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Commit 79c6ff93 authored by Guennadi Liakhovetski's avatar Guennadi Liakhovetski Committed by Mauro Carvalho Chehab
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V4L/DVB: V4L2: add a generic function to find the nearest discrete format to the required one 



Many video drivers implement a fixed set of frame formats and thus face a task
of finding the best match for a user-requested format. Implementing this in a
generic function has also an advantage, that different drivers with similar
supported format sets will select the same format for the user, which improves
consistency across drivers.

Signed-off-by: default avatarGuennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab@redhat.com>
parent 45f4d4e8

drivers/media/video/v4l2-common.c

+24 −0
Original line number Diff line number Diff line
@@ -676,3 +676,27 @@ int v4l_fill_dv_preset_info(u32 preset, struct v4l2_dv_enum_preset *info) 
	return 0;

}

EXPORT_SYMBOL_GPL(v4l_fill_dv_preset_info);



struct v4l2_frmsize_discrete *v4l2_find_nearest_format(struct v4l2_discrete_probe *probe,

						       s32 width, s32 height)

{

	int i;

	u32 error, min_error = UINT_MAX;

	struct v4l2_frmsize_discrete *size, *best = NULL;



	if (!probe)

		return best;



	for (i = 0, size = probe->sizes; i < probe->num_sizes; i++, size++) {

		error = abs(size->width - width) + abs(size->height - height);

		if (error < min_error) {

			min_error = error;

			best = size;

		}

		if (!error)

			break;

	}



	return best;

}

EXPORT_SYMBOL_GPL(v4l2_find_nearest_format);

include/linux/videodev2.h

+8 −0
Original line number Diff line number Diff line
@@ -397,6 +397,14 @@ struct v4l2_frmsize_discrete { 
	__u32			height;		/* Frame height [pixel] */

};



struct v4l2_discrete_probe {

	const struct v4l2_frmsize_discrete	*sizes;

	int					num_sizes;

};



struct v4l2_frmsize_discrete *v4l2_find_nearest_format(struct v4l2_discrete_probe *probe,

						       s32 width, s32 height);



struct v4l2_frmsize_stepwise {

	__u32			min_width;	/* Minimum frame width [pixel] */

	__u32			max_width;	/* Maximum frame width [pixel] */