PlumePack

Can I transcode my media with PlumePack ?

No, PlumePack can only copy or Trim your media. By Trimming, you keep the same codec, metadata and pixel quality.
However, you can use PlumePack to clean/filter your project first (because it gives you better features than the native Project Manager for that) and select the "No Process" Main Media Process. Then use the native Project Manager to transcode your cleaned project !