1 /*
2 * Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
3 *
4 * Use of this source code is governed by a BSD-style license
5 * that can be found in the LICENSE file in the root of the source
6 * tree. An additional intellectual property rights grant can be found
7 * in the file PATENTS. All contributing project authors may
8 * be found in the AUTHORS file in the root of the source tree.
9 */
10
11 /*
12 * filterbanks.c
13 *
14 * This file contains function
15 * WebRtcIsacfix_SplitAndFilter, and WebRtcIsacfix_FilterAndCombine
16 * which implement filterbanks that produce decimated lowpass and
17 * highpass versions of a signal, and performs reconstruction.
18 *
19 */
20
21 #include "modules/audio_coding/codecs/isac/fix/source/filterbank_internal.h"
22
23 #include "modules/audio_coding/codecs/isac/fix/source/codec.h"
24 #include "modules/audio_coding/codecs/isac/fix/source/filterbank_tables.h"
25 #include "modules/audio_coding/codecs/isac/fix/source/settings.h"
26 #include "rtc_base/checks.h"
27
28 // Declare a function pointer.
29 AllpassFilter2FixDec16 WebRtcIsacfix_AllpassFilter2FixDec16;
30
WebRtcIsacfix_AllpassFilter2FixDec16C(int16_t * data_ch1,int16_t * data_ch2,const int16_t * factor_ch1,const int16_t * factor_ch2,const int length,int32_t * filter_state_ch1,int32_t * filter_state_ch2)31 void WebRtcIsacfix_AllpassFilter2FixDec16C(
32 int16_t *data_ch1, // Input and output in channel 1, in Q0
33 int16_t *data_ch2, // Input and output in channel 2, in Q0
34 const int16_t *factor_ch1, // Scaling factor for channel 1, in Q15
35 const int16_t *factor_ch2, // Scaling factor for channel 2, in Q15
36 const int length, // Length of the data buffers
37 int32_t *filter_state_ch1, // Filter state for channel 1, in Q16
38 int32_t *filter_state_ch2) { // Filter state for channel 2, in Q16
39 int n = 0;
40 int32_t state0_ch1 = filter_state_ch1[0], state1_ch1 = filter_state_ch1[1];
41 int32_t state0_ch2 = filter_state_ch2[0], state1_ch2 = filter_state_ch2[1];
42 int16_t in_out = 0;
43 int32_t a = 0, b = 0;
44
45 // Assembly file assumption.
46 RTC_DCHECK_EQ(0, length % 2);
47
48 for (n = 0; n < length; n++) {
49 // Process channel 1:
50 in_out = data_ch1[n];
51 a = factor_ch1[0] * in_out; // Q15 * Q0 = Q15
52 a *= 1 << 1; // Q15 -> Q16
53 b = WebRtcSpl_AddSatW32(a, state0_ch1);
54 a = -factor_ch1[0] * (int16_t)(b >> 16); // Q15
55 state0_ch1 =
56 WebRtcSpl_AddSatW32(a * (1 << 1), (int32_t)in_out * (1 << 16)); // Q16
57 in_out = (int16_t) (b >> 16); // Save as Q0
58
59 a = factor_ch1[1] * in_out; // Q15 * Q0 = Q15
60 a *= 1 << 1; // Q15 -> Q16
61 b = WebRtcSpl_AddSatW32(a, state1_ch1); // Q16
62 a = -factor_ch1[1] * (int16_t)(b >> 16); // Q15
63 state1_ch1 =
64 WebRtcSpl_AddSatW32(a * (1 << 1), (int32_t)in_out * (1 << 16)); // Q16
65 data_ch1[n] = (int16_t) (b >> 16); // Save as Q0
66
67 // Process channel 2:
68 in_out = data_ch2[n];
69 a = factor_ch2[0] * in_out; // Q15 * Q0 = Q15
70 a *= 1 << 1; // Q15 -> Q16
71 b = WebRtcSpl_AddSatW32(a, state0_ch2); // Q16
72 a = -factor_ch2[0] * (int16_t)(b >> 16); // Q15
73 state0_ch2 =
74 WebRtcSpl_AddSatW32(a * (1 << 1), (int32_t)in_out * (1 << 16)); // Q16
75 in_out = (int16_t) (b >> 16); // Save as Q0
76
77 a = factor_ch2[1] * in_out; // Q15 * Q0 = Q15
78 a *= (1 << 1); // Q15 -> Q16
79 b = WebRtcSpl_AddSatW32(a, state1_ch2); // Q16
80 a = -factor_ch2[1] * (int16_t)(b >> 16); // Q15
81 state1_ch2 =
82 WebRtcSpl_AddSatW32(a * (1 << 1), (int32_t)in_out * (1 << 16)); // Q16
83 data_ch2[n] = (int16_t) (b >> 16); // Save as Q0
84 }
85
86 filter_state_ch1[0] = state0_ch1;
87 filter_state_ch1[1] = state1_ch1;
88 filter_state_ch2[0] = state0_ch2;
89 filter_state_ch2[1] = state1_ch2;
90 }
91
92 // Declare a function pointer.
