[Tex/LaTex] How to align text on Beamer titlepage

Question

I am creating a presentation for a thesis defense, and want to align a certain part of text on my title slide.

If I use the following

\documentclass{beamer}
\let\Tiny=\tiny 

\usepackage[utf8]{inputenc}
\usepackage[english]{babel}

\title{This is a long title which goes over two rows}
\author{
My name\\ 
\vspace{0.25cm}
Something else \\
\vspace{0.5cm}
{\footnotesize Chair: Prof.~Dr.~Hix}\\
{\footnotesize 1. Co-chair: Dr.~Dr.~Dr.~Frankenstein}\\
{\footnotesize 2. Co-chair: Prof.~Dr.~X}
\\
\vspace{0.5cm}
University\\
\vspace{0.25cm}
May 13, 2016
}
\date{ }
\titlegraphic{
 \texorpdfstring{\vspace{-1.25cm}}{}
 \begin{minipage}[b][1.3cm][b]{\textwidth}
 some logos 
 \end{minipage}
}

\begin{document}

\frame{ 
\titlepage
}

\end{document}

I get a standard titlepage that looks like this:

Now, I want to align the middle text part (list of chairs), so I tried the following:

\title{This is a long title which goes over two rows}
\author{
My name\\ 
\vspace{0.25cm}
Something else \\
\vspace{0.5cm}
\begin{tabular}{l@{ }l}
Chair:& Prof.~Dr.~Hix\\
1. Co-chair:& Dr.~Dr.~Dr.~Frankenstein\\
2. Co-chair:& Prof.~Dr.~X
\end{tabular}
\\
\vspace{0.5cm}
University \\
\vspace{0.25cm}
May 13, 2016
}
\date{ }
\titlegraphic{
 \texorpdfstring{\vspace{-1.25cm}}{}
 \begin{minipage}[b][1.3cm][b]{\textwidth}
 some logos 
 \end{minipage}
}

which, however, only gives a bunch of errors. Strangely, placing the tabular environment into the \institute field works as intended.

\title{This is a long title which goes over two rows}
\author{
My name\\ 
\vspace{0.25cm}
Something else \\
\vspace{0.5cm}
University \\
\vspace{0.25cm}
May 13, 2016
}
\date{ }
\institute{
\begin{tabular}{r@{ }l}
Chair:& Prof.~Dr.~Hix\\
1. Co-chair:& Dr.~Dr.~Dr.~Frankenstein\\
2. Co-chair:& Prof.~Dr.~X
\end{tabular}
}
\titlegraphic{
 \texorpdfstring{\vspace{-1.25cm}}{}
 \begin{minipage}[b][1.3cm][b]{\textwidth}
 some logos 
 \end{minipage}
}

and looks like this:

So, how can I achieve the placement from the first picture, but with the alignment as in the second one?

Answer 1

\author is an special command which could not accept all kind of contents. In you particular case I'd suggest to define a customized title page template where you can insert what you want.

I've taken \defbeamertemplate*{title page}... from beamerinnerthemedefault.sty (change it according your theme) and copied it into your preamble. \defbeamertemplate has been changed to \setbeamertemplate and a new beamercolorbox with chairs has been inserted between author box and institute box. You can change its contents and format as you want.

\documentclass{beamer}
\let\Tiny=\tiny 

\usepackage[utf8]{inputenc}
\usepackage[english]{babel}

\makeatletter
\setbeamertemplate{title page}
{
  \vbox{}
  \vfill
  \begingroup
    \centering
    \begin{beamercolorbox}[sep=8pt,center]{title}
      \usebeamerfont{title}\inserttitle\par%
      \ifx\insertsubtitle\@empty%
      \else%
        \vskip0.25em%
        {\usebeamerfont{subtitle}\usebeamercolor[fg]{subtitle}\insertsubtitle\par}%
      \fi%     
    \end{beamercolorbox}%
    \vskip1em\par
    \begin{beamercolorbox}[sep=8pt,center]{author}
      \usebeamerfont{author}\insertauthor
    \end{beamercolorbox}
    \begin{beamercolorbox}[sep=8pt,center]{author}
      \usebeamerfont{institute}\begin{tabular}{r@{}l}
Chair:& Prof.~Dr.~Hix\\
1. Co-chair:& Dr.~Dr.~Dr.~Frankenstein\\
2. Co-chair:& Prof.~Dr.~X
\end{tabular}
    \end{beamercolorbox}      
    \begin{beamercolorbox}[sep=8pt,center]{institute}
      \usebeamerfont{institute}\insertinstitute
    \end{beamercolorbox}
    \begin{beamercolorbox}[sep=8pt,center]{date}
      \usebeamerfont{date}\insertdate
    \end{beamercolorbox}\vskip0.5em
    {\usebeamercolor[fg]{titlegraphic}\inserttitlegraphic\par}
  \endgroup
  \vfill
}
\makeatother

\title{This is a long title which goes over two rows}
\author{
My name\\ 
\vspace{0.25cm}
Something else 
}
\institute{University}
\date{\today}

\titlegraphic{
 \texorpdfstring{\vspace{-1.25cm}}{}
 \begin{minipage}[b][1.3cm][b]{\textwidth}
 some logos 
 \end{minipage}
}

\begin{document}

\frame{ 
\titlepage
}

\end{document}

The result looks like: