From b4f400b018552a62bc479c77fd9b91f22838f070 Mon Sep 17 00:00:00 2001
From: Sebastian Reimers <hallo@studio-link.de>
Date: Tue, 10 Dec 2024 08:05:30 +0100
Subject: [PATCH 1/2] rem/vidconv: add vidconv_center and x and y source
 offsets

---
 include/rem_vid.h     |   2 +
 include/rem_vidconv.h |   2 +
 rem/vidconv/vconv.c   | 311 ++++++++++++++++++++++--------------------
 test/vidconv.c        |  64 ++++++++-
 4 files changed, 229 insertions(+), 150 deletions(-)

diff --git a/include/rem_vid.h b/include/rem_vid.h
index 4103477c0..3071d345c 100644
--- a/include/rem_vid.h
+++ b/include/rem_vid.h
@@ -55,6 +55,8 @@ struct vidframe {
 	uint16_t linesize[4];  /**< Array of line-sizes */
 	struct vidsz size;     /**< Frame resolution    */
 	enum vidfmt fmt;       /**< Video pixel format  */
+	unsigned xoffs;        /**< x offset            */
+	unsigned yoffs;        /**< y offset            */
 };
 
 /** Video point */
diff --git a/include/rem_vidconv.h b/include/rem_vidconv.h
index 94fee1d65..44120f4d9 100644
--- a/include/rem_vidconv.h
+++ b/include/rem_vidconv.h
@@ -9,3 +9,5 @@ void vidconv(struct vidframe *dst, const struct vidframe *src,
 	     struct vidrect *r);
 void vidconv_aspect(struct vidframe *dst, const struct vidframe *src,
 		    struct vidrect *r);
+void vidconv_center(struct vidframe *dst, const struct vidframe *src,
+		    struct vidrect *r);
diff --git a/rem/vidconv/vconv.c b/rem/vidconv/vconv.c
index b0a320786..97840d113 100644
--- a/rem/vidconv/vconv.c
+++ b/rem/vidconv/vconv.c
@@ -180,31 +180,29 @@ static inline void _yuv2rgb(uint8_t *rgb, uint8_t y, uint8_t u, uint8_t v)
 }
 
 
-typedef void (line_h)(unsigned xoffs, unsigned width, double rw,
-		      unsigned yd, unsigned ys, unsigned ys2,
-		      uint8_t *dd0, uint8_t *dd1, uint8_t *dd2,
-		      unsigned lsd,
-		      const uint8_t *sd0, const uint8_t *sd1,
-		      const uint8_t *sd2, unsigned lss);
-
-
-static void yuv420p_to_yuv420p(unsigned xoffs, unsigned width, double rw,
-			       unsigned yd, unsigned ys, unsigned ys2,
-			       uint8_t *dd0, uint8_t *dd1, uint8_t *dd2,
-			       unsigned lsd,
+typedef void(line_h)(unsigned xsoffs, unsigned xdoffs, unsigned width,
+		     double rw, unsigned yd, unsigned ys, unsigned ys2,
+		     uint8_t *dd0, uint8_t *dd1, uint8_t *dd2, unsigned lsd,
+		     const uint8_t *sd0, const uint8_t *sd1,
+		     const uint8_t *sd2, unsigned lss);
+
+
+static void yuv420p_to_yuv420p(unsigned xsoffs, unsigned xdoffs,
+			       unsigned width, double rw, unsigned yd,
+			       unsigned ys, unsigned ys2, uint8_t *dd0,
+			       uint8_t *dd1, uint8_t *dd2, unsigned lsd,
 			       const uint8_t *ds0, const uint8_t *ds1,
-			       const uint8_t *ds2, unsigned lss
-			       )
+			       const uint8_t *ds2, unsigned lss)
 {
 	unsigned x, xd, xs, xs2;
 	unsigned id, is;
 
 	for (x=0; x<width; x+=2) {
 
-		xd  = x + xoffs;
+		xd  = x + xdoffs;
 
