$ pacman -Qs mpv
local/mpv 1:0.33.1-1.0
    a free, open source, and cross-platform media player
$ pacman -Qs srt
local/srt 1.4.3-1.0
    Secure Reliable Transport library
$ pacman -Fl srt | grep libsrt
srt usr/lib/libsrt.so
srt usr/lib/libsrt.so.1.4
srt usr/lib/libsrt.so.1.4.3
$ mpv
mpv: error while loading shared libraries: libsrt.so.1: cannot open shared object file: No such file or directory
$ ldd /usr/bin/mpv | grep srt
	libsrt.so.1 => not found
$ sudo ln -s /usr/lib/libsrt.so.1.4.3 /usr/lib/libsrt.so.1
$ mpv --version
mpv 0.33.1-dirty Copyright © 2000-2020 mpv/MPlayer/mplayer2 projects
 built on UNKNOWN
FFmpeg library versions:
   libavutil       56.51.100
   libavcodec      58.91.100
   libavformat     58.45.100
   libswscale      5.7.100
   libavfilter     7.85.100
   libswresample   3.7.100
FFmpeg version: n4.3.2

$ ldd /usr/bin/mpv | grep srt
	libsrt.so.1 => /usr/lib/libsrt.so.1 (0xb2a54000)

Running ldconfig does not create the missing symlink.

Here’s 1:0.33.1-1.0-pentium4:

$ pacman -Qs mpv
local/mpv 1:0.33.1-1.0
    a free, open source, and cross-platform media player

$ mpv --version
mpv 0.33.1-dirty Copyright © 2000-2020 mpv/MPlayer/mplayer2 projects
 built on UNKNOWN
FFmpeg library versions:
   libavutil       56.51.100
   libavcodec      58.91.100
   libavformat     58.45.100
   libswscale      5.7.100
   libavfilter     7.85.100
   libswresample   3.7.100
FFmpeg version: n4.3.2

Here’s 1:0.33.1-2.0-pentium4:

$ pacman -Qs mpv
local/mpv 1:0.33.1-2.0
    a free, open source, and cross-platform media player

$ mpv --msg-level=all=trace --version
libavutil: 56.70.100 -> 56.51.100
Aborted (core dumped)

Looks to me like it might be a library version thing (I’m up-to-date according to

pacman -Syu

), but I’ve only been running Arch32 for 24 hours so I’m not sure where further to dig.