An introduction to computer audio
You have your music on your PC but you also want it on a portable.
Often people do so by maintaining 2 libraries say one in lossless e.g. FLAC and a copy in MP3 for the portable.
You better look for a media player supporting transcoding.
Regardless of the format of the audio, when you connect a media player, all audio is converted on the fly to a format supported by the portable.
Transcoding relieves you of the burden to maintain duplicate libraries.
Your audio collection probably won’t fit on your portable so the sync will fail.
The trick is to make a play list and use this for the synchronization.
Well-designed media players allow you to do so.