| /* |
| * Copyright (C) 2010 The Android Open Source Project |
| * |
| * 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. |
| */ |
| |
| #ifndef COMPARE_SPECTRA_H |
| #define COMPARE_SPECTRA_H |
| |
| /* Compare the average magnitude spectra of the signals in pcm and |
| refPcm, which are of length numSamples and nRefSamples, |
| respectively; both sampled at sample_rate. The maximum deviation |
| between average spectra, expressed in dB, is returned in |
| maxDeviation, and the rms of all dB variations is returned in |
| rmsDeviation. Note that a lower limit is set on the frequencies that |
| are compared so as to ignore irrelevant DC and rumble components. If |
| the measurement fails for some reason, return 0; else return 1, for |
| success. Causes for failure include the amplitude of one or both of |
| the signals being too low, or the duration of the signals being too |
| short. |
| |
| Note that the expected signal collection scenario is that the phone |
| would be stimulated with a broadband signal as in a recognition |
| attempt, so that there will be some "silence" regions at the start and |
| end of the pcm signals. The preferred stimulus would be pink noise, |
| but any broadband signal should work. */ |
| |
| int compareSpectra(short* pcm, int numSamples, short* refPcm, |
| int nRefSamples, float sampleRate, |
| float* maxDeviation, float* rmsDeviation); |
| |
| #endif // COMPARE_SPECTRA_H |
