/usr/include/alsaplayer/ is in libalsaplayer-dev 0.99.81-1+b1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/alsaplayer/AlsaNode.h
/usr/include/alsaplayer/AlsaPlayer.h
/usr/include/alsaplayer/AlsaSubscriber.h
/usr/include/alsaplayer/CorePlayer.h
/usr/include/alsaplayer/Effects.h
/usr/include/alsaplayer/Playlist.h
/usr/include/alsaplayer/SampleBuffer.h
/usr/include/alsaplayer/alsaplayer_error.h
/usr/include/alsaplayer/control.h
/usr/include/alsaplayer/input_plugin.h
/usr/include/alsaplayer/interface_plugin.h
/usr/include/alsaplayer/output_plugin.h
/usr/include/alsaplayer/prefs.h
/usr/include/alsaplayer/reader.h
/usr/include/alsaplayer/scope_plugin.h
/usr/include/alsaplayer/stream_info.h
/usr/include/alsaplayer/utilities.h