Currently the MP3 file exceeds the limit set in wordpress. And Although I am going to raise that limit with some information I found on the topic, the Mp3s are still rather large. If the site were for me, I'd simply compress them. So I need to find a method to compress them. I assume it needs to save that large file, to transcode it to a smaller file, and then delete the old one. Any ideas?
I assume it needs to save that large file, to transcode it to a smaller file, and then delete the old one
This is correct. You always have to store the content first. Encoding should not be done via PHP though, there are more effective libraries for that. For example, you can run lame mp3 encoder on the command line via a system() call in php. Be aware though that encoding might fail and also that it takes quite long. So you should run a cleaner script for the big files via cron instead of trying to delete them via the upload script.