I'll be doing video projects soon where the end result will be posted to the web (YouTube, Vimo, etc).
I'm taking great pains to ensure the VO is compressed so the peaks are even and I can utilize the available headroom properly.
However, the show will have an intro and a logo sting at the end. Each piece of footage has audio loops that were purchased from the Envato Marketplace (a community for audio professionals to sell their work).
My question is this:
I'll be using my audio program to uniformly bring all the audio sources to the same level of "perceived loudness" (my intro music, the actual show featuring the vocal track I have already mixed and the tag/logo sting at the end).
However, should I take these 3rd party audio sources at the beginning and the end into my audio program and compress them first to even out the dynamics to ensure everything is even? My program says it accounts for "perceived loudness" when evening out the levels.
I just want everything to sound as if it were mixed all together, in the same session, and not three different sources...as it actually is.
I think that you might want to leave the music mix as is, other than just matching levels with the VO. If the music came from a production source - which it sounds as if it did - my guess is that there is already compression on it.
I would just put together a rough audio mix with everything in place, then sit there with my eyes closed, and headphones on (or near-field monitors if you've got them), and tweak levels until it sounds right. Just an opinion - that's how I'd do it. You might want to try a second mix if you've got the time, with compression on the music, then A/B them to see which one you like best. It's really a matter of preference, I think.
Here's an interesting read on audio compression - somewhere in there he warns about compressing music which is already compressed: