Re: [PATCH 3/5] [media] v4l: simulate old crop API using extended crop/compose API

Tomasz Stanislawski <t.stanislaws@xxxxxxxxxxx> · Wed, 28 Sep 2011 12:27:19 +0200

Hi Hans,

On 09/27/2011 11:30 AM, Hans Verkuil wrote:
On Friday, August 26, 2011 15:06:05 Tomasz Stanislawski wrote:
This patch allows new video drivers to work correctly with applications that
use the old-style crop API.  The old crop ioctl is simulated by using selection
callbacks.

Signed-off-by: Tomasz Stanislawski<t.stanislaws@xxxxxxxxxxx>
Signed-off-by: Kyungmin Park<kyungmin.park@xxxxxxxxxxx>
---
  drivers/media/video/v4l2-ioctl.c |   86 +++++++++++++++++++++++++++++++++----
  1 files changed, 76 insertions(+), 10 deletions(-)

diff --git a/drivers/media/video/v4l2-ioctl.c b/drivers/media/video/v4l2-ioctl.c
index 6e02b45..543405b 100644
--- a/drivers/media/video/v4l2-ioctl.c
+++ b/drivers/media/video/v4l2-ioctl.c
@@ -1696,11 +1696,31 @@ static long __video_do_ioctl(struct file *file,
  	{
  		struct v4l2_crop *p = arg;

-		if (!ops->vidioc_g_crop)
+		dbgarg(cmd, "type=%s\n", prt_names(p->type, v4l2_type_names));
+
+		if (ops->vidioc_g_crop) {
+			ret = ops->vidioc_g_crop(file, fh, p);
+		} else
+		if (ops->vidioc_g_selection) {
+			/* simulate capture crop using selection api */
+			struct v4l2_selection s = {
+				.type = p->type,
+				.target = V4L2_SEL_CROP_ACTIVE,
+			};
+
+			/* crop means compose for output devices */
+			if (p->type == V4L2_BUF_TYPE_VIDEO_OUTPUT)
+				s.target = V4L2_SEL_COMPOSE_ACTIVE;
+
+			ret = ops->vidioc_g_selection(file, fh,&s);
+
+			/* copying results to old structure on success */
+			if (!ret)
+				p->c = s.r;
+		} else {
  			break;
+		}

-		dbgarg(cmd, "type=%s\n", prt_names(p->type, v4l2_type_names));
-		ret = ops->vidioc_g_crop(file, fh, p);
  		if (!ret)
  			dbgrect(vfd, "",&p->c);
  		break;
@@ -1709,11 +1729,26 @@ static long __video_do_ioctl(struct file *file,
  	{
  		struct v4l2_crop *p = arg;

-		if (!ops->vidioc_s_crop)
-			break;
  		dbgarg(cmd, "type=%s\n", prt_names(p->type, v4l2_type_names));
  		dbgrect(vfd, "",&p->c);
-		ret = ops->vidioc_s_crop(file, fh, p);
+
+		if (ops->vidioc_s_crop) {
+			ret = ops->vidioc_s_crop(file, fh, p);
+		} else
+		if (ops->vidioc_s_selection) {
+			/* simulate capture crop using selection api */
+			struct v4l2_selection s = {
+				.type = p->type,
+				.target = V4L2_SEL_CROP_ACTIVE,
+				.r = p->c,
+			};
+
+			/* crop means compose for output devices */
+			if (p->type == V4L2_BUF_TYPE_VIDEO_OUTPUT)
+				s.target = V4L2_SEL_COMPOSE_ACTIVE;
+
+			ret = ops->vidioc_s_selection(file, fh,&s);
+		}
  		break;
  	}
  	case VIDIOC_G_SELECTION:
@@ -1746,12 +1781,43 @@ static long __video_do_ioctl(struct file *file,
  	{
  		struct v4l2_cropcap *p = arg;

-		/*FIXME: Should also show v4l2_fract pixelaspect */
-		if (!ops->vidioc_cropcap)
+		dbgarg(cmd, "type=%s\n", prt_names(p->type, v4l2_type_names));
+		if (ops->vidioc_cropcap) {
+			ret = ops->vidioc_cropcap(file, fh, p);
+		} else
+		if (ops->vidioc_g_selection) {
+			struct v4l2_selection s = { .type = p->type };
+			struct v4l2_rect bounds;
+
+			/* obtaining bounds */
+			if (p->type == V4L2_BUF_TYPE_VIDEO_OUTPUT)
+				s.target = V4L2_SEL_COMPOSE_BOUNDS;
+			else
+				s.target = V4L2_SEL_CROP_BOUNDS;
+			ret = ops->vidioc_g_selection(file, fh,&s);
+			if (ret)
+				break;
+			bounds = s.r;
+
+			/* obtaining defrect */
+			if (p->type == V4L2_BUF_TYPE_VIDEO_OUTPUT)
+				s.target = V4L2_SEL_COMPOSE_DEFAULT;
+			else
+				s.target = V4L2_SEL_CROP_DEFAULT;
+			ret = ops->vidioc_g_selection(file, fh,&s);
+			if (ret)
+				break;
+
+			/* storing results */
+			p->bounds = bounds;
+			p->defrect = s.r;
+			p->pixelaspect.numerator = 1;
+			p->pixelaspect.denominator = 1;
+		} else {
  			break;
+		}

-		dbgarg(cmd, "type=%s\n", prt_names(p->type, v4l2_type_names));
-		ret = ops->vidioc_cropcap(file, fh, p);
+		/*FIXME: Should also show v4l2_fract pixelaspect */

We really need a solution for this. I'm not happy that this hasn't been
resolved yet.

What about this: if ops->vidioc_g_selection is non-NULL, then fill in bounds
and defrect as above. But also call ops->vidioc_cropcap at the end if non-NULL,
so that the driver can fill in the pixelaspect.

So the code would look like this:

	if (ops->vidioc_g_selection) {
		fill in bounds and defrect and set pixelaspect to 1, 1
	}
	if (ops->vidioc_cropcap)
		ops->vidioc_cropcap();

If a driver supports g_selection, then cropcap only needs to fill in the
pixelaspect.

If cropcap ioctl is missing there is no way to obtain pixelaspect from 
the driver, so 1/1 value is used. On the other hand, if cropcap is 
present there is no need to call g_selection calls to get defrect and 
bounds.

I think that there is a problem with pixel aspect field. Please refer to 
post:

http://thread.gmane.org/gmane.linux.drivers.video-input-infrastructure/38440/focus=38730

The idea was to move pixelaspect to v4l2_standard. The value would be 
selected from look-up table using standard returned by vidioc_g_std or 
using 1/1 is no analog TV is used. It should work well because majority 
of drivers use 1/1 value. Only some TV drivers behaves differently 
returning values depending on refresh rate that depends only on TV standard.

What do think about this idea?

Best regards,
Tomasz Stanislawski


  		if (!ret) {
  			dbgrect(vfd, "bounds ",&p->bounds);
  			dbgrect(vfd, "defrect ",&p->defrect);


And let's show the pixelaspect here as well.

Does this sounds reasonable?

Regards,

	Hans

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