.0) {
+               return q0 + x * (q1 + x * (q2 + x * q3));
+       } else {
+               return 0.0;
+       }
+}
+
+struct pix_desc {
+       unsigned start, end;
+       unsigned startcoeff;
+};
+
+static void hscale(float *pix, unsigned char *npix, unsigned w, unsigned h, unsigned nw, unsigned sstride, unsigned dstride, enum qscale_scaling_filter scaling_filter)
+{
+       struct pix_desc *pd = (struct pix_desc *)malloc(nw * sizeof(struct pix_desc));
+       int size_coeffs = 8;
+       float *coeffs = (float *)malloc(size_coeffs * sizeof(float));
+       int num_coeffs = 0;
+       int x, y;
+       double sf = (double)w / (double)nw;
+       double support;
+       
+       if (scaling_filter == LANCZOS) {
+               support = (w > nw) ? (3.0 * sf) : (3.0 / sf);
+       } else {  /* Mitchell */
+               support = (w > nw) ? (2.0 * sf) : (2.0 / sf);
+       }
+
+       /* calculate the filter */
+       for (x = 0; x < nw; ++x) {
+               int start = ceil(x * sf - support);
+               int end = floor(x * sf + support);
+               int sx;
+               double sum = 0.0;
+
+               if (start < 0) {
+                       start = 0;
+               }
+               if (end > w - 1) {
+                       end = w - 1;
+               }
+
+#if USE_HORIZONTAL_SSE
+               /* round up so we get a multiple of four for the SSE code */
+               int num = (end - start + 1);
+               if (num % 4 != 0) {
+                       /* prefer aligning it if possible */
+                       if (start % 4 != 0 && start % 4 <= num % 4) {
+                               num += start % 4;
+                               start -= start % 4;
+                       }
+                       if (num % 4 != 0) {
+                               end += 4 - (num % 4);
+                       }
+               }
+#endif
+
+               pd[x].start = start;
+               pd[x].end = end;
+               pd[x].startcoeff = num_coeffs;
+
+               for (sx = start; sx <= end; ++sx) {
+                       double nd = (w > nw) ? (sx/sf - x) : (sx - x*sf);
+                       double f;
+                       if (scaling_filter == LANCZOS) {
+                               f = lanczos_tap(nd);
+                       } else {  /* Mitchell */
+                               f = mitchell_tap(nd);
+                       }
+                       if (num_coeffs == size_coeffs) {
+                               size_coeffs <<= 1;
+                               coeffs = (float *)realloc(coeffs, size_coeffs * sizeof(float));
+                       }
+
+                       coeffs[num_coeffs++] = f;
+                       sum += f;
+               }
+
+               for (sx = start; sx <= end; ++sx) {
+                       coeffs[pd[x].startcoeff + sx - start] /= sum;
+               }
+       }
+
+       for (y = 0; y < h; ++y) {
+               float *sptr = pix + y*sstride;
+               unsigned char *dptr = npix + y*dstride;
+               unsigned char ch;
+               for (x = 0; x < nw; ++x) {
+#if USE_HORIZONTAL_SSE
+                       v4sf acc = { 0.0f, 0.0f, 0.0f, 0.0f };
+                       static const v4sf low = { 0.0f, 0.0f, 0.0f, 0.0f };
+                       static const v4sf high = { 255.0f, 255.0f, 255.0f, 255.0f };
+                       int result;
+                       int i;
+               
+                       const float *sptr_xmm = &sptr[pd[x].start];
+                       const float *coeffptr = &coeffs[pd[x].startcoeff];
+                       const int filter_len = (pd[x].end - pd[x].start + 1) / 4;
+
+                       for (i = 0; i < filter_len; ++i) {
+                               v4sf pixels = __builtin_ia32_loadups(&sptr_xmm[i * 4]);
+                               v4sf coeffs = __builtin_ia32_loadups(&coeffptr[i * 4]);
