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Don't recompute res for each subframe

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This commit is contained in:
Sean DuBois 2022-09-21 23:02:46 -04:00
parent 42288fd1e3
commit 903249e356
1 changed files with 22 additions and 30 deletions
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52
internal/silk/decoder.go
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@ -1348,35 +1348,8 @@ func (d *Decoder) ltpSynthesis(
LTPScaleQ14 float32,
bandwidth Bandwidth,
wQ2 int16,
aQ12, gainQ16, lpc []float32,
) (res []float32) {
// For unvoiced frames (see Section 4.2.7.3), the LPC residual for i
// such that j <= i < (j + n) is simply a normalized copy of the
// excitation signal, i.e.,
//
// e_Q23[i]
// res[i] = ---------
// 2.0**23
res = make([]float32, len(eQ23))
if signalType != frameSignalTypeVoiced {
for i := j; i < (j + n); i++ {
res[i] = float32(eQ23[i]) / 8388608
}
return
}
// Voiced SILK frames, on the other hand, pass the excitation through an
// LTP filter using the parameters decoded in Section 4.2.7.6 to produce
// an LPC residual.
for i := range res {
res[i] = float32(eQ23[i]) / 8388608.0
}
// Voiced SILK frames, on the other hand, pass the excitation through an
// LTP filter using the parameters decoded in Section 4.2.7.6 to produce
// an LPC residual.
aQ12, gainQ16, lpc, res []float32,
) {
// If this is the third or fourth subframe of a 20 ms SILK frame and the LSF
// interpolation factor, w_Q2 (see Section 4.2.7.5.5), is less than 4,
// then let out_end be set to (j - (s-2)*n) and let LTP_scale_Q14 be set
@ -1402,6 +1375,7 @@ func (d *Decoder) ltpSynthesis(
// out[i] - \ out[i-k-1] * --------, 1.0)
// /_ 4096.0
// k=0
var outVal float32
for i := (j - pitchLags[s] - 2); i < out_end; i++ {
index := i + j
@ -1587,6 +1561,18 @@ func (d *Decoder) silkFrameReconstruction(
// previous subframe or zeros in the first subframe for this channel
lpc := make([]float32, n*subframeCount)
// For unvoiced frames (see Section 4.2.7.3), the LPC residual for i
// such that j <= i < (j + n) is simply a normalized copy of the
// excitation signal, i.e.,
//
// e_Q23[i]
// res[i] = ---------
// 2.0**23
res := make([]float32, len(eQ23))
for i := range res {
res[i] = float32(eQ23[i]) / 8388608.0
}
// s be the index of the current subframe in this SILK frame
// (0 or 1 for 10 ms frames, or 0 to 3 for 20 ms frames)
for s := 0; s < subframeCount; s++ {
@ -1596,8 +1582,14 @@ func (d *Decoder) silkFrameReconstruction(
// https://www.rfc-editor.org/rfc/rfc6716.html#section-4.2.7.9
j := n * s
// Voiced SILK frames, on the other hand, pass the excitation through an
// LTP filter using the parameters decoded in Section 4.2.7.6 to produce
// an LPC residual.
//
// https://www.rfc-editor.org/rfc/rfc6716.html#section-4.2.7.9.1
res := d.ltpSynthesis(out, signalType, bQ7, pitchLags, eQ23, n, j, s, dLPC, LTPscaleQ14, bandwidth, wQ2, aQ12, gainQ16, lpc)
if signalType == frameSignalTypeVoiced {
d.ltpSynthesis(out, signalType, bQ7, pitchLags, eQ23, n, j, s, dLPC, LTPscaleQ14, bandwidth, wQ2, aQ12, gainQ16, lpc, res)
}
//https://www.rfc-editor.org/rfc/rfc6716.html#section-4.2.7.9.2
d.lpcSynthesis(out[n*s:], bandwidth, n, s, dLPC, aQ12, res, gainQ16, lpc)