libswscale: Adding RGB => XYZ support

3 files changed, 79 insertions, 3 deletions

diff --git a/libswscale/swscale.c b/libswscale/swscale.c
index cec428847b..6721dc3a2d 100644
--- a/libswscale/swscale.c
+++ b/libswscale/swscale.c
@@ -849,6 +849,62 @@ static void xyz12Torgb48(struct SwsContext *c, uint16_t *dst,
     }
 }
 
+static void rgb48Toxyz12(struct SwsContext *c, uint16_t *dst,
+                         const uint16_t *src, int stride, int h)
+{
+    int xp,yp;
+    const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(c->srcFormat);
+
+    for (yp=0; yp<h; yp++) {
+        for (xp=0; xp+2<stride; xp+=3) {
+            int x, y, z, r, g, b;
+
+            if (desc->flags & AV_PIX_FMT_FLAG_BE) {
+                r = AV_RB16(src + xp + 0);
+                g = AV_RB16(src + xp + 1);
+                b = AV_RB16(src + xp + 2);
+            } else {
+                r = AV_RL16(src + xp + 0);
+                g = AV_RL16(src + xp + 1);
+                b = AV_RL16(src + xp + 2);
+            }
+
+            r = c->rgbgammainv[r>>4];
+            g = c->rgbgammainv[g>>4];
+            b = c->rgbgammainv[b>>4];
+
+            // convert from sRGBlinear to XYZlinear
+            x = c->rgb2xyz_matrix[0][0] * r +
+                c->rgb2xyz_matrix[0][1] * g +
+                c->rgb2xyz_matrix[0][2] * b >> 12;
+            y = c->rgb2xyz_matrix[1][0] * r +
+                c->rgb2xyz_matrix[1][1] * g +
+                c->rgb2xyz_matrix[1][2] * b >> 12;
+            z = c->rgb2xyz_matrix[2][0] * r +
+                c->rgb2xyz_matrix[2][1] * g +
+                c->rgb2xyz_matrix[2][2] * b >> 12;
+
+            // limit values to 12-bit depth
+            x = av_clip_c(x,0,4095);
+            y = av_clip_c(y,0,4095);
+            z = av_clip_c(z,0,4095);
+
+            // convert from XYZlinear to X'Y'Z' and scale from 12bit to 16bit
+            if (desc->flags & AV_PIX_FMT_FLAG_BE) {
+                AV_WB16(dst + xp + 0, c->xyzgammainv[x] << 4);
+                AV_WB16(dst + xp + 1, c->xyzgammainv[y] << 4);
+                AV_WB16(dst + xp + 2, c->xyzgammainv[z] << 4);
+            } else {
+                AV_WL16(dst + xp + 0, c->xyzgammainv[x] << 4);
+                AV_WL16(dst + xp + 1, c->xyzgammainv[y] << 4);
+                AV_WL16(dst + xp + 2, c->xyzgammainv[z] << 4);
+            }
+        }
+        src += stride;
+        dst += stride;
+    }
+}
+
 /**
  * swscale wrapper, so we don't need to export the SwsContext.
  * Assumes planar YUV to be in YUV order instead of YVU.
@@ -1045,6 +1101,12 @@ int attribute_align_arg sws_scale(struct SwsContext *c,
                           srcSliceH, dst2, dstStride2);
     }
 
+
+    if (c->dstXYZ && !(c->srcXYZ && c->srcW==c->dstW && c->srcH==c->dstH)) {
+        /* replace on the same data */
+        rgb48Toxyz12(c, (uint16_t*)dst2[0], (const uint16_t*)dst2[0], dstStride[0]/2, ret);
+    }
+
     av_free(rgb0_tmp);
     return ret;
 }
diff --git a/libswscale/swscale_internal.h b/libswscale/swscale_internal.h
index 02214f3473..e7cc26ea54 100644
--- a/libswscale/swscale_internal.h
+++ b/libswscale/swscale_internal.h
@@ -484,7 +484,10 @@ typedef struct SwsContext {
 #define RGB_GAMMA (2.2f)
     int16_t *xyzgamma;
     int16_t *rgbgamma;
+    int16_t *xyzgammainv;
+    int16_t *rgbgammainv;
     int16_t xyz2rgb_matrix[3][4];
+    int16_t rgb2xyz_matrix[3][4];
 
     /* function pointers for swScale() */
     yuv2planar1_fn yuv2plane1;
diff --git a/libswscale/utils.c b/libswscale/utils.c
index 59bf49a0b2..00308e1553 100644
--- a/libswscale/utils.c
+++ b/libswscale/utils.c
@@ -201,8 +201,8 @@ static const FormatEntry format_entries[AV_PIX_FMT_NB] = {
     [AV_PIX_FMT_GBRP14BE]    = { 1, 1 },
     [AV_PIX_FMT_GBRP16LE]    = { 1, 0 },
     [AV_PIX_FMT_GBRP16BE]    = { 1, 0 },
-    [AV_PIX_FMT_XYZ12BE]     = { 1, 0, 1 },
-    [AV_PIX_FMT_XYZ12LE]     = { 1, 0, 1 },
+    [AV_PIX_FMT_XYZ12BE]     = { 1, 1, 1 },
+    [AV_PIX_FMT_XYZ12LE]     = { 1, 1, 1 },
     [AV_PIX_FMT_GBRAP]       = { 1, 1 },
     [AV_PIX_FMT_GBRAP16LE]   = { 1, 0 },
     [AV_PIX_FMT_GBRAP16BE]   = { 1, 0 },
@@ -924,15 +924,24 @@ static void fill_xyztables(struct SwsContext *c)
     int i;
     double xyzgamma = XYZ_GAMMA;
     double rgbgamma = 1.0 / RGB_GAMMA;
+    double xyzgammainv = 1.0 / XYZ_GAMMA;
+    double rgbgammainv = RGB_GAMMA;
     static const int16_t xyz2rgb_matrix[3][4] = {
         {13270, -6295, -2041},
         {-3969,  7682,   170},
         {  228,  -835,  4329} };
-    static int16_t xyzgamma_tab[4096], rgbgamma_tab[4096];
+    static const int16_t rgb2xyz_matrix[3][4] = {
+        {1689, 1464,  739},
+        { 871, 2929,  296},
+        {  79,  488, 3891} };
+    static int16_t xyzgamma_tab[4096], rgbgamma_tab[4096], xyzgammainv_tab[4096], rgbgammainv_tab[4096];
 
     memcpy(c->xyz2rgb_matrix, xyz2rgb_matrix, sizeof(c->xyz2rgb_matrix));
+    memcpy(c->rgb2xyz_matrix, rgb2xyz_matrix, sizeof(c->rgb2xyz_matrix));
     c->xyzgamma = xyzgamma_tab;
     c->rgbgamma = rgbgamma_tab;
+    c->xyzgammainv = xyzgammainv_tab;
+    c->rgbgammainv = rgbgammainv_tab;
 
     if (rgbgamma_tab[4095])
         return;
@@ -941,6 +950,8 @@ static void fill_xyztables(struct SwsContext *c)
     for (i = 0; i < 4096; i++) {
         xyzgamma_tab[i] = lrint(pow(i / 4095.0, xyzgamma) * 4095.0);
         rgbgamma_tab[i] = lrint(pow(i / 4095.0, rgbgamma) * 4095.0);
+        xyzgammainv_tab[i] = lrint(pow(i / 4095.0, xyzgammainv) * 4095.0);
+        rgbgammainv_tab[i] = lrint(pow(i / 4095.0, rgbgammainv) * 4095.0);
     }
 }