libv4l: add support for adding black borders (reverse cropping)

From: Hans de Goede <hdegoede@redhat.com>

Add the capability to provide 320x240 to apps if the cam can only
do 320x232 (some zc3xx cams) by adding black borders. And more in
general the capability to make certain standard resolutions available
by adding black borders to slightly smaller resolutions, in case we
encounter more cams which have a hardware limitation which makes them do
a resolution slightly smaller then the standard ones.

Priority: normal

Signed-off-by: Hans de Goede <hdegoede@redhat.com>

2 files changed, 136 insertions, 8 deletions

diff --git a/v4l2-apps/libv4l/libv4lconvert/crop.c b/v4l2-apps/libv4l/libv4lconvert/crop.c
index 4294fbeaf..f01772c07 100644
--- a/v4l2-apps/libv4l/libv4lconvert/crop.c
+++ b/v4l2-apps/libv4l/libv4lconvert/crop.c
@@ -143,26 +143,146 @@ static void v4lconvert_crop_yuv420(unsigned char *src, unsigned char *dest,
   }
 }
 
+/* Ok, so this is not really cropping, but more the reverse, whatever */
+static void v4lconvert_add_border_rgbbgr24(
+  unsigned char *src, unsigned char *dest,
+  const struct v4l2_format *src_fmt, const struct v4l2_format *dest_fmt)
+{
+  int y;
+  int borderx = (dest_fmt->fmt.pix.width - src_fmt->fmt.pix.width) / 2;
+  int bordery = (dest_fmt->fmt.pix.height - src_fmt->fmt.pix.height) / 2;
+
+  for (y = 0; y < bordery; y++) {
+    memset(dest, 0, dest_fmt->fmt.pix.width * 3);
+    dest += dest_fmt->fmt.pix.bytesperline;
+  }
+
+  for (y = 0; y < src_fmt->fmt.pix.height; y++) {
+    memset(dest, 0, borderx * 3);
+    dest += borderx * 3;
+
+    memcpy(dest, src, src_fmt->fmt.pix.width * 3);
+    src += src_fmt->fmt.pix.bytesperline;
+    dest += src_fmt->fmt.pix.width * 3;
+
+    memset(dest, 0, borderx * 3);
+    dest += dest_fmt->fmt.pix.bytesperline -
+	    (borderx + src_fmt->fmt.pix.width) * 3;
+  }
+
+  for (y = 0; y < bordery; y++) {
+    memset(dest, 0, dest_fmt->fmt.pix.width * 3);
+    dest += dest_fmt->fmt.pix.bytesperline;
+  }
+}
+
+static void v4lconvert_add_border_yuv420(
+  unsigned char *src, unsigned char *dest,
+  const struct v4l2_format *src_fmt, const struct v4l2_format *dest_fmt)
+{
+  int y;
+  int borderx = (dest_fmt->fmt.pix.width - src_fmt->fmt.pix.width) / 2;
+  int bordery = (dest_fmt->fmt.pix.height - src_fmt->fmt.pix.height) / 2;
+
+  /* Y */
+  for (y = 0; y < bordery; y++) {
+    memset(dest, 16, dest_fmt->fmt.pix.width);
+    dest += dest_fmt->fmt.pix.bytesperline;
+  }
+
+  for (y = 0; y < src_fmt->fmt.pix.height; y++) {
+    memset(dest, 16, borderx);
+    dest += borderx;
+
+    memcpy(dest, src, src_fmt->fmt.pix.width);
+    src += src_fmt->fmt.pix.bytesperline;
+    dest += src_fmt->fmt.pix.width;
+
+    memset(dest, 16, borderx);
+    dest += dest_fmt->fmt.pix.bytesperline -
+	    (borderx + src_fmt->fmt.pix.width);
+  }
+
+  for (y = 0; y < bordery; y++) {
+    memset(dest, 16, dest_fmt->fmt.pix.width);
+    dest += dest_fmt->fmt.pix.bytesperline;
+  }
+
+  /* U */
+  for (y = 0; y < bordery / 2; y++) {
+    memset(dest, 128, dest_fmt->fmt.pix.width / 2);
+    dest += dest_fmt->fmt.pix.bytesperline / 2;
+  }
+
+  for (y = 0; y < src_fmt->fmt.pix.height / 2; y++) {
+    memset(dest, 128, borderx / 2);
+    dest += borderx / 2;
+
+    memcpy(dest, src, src_fmt->fmt.pix.width / 2);
+    src += src_fmt->fmt.pix.bytesperline / 2;
+    dest += src_fmt->fmt.pix.width / 2;
+
+    memset(dest, 128, borderx / 2);
+    dest += (dest_fmt->fmt.pix.bytesperline -
+	     (borderx + src_fmt->fmt.pix.width)) / 2;
+  }
+
+  for (y = 0; y < bordery / 2; y++) {
+    memset(dest, 128, dest_fmt->fmt.pix.width / 2);
+    dest += dest_fmt->fmt.pix.bytesperline / 2;
+  }
+
+  /* V */
+  for (y = 0; y < bordery / 2; y++) {
+    memset(dest, 128, dest_fmt->fmt.pix.width / 2);
+    dest += dest_fmt->fmt.pix.bytesperline / 2;
+  }
+
+  for (y = 0; y < src_fmt->fmt.pix.height / 2; y++) {
+    memset(dest, 128, borderx / 2);
+    dest += borderx / 2;
+
+    memcpy(dest, src, src_fmt->fmt.pix.width / 2);
+    src += src_fmt->fmt.pix.bytesperline / 2;
+    dest += src_fmt->fmt.pix.width / 2;
+
+    memset(dest, 128, borderx / 2);
+    dest += (dest_fmt->fmt.pix.bytesperline -
+	     (borderx + src_fmt->fmt.pix.width)) / 2;
+  }
+
+  for (y = 0; y < bordery / 2; y++) {
+    memset(dest, 128, dest_fmt->fmt.pix.width / 2);
+    dest += dest_fmt->fmt.pix.bytesperline / 2;
+  }
+}
+
 void v4lconvert_crop(unsigned char *src, unsigned char *dest,
   const struct v4l2_format *src_fmt, const struct v4l2_format *dest_fmt)
 {
   switch (dest_fmt->fmt.pix.pixelformat) {
     case V4L2_PIX_FMT_RGB24:
     case V4L2_PIX_FMT_BGR24:
-      if (src_fmt->fmt.pix.width  >= 2 * dest_fmt->fmt.pix.width &&
-	  src_fmt->fmt.pix.height >= 2 * dest_fmt->fmt.pix.height)
+      if (src_fmt->fmt.pix.width  <= dest_fmt->fmt.pix.width &&
+	  src_fmt->fmt.pix.height <= dest_fmt->fmt.pix.height)
+	v4lconvert_add_border_rgbbgr24(src, dest, src_fmt, dest_fmt);
+      else if (src_fmt->fmt.pix.width  >= 2 * dest_fmt->fmt.pix.width &&
+	       src_fmt->fmt.pix.height >= 2 * dest_fmt->fmt.pix.height)
 	v4lconvert_reduceandcrop_rgbbgr24(src, dest, src_fmt, dest_fmt);
       else
 	v4lconvert_crop_rgbbgr24(src, dest, src_fmt, dest_fmt);
       break;
+
     case V4L2_PIX_FMT_YUV420:
     case V4L2_PIX_FMT_YVU420:
-      if (src_fmt->fmt.pix.width  >= 2 * dest_fmt->fmt.pix.width &&
-	  src_fmt->fmt.pix.height >= 2 * dest_fmt->fmt.pix.height)
+      if (src_fmt->fmt.pix.width  <= dest_fmt->fmt.pix.width &&
+	  src_fmt->fmt.pix.height <= dest_fmt->fmt.pix.height)
+	v4lconvert_add_border_yuv420(src, dest, src_fmt, dest_fmt);
+      else if (src_fmt->fmt.pix.width  >= 2 * dest_fmt->fmt.pix.width &&
+	       src_fmt->fmt.pix.height >= 2 * dest_fmt->fmt.pix.height)
 	v4lconvert_reduceandcrop_yuv420(src, dest, src_fmt, dest_fmt);
       else
 	v4lconvert_crop_yuv420(src, dest, src_fmt, dest_fmt);
-
       break;
   }
 }
diff --git a/v4l2-apps/libv4l/libv4lconvert/libv4lconvert.c b/v4l2-apps/libv4l/libv4lconvert/libv4lconvert.c
index 1a94b53ba..afb0c854c 100644
--- a/v4l2-apps/libv4l/libv4lconvert/libv4lconvert.c
+++ b/v4l2-apps/libv4l/libv4lconvert/libv4lconvert.c
@@ -373,7 +373,8 @@ int v4lconvert_try_format(struct v4lconvert_data *data,
 