+                               acc = __builtin_ia32_addps(acc, __builtin_ia32_mulps(pixels, coeffs));
+                       }
+                       acc = __builtin_ia32_haddps(acc, acc);  
+                       acc = __builtin_ia32_haddps(acc, acc);
+                       acc = __builtin_ia32_maxss(acc, low);
+                       acc = __builtin_ia32_minss(acc, high);
+                       result = __builtin_ia32_cvtss2si(acc);
+
+                       *dptr++ = (unsigned char)result;
+#else
+                       float acc = 0.0;
+                       float *cf = &coeffs[pd[x].startcoeff];
+                       unsigned sx;
+                       
+                       for (sx = pd[x].start; sx <= pd[x].end; ++sx) {
+                               acc += sptr[sx] * *cf++;
+                       }
+
+                       if (acc < 0.0)
+                               ch = 0;
+                       else if (acc > 255.0)
+                               ch = 255;
+                       else
+                               ch = (unsigned char)acc;
+                       *dptr++ = ch;
+#endif
+               }
+               ch = dptr[-1];
+               for ( ; x < dstride; ++x) {
+                       *dptr++ = ch;
+               }
+       }
+
+       free(pd);
+       free(coeffs);
+}
+
+static void vscale(unsigned char *pix, float *npix, unsigned w, unsigned h, unsigned nh, unsigned dstride, enum qscale_scaling_filter scaling_filter)
+{
+       struct pix_desc *pd = (struct pix_desc *)malloc(nh * sizeof(struct pix_desc));
+       int size_coeffs = 8;
+       float *coeffs = (float *)malloc(size_coeffs * sizeof(float));
+       int num_coeffs = 0;
+       int x, y, sy;
+       double sf = (double)h / (double)nh;
+       double support;
+       
+       if (scaling_filter == LANCZOS) {
+               support = (h > nh) ? (3.0 * sf) : (3.0 / sf);
+       } else {  /* Mitchell */
+               support = (h > nh) ? (2.0 * sf) : (2.0 / sf);
+       }
+
+       /* calculate the filter */
+       for (y = 0; y < nh; ++y) {
+               int start = ceil(y * sf - support);
+               int end = floor(y * sf + support);
+               double sum = 0.0;
+
+               if (start < 0) {
+                       start = 0;
+               }
+               if (end > h - 1) {
+                       end = h - 1;
+               }
+
+               pd[y].start = start;
+               pd[y].end = end;
+               pd[y].startcoeff = num_coeffs;
+
+               for (sy = start; sy <= end; ++sy) {
+                       double nd = (h > nh) ? (sy/sf - y) : (sy - y*sf);
+                       double f;
+                       if (scaling_filter == LANCZOS) {
+                               f = lanczos_tap(nd);
+                       } else {  /* Mitchell */
+                               f = mitchell_tap(nd);
+                       }
+                       if (num_coeffs == size_coeffs) {
+                               size_coeffs <<= 1;
+                               coeffs = (float *)realloc(coeffs, size_coeffs * sizeof(float));
+                       }
+                       
+                       coeffs[num_coeffs++] = f;
+                       sum += f;
+               }
+
+               for (sy = start; sy <= end; ++sy) {
+                       coeffs[pd[y].startcoeff + sy - start] /= sum;
+               }
+       }
+
+#if CACHE_LINE_FACTOR > 1
+       for (x = 0; x < (w/CACHE_LINE_FACTOR) * CACHE_LINE_FACTOR; x += CACHE_LINE_FACTOR) {
+               unsigned char *sptr = pix + x;
+               float *dptr = npix + x;
+               for (y = 0; y < nh; ++y) {
+#if USE_VERTICAL_SSE
+                       /* A zero is useful during unpacking. */
+                       static const v4sf zero = { 0.0f, 0.0f, 0.0f, 0.0f };
+                       const unsigned char *sptr_xmm = &sptr[pd[y].start * w];
+                       const float *coeffptr = &coeffs[pd[y].startcoeff];
