S.O.N.G/opus-go
S.O.N.G/opus-go
3
0
Fork 0
Code Issues Pull requests Releases Activity

Remove finalLPCValues from silk.Decoder

Browse source 
LPC values shouldn't be stored across frames
This commit is contained in:
Sean DuBois 2022-09-25 20:20:06 -04:00
parent 3a79dec65f
commit 4c632df5ac
1 changed files with 7 additions and 26 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

33
internal/silk/decoder.go
View file

@ -17,14 +17,6 @@ type Decoder struct {
previousLogGain int32
// The decoder saves the final d_LPC values, i.e., lpc[i] such that
// (j + n - d_LPC) <= i < (j + n), to feed into the LPC synthesis of the
// next subframe. This requires storage for up to 16 values of lpc[i]
// (for WB frames).
//
// https://www.rfc-editor.org/rfc/rfc6716.html#section-4.2.7.9.2
finalLPCValues []float32
// This requires storage to buffer up to 306 values of out[i] from
// previous subframes.
// https://www.rfc-editor.org/rfc/rfc6716#section-4.2.7.9.1
@ -38,7 +30,6 @@ type Decoder struct {
// NewDecoder creates a new Silk Decoder
func NewDecoder() Decoder {
return Decoder{
finalLPCValues: make([]float32, 16),
finalOutValues: make([]float32, 306),
}
}
@ -1432,11 +1423,12 @@ func (d *Decoder) ltpSynthesis(
res[index] = 0
for k := 0; k < dLPC; k++ {
if i-k > 0 {
lpcVal = lpc[index-k-1]
if lpcIndex := index - k - 1; lpcIndex >= 0 {
lpcVal = lpc[lpcIndex]
} else {
lpcVal = d.finalLPCValues[len(d.finalLPCValues)-1+(i-k)]
lpcVal = 0
}
res[index] += lpcVal * (aQ12[k] / 4096.0)
}
@ -1495,8 +1487,6 @@ func (d *Decoder) lpcSynthesis(out []float32, bandwidth Bandwidth, n, s, dLPC in
d.finalOutValues[i] = d.finalOutValues[i+n]
}
finalLPCValuesIndex := 0
// j be the index of the first sample in the residual corresponding to
// the current subframe.
j := 0
@ -1518,10 +1508,10 @@ func (d *Decoder) lpcSynthesis(out []float32, bandwidth Bandwidth, n, s, dLPC in
lpcVal *= res[sampleIndex]
for k := 0; k < dLPC; k++ {
if i-k > 0 {
currentLPCVal = lpc[sampleIndex-k-1]
if lpcIndex := sampleIndex - k - 1; lpcIndex >= 0 {
currentLPCVal = lpc[lpcIndex]
} else {
currentLPCVal = d.finalLPCValues[len(d.finalLPCValues)-1+(i-k)]
currentLPCVal = 0
}
lpcVal += currentLPCVal * (aQ12[k] / 4096.0)
@ -1529,15 +1519,6 @@ func (d *Decoder) lpcSynthesis(out []float32, bandwidth Bandwidth, n, s, dLPC in
lpc[sampleIndex] = lpcVal
// The decoder saves the final d_LPC values, i.e., lpc[i] such that
// (j + n - d_LPC) <= i < (j + n), to feed into the LPC synthesis of the
// next subframe. This requires storage for up to 16 values of lpc[i]
// (for WB frames).
if (j+n-dLPC) <= i && i < (j+n) {
d.finalLPCValues[finalLPCValuesIndex] = lpcVal
finalLPCValuesIndex++
}
// Then, the signal is clamped into the final nominal range:
//
// out[i] = clamp(-1.0, lpc[i], 1.0)