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restore linear predictor

main
Steve Ayerhart 2022-08-11 14:35:55 -04:00
parent 184567d2f7
commit 9965f317b1
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GPG Key ID: 4CB33EB9BB156C97
1 changed files with 14 additions and 25 deletions
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37
src/flac/decoder.scm
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@ -141,49 +141,38 @@
(define (read-subframe-fixed predictor-order blocksize sample-depth)
(let ((warmup (list-ec (: o predictor-order) (flac-read-sint sample-depth))))
(let ((warmup (list-ec (: o predictor-order) (flac-read-sint sample-depth)))
(fixed-coefficients '(() (1) (2 -1) (3 -3 1) (4 -6 4 -1))))
(let-values (((entropy-coding-method residual) (read-residual-partiioned-rice blocksize predictor-order)))
(list
(%make-subframe-fixed entropy-coding-method predictor-order warmup residual)
(restore-linear-prediction warmup residual (list-ref '(() (1) (2 -1) (3 -3 1) (4 -6 4 -1)) predictor-order) predictor-order 0)))))
(restore-linear-prediction warmup residual (list-ref fixed-coefficients predictor-order) predictor-order 0)))))
(define (read-subframe-lpc lpc-order blocksize sample-depth)
(let* ((warmup (list-ec (: o lpc-order) (flac-read-sint sample-depth)))
(precision (+ 1 (flac-read-uint 4)))
(shift (flac-read-sint 5))
(coefs (list-ec (: o lpc-order) (flac-read-sint precision))))
(coefs (reverse (list-ec (: o lpc-order) (flac-read-sint precision)))))
(let-values (((entropy-coding-method residual) (read-residual-partiioned-rice blocksize lpc-order)))
(list
(%make-subframe-lpc entropy-coding-method lpc-order precision shift coefs warmup residual)
(restore-linear-prediction warmup residual coefs lpc-order shift)))))
; (restore-fixed-signal warmup residual lpc-order shift)))))
;(let ((fixed-prediction-coefficients (list-ref '(() (1) (2 -1) (3 -3 1) (4 -6 4 -1)) order)))
(define (restore-linear-prediction warmup residuals coefficients order shift)
(fold (λ (i r samples)
(fold (λ (residual samples)
(append
samples
(list (+ r (bitwise-arithmetic-shift-left
(sum-ec (: c coefficients) (: j (take-right samples order)) (* j c))
(list
(+ residual
(bitwise-arithmetic-shift-right
(fold (λ (residual coefficient predictor)
(+ predictor (* residual coefficient)))
0
(take-right samples order)
coefficients)
shift)))))
warmup
(iota (length residuals))
residuals))
; (list-ec (:range i (length coefficients) (length data))
; (+ (list-ref data i)
; (bitwise-arithmetic-shift-right
; (sum-ec (: j (iota (length coefficients))) (: c coefficients)
; (begin
; (format #t "data: ~a\n" (list-ref data i))
; (format #t "ref: ~a\n" (list-ref data (- (- i 1) j)))
; (* (list-ref data (- (- i 1) j)) c)))
; shift))))
; (let ((sum (fold (λ (c sum) (+ )))))
; (let ((test (sum-ec (:range (length coefficients) (length data))
;
; )))
; (fold (λ (i restored-data)
; (cons () ))))
;;; 000000 constant
;;; 000001 verbatim