STLXML2EBU-TT: Bug in calculating teletext rows

[andreastai]

scf/modules/STLXML2EBU-TT/STLXML2EBU-TT.xslt

Lines 1043 to 1048 in dc839a1

	<!-- It is assumed here that
	1. all subtitle lines in a TextField are of the same height, either DoubleHeight or SingleHeight
	2. every newline-Element adds a new subtitle row -->
	<xsl:when test="count(child::*[name(.) = 'DoubleHeight']) &gt; 0">
	<xsl:value-of select="2 * (1 + count(child::*[name(.) = 'newline']))"/>
	</xsl:when>

The calculation of how many lines a subtitle covers does not consider that in some subtitle software, two consecutive DoubleHeight text lines in STL are separated by two newline control codes instead of one. Therefore a multi-line subtitle is pushed by too few calculated br elements to an incorrect Teletext line position

[andreastai]

See also the first note in EBU Tech 3360 on page 21.