Re: [PATCH] [resend] usbvision: disable scaling for Nogatech MicroCam

Em 22-07-2011 18:44, Ondrej Zary escreveu:

quoted

On Friday 22 July 2011 23:31:46 Devin Heitmueller wrote:

quoted

On Fri, Jul 22, 2011 at 5:22 PM, Ondrej Zary [off-list ref] wrote:

quoted

Seems that this bug is widespread - the same problem appears also in guvcview
and adobe flash. I think that the driver is broken too - it should return
corrected resolution in TRY_FMT.

Well, if the driver does not return the resolution it is actually
capturing in, then that indeed is a driver bug.  That's a different
issue though than what your patch proposed.

You should make the TRY_FMT call specifying an invalid resolution and
see if it returns the real resolution the device will capture at.  If
it doesn't, then fix *that* bug.

It does not, there's no code that would do that. I actually fixed that only
to find out that the scaling is unusable at least with the MicroCam because
of black horizontal lines that appear in the image (amount of the lines
depend on the scaling factor). So I just disabled the scaling completely for
MicroCam.

I also don't know if the multiple-of-64 width limit is valid for all
usbvision devices - that's why I haven't posted patch to fix this.

quoted

The application needs to know the capturing resolution, so it's
possible that it does properly handle the driver passing back the real
resolution and the driver is at fault, in which case no change is
needed to the app at all.

Well, for sure you don't need to touch at s_fmt, as it calls try_fmt. Also,
if the problem is that the scaler requrires that the vertical resolution to be
multiple of some limit, a patch like the one bellow would do a better job:

diff --git a/drivers/media/video/usbvision/usbvision-video.c b/drivers/media/video/usbvision/usbvision-video.c
index 5a74f5e..6907eff 100644
--- a/drivers/media/video/usbvision/usbvision-video.c
+++ b/drivers/media/video/usbvision/usbvision-video.c

@@ -922,6 +922,9 @@ static int vidioc_try_fmt_vid_cap(struct file *file, void *priv,
 	RESTRICT_TO_RANGE(vf->fmt.pix.width, MIN_FRAME_WIDTH, MAX_FRAME_WIDTH);
 	RESTRICT_TO_RANGE(vf->fmt.pix.height, MIN_FRAME_HEIGHT, MAX_FRAME_HEIGHT);
 
+	/* FIXME: please correct the minimum resolution here */
+	vf->fmt.pix.width &= ~0x01;
+
 	vf->fmt.pix.bytesperline = vf->fmt.pix.width*
 		usbvision->palette.bytes_per_pixel;
 	vf->fmt.pix.sizeimage = vf->fmt.pix.bytesperline*vf->fmt.pix.height;

Some scalers require an even vertical resolution. So, you'll need to adjust the
above, according with the restrictions you may have on the scaler your webcam
has.

Btw, V4L2 core defines a macro for such type of adjustments. For example,
em28xx uses it as:

		/* width must even because of the YUYV format
		   height must be even because of interlacing */
		v4l_bound_align_image(&width, 48, maxw, 1, &height, 32, maxh,
				      1, 0);

(

So, a better fix would be to remove the RESTRICT_TO_RANGE() calls, and use
the v4l_bound_align_image() macro instead, filled with the needed restrictions,
like:
	v4l_bound_align_image(&width, MIN_FRAME_WIDTH, MAX_FRAME_WIDTH, 1,
			      &height, MIN_FRAME_HEIGHT, MAX_FRAME_HEIGHT, 0);


-

[usbvision] Fix width/height scaling limits

It assumes that both just width is required to be even number.

NOT TESTED.

Signed-of-by: Mauro Carvalho Chehab [off-list ref]

diff --git a/drivers/media/video/usbvision/usbvision-video.c b/drivers/media/video/usbvision/usbvision-video.c
index 5a74f5e..41d3b47 100644
--- a/drivers/media/video/usbvision/usbvision-video.c
+++ b/drivers/media/video/usbvision/usbvision-video.c

@@ -919,8 +919,11 @@ static int vidioc_try_fmt_vid_cap(struct file *file, void *priv,
 	/* robustness */
 	if (format_idx == USBVISION_SUPPORTED_PALETTES)
 		return -EINVAL;
-	RESTRICT_TO_RANGE(vf->fmt.pix.width, MIN_FRAME_WIDTH, MAX_FRAME_WIDTH);
-	RESTRICT_TO_RANGE(vf->fmt.pix.height, MIN_FRAME_HEIGHT, MAX_FRAME_HEIGHT);
+
+	v4l_bound_align_image(&vf->fmt.pix.width,
+			      MIN_FRAME_WIDTH, MAX_FRAME_WIDTH, 1,
+			      &vf->fmt.pix.height,
+			      MIN_FRAME_HEIGHT, MAX_FRAME_HEIGHT, 0, 0);
 
 	vf->fmt.pix.bytesperline = vf->fmt.pix.width*
 		usbvision->palette.bytes_per_pixel;
--

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