| /****************************************************************************** |
| * |
| * Copyright 2022 Google LLC |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at: |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| * |
| ******************************************************************************/ |
| |
| #include "energy.h" |
| #include "tables.h" |
| |
| |
| /** |
| * Energy estimation per band |
| */ |
| bool lc3_energy_compute( |
| enum lc3_dt dt, enum lc3_srate sr, const float *x, float *e) |
| { |
| int nb = lc3_num_bands[dt][sr]; |
| const int *lim = lc3_band_lim[dt][sr]; |
| |
| /* Mean the square of coefficients within each band */ |
| |
| float e_sum[2] = { 0, 0 }; |
| int iband_h = nb - (const int []){ |
| [LC3_DT_2M5] = 2, [LC3_DT_5M ] = 3, |
| [LC3_DT_7M5] = 4, [LC3_DT_10M] = 2 }[dt]; |
| |
| for (int iband = 0, i = lim[iband]; iband < nb; iband++) { |
| int ie = lim[iband+1]; |
| int n = ie - i; |
| |
| float sx2 = x[i] * x[i]; |
| for (i++; i < ie; i++) |
| sx2 += x[i] * x[i]; |
| |
| *e = sx2 / n; |
| e_sum[iband >= iband_h] += *(e++); |
| } |
| |
| /* Return the near nyquist flag */ |
| |
| return e_sum[1] > 30 * e_sum[0]; |
| } |