-		xs  = (unsigned)(x * rw);
-		xs2 = (unsigned)((x+1) * rw);
+		xs  = (unsigned)((x + xsoffs) * rw);
+		xs2 = (unsigned)((x + xsoffs + 1) * rw);
 
 		id = xd + yd*lsd;
 
@@ -222,13 +220,12 @@ static void yuv420p_to_yuv420p(unsigned xoffs, unsigned width, double rw,
 }
 
 
-static void yuyv422_to_yuv420p(unsigned xoffs, unsigned width, double rw,
-			       unsigned yd, unsigned ys, unsigned ys2,
-			       uint8_t *dd0, uint8_t *dd1, uint8_t *dd2,
-			       unsigned lsd,
+static void yuyv422_to_yuv420p(unsigned xsoffs, unsigned xdoffs,
+			       unsigned width, double rw, unsigned yd,
+			       unsigned ys, unsigned ys2, uint8_t *dd0,
+			       uint8_t *dd1, uint8_t *dd2, unsigned lsd,
 			       const uint8_t *sd0, const uint8_t *sd1,
-			       const uint8_t *sd2, unsigned lss
-			       )
+			       const uint8_t *sd2, unsigned lss)
 {
 	unsigned x, xd, xs;
 	unsigned id, is, is2;
@@ -238,13 +235,13 @@ static void yuyv422_to_yuv420p(unsigned xoffs, unsigned width, double rw,
 
 	for (x=0; x<width; x+=2) {
 
-		xd  = x + xoffs;
+		xd  = x + xdoffs;
 
-		xs  = ((unsigned)(x * rw * 2)) & ~3;
+		xs  = ((unsigned)((x + xsoffs) * rw * 2)) & ~3;
 
 		id  = xd + yd*lsd;
 		is  = xs + ys*lss;
-		is2 = xs  + ys2*lss;
+		is2 = xs + ys2*lss;
 
 		dd0[id]         = sd0[is];
 		dd0[id+1]       = sd0[is + 2];
@@ -259,13 +256,12 @@ static void yuyv422_to_yuv420p(unsigned xoffs, unsigned width, double rw,
 }
 
 
-static void uyvy422_to_yuv420p(unsigned xoffs, unsigned width, double rw,
-			       unsigned yd, unsigned ys, unsigned ys2,
-			       uint8_t *dd0, uint8_t *dd1, uint8_t *dd2,
-			       unsigned lsd,
+static void uyvy422_to_yuv420p(unsigned xsoffs, unsigned xdoffs,
+			       unsigned width, double rw, unsigned yd,
+			       unsigned ys, unsigned ys2, uint8_t *dd0,
+			       uint8_t *dd1, uint8_t *dd2, unsigned lsd,
 			       const uint8_t *sd0, const uint8_t *sd1,
-			       const uint8_t *sd2, unsigned lss
-			       )
+			       const uint8_t *sd2, unsigned lss)
 {
 	unsigned x, xd, xs;
 	unsigned id, is, is2;
@@ -275,13 +271,13 @@ static void uyvy422_to_yuv420p(unsigned xoffs, unsigned width, double rw,
 
 	for (x=0; x<width; x+=2) {
 
-		xd  = x + xoffs;
+		xd  = x + xdoffs;
 
-		xs  = ((unsigned)(x * rw * 2)) & ~3;
+		xs = ((unsigned)((x + xsoffs) * rw * 2)) & ~3;
 
 		id  = xd + yd*lsd;
 		is  = xs + ys*lss;
-		is2 = xs  + ys2*lss;
+		is2 = xs + ys2*lss;
 
 		dd0[id]         = sd0[is + 1];
 		dd0[id+1]       = sd0[is + 3];
@@ -296,13 +292,12 @@ static void uyvy422_to_yuv420p(unsigned xoffs, unsigned width, double rw,
 }
 