+                       const int filter_len = pd[y].end - pd[y].start + 1;
+                       int i;
+
+                       v4sf acc0 = { 0.0f, 0.0f, 0.0f, 0.0f };
+                       v4sf acc1 = { 0.0f, 0.0f, 0.0f, 0.0f };
+                       v4sf acc2 = { 0.0f, 0.0f, 0.0f, 0.0f };
+                       v4sf acc3 = { 0.0f, 0.0f, 0.0f, 0.0f };
+                       
+                       for (i = 0; i < filter_len; ++i, ++coeffptr, sptr_xmm += w) {
+                               __builtin_prefetch(sptr_xmm + w, 0);
+                               v16qi src = (v16qi)__builtin_ia32_loadups((float*)sptr_xmm);
+
+                               // unpack into words
+                               v8hi src_lo = (v8hi)__builtin_ia32_punpcklbw128(src, (v16qi)zero);
+                               v8hi src_hi = (v8hi)__builtin_ia32_punpckhbw128(src, (v16qi)zero);
+
+                               // unpack into dwords, convert to floats
+                               v4si src0_i = (v4si)__builtin_ia32_punpcklwd128(src_lo, (v8hi)zero);
+                               v4si src1_i = (v4si)__builtin_ia32_punpckhwd128(src_lo, (v8hi)zero);
+                               v4si src2_i = (v4si)__builtin_ia32_punpcklwd128(src_hi, (v8hi)zero);
+                               v4si src3_i = (v4si)__builtin_ia32_punpckhwd128(src_hi, (v8hi)zero);
+
+                               v4sf src0 = __builtin_ia32_cvtdq2ps(src0_i);
+                               v4sf src1 = __builtin_ia32_cvtdq2ps(src1_i);
+                               v4sf src2 = __builtin_ia32_cvtdq2ps(src2_i);
+                               v4sf src3 = __builtin_ia32_cvtdq2ps(src3_i);
+                       
+                               // fetch the coefficient, and replicate it
+                               v4sf coeff = { *coeffptr, *coeffptr, *coeffptr, *coeffptr };
+
+                               // do the actual muladds
+                               acc0 = __builtin_ia32_addps(acc0, __builtin_ia32_mulps(src0, coeff));
+                               acc1 = __builtin_ia32_addps(acc1, __builtin_ia32_mulps(src1, coeff));
+                               acc2 = __builtin_ia32_addps(acc2, __builtin_ia32_mulps(src2, coeff));
+                               acc3 = __builtin_ia32_addps(acc3, __builtin_ia32_mulps(src3, coeff));
+                       }
+
+                       *(v4sf *)(&dptr[0]) = acc0;
+                       *(v4sf *)(&dptr[4]) = acc1;
+                       *(v4sf *)(&dptr[8]) = acc2;
+                       *(v4sf *)(&dptr[12]) = acc3;
+#else
+                       int i;
+                       float acc[CACHE_LINE_FACTOR];
+                       for (i = 0; i < CACHE_LINE_FACTOR; ++i)
+                               acc[i] = 0.0;
+                       float *cf = &coeffs[pd[y].startcoeff];
+                       unsigned sy;
+               
+                       for (sy = pd[y].start; sy <= pd[y].end; ++sy) {
+                               for (i = 0; i < CACHE_LINE_FACTOR; ++i) {
+                                       acc[i] += sptr[sy * w + i] * *cf;
+                               }
+                               ++cf;
+                       }
+
+                       for (i = 0; i < CACHE_LINE_FACTOR; ++i) {
+                               dptr[i] = acc[i];
+                       }
+#endif
+                       dptr += dstride;
+               }
+       }
+       for (x = (x/CACHE_LINE_FACTOR)*CACHE_LINE_FACTOR; x < w; ++x) {
+#else
+       for (x = 0; x < w; ++x) {
+#endif
+               unsigned char *sptr = pix + x;
+               float *dptr = npix + x;
+               for (y = 0; y < nh; ++y) {
+                       float acc = 0.0;
+                       float *cf = &coeffs[pd[y].startcoeff];
+                       unsigned sy;
+                       
+                       for (sy = pd[y].start; sy <= pd[y].end; ++sy) {
+                               acc += sptr[sy * w] * *cf++;
