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V4L/DVB: V4L2: add a generic function to find the nearest discrete format to the required one

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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: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
This commit is contained in:
Guennadi Liakhovetski 2010-08-27 13:41:44 -03:00 committed by Mauro Carvalho Chehab
parent 45f4d4e879
commit 79c6ff93c7
2 changed files with 32 additions and 0 deletions
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24
drivers/media/video/v4l2-common.c
View File

@ -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);

8
include/linux/videodev2.h
View File

@ -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] */