libv4l: add support for downscaling

From: Lukáš Karas <lukas.karas@centrum.cz>

Add support for downscaling to make apps which want low resolutions
(skype, spcaview) happy when used with cams which can only do high
resolutions.

Priority: normal

Signed-off-by: Lukáš Karas <lukas.karas@centrum.cz>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>

3 files changed, 99 insertions, 16 deletions

diff --git a/v4l2-apps/libv4l/ChangeLog b/v4l2-apps/libv4l/ChangeLog
index 624f6dc43..b6097fe41 100644
--- a/v4l2-apps/libv4l/ChangeLog
+++ b/v4l2-apps/libv4l/ChangeLog
@@ -2,6 +2,9 @@ libv4l-0.5.4
 ------------
 * Don't report DQBUF errors when errno is EAGAIN, this fixes flooding the
   screen with errors when applications use non blocking mode
+* Add support for downscaling to make apps which want low resolutions
+  (skype, spcaview) happy when used with cams which can only do high
+  resolutions (by Lukáš Karas <lukas.karas@centrum.cz>).
 
 libv4l-0.5.3
 ------------
diff --git a/v4l2-apps/libv4l/libv4lconvert/crop.c b/v4l2-apps/libv4l/libv4lconvert/crop.c
index 290756b99..dcfa5152a 100644
--- a/v4l2-apps/libv4l/libv4lconvert/crop.c
+++ b/v4l2-apps/libv4l/libv4lconvert/crop.c
@@ -23,6 +23,29 @@
 #include <string.h>
 #include "libv4lconvert-priv.h"
 
+
+static void v4lconvert_reduceandcrop_rgbbgr24(
+  unsigned char *src, unsigned char *dest,
+  const struct v4l2_format *src_fmt, const struct v4l2_format *dest_fmt)
+{
+  int x, y;
+  int startx = src_fmt->fmt.pix.width / 2 - dest_fmt->fmt.pix.width;
+  int starty = src_fmt->fmt.pix.height / 2 - dest_fmt->fmt.pix.height;
+
+  src += starty * src_fmt->fmt.pix.bytesperline + 3 * startx;
+
+  for (y = 0; y < dest_fmt->fmt.pix.height; y++) {
+    unsigned char *mysrc = src;
+    for (x = 0; x < dest_fmt->fmt.pix.width; x++) {
+      *(dest++) = *(mysrc++);
+      *(dest++) = *(mysrc++);
+      *(dest++) = *(mysrc++);
+      mysrc += 3; /* skip one pixel */
+    }
+    src += 2 * src_fmt->fmt.pix.bytesperline; /* skip one line */
+  }
+}
+
 static void v4lconvert_crop_rgbbgr24(unsigned char *src, unsigned char *dest,
   const struct v4l2_format *src_fmt, const struct v4l2_format *dest_fmt)
 {
@@ -39,6 +62,53 @@ static void v4lconvert_crop_rgbbgr24(unsigned char *src, unsigned char *dest,
   }
 }
 