+                       }
+
+                       *dptr = acc;
+                       dptr += dstride;
+               }
+       }
+       
+       free(pd);
+       free(coeffs);
+}
+
+qscale_img *qscale_clone(const qscale_img *img)
+{
+       qscale_img *dst = (qscale_img *)malloc(sizeof(qscale_img));
+       if (dst == NULL) {
+               return NULL;
+       }
+
+       *dst = *img;
+
+       unsigned dstride0 = (dst->w0 + DCTSIZE-1) & ~(DCTSIZE-1);
+       unsigned dstride1 = (dst->w1 + DCTSIZE-1) & ~(DCTSIZE-1);
+       unsigned dstride2 = (dst->w2 + DCTSIZE-1) & ~(DCTSIZE-1);
+
+       /* FIXME: handle out-of-memory gracefully */
+       {
+               dst->data_y = (unsigned char *)malloc(dst->h0 * dstride0);
+               memcpy(dst->data_y, img->data_y, dst->h0 * dstride0);
+       }
+       {
+               dst->data_cb = (unsigned char *)malloc(dst->h1 * dstride1);
+               memcpy(dst->data_cb, img->data_cb, dst->h1 * dstride1);
+       }
+       {
+               dst->data_cr = (unsigned char *)malloc(dst->h2 * dstride2);
+               memcpy(dst->data_cr, img->data_cr, dst->h2 * dstride2);
+       }
+
+       return dst;
+}
+
+qscale_img *qscale_scale(qscale_img *src, unsigned width, unsigned height, unsigned samp_h0, unsigned samp_v0, unsigned samp_h1, unsigned samp_v1, unsigned samp_h2, unsigned samp_v2, enum qscale_scaling_filter scaling_filter)
+{
+       qscale_img *dst = (qscale_img *)malloc(sizeof(qscale_img));
+       if (dst == NULL) {
+               return NULL;
+       }
+
+       dst->width = width;
+       dst->height = height;
+       dst->num_components = src->num_components;
+
+       unsigned max_samp_h, max_samp_v;
+        max_samp_h = samp_h0;
+       if (src->num_components == 3) {
+               if (samp_h1 > max_samp_h)
+                       max_samp_h = samp_h1;
+               if (samp_h2 > max_samp_h)
+                       max_samp_h = samp_h2;
+       }
+
+        max_samp_v = samp_v0;
+       if (src->num_components == 3) {
+               if (samp_v1 > max_samp_v)
+                       max_samp_v = samp_v1;
+               if (samp_v2 > max_samp_v)
+                       max_samp_v = samp_v2;
+       }
+
+       dst->w0 = width * samp_h0 / max_samp_h;
+       dst->h0 = height * samp_v0 / max_samp_v;
+
+       if (src->num_components == 3) {
+               dst->w1 = width * samp_h1 / max_samp_h;
+               dst->h1 = height * samp_v1 / max_samp_v;
+
+               dst->w2 = width * samp_h2 / max_samp_h;
+               dst->h2 = height * samp_v2 / max_samp_v;
+       }
+
+       dst->samp_h0 = samp_h0;
+       dst->samp_v0 = samp_v0;
+
+       if (src->num_components == 3) {
+               dst->samp_h1 = samp_h1;
+               dst->samp_v1 = samp_v1;
+
+               dst->samp_h2 = samp_h2;
+               dst->samp_v2 = samp_v2;
+       }
+
+       unsigned dstride0 = (dst->w0 + DCTSIZE-1) & ~(DCTSIZE-1);
+       unsigned dstride1 = (dst->w1 + DCTSIZE-1) & ~(DCTSIZE-1);
+       unsigned dstride2 = (dst->w2 + DCTSIZE-1) & ~(DCTSIZE-1);
+
+       unsigned sstride0 = (src->w0 + DCTSIZE-1) & ~(DCTSIZE-1);
+       unsigned sstride1 = (src->w1 + DCTSIZE-1) & ~(DCTSIZE-1);
+       unsigned sstride2 = (src->w2 + DCTSIZE-1) & ~(DCTSIZE-1);
+
+       /* FIXME: handle out-of-memory gracefully */
+       {
+               float *npix = (float*)memalign(16, sstride0 * dst->h0 * sizeof(float));
+               vscale(src->data_y, npix, sstride0, src->h0, dst->h0, sstride0, scaling_filter);
+               dst->data_y = (unsigned char *)malloc(dst->h0 * dstride0);
+               hscale(npix, dst->data_y, src->w0, dst->h0, dst->w0, sstride0, dstride0, scaling_filter);
+               free(npix);
+       }
+       if (src->num_components == 3) {
+               {
+                       float *npix = (float*)memalign(16, sstride1 * dst->h1 * sizeof(float));
