Haha, just as what I guess, a 48000Hz mp3 have 1152 samples per frame, while if we resample it to 44100, even we set out samples to 1152 but the really return samples from swr_convert is only around 1058-1059 (could be one of the two in test of Miku). But the game has reserved the channel via sceVaudioChReserve function with sampleCount = 1152. So more samples will trying to be played thus yield nonsmooth sound.