 
-static void rgb32_to_yuv420p(unsigned xoffs, unsigned width, double rw,
-			     unsigned yd, unsigned ys, unsigned ys2,
+static void rgb32_to_yuv420p(unsigned xsoffs, unsigned xdoffs, unsigned width,
+			     double rw, unsigned yd, unsigned ys, unsigned ys2,
 			     uint8_t *dd0, uint8_t *dd1, uint8_t *dd2,
-			     unsigned lsd,
-			     const uint8_t *ds0, const uint8_t *ds1,
-			     const uint8_t *ds2, unsigned lss
-			     )
+			     unsigned lsd, const uint8_t *ds0,
+			     const uint8_t *ds1, const uint8_t *ds2,
+			     unsigned lss)
 {
 	unsigned x, xd, xs, xs2;
 	unsigned id;
@@ -317,10 +312,10 @@ static void rgb32_to_yuv420p(unsigned xoffs, unsigned width, double rw,
 		uint32_t x2;
 		uint32_t x3;
 
-		xd  = x + xoffs;
+		xd  = x + xdoffs;
 
-		xs  = 4 * ((unsigned)( x    * rw));
-		xs2 = 4 * ((unsigned)((x+1) * rw));
+		xs  = 4 * ((unsigned)((x + xsoffs) * rw));
+		xs2 = 4 * ((unsigned)((x + xsoffs + 1) * rw));
 
 		id = xd + yd*lsd;
 
@@ -342,13 +337,12 @@ static void rgb32_to_yuv420p(unsigned xoffs, unsigned width, double rw,
 }
 
 
-static void rgb32_to_yuv444p(unsigned xoffs, unsigned width, double rw,
-			     unsigned yd, unsigned ys, unsigned ys2,
+static void rgb32_to_yuv444p(unsigned xsoffs, unsigned xdoffs, unsigned width,
+			     double rw, unsigned yd, unsigned ys, unsigned ys2,
 			     uint8_t *dd0, uint8_t *dd1, uint8_t *dd2,
-			     unsigned lsd,
-			     const uint8_t *ds0, const uint8_t *ds1,
-			     const uint8_t *ds2, unsigned lss
-			     )
+			     unsigned lsd, const uint8_t *ds0,
+			     const uint8_t *ds1, const uint8_t *ds2,
+			     unsigned lss)
 {
 	unsigned x, xd, xs;
 	unsigned id;
@@ -361,9 +355,9 @@ static void rgb32_to_yuv444p(unsigned xoffs, unsigned width, double rw,
 		uint32_t x0;
 		uint32_t x1;
 
-		xd = x + xoffs;
+		xd = x + xdoffs;
 
-		xs = 4 * ((unsigned)(x * rw));
+		xs = 4 * ((unsigned)((x + xsoffs) * rw));
 
 		id = xd + yd*lsd;
 
@@ -382,12 +376,12 @@ static void rgb32_to_yuv444p(unsigned xoffs, unsigned width, double rw,
 }
 
 
-static void yuv420p_to_rgb32(unsigned xoffs, unsigned width, double rw,
-			     unsigned yd, unsigned ys, unsigned ys2,
+static void yuv420p_to_rgb32(unsigned xsoffs, unsigned xdoffs, unsigned width,
+			     double rw, unsigned yd, unsigned ys, unsigned ys2,
 			     uint8_t *dd0, uint8_t *dd1, uint8_t *dd2,
-			     unsigned lsd,
-			     const uint8_t *ds0, const uint8_t *ds1,
-			     const uint8_t *ds2, unsigned lss)
+			     unsigned lsd, const uint8_t *ds0,
+			     const uint8_t *ds1, const uint8_t *ds2,
+			     unsigned lss)
 {
 	unsigned x, xd, xs, xs2;
 	unsigned id, is;
@@ -400,10 +394,10 @@ static void yuv420p_to_rgb32(unsigned xoffs, unsigned width, double rw,
 		int ruv, guv, buv;
 		uint8_t u, v;
 
-		xd  = (x + xoffs) * 4;
+		xd  = (x + xdoffs) * 4;
 
