feat(capability): 转码能力包（vendor 纯 Go AMR-NB 解码器 + 黄金向量逐样本对照 + 8 哨兵 + 注册面）

internal/capability/transcode/amrnb/dsp_enc_subfr.go

@@ -0,0 +1,88 @@
+package amrnb
+
+// Per-subframe codebook dispatch and post-processing, ported from opencore-amrnb
+// cbsearch.cpp (cbsearch) and spstproc.cpp (subframePostProc). cbsearch routes
+// to the mode's algebraic codebook search (and applies the MR102/MR122 pitch
+// sharpening around it); subframePostProc forms the total excitation, runs the
+// local synthesis, and updates the synthesis/error/weighting filter memories
+// for the next subframe. Bit-exact with the reference.
+
+// cbsearch runs the fixed-codebook search for the mode, writing the innovation
+// code and filtered code y and the analysis indices into anap (returning the
+// count). Mirrors cbsearch.
+func cbsearch(x, h []int16, T0, pitchSharp, gainPit int16, res2, code, y []int16, mode, subNr int, anap []int16) int {
+	switch {
+	case mode == dMR475 || mode == dMR515:
+		idx, sgn := code2i40_9bits(int16(subNr), x, h, T0, pitchSharp, code, y)
+		anap[0], anap[1] = idx, sgn
+		return 2
+	case mode == dMR59:
+		idx, sgn := code2i40_11bits(x, h, T0, pitchSharp, code, y)
+		anap[0], anap[1] = idx, sgn
+		return 2
+	case mode == dMR67:
+		idx, sgn := code3i40_14bits(x, h, T0, pitchSharp, code, y)
+		anap[0], anap[1] = idx, sgn
+		return 2
+	case mode == dMR74 || mode == dMR795:
+		idx, sgn := code4i40_17bits(x, h, T0, pitchSharp, code, y)
+		anap[0], anap[1] = idx, sgn
+		return 2
+	case mode == dMR102:
+		ps := shl(pitchSharp, 1)
+		for i := T0; i < cL_SUBFR; i++ {
+			h[i] = add(h[i], mult(h[i-T0], ps))
+		}
+		code8i40_31bits(x, res2, h, code, y, anap[0:7])
+		for i := T0; i < cL_SUBFR; i++ {
+			code[i] = add(code[i], mult(code[i-T0], ps))
+		}
+		return 7
+	default: // MR122
+		ps := shl(gainPit, 1)
+		for i := T0; i < cL_SUBFR; i++ {
+			h[i] = add(h[i], int16((int32(h[i-T0])*int32(ps))>>15))
+		}
+		code10i40_35bits(x, res2, h, code, y, anap[0:10])
+		for i := T0; i < cL_SUBFR; i++ {
+			code[i] = add(code[i], mult(code[i-T0], ps))
+		}
+		return 10
+	}
+}
+
+// subframePostProc builds the total excitation (gain_pit·adaptive +
+// gain_code·code), runs the local synthesis (updating mem_syn), and refreshes
+// the error and weighting-filter memories. sharp is updated with the clamped
+// pitch gain. Mirrors subframePostProc.
+func subframePostProc(speech []int16, speechOff, mode, iSubfr int, gainPit, gainCode int16, aq, synth, xn, code, y1, y2, memSyn, memErr, memW0, exc []int16, excOff int, sharp *int16) {
+	var tempShift, kShift, pitchFac int16
+	if mode != dMR122 {
+		tempShift, kShift, pitchFac = 1, 16-2-1, gainPit
+	} else {
+		tempShift, kShift, pitchFac = 2, 16-4-1, gainPit>>1
+	}
+
+	if gainPit < cSHARPMAX {
+		*sharp = gainPit
+	} else {
+		*sharp = cSHARPMAX
+	}
+
+	base := excOff + iSubfr
+	for i := 0; i < cL_SUBFR; i++ {
+		L := (int32(exc[base+i]) * int32(pitchFac)) << 1
+		L += (int32(code[i]) * int32(gainCode)) << 1
+		L <<= uint(tempShift)
+		exc[base+i] = int16((L + 0x8000) >> 16)
+	}
+
+	synFilt(aq, exc[base:base+cL_SUBFR], synth[iSubfr:iSubfr+cL_SUBFR], cL_SUBFR, memSyn, true)
+
+	for i, j := cL_SUBFR-cM, 0; i < cL_SUBFR; i, j = i+1, j+1 {
+		memErr[j] = speech[speechOff+iSubfr+i] - synth[iSubfr+i]
+		temp := int16((int32(y1[i]) * int32(gainPit)) >> 14)
+		temp += int16((int32(y2[i]) * int32(gainCode)) >> uint(kShift))
+		memW0[j] = xn[i] - temp
+	}
+}