\NeedsTeXFormat{LaTeX2e}
\documentclass[10pt,twoside]{letter}
\usepackage{geometry}
\geometry{a4paper,noheadfoot,nomarginpar,left=1.5cm,right=1.5cm,top=1.5cm,bottom=1.5cm,}
\usepackage{fontspec}
\defaultfontfeatures{Ligatures=TeX}
\usepackage{polyglossia}
\setdefaultlanguage[spelling=old]{german}
\setmainfont{CMU Serif}
\setsansfont{CMU Sans Serif}
\setmonofont{CMU Typewriter Text}
\usepackage{graphicx}
\usepackage{luatex}
\pdfcompresslevel=9

% lualatex and lilypond mixed in one file
%
% tex, lilypond headers and lyrics use the same fonts.
%
% lyrics fontsize matches the fontsize of the TeX \normalsize.
%
% Use lualatex --shell-escape lilyinluatex to generate pdf.
%
% lualatex will
%   write tmplily.ly,
%   call lilypond to generate tmplily.pdf
%   call pdfcrop to remove extra white space
%

\def\tmplilyname{tmplily.ly }
\def\tmppdfname{tmplily.pdf }
\def\lilycommand{lilypond }

\newwrite\tmplilyfile

{
  \catcode`|=0 \catcode`[=1 \catcode`]=2
  \catcode`\{=12 \catcode`\}=12 \catcode`\\=12
  |gdef|eolily[\end{lilypage}]
]

\obeylines
\def\doline#1
{
  \def\oneline{#1}
  \ifx\oneline\eolily
     \def\next{\end{lilypage}}
  \else
     \immediate\write\tmplilyfile{\oneline}
     \let\next\doline
  \fi
  \next%
}

\makeatletter
\newenvironment{lilypage}[1]{
  \gdef\lilypdf{#1}
  \immediate\openout\tmplilyfile=\tmplilyname
  address@hidden
}{
  \immediate\closeout\tmplilyfile
  \immediate\write18{\lilycommand \tmplilyname}%
  \immediate\write18{pdfcrop \tmppdfname \lilypdf}%
}

\makeatother

\begin{document}
\pagestyle{empty}

Remember to use \verb+lualtex --shell-escape example.tex+

\begin{lilypage}{example1.pdf}
\version "2.18.2"
\include "deutsch.ly"
#(set! paper-alist (cons '("mySize" . (cons (* 10 cm) (* 4.5 cm))) paper-alist))

\paper {
  #(set-paper-size "mySize") left-margin = 0\cm top-margin = 0\cm bottom-margin = 0\cm 
  line-width = \paper-width indent = 0 page-count = #1 
  ragged-bottom = ##f ragged-last-bottom = ##f annotate-spacing=##f
}

\header {
  title = \markup { \override #'(font-name . "CMU Serif Bold") "Macht hoch die Tür" }
  subtitle = \markup { \override #'(font-name . "CMU Serif Bold") "Only an example" }
  tagline = ##f
}

#(set-global-staff-size 17)
allowGrobCallback = #(define-scheme-function (parser location syms) (symbol-list?)
  (let ((interface (car syms)) (sym (cadr syms))) #{ \with { \consists #(lambda (context)
  `((acknowledgers . ((,interface . ,(lambda (engraver grob source-engraver)
  (let ((prop (ly:grob-property grob sym))) (if (procedure? prop) 
  (ly:grob-set-property! grob sym (prop grob))))))))))}#}))

absFontSize = #(define-scheme-function (parser location pt)(number?)
  (lambda (grob) (let* ((layout (ly:grob-layout grob))
  (ref-size (ly:output-def-lookup (ly:grob-layout grob) 'text-font-size 12)))
  (magnification->font-size (/ pt ref-size))))) 

\score {
  <<
    \new Voice = "Melody" \relative g'{
      \key es \major \time 6/4 \partial 4
      g4 b2 as4 g2 f4 es (f) g f2 \breathe \bar"" \break
      b4 as2 as4 g2 g4 f (es) f es2 \breathe
    }
    \new Lyrics \lyricsto "Melody" {
      \set stanza = "1."
      Macht hoch die Tür, die Tor macht weit;
      es kommt der Herr der Herr -- lich -- keit,
    }
  >>
  \layout {
    \context {
      \Score
      \allowGrobCallback font-interface.font-size
      \omit BarNumber
    }
    \override LyricText.font-size = \absFontSize #10
    \override Lyrics.LyricText  #'font-name = #"CMU Serif"
    \override StanzaNumber.font-name = #"CMU Serif Extra"
    \override StanzaNumber.font-size = \absFontSize #10
  }
}
\end{lilypage}

\includegraphics{\lilypdf} 

\end{document}