93 HighpassFilterFixDec32 WebRtcIsacfix_HighpassFilterFixDec32;
94
WebRtcIsacfix_HighpassFilterFixDec32C(int16_t * io,int16_t len,const int16_t * coefficient,int32_t * state)95 void WebRtcIsacfix_HighpassFilterFixDec32C(int16_t *io,
96 int16_t len,
97 const int16_t *coefficient,
98 int32_t *state)
99 {
100 int k;
101 int32_t a1 = 0, b1 = 0, c = 0, in = 0;
102 int32_t a2 = 0, b2 = 0;
103 int32_t state0 = state[0];
104 int32_t state1 = state[1];
105
106 for (k=0; k<len; k++) {
107 in = (int32_t)io[k];
108
109 #ifdef WEBRTC_ARCH_ARM_V7
110 {
111 register int tmp_coeff0;
112 register int tmp_coeff1;
113 __asm __volatile(
114 "ldr %[tmp_coeff0], [%[coeff]]\n\t"
115 "ldr %[tmp_coeff1], [%[coeff], #4]\n\t"
116 "smmulr %[a2], %[tmp_coeff0], %[state0]\n\t"
117 "smmulr %[b2], %[tmp_coeff1], %[state1]\n\t"
118 "ldr %[tmp_coeff0], [%[coeff], #8]\n\t"
119 "ldr %[tmp_coeff1], [%[coeff], #12]\n\t"
120 "smmulr %[a1], %[tmp_coeff0], %[state0]\n\t"
121 "smmulr %[b1], %[tmp_coeff1], %[state1]\n\t"
122 :[a2]"=&r"(a2),
123 [b2]"=&r"(b2),
124 [a1]"=&r"(a1),
125 [b1]"=r"(b1),
126 [tmp_coeff0]"=&r"(tmp_coeff0),
127 [tmp_coeff1]"=&r"(tmp_coeff1)
128 :[coeff]"r"(coefficient),
129 [state0]"r"(state0),
130 [state1]"r"(state1)
131 );
132 }
133 #else
134 /* Q35 * Q4 = Q39 ; shift 32 bit => Q7 */
135 a1 = WEBRTC_SPL_MUL_16_32_RSFT16(coefficient[5], state0) +
136 (WEBRTC_SPL_MUL_16_32_RSFT16(coefficient[4], state0) >> 16);
137 b1 = WEBRTC_SPL_MUL_16_32_RSFT16(coefficient[7], state1) +
138 (WEBRTC_SPL_MUL_16_32_RSFT16(coefficient[6], state1) >> 16);
139
140 /* Q30 * Q4 = Q34 ; shift 32 bit => Q2 */
141 a2 = WEBRTC_SPL_MUL_16_32_RSFT16(coefficient[1], state0) +
142 (WEBRTC_SPL_MUL_16_32_RSFT16(coefficient[0], state0) >> 16);
143 b2 = WEBRTC_SPL_MUL_16_32_RSFT16(coefficient[3], state1) +
144 (WEBRTC_SPL_MUL_16_32_RSFT16(coefficient[2], state1) >> 16);
145 #endif
146
147 c = in + ((a1 + b1) >> 7); // Q0.
