Just found out how to nightcore with FL Studio and how to avoid killing the quality even when the tempo and pitch do not match.
The following sample is Clutch feat. Beha - The Light (Edit), the goal is to add 33% in pitch and 20% in tempo.https://drive.google.com/folderview?id=0B151yw6KLtfGfjc2ZXhkQXNpTGtFUlIwMmh6OXBWWnRuY05keGhVbTVFZmlqZFJhX3lsRXM&usp=sharing
1 The Light (Edit).mp3 is the original
2 Audacity 52920 11.1111Pitch is used Audacity to set the rate to 52920 (120% to 44100), then add 11.1111 in Change Pitch. Not sure how to describe it, messed the bass drum/doubled bass drum? Older fan made nightcore tend to be having more of this issue.
3 WavePad 120Speed and Pitch 11.1111Pitch.mp3, 120 Speed and Pitch change then add 11.1111 to Pitch. No more double bass drum but muffled.
4 VDJ 33Keylock 20Tempo.mp3, the best result before FL, slide the pitch bar to 33%, toggle key lick, slide the pitch bar to 20%, so the pitch is 33% and the tempo is 20%, no muffled bass drum but still has some doubled bass drum.
Here is the tricky part. With FL, I have two way of achieving 33% in pitch and 20% in tempo but sure which is better. First one is change pitch and tempo to 120% then add 111% to pitch, the second one is change pitch and tempo to 133% then add 111% to time to lengthen the song and to lower the tempo.
FL 52920 110.96Pitch ProDefault.mp3, set rate to 52920 (120% compare to 44100) then set pitch to 110.96% (cloest to 111%), Method used is Pro Default
FL 58800 110.96Time ProDefault.mp3, set rate to58800 (133.3333% compare to 44100) then set time to 110.96 to lengthen the song (to lower the tempo), Method used is Pro Default
The wav files are exported from FL, and the m4a files are exported from Audacity using the wav files.
The following is the comparison of the spectrum image of the WAVs of the 58800 one and the 52920 one.
58800 has a taller spectrum than 52920. Not sure how does it affect the quality though.
Things to compare
FL Methods, not sure which is the best for nigthcorehttp://www.image-line.com/support/FLHelp/html/plugins/editortool_stretch.htm