usege of v4lconvert_try_format is wrong

[nomaddo]

actfw-core/actfw_core/v4l2/video.py

Lines 548 to 574 in 563c2c5

	def try_convert(self, conf, expected_width, expected_height, expected_format):
	fmt = format()
	fmt.type = V4L2_BUF_TYPE.VIDEO_CAPTURE
	fmt.fmt.pix.width = conf.width
	fmt.fmt.pix.height = conf.height
	fmt.fmt.pix.pixelformat = conf.pixel_format
	fmt.fmt.pix.field = V4L2_FIELD.INTERLACED
	expected_fmt = format()
	expected_fmt.type = V4L2_BUF_TYPE.VIDEO_CAPTURE
	expected_fmt.fmt.pix.width = expected_width
	expected_fmt.fmt.pix.height = expected_height
	expected_fmt.fmt.pix.pixelformat = expected_format
	expected_fmt.fmt.pix.field = V4L2_FIELD.INTERLACED
	result = _v4lconvert.try_format(self.converter, byref(expected_fmt), byref(fmt))
	if -1 == result:
	raise RuntimeError("incompatible format")
	before = (expected_width, expected_height, expected_format)
	after = (expected_fmt.fmt.pix.width, expected_fmt.fmt.pix.height, expected_fmt.fmt.pix.pixelformat)
	if before == after:
	return (fmt, expected_fmt)
	else:
	return None

The header file says:

https://github.com/philips/libv4l/blob/master/include/libv4lconvert.h#L63-L75

The function v4lconvert_try_format is not for check whether we can convert pictures from src_fmt to dest_fmt:
The function is to get src_fmt which we finally get dest_fmt.

[nomaddo]

And, v4lconvert_try_format may change dest_fmt.
The checking is lack.