-		xs  = (unsigned)(x * rw);
-		xs2 = (unsigned)((x+1) * rw);
+		xs  = (unsigned)((x + xsoffs) * rw);
+		xs2 = (unsigned)((x + xsoffs + 1) * rw);
 
 		id = (xd + yd*lsd);
 		is  = (xs>>1) + (ys>>1)*lss/2;
@@ -423,12 +417,12 @@ static void yuv420p_to_rgb32(unsigned xoffs, unsigned width, double rw,
 }
 
 
-static void yuv420p_to_rgb565(unsigned xoffs, unsigned width, double rw,
-			      unsigned yd, unsigned ys, unsigned ys2,
-			      uint8_t *dd0, uint8_t *dd1, uint8_t *dd2,
-			      unsigned lsd,
-			      const uint8_t *ds0, const uint8_t *ds1,
-			      const uint8_t *ds2, unsigned lss)
+static void yuv420p_to_rgb565(unsigned xsoffs, unsigned xdoffs, unsigned width,
+			      double rw, unsigned yd, unsigned ys,
+			      unsigned ys2, uint8_t *dd0, uint8_t *dd1,
+			      uint8_t *dd2, unsigned lsd, const uint8_t *ds0,
+			      const uint8_t *ds1, const uint8_t *ds2,
+			      unsigned lss)
 {
 	unsigned x, xd, xs, xs2;
 	unsigned id, is;
@@ -441,10 +435,10 @@ static void yuv420p_to_rgb565(unsigned xoffs, unsigned width, double rw,
 		int ruv, guv, buv;
 		uint8_t u, v;
 
-		xd  = (x + xoffs) * 2;
+		xd  = (x + xdoffs) * 2;
 
-		xs  = (unsigned)(x * rw);
-		xs2 = (unsigned)((x+1) * rw);
+		xs  = (unsigned)((x + xsoffs) * rw);
+		xs2 = (unsigned)((x + xsoffs + 1) * rw);
 
 		id = (xd + yd*lsd);
 		is  = (xs>>1) + (ys>>1)*lss/2;
@@ -464,13 +458,12 @@ static void yuv420p_to_rgb565(unsigned xoffs, unsigned width, double rw,
 }
 
 
-static void nv12_to_yuv420p(unsigned xoffs, unsigned width, double rw,
-			    unsigned yd, unsigned ys, unsigned ys2,
+static void nv12_to_yuv420p(unsigned xsoffs, unsigned xdoffs, unsigned width,
+			    double rw, unsigned yd, unsigned ys, unsigned ys2,
 			    uint8_t *dd0, uint8_t *dd1, uint8_t *dd2,
-			    unsigned lsd,
-			    const uint8_t *ds0, const uint8_t *ds1,
-			    const uint8_t *ds2, unsigned lss
-			    )
+			    unsigned lsd, const uint8_t *ds0,
+			    const uint8_t *ds1, const uint8_t *ds2,
+			    unsigned lss)
 {
 	unsigned x, xd, xs, xs2;
 	unsigned id, is;
@@ -479,10 +472,10 @@ static void nv12_to_yuv420p(unsigned xoffs, unsigned width, double rw,
 
 	for (x=0; x<width; x+=2) {
 
-		xd  = x + xoffs;
+		xd  = x + xdoffs;
 
-		xs  = (unsigned)(x * rw);
-		xs2 = (unsigned)((x+1) * rw);
+		xs  = (unsigned)((x + xsoffs) * rw);
+		xs2 = (unsigned)((x + xsoffs + 1) * rw);
 
 		id = xd + yd*lsd;
 
@@ -500,13 +493,12 @@ static void nv12_to_yuv420p(unsigned xoffs, unsigned width, double rw,
 }
 