+                       vscale(src->data_cr, npix, sstride1, src->h1, dst->h1, sstride1, scaling_filter);
+                       dst->data_cr = (unsigned char *)malloc(dst->h1 * dstride1);
+                       hscale(npix, dst->data_cr, src->w1, dst->h1, dst->w1, sstride1, dstride1, scaling_filter);
+                       free(npix);
+               }
+               {
+                       float *npix = (float*)memalign(16, sstride2 * dst->h2 * sizeof(float));
+                       vscale(src->data_cb, npix, sstride2, src->h2, dst->h2, sstride2, scaling_filter);
+                       dst->data_cb = (unsigned char *)malloc(dst->h2 * dstride2);
+                       hscale(npix, dst->data_cb, src->w2, dst->h2, dst->w2, sstride2, dstride2, scaling_filter);
+                       free(npix);
+               }
+       }
+
+       return dst;
+}
+
+int qscale_save_jpeg(const qscale_img *img, const char *filename, unsigned jpeg_quality, enum qscale_jpeg_mode jpeg_mode)
+{
+       FILE *file = fopen(filename, "wb");
+       if (file == NULL) {
+               return -1;
+       }
+
+       int err = qscale_save_jpeg_to_stdio(img, file, jpeg_quality, jpeg_mode);
+
+       fclose(file);
+       return err;
+}
+
+int qscale_save_jpeg_to_stdio(const qscale_img *img, FILE *file, unsigned jpeg_quality, enum qscale_jpeg_mode jpeg_mode)
+{
+        struct jpeg_compress_struct cinfo;
+        struct jpeg_error_mgr jerr;
+        cinfo.err = jpeg_std_error(&jerr);
+        jpeg_create_compress(&cinfo);
+        jpeg_stdio_dest(&cinfo, file);
+        cinfo.input_components = img->num_components;
+        jpeg_set_defaults(&cinfo);
+        jpeg_set_quality(&cinfo, jpeg_quality, FALSE);
+
+       if (jpeg_mode == PROGRESSIVE) {
+               jpeg_simple_progression(&cinfo);
+       }
+
+        cinfo.image_width = img->width;
+        cinfo.image_height = img->height;
+        cinfo.raw_data_in = TRUE;
+       if (img->num_components == 3) {
+               jpeg_set_colorspace(&cinfo, JCS_YCbCr);
+       } else {
+               jpeg_set_colorspace(&cinfo, JCS_GRAYSCALE);
+       }
+        cinfo.comp_info[0].h_samp_factor = img->samp_h0;
+        cinfo.comp_info[0].v_samp_factor = img->samp_v0;
+       if (img->num_components == 3) {
+               cinfo.comp_info[1].h_samp_factor = img->samp_h1;
+               cinfo.comp_info[1].v_samp_factor = img->samp_v1;
+               cinfo.comp_info[2].h_samp_factor = img->samp_h2;
+               cinfo.comp_info[2].v_samp_factor = img->samp_v2;
+       }
+        jpeg_start_compress(&cinfo, TRUE);
+
+        unsigned dstride0 = (img->w0 + DCTSIZE-1) & ~(DCTSIZE-1);
+        unsigned dstride1 = (img->w1 + DCTSIZE-1) & ~(DCTSIZE-1);
+        unsigned dstride2 = (img->w2 + DCTSIZE-1) & ~(DCTSIZE-1);
+
+        int total_lines = 0;
+        int 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 > img->h0 - 1)
+                                yline = img->h0 - 1;
+
+                        y_row_ptrs[i]  = img->data_y  + yline * dstride0;
+
+                       if (img->num_components == 3) {
+                               int cbline = i + blocks*DCTSIZE*cinfo.comp_info[1].v_samp_factor;
+                               if (cbline > img->h1 - 1)
+                                       cbline = img->h1 - 1;
+
+                               int crline = i + blocks*DCTSIZE*cinfo.comp_info[2].v_samp_factor;
+                               if (crline > img->h2 - 1)
+                                       crline = img->h2 - 1;
+
+                               cb_row_ptrs[i] = img->data_cb + cbline * dstride1;
+                               cr_row_ptrs[i] = img->data_cr + crline * dstride2;
+                       }
+                }
+
+                total_lines += max_lines;
+                ++blocks;
+
+                jpeg_write_raw_data(&cinfo, ptrs, max_lines);
+        }
+        jpeg_finish_compress(&cinfo);
+        jpeg_destroy_compress(&cinfo);
+
+       return 0;
+}