148 io[k] = (int16_t)WebRtcSpl_SatW32ToW16(c); // Write output as Q0.
149
150 c = in * (1 << 2) - a2 - b2; // In Q2.
151 c = (int32_t)WEBRTC_SPL_SAT(536870911, c, -536870912);
152
153 state1 = state0;
154 state0 = c * (1 << 2); // Write state as Q4
155 }
156 state[0] = state0;
157 state[1] = state1;
158 }
159
160
WebRtcIsacfix_SplitAndFilter1(int16_t * pin,int16_t * LP16,int16_t * HP16,PreFiltBankstr * prefiltdata)161 void WebRtcIsacfix_SplitAndFilter1(int16_t *pin,
162 int16_t *LP16,
163 int16_t *HP16,
164 PreFiltBankstr *prefiltdata)
165 {
166 /* Function WebRtcIsacfix_SplitAndFilter */
167 /* This function creates low-pass and high-pass decimated versions of part of
168 the input signal, and part of the signal in the input 'lookahead buffer'. */
169
170 int k;
171
172 int16_t tempin_ch1[FRAMESAMPLES/2 + QLOOKAHEAD];
173 int16_t tempin_ch2[FRAMESAMPLES/2 + QLOOKAHEAD];
174 int32_t tmpState_ch1[2 * (QORDER-1)]; /* 4 */
175 int32_t tmpState_ch2[2 * (QORDER-1)]; /* 4 */
176
177 /* High pass filter */
178 WebRtcIsacfix_HighpassFilterFixDec32(pin, FRAMESAMPLES, WebRtcIsacfix_kHpStCoeffInQ30, prefiltdata->HPstates_fix);
179
180
181 /* First Channel */
182 for (k=0;k<FRAMESAMPLES/2;k++) {
183 tempin_ch1[QLOOKAHEAD + k] = pin[1 + 2 * k];
184 }
185 for (k=0;k<QLOOKAHEAD;k++) {
186 tempin_ch1[k]=prefiltdata->INLABUF1_fix[k];
187 prefiltdata->INLABUF1_fix[k] = pin[FRAMESAMPLES + 1 - 2 * (QLOOKAHEAD - k)];
188 }
189
190 /* Second Channel. This is exactly like the first channel, except that the
191 even samples are now filtered instead (lower channel). */
192 for (k=0;k<FRAMESAMPLES/2;k++) {
193 tempin_ch2[QLOOKAHEAD + k] = pin[2 * k];
194 }
195 for (k=0;k<QLOOKAHEAD;k++) {
196 tempin_ch2[k]=prefiltdata->INLABUF2_fix[k];
197 prefiltdata->INLABUF2_fix[k] = pin[FRAMESAMPLES - 2 * (QLOOKAHEAD - k)];
198 }
199
200
201 /*obtain polyphase components by forward all-pass filtering through each channel */
202 /* The all pass filtering automatically updates the filter states which are exported in the
203 prefiltdata structure */
204 WebRtcIsacfix_AllpassFilter2FixDec16(tempin_ch1,
205 tempin_ch2,
206 WebRtcIsacfix_kUpperApFactorsQ15,
207 WebRtcIsacfix_kLowerApFactorsQ15,
208 FRAMESAMPLES/2,
209 prefiltdata->INSTAT1_fix,
210 prefiltdata->INSTAT2_fix);
211
212 for (k = 0; k < 2 * (QORDER - 1); k++) {
213 tmpState_ch1[k] = prefiltdata->INSTAT1_fix[k];
214 tmpState_ch2[k] = prefiltdata->INSTAT2_fix[k];
215 }
216 WebRtcIsacfix_AllpassFilter2FixDec16(tempin_ch1 + FRAMESAMPLES/2,
217 tempin_ch2 + FRAMESAMPLES/2,
218 WebRtcIsacfix_kUpperApFactorsQ15,
219 WebRtcIsacfix_kLowerApFactorsQ15,
220 QLOOKAHEAD,
221 tmpState_ch1,
222 tmpState_ch2);
223
224 /* Now Construct low-pass and high-pass signals as combinations of polyphase components */
225 for (k=0; k<FRAMESAMPLES/2 + QLOOKAHEAD; k++) {
226 int32_t tmp1, tmp2, tmp3;
227 tmp1 = (int32_t)tempin_ch1[k]; // Q0 -> Q0
228 tmp2 = (int32_t)tempin_ch2[k]; // Q0 -> Q0