 
-static void yuv420p_to_nv12(unsigned xoffs, unsigned width, double rw,
-			    unsigned yd, unsigned ys, unsigned ys2,
+static void yuv420p_to_nv12(unsigned xsoffs, unsigned xdoffs, unsigned width,
+			    double rw, unsigned yd, unsigned ys, unsigned ys2,
 			    uint8_t *dd0, uint8_t *dd1, uint8_t *dd2,
-			    unsigned lsd,
-			    const uint8_t *ds0, const uint8_t *ds1,
-			    const uint8_t *ds2, unsigned lss
-			    )
+			    unsigned lsd, const uint8_t *ds0,
+			    const uint8_t *ds1, const uint8_t *ds2,
+			    unsigned lss)
 {
 	unsigned x, xd, xs, xs2;
 	unsigned id, is;
@@ -515,10 +507,10 @@ static void yuv420p_to_nv12(unsigned xoffs, unsigned width, double rw,
 
 	for (x=0; x<width; x+=2) {
 
-		xd  = x + xoffs;
+		xd  = x + xdoffs;
 
-		xs  = (unsigned)(x * rw);
-		xs2 = (unsigned)((x+1) * rw);
+		xs  = (unsigned)((x + xsoffs) * rw);
+		xs2 = (unsigned)((x + xsoffs + 1) * rw);
 
 		id = xd + yd*lsd;
 
@@ -536,13 +528,12 @@ static void yuv420p_to_nv12(unsigned xoffs, unsigned width, double rw,
 }
 
 
-static void nv21_to_yuv420p(unsigned xoffs, unsigned width, double rw,
-			    unsigned yd, unsigned ys, unsigned ys2,
+static void nv21_to_yuv420p(unsigned xsoffs, unsigned xdoffs, unsigned width,
+			    double rw, unsigned yd, unsigned ys, unsigned ys2,
 			    uint8_t *dd0, uint8_t *dd1, uint8_t *dd2,
-			    unsigned lsd,
-			    const uint8_t *ds0, const uint8_t *ds1,
-			    const uint8_t *ds2, unsigned lss
-			    )
+			    unsigned lsd, const uint8_t *ds0,
+			    const uint8_t *ds1, const uint8_t *ds2,
+			    unsigned lss)
 {
 	unsigned x, xd, xs, xs2;
 	unsigned id, is;
@@ -551,10 +542,10 @@ static void nv21_to_yuv420p(unsigned xoffs, unsigned width, double rw,
 
 	for (x=0; x<width; x+=2) {
 
-		xd  = x + xoffs;
+		xd  = x + xdoffs;
 
-		xs  = (unsigned)(x * rw);
-		xs2 = (unsigned)((x+1) * rw);
+		xs  = (unsigned)((x + xsoffs) * rw);
+		xs2 = (unsigned)((x + xsoffs + 1) * rw);
 
 		id = xd + yd*lsd;
 
@@ -572,12 +563,12 @@ static void nv21_to_yuv420p(unsigned xoffs, unsigned width, double rw,
 }
 
 
-static void yuv444p_to_rgb32(unsigned xoffs, unsigned width, double rw,
-			     unsigned yd, unsigned ys, unsigned ys2,
+static void yuv444p_to_rgb32(unsigned xsoffs, unsigned xdoffs, unsigned width,
+			     double rw, unsigned yd, unsigned ys, unsigned ys2,
 			     uint8_t *dd0, uint8_t *dd1, uint8_t *dd2,
-			     unsigned lsd,
-			     const uint8_t *ds0, const uint8_t *ds1,
-			     const uint8_t *ds2, unsigned lss)
+			     unsigned lsd, const uint8_t *ds0,
+			     const uint8_t *ds1, const uint8_t *ds2,
+			     unsigned lss)
 {
 	unsigned x, xd, xs;
 	unsigned id;
@@ -588,9 +579,9 @@ static void yuv444p_to_rgb32(unsigned xoffs, unsigned width, double rw,
 
 	for (x=0; x<width; x++) {
 
-		xd = (x + xoffs) * 4;
+		xd = (x + xdoffs) * 4;
 
-		xs = (unsigned)(x * rw);
+		xs = (unsigned)((x + xsoffs) * rw);
 
 		id = xd + yd*lsd;
 
