To play some old flash animations I need a flash player for ubuntu 20.04. I was used to use Gnash, but this is no longer shipped with ubuntu. So I tried to compile it by myself, i.e. cloned the git repository, did ./autogen.sh, ./configure and tried to install all missing libraries. That worked except for:

ERROR: GST media handling requested but gstreamer-0.10+ not found

                 Install it from http://www.gstreamer.net

                 or .deb users: apt-get install libgstreamer0.10-dev

                 or .rpm users: yum install gstreamer-devel

                 or yast users: yast install gstreamer010-devel

ERROR: Base plugins are required for gstreamer media!

       Install gstreamer-plugins-base from http://www.gstreamer.net

       or .deb users: apt-get install 

                      libgstreamer-plugins-base0.10-dev

       or .rpm users: yum install gstreamer-plugins-base-devel

ERROR: No xulrunner development package is installed!

       Install it from 

       http://releases.mozilla.org/pub/mozilla.org/xulrunner

       or .deb users: apt-get install xulrunner-dev

       or maybe     : apt-get install npapi-sdk-dev

       or maybe     : apt-get install firefox-dev

       or .rpm users: yum install xulrunner-devel

       or specify --disable-npapi

For the last one I didn't find a xulrunner-dev or an npapi-dev package in the ubuntu repositories, but installed firefox-dev. This didn't work, so I used --disable-npapi.

For the gstreamer plugins I installed the version 1.0 instead. But if I do make I get the following error message:

make  all-recursive

make[1]: Entering directory '/home/myuser/build/gnash'

Making all in desktop

make[2]: Entering directory '/home/myuser/build/gnash/desktop'

make[2]: Nothing to be done for 'all'.

make[2]: Leaving directory '/home/myuser/build/gnash/desktop'

Making all in libdevice

make[2]: Entering directory '/home/myuser/build/gnash/libdevice'

make[2]: Nothing to be done for 'all'.

make[2]: Leaving directory '/home/myuser/build/gnash/libdevice'

Making all in libbase

make[2]: Entering directory '/home/myuser/build/gnash/libbase'

sed -e 's|@DEFAULT_FLASH_PLATFORM_ID[@]|LNX|g' -e 's|@DEFAULT_FLASH_MAJOR_VERSION[@]|10|g' -e 's|@DEFAULT_FLASH_MINOR_VERSION[@]|1|g' -e 's|@DEFAULT_FLASH_REV_NUMBER[@]|999|g' -e 's|@DEFAULT_STREAMS_TIMEOUT[@]|60|g' -e 's|@DEFAULT_SOL_SAFEDIR[@]|~/.gnash/SharedObjects|g'  './gnashrc.in' >gnashrc

make[2]: Leaving directory '/home/myuser/build/gnash/libbase'

Making all in libmedia

make[2]: Entering directory '/home/myuser/build/gnash/libmedia'

  CXX      libgnashmedia_la-AudioDecoderGst.lo

In file included from gst/AudioDecoderGst.cpp:20:

gst/AudioDecoderGst.h:27:10: fatal error: gst/gst.h: No such file or directory

   27 | #include <gst/gst.h>

      |          ^~~~~~~~~~~

compilation terminated.

make[2]: *** [Makefile:1126: libgnashmedia_la-AudioDecoderGst.lo] Error 1

make[2]: Leaving directory '/home/myuser/build/gnash/libmedia'

make[1]: *** [Makefile:1163: all-recursive] Error 1

make[1]: Leaving directory '/home/myuser/build/gnash'

make: *** [Makefile:1071: all] Error 2

So how can I make gnash work on ubuntu 20.04.?