+static void v4lconvert_reduceandcrop_yuv420(
+  unsigned char *src, unsigned char *dest,
+  const struct v4l2_format *src_fmt, const struct v4l2_format *dest_fmt)
+{
+  int x,y;
+  int dest_height_half = dest_fmt->fmt.pix.height / 2;
+  int dest_width_half = dest_fmt->fmt.pix.width / 2;
+  int startx = src_fmt->fmt.pix.width / 2 - dest_fmt->fmt.pix.width;
+  int starty = src_fmt->fmt.pix.height / 2 - dest_fmt->fmt.pix.height;
+  unsigned char *mysrc, *mysrc2;
+
+  /* Y */
+  mysrc = src + starty * src_fmt->fmt.pix.bytesperline + startx;
+  for (y = 0; y < dest_fmt->fmt.pix.height; y++){
+    mysrc2 = mysrc;
+    for (x = 0; x < dest_fmt->fmt.pix.width; x++){
+      *(dest++) = *mysrc2;
+      mysrc2 += 2; /* skip one pixel */
+    }
+    mysrc += 2 * src_fmt->fmt.pix.bytesperline; /* skip one line */
+  }
+
+  /* U */
+  mysrc = src + src_fmt->fmt.pix.height * src_fmt->fmt.pix.bytesperline +
+      (starty / 2) * src_fmt->fmt.pix.bytesperline / 2 + startx / 2;
+  for (y = 0; y < dest_height_half; y++){
+    mysrc2 = mysrc;
+    for (x = 0; x < dest_width_half; x++){
+      *(dest++) = *mysrc2;
+      mysrc2 += 2; /* skip one pixel */
+    }
+    mysrc += src_fmt->fmt.pix.bytesperline ; /* skip one line */
+  }
+
+  /* V */
+  mysrc = src + src_fmt->fmt.pix.height * src_fmt->fmt.pix.bytesperline * 5 / 4
+      + (starty / 2) * src_fmt->fmt.pix.bytesperline / 2 + startx / 2;
+  for (y = 0; y < dest_height_half; y++){
+    mysrc2 = mysrc;
+    for (x = 0; x < dest_width_half; x++){
+      *(dest++) = *mysrc2;
+      mysrc2 += 2; /* skip one pixel */
+    }
+    mysrc += src_fmt->fmt.pix.bytesperline ; /* skip one line */
+  }
+}
+
 static void v4lconvert_crop_yuv420(unsigned char *src, unsigned char *dest,
   const struct v4l2_format *src_fmt, const struct v4l2_format *dest_fmt)
 {
@@ -79,10 +149,19 @@ void v4lconvert_crop(unsigned char *src, unsigned char *dest,
   switch (dest_fmt->fmt.pix.pixelformat) {
     case V4L2_PIX_FMT_RGB24:
     case V4L2_PIX_FMT_BGR24:
-      v4lconvert_crop_rgbbgr24(src, dest, src_fmt, dest_fmt);
+      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:
-      v4lconvert_crop_yuv420(src, dest, src_fmt, dest_fmt);
+      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 ee6ef33a0..536e5363d 100644
--- a/v4l2-apps/libv4l/libv4lconvert/libv4lconvert.c
+++ b/v4l2-apps/libv4l/libv4lconvert/libv4lconvert.c
@@ -268,29 +268,30 @@ int v4lconvert_try_format(struct v4lconvert_data *data,
     return result;
   }
 
-  /* In case of a non exact resolution match, see if this is a resolution we
-     can support by cropping a slightly larger resolution to give the app
-     exactly what it asked for */
+  /* 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 */
   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++) {
       if (v4lconvert_crop_res[i][0] == desired_width &&
 	  v4lconvert_crop_res[i][1] == desired_height) {
-	struct v4l2_format try2_dest, try2_src;
+	struct v4l2_format try2_src, try2_dest = *dest_fmt;
+
 	/* Note these are chosen so that cropping to vga res just works for
 	   vv6410 sensor cams, which have 356x292 and 180x148 */
-	unsigned int max_width = desired_width * 113 / 100;
-	unsigned int max_height = desired_height * 124 / 100;
-
-	try2_dest = *dest_fmt;
-	try2_dest.fmt.pix.width = max_width;
-	try2_dest.fmt.pix.height = max_height;
+	try2_dest.fmt.pix.width = desired_width * 113 / 100;
+	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 &&
-	    try2_dest.fmt.pix.width <= max_width &&
-	    try2_dest.fmt.pix.height >= desired_height &&
-	    try2_dest.fmt.pix.height <= max_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) ||
+	     (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 * 5 / 2))) {
 	  /* Success! */
 	  try2_dest.fmt.pix.width = desired_width;
 	  try2_dest.fmt.pix.height = desired_height;