@@ -603,13 +594,11 @@ static void yuv444p_to_rgb32(unsigned xoffs, unsigned width, double rw,
 }
 
 
-static void nv12_to_rgb32(unsigned xoffs, unsigned width, double rw,
-                           unsigned yd, unsigned ys, unsigned ys2,
-                           uint8_t *dd0, uint8_t *dd1, uint8_t *dd2,
-                           unsigned lsd,
-                           const uint8_t *ds0, const uint8_t *ds1,
-                           const uint8_t *ds2, unsigned lss
-                           )
+static void nv12_to_rgb32(unsigned xsoffs, unsigned xdoffs, unsigned width,
+			  double rw, unsigned yd, unsigned ys, unsigned ys2,
+			  uint8_t *dd0, uint8_t *dd1, uint8_t *dd2,
+			  unsigned lsd, const uint8_t *ds0, const uint8_t *ds1,
+			  const uint8_t *ds2, unsigned lss)
 {
        unsigned x, xd, xs, xs2;
        unsigned id, is;
@@ -622,12 +611,12 @@ static void nv12_to_rgb32(unsigned xoffs, unsigned width, double rw,
                int ruv, guv, buv;
                uint8_t u, v;
 
-               xd  = (x + xoffs) * 4;
+               xd  = (x + xdoffs) * 4;
 
-               xs  = (unsigned)(x * rw);
-               xs2 = (unsigned)((x+1) * rw);
+	       xs  = (unsigned)((x + xsoffs) * rw);
+	       xs2 = (unsigned)((x + xsoffs + 1) * rw);
 
-               id = (xd + yd*lsd);
+	       id = (xd + yd*lsd);
                is = xs/2 + ys*lss/4;
 
                u = ds1[2*is];
@@ -644,44 +633,43 @@ static void nv12_to_rgb32(unsigned xoffs, unsigned width, double rw,
 }
 
 
-static void nv21_to_rgb32(unsigned xoffs, unsigned width, double rw,
-                           unsigned yd, unsigned ys, unsigned ys2,
-                           uint8_t *dd0, uint8_t *dd1, uint8_t *dd2,
-                           unsigned lsd,
-                           const uint8_t *ds0, const uint8_t *ds1,
-                           const uint8_t *ds2, unsigned lss
-                           )
+static void nv21_to_rgb32(unsigned xsoffs, unsigned xdoffs, unsigned width,
+			  double rw, unsigned yd, unsigned ys, unsigned ys2,
+			  uint8_t *dd0, uint8_t *dd1, uint8_t *dd2,
+			  unsigned lsd, const uint8_t *ds0, const uint8_t *ds1,
+			  const uint8_t *ds2, unsigned lss)
 {
-       unsigned x, xd, xs, xs2;
-       unsigned id, is;
+	unsigned x, xd, xs, xs2;
+	unsigned id, is;
 
-       (void)ds2;
-       (void)dd1;
-       (void)dd2;
+	(void)ds2;
+	(void)dd1;
+	(void)dd2;
 
-       for (x=0; x<width; x+=2) {
-               int ruv, guv, buv;
-               uint8_t u, v;
+	for (x = 0; x < width; x += 2) {
+		int ruv, guv, buv;
+		uint8_t u, v;
 
-               xd  = (x + xoffs) * 4;
+		xd = (x + xdoffs) * 4;
 
-               xs  = (unsigned)(x * rw);
-               xs2 = (unsigned)((x+1) * rw);
+		xs  = (unsigned)((x + xsoffs) * rw);
+		xs2 = (unsigned)((x + xsoffs + 1) * rw);
 
-               id = (xd + yd*lsd);
-               is = xs/2 + ys*lss/4;
+		id = (xd + yd * lsd);
+		is = xs / 2 + ys * lss / 4;
 