   /* In case of a non exact resolution match, see if this is a well known
      resolution some apps are hardcoded too and try to give the app what it
-     asked for by cropping a slightly larger resolution */
+     asked for by cropping a slightly larger resolution or adding a small
+     black border to a slightly smaller resolution */
   if (try_dest.fmt.pix.width != desired_width ||
       try_dest.fmt.pix.height != desired_height) {
     for (i = 0; i < ARRAY_SIZE(v4lconvert_crop_res); i++) {
@@ -387,13 +388,20 @@ int v4lconvert_try_format(struct v4lconvert_data *data,
 	try2_dest.fmt.pix.height = desired_height * 124 / 100;
 	result = v4lconvert_do_try_format(data, &try2_dest, &try2_src);
 	if (result == 0 &&
-	    ((try2_dest.fmt.pix.width >= desired_width &&
+	    (/* Add a small black border of max 16 pixels */
+	     (try2_dest.fmt.pix.width >= desired_width - 16 &&
+	      try2_dest.fmt.pix.width <= desired_width &&
+	      try2_dest.fmt.pix.height >= desired_height - 16 &&
+	      try2_dest.fmt.pix.height <= desired_height) ||
+	     /* Standard cropping to max 80% of actual width / height */
+	     (try2_dest.fmt.pix.width >= desired_width &&
 	      try2_dest.fmt.pix.width <= desired_width * 5 / 4 &&
 	      try2_dest.fmt.pix.height >= desired_height &&
 	      try2_dest.fmt.pix.height <= desired_height * 5 / 4) ||
+	     /* Downscale 2x + cropping to max 80% of actual width / height */
 	     (try2_dest.fmt.pix.width >= desired_width * 2 &&
 	      try2_dest.fmt.pix.width <= desired_width * 5 / 2 &&
-	      try2_dest.fmt.pix.height >= desired_height &&
+	      try2_dest.fmt.pix.height >= desired_height * 2 &&
 	      try2_dest.fmt.pix.height <= desired_height * 5 / 2))) {
 	  /* Success! */
 	  try2_dest.fmt.pix.width = desired_width;