229 tmp3 = (tmp1 + tmp2) >> 1; /* Low pass signal. */
230 LP16[k] = (int16_t)WebRtcSpl_SatW32ToW16(tmp3); /*low pass */
231 tmp3 = (tmp1 - tmp2) >> 1; /* High pass signal. */
232 HP16[k] = (int16_t)WebRtcSpl_SatW32ToW16(tmp3); /*high pass */
233 }
234
235 }/*end of WebRtcIsacfix_SplitAndFilter */
236
237
238
239 //////////////////////////////////////////////////////////
240 ////////// Combining
241 /* Function WebRtcIsacfix_FilterAndCombine */
242 /* This is a decoder function that takes the decimated
243 length FRAMESAMPLES/2 input low-pass and
244 high-pass signals and creates a reconstructed fullband
245 output signal of length FRAMESAMPLES. WebRtcIsacfix_FilterAndCombine
246 is the sibling function of WebRtcIsacfix_SplitAndFilter */
247 /* INPUTS:
248 inLP: a length FRAMESAMPLES/2 array of input low-pass
249 samples.
250 inHP: a length FRAMESAMPLES/2 array of input high-pass
251 samples.
252 postfiltdata: input data structure containing the filterbank
253 states from the previous decoding iteration.
254 OUTPUTS:
255 Out: a length FRAMESAMPLES array of output reconstructed
256 samples (fullband) based on the input low-pass and
257 high-pass signals.
258 postfiltdata: the input data structure containing the filterbank
259 states is updated for the next decoding iteration */
WebRtcIsacfix_FilterAndCombine1(int16_t * tempin_ch1,int16_t * tempin_ch2,int16_t * out16,PostFiltBankstr * postfiltdata)260 void WebRtcIsacfix_FilterAndCombine1(int16_t *tempin_ch1,
261 int16_t *tempin_ch2,
262 int16_t *out16,
263 PostFiltBankstr *postfiltdata)
264 {
265 int k;
266 int16_t in[FRAMESAMPLES];
267
268 /* all-pass filter the new upper and lower channel signal.
269 For upper channel, use the all-pass filter factors that were used as a
270 lower channel at the encoding side. So at the decoder, the corresponding
271 all-pass filter factors for each channel are swapped.
272 For lower channel signal, since all-pass filter factors at the decoder are
273 swapped from the ones at the encoder, the 'upper' channel all-pass filter
274 factors (kUpperApFactors) are used to filter this new lower channel signal.
275 */
276 WebRtcIsacfix_AllpassFilter2FixDec16(tempin_ch1,
277 tempin_ch2,
278 WebRtcIsacfix_kLowerApFactorsQ15,
279 WebRtcIsacfix_kUpperApFactorsQ15,
280 FRAMESAMPLES/2,
281 postfiltdata->STATE_0_UPPER_fix,
282 postfiltdata->STATE_0_LOWER_fix);
283
284 /* Merge outputs to form the full length output signal.*/
285 for (k=0;k<FRAMESAMPLES/2;k++) {
286 in[2 * k] = tempin_ch2[k];
287 in[2 * k + 1] = tempin_ch1[k];
288 }
289
290 /* High pass filter */
291 WebRtcIsacfix_HighpassFilterFixDec32(in, FRAMESAMPLES, WebRtcIsacfix_kHPStCoeffOut1Q30, postfiltdata->HPstates1_fix);
292 WebRtcIsacfix_HighpassFilterFixDec32(in, FRAMESAMPLES, WebRtcIsacfix_kHPStCoeffOut2Q30, postfiltdata->HPstates2_fix);
293
294 for (k=0;k<FRAMESAMPLES;k++) {
295 out16[k] = in[k];
296 }
297 }
298