nseries

Which is the best quality audio file format for nokia Nseries devices.... .aac or .m4a recently i copied/converted some mp3 files 2 my N82...but some files were not converted/copied resulting an error msg dat "the following files were not converted because either they r already in following...

I transferred the nokia nseries 'In my heart' from a friends n73 to my 5700 xm.As i thought my phone was unable to play the received file,due to nonavailability of key. Also the file is in .dcf format.What is this format.Help me to play this file on phone & pc. If you think this is...