-               v = ds1[2*is];
-               u = ds1[2*is+1];
-               ruv = CRV[v];
-               guv = CGV[v] + CGU[u];
-               buv = CBU[u];
+		v   = ds1[2 * is];
+		u   = ds1[2 * is + 1];
+		ruv = CRV[v];
+		guv = CGV[v] + CGU[u];
+		buv = CBU[u];
 
-               yuv2rgb(&dd0[id],         ds0[xs  + ys*lss],  ruv, guv, buv);
-               yuv2rgb(&dd0[id+4],       ds0[xs2 + ys*lss],  ruv, guv, buv);
-               yuv2rgb(&dd0[id   + lsd], ds0[xs  + ys2*lss], ruv, guv, buv);
-               yuv2rgb(&dd0[id+4 + lsd], ds0[xs2 + ys2*lss], ruv, guv, buv);
-       }
+		yuv2rgb(&dd0[id], ds0[xs + ys * lss], ruv, guv, buv);
+		yuv2rgb(&dd0[id + 4], ds0[xs2 + ys * lss], ruv, guv, buv);
+		yuv2rgb(&dd0[id + lsd], ds0[xs + ys2 * lss], ruv, guv, buv);
+		yuv2rgb(&dd0[id + 4 + lsd], ds0[xs2 + ys2 * lss], ruv, guv,
+			buv);
+	}
 }
 
 
@@ -789,10 +777,10 @@ void vidconv(struct vidframe *dst, const struct vidframe *src,
 
 		yd  = y + r->y;
 
-		ys  = (unsigned)(y * rh);
-		ys2 = (unsigned)((y+1) * rh);
+		ys  = (unsigned)((y + src->yoffs) * rh);
+		ys2 = (unsigned)((y + src->yoffs + 1) * rh);
 
-		lineh(r->x, r->w, rw, yd, ys, ys2,
+		lineh(src->xoffs, r->x, r->w, rw, yd, ys, ys2,
 		      dd0, dd1, dd2, lsd,
 		      ds0, ds1, ds2, lss);
 	}
@@ -824,3 +812,32 @@ void vidconv_aspect(struct vidframe *dst, const struct vidframe *src,
 
 	vidconv(dst, src, r);
 }
+
+
+/**
+ * Same as vidconv(), but maintain source min. center within bounds of r
+ *
+ * @param dst  Destination video frame
+ * @param src  Source video frame
+ * @param r    Drawing area in destination frame
+ */
+void vidconv_center(struct vidframe *dst, const struct vidframe *src,
+		    struct vidrect *r)
+{
+	struct vidframe sc = *src;
+
+	if (src->size.w >= src->size.h) {
+		double rh = (double)src->size.h / (double)r->h;
+		sc.size.w =
+			(unsigned)min((double)src->size.w, (double)r->w * rh);
+		sc.xoffs = ((unsigned)(src->size.w / rh) - r->w) / 2;
+	}
+	else {
+		double rw = (double)src->size.w / (double)r->w;
+		sc.size.h =
+			(unsigned)min((double)src->size.h, (double)r->h * rw);
+		sc.yoffs = ((unsigned)(src->size.h / rw) - r->h) / 2;
+	}
+
+	vidconv(dst, &sc, r);
+}
diff --git a/test/vidconv.c b/test/vidconv.c
index d4bf8bf01..c9bd5c0c7 100644
--- a/test/vidconv.c
+++ b/test/vidconv.c
@@ -157,9 +157,7 @@ static void write_pattern(uint8_t *buf, size_t len)
  */
 static int test_vidconv_scaling_base(enum vidfmt via_fmt)
 {
-#define WIDTH 40
-#define HEIGHT 30
-#define SCALE 2
+	enum { WIDTH = 40, HEIGHT = 30, SCALE = 2 };
 	struct vidframe *f0 = NULL, *f1 = NULL, *f2 = NULL;
 	const struct vidsz size0 = {WIDTH, HEIGHT};
 	const struct vidsz size1 = {WIDTH*SCALE, HEIGHT*SCALE};
@@ -369,12 +367,72 @@ int test_vidconv_pixel_formats(void)
 }
 
