libv4l: crop widths to the nearest multiple of 8 when converting to YUV420

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

Some applications / libs (*cough* gstreamer *cough*) will not work
correctly with planar YUV formats when the width is not a multiple of 8,
so crop widths which are not a multiple of 8 to the nearest multiple of 8
when converting to planar YUV

Priority: normal

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

2 files changed, 26 insertions, 0 deletions

diff --git a/v4l2-apps/libv4l/ChangeLog b/v4l2-apps/libv4l/ChangeLog
index b1f4c3a22..e60ccdbb2 100644
--- a/v4l2-apps/libv4l/ChangeLog
+++ b/v4l2-apps/libv4l/ChangeLog
@@ -16,6 +16,10 @@ libv4l-0.5.97
   can then change the settings using a v4l2 control panel like v4l2ucp
 * Only report / allow supported destination formats in enum_fmt / try_fmt /
   g_fmt / s_fmt when processing, rotating or flipping.
+* Some applications / libs (*cough* gstreamer *cough*) will not work
+  correctly with planar YUV formats when the width is not a multiple of 8,
+  so crop widths which are not a multiple of 8 to the nearest multiple of 8
+  when converting to planar YUV
 * Add dependency generation to libv4l by: Gilles Gigan <gilles.gigan@gmail.com>
 * Add support to use orientation from VIDIOC_ENUMINPUT by:
   Adam Baker <linux@baker-net.org.uk>
diff --git a/v4l2-apps/libv4l/libv4lconvert/libv4lconvert.c b/v4l2-apps/libv4l/libv4lconvert/libv4lconvert.c
index 2e029a81c..39e9d8669 100644
--- a/v4l2-apps/libv4l/libv4lconvert/libv4lconvert.c
+++ b/v4l2-apps/libv4l/libv4lconvert/libv4lconvert.c
@@ -398,6 +398,21 @@ int v4lconvert_try_format(struct v4lconvert_data *data,
     }
   }
 
+  /* Some applications / libs (*cough* gstreamer *cough*) will not work
+     correctly with planar YUV formats when the width is not a multiple of 8
+     or the height is not a multiple of 2 */
+  if (try_dest.fmt.pix.pixelformat == V4L2_PIX_FMT_YUV420 ||
+      try_dest.fmt.pix.pixelformat == V4L2_PIX_FMT_YVU420) {
+    try_dest.fmt.pix.width &= ~7;
+    try_dest.fmt.pix.height &= ~1;
+  }
+
+  /* Likewise the width needs to be a multiple of 4 for RGB formats
+     (although I've never seen a device with a width not a multiple of 4) */
+  if (try_dest.fmt.pix.pixelformat == V4L2_PIX_FMT_RGB24 ||
+      try_dest.fmt.pix.pixelformat == V4L2_PIX_FMT_BGR24)
+    try_dest.fmt.pix.width &= ~3;
+
   /* Are we converting? */
   if(try_src.fmt.pix.width != try_dest.fmt.pix.width ||
      try_src.fmt.pix.height != try_dest.fmt.pix.height ||
@@ -1083,6 +1098,13 @@ int v4lconvert_enum_framesizes(struct v4lconvert_data *data,
   switch(frmsize->type) {
     case V4L2_FRMSIZE_TYPE_DISCRETE:
       frmsize->discrete = data->framesizes[frmsize->index].discrete;
+      /* Apply the same rounding algorithm as v4lconvert_try_format */
+      if (frmsize->pixel_format == V4L2_PIX_FMT_YUV420 ||
+	  frmsize->pixel_format == V4L2_PIX_FMT_YVU420) {
+	frmsize->discrete.width &= ~7;
+	frmsize->discrete.height &= ~1;
+      } else
+	frmsize->discrete.width &= ~3;
       break;
     case V4L2_FRMSIZE_TYPE_CONTINUOUS:
     case V4L2_FRMSIZE_TYPE_STEPWISE: