Now, on to uploading...
Your big honking MP3 file has to upload to the server. It takes awhile. Go get a cup of coffee or practice or something.
If your song is playing back too fast or too slow your song MP3 file probably uses variable bitrate (VBR) encoding. Flash isn't very good at handling these, so it's best to stick to constant bitrate encoding.
Also make sure to stick to a sampling frequency that is a multiple of 11.025kHz (48kHz, for example, poses problems).
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