(define get_wt_expr
(lambda (wt)
(let ((b64str (cptr->string (AudioBuffer_data_b64_cstring wt))))
`(AudioBuffer_cstring
,(AudioBuffer_frames wt)
,(AudioBuffer_channels wt)
,(AudioBuffer_samplerate wt)
0.0 ;; phase
,(AudioBuffer_root_pitch wt)
,(AudioBuffer_loop_start wt)
,(AudioBuffer_loop_frames wt)
,b64str))))