Heavy Memory Usage

[Balder86]

Describe the bug
Since the readme section heavy-memory-usage seemed a bit lost, I did some debugging to narrow the issue down.

I'm running the jellyfin-mpv-shim on linux with the external player option.

To create the bloat:

1. start the shim -> ~50M usage
2. play high bitrate 4k media -> 1300M usage
3. close the player -> 1000M usage
4. play high bitrate 4k media -> 1600M usage
5. close the player -> 1400M usage
6. repeat and grow
   (playing the same video again also lets the bloat grow)

That bloat directly correlates to the mpv demuxer-max-bytes setting. I was using 500M. With a decreased size (100M) the bloat is much smaller - but still the behavior of endless growth persists.

• the memory is directly assigned to the mpv proccess
• I tried various reset attempts via IPC to force mpv to release, only "stop" worked ...
• I played around with malloc and jemalloc but with no success

I hope that description lets you developers reproduce the "heavy-memory-usage" issue.
Besides that, thank you for the project :)