Different line spacings for main text and footnotes in beamer

Question

In my beamer presentation, I want

• the main text to have a line spacing of 1.5,
• footnotes to have a line spacing of 1, both within them and between two consecutive footnotes.

Inserting \linespread{1.5} in the document's scope results in a line spacing of 1.5 in both main text and footnotes, which is undesirable.

I know that, generally, the preferred way of achieving the desired output is to load the setspace package and insert \setstretch{1.5} somewhere in the document's scope, but loading setspace seems to break beamer's \footnote. For instance, the following MWE does not produce any footnote:

\documentclass{beamer}

\usepackage{setspace}

\begin{document}
\begin{frame}
foo\footnote{bar}
\end{frame}
\end{document}

A workaround is to entirely eschew the setspace package and use \linespread to locally change the line spacing in footnotes, like so:

\documentclass{beamer}

\usepackage{lipsum}

\let\oldfootnote\footnote
\renewcommand\footnote[2][]{{\linespread{1}\oldfootnote[#1]{#2}}}
\linespread{1.5}

\begin{document}
\begin{frame}
foo\footnote{\lipsum[2]}\\
bar\footnote{sdfsdf}
\end{frame}
\end{document}

which produces the desired line spacing (1) within footnotes, but not between them:

What should I do to produce the desired output?

Answer 1

It's a design feature. T. Tantau defends the opinion that there should not be a footnote on a slide. Stuff that is not inline with his view is usually difficult to do in beamer and many macros are overwritten accordingly. To be honest I agree with him after suffering from undescribable pain in many conferences. Funny thing is that most people are driving beamer to act like PowerPoint which is interesting to see.

\documentclass{beamer}
\usepackage{setspace}

\setbeamertemplate{footnote}%
{%
  \parindent 1em\noindent%
  \raggedright\setstretch{1}%
  \hbox to 1.8em{\hfil\insertfootnotemark}\insertfootnotetext\par%
}

\begin{document}
\setstretch{1.5}
\begin{frame}

foo\footnote[frame]{bar}\par
foobar

\vspace{2cm}

\begin{minipage}{.5\textwidth}
foo\footnote{bar}

bar\footnote[frame]{Nam dui ligula, fringilla a, euismod sodales, sollicitudin vel, 
wisi. Morbi auctor lorem non justo. Nam lacus libero, pretium at, lobortis vitae, 
ultricies et, tellus. Donec aliquet, tortor sed accumsan bibendum, erat ligula 
aliquet magna, vitae ornare odio metus a mi. Morbi ac orci et nisl hendrerit mollis.}
\end{minipage}

\end{frame}
\end{document}

Answer 2

The accepted answer did not work for me at all, as all my footnotes kept disappearing as soon as I used the setspace package. I managed to get a simpler solution by combining this answer and footfullcite not working when package setspace is present

\documentclass{beamer}


\setbeamertemplate{footnote}%
{%
  \parindent 1em\noindent%
  \raggedright\linespread{1}\selectfont%
  \hbox to 1.8em{\hfil\insertfootnotemark}\insertfootnotetext\par%
}

\linespread{1.5}

\begin{document}
\begin{frame}

foo\footnote[frame]{bar}\par
foobar
\vspace{2cm}

\begin{minipage}{.5\textwidth}
foo\footnote{bar}

bar\footnote[frame]{Nam dui ligula, fringilla a, euismod sodales, sollicitudin vel, 
wisi. Morbi auctor lorem non justo. Nam lacus libero, pretium at, lobortis vitae, 
ultricies et, tellus. Donec aliquet, tortor sed accumsan bibendum, erat ligula 
aliquet magna, vitae ornare odio metus a mi. Morbi ac orci et nisl hendrerit mollis.}
\end{minipage}

\end{frame}
\end{document}