 
+static int test_vidconv_center(void)
+{
+	int err;
+	struct vidframe *dst = NULL;
+	struct vidframe *src = NULL;
+
+	static struct test {
+		struct vidrect r;
+		struct vidsz src_sz;
+		struct vidsz dst_sz;
+	} testv[] = {
+		{.r	 = {.x = 0, .y = 0, .w = 960, .h = 1080},
+		 .src_sz = {.w = 320, .h = 180},
+		 .dst_sz = {.w = 1920, .h = 1080}},
+		{.r	 = {.x = 0, .y = 0, .w = 960, .h = 1080},
+		 .src_sz = {.w = 180, .h = 320},
+		 .dst_sz = {.w = 1920, .h = 1080}},
+		{.r	 = {.x = 0, .y = 0, .w = 960, .h = 1080},
+		 .src_sz = {.w = 1920, .h = 1080},
+		 .dst_sz = {.w = 1920, .h = 1080}},
+		{.r	 = {.x = 0, .y = 0, .w = 960, .h = 1080},
+		 .src_sz = {.w = 1080, .h = 1920},
+		 .dst_sz = {.w = 1920, .h = 1080}},
+		{.r	 = {.x = 0, .y = 0, .w = 640, .h = 720},
+		 .src_sz = {.w = 1920, .h = 1080},
+		 .dst_sz = {.w = 1280, .h = 720}},
+		{.r	 = {.x = 960, .y = 0, .w = 960, .h = 1080},
+		 .src_sz = {.w = 1024, .h = 768}, /* 4:3 */
+		 .dst_sz = {.w = 1920, .h = 1080}},
+		{.r	 = {.x = 0, .y = 0, .w = 960, .h = 1080},
+		 .src_sz = {.w = 320, .h = 320}, /* square */
+		 .dst_sz = {.w = 1920, .h = 1080}},
+	};
+
+	for (size_t i = 0; i < RE_ARRAY_SIZE(testv); i++) {
+		struct test *test    = &testv[i];
+
+		err = vidframe_alloc(&src, VID_FMT_YUV420P, &test->src_sz);
+		err |= vidframe_alloc(&dst, VID_FMT_YUV420P, &test->dst_sz);
+		TEST_ERR(err);
+
+		vidconv_center(dst, src, &test->r);
+
+		src = mem_deref(src);
+		dst = mem_deref(dst);
+	}
+
+out:
+	src = mem_deref(src);
+	dst = mem_deref(dst);
+
+	return err;
+}
+
+
 int test_vidconv(void)
 {
 	int err;
 
 	err = test_vid_rgb2yuv();
+	TEST_ERR(err);
+
+	err = test_vidconv_center();
+	TEST_ERR(err);
 
+out:
 	return err;
 }
 

From caf530d2374a8b0378df0501ab6a407c18cab702 Mon Sep 17 00:00:00 2001
From: Sebastian Reimers <hallo@studio-link.de>
Date: Tue, 10 Dec 2024 08:08:18 +0100
Subject: [PATCH 2/2] vidmix/source_mix: use vidconv_center (full height
 center)

---
 rem/vidmix/vidmix.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/rem/vidmix/vidmix.c b/rem/vidmix/vidmix.c
index 4eeb4e5d0..f4a3b5e73 100644
--- a/rem/vidmix/vidmix.c
+++ b/rem/vidmix/vidmix.c
@@ -132,6 +132,14 @@ static inline void source_mix(struct vidframe *mframe,
 		source_mix_full(mframe, frame_src);
 		return;
 	}
+	else if (n <= 3) {
+		rect.w = mframe->size.w / n;
+		rect.h = mframe->size.h;
+		rect.x = (rect.w) * (idx % n);
+		rect.y = 0;
+		vidconv_center(mframe, frame_src, &rect);
+		return;
+	}
 	else {
 		rect.w = mframe->size.w / rows;
 		rect.h = mframe->size.h / rows;