1 /* 2 * Copyright (C) 2010 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); you may not 5 * use this file except in compliance with the License. You may obtain a copy of 6 * the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 12 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the 13 * License for the specific language governing permissions and limitations under 14 * the License. 15 */ 16 17 #ifndef MEASURE_RMS_H 18 #define MEASURE_RMS_H 19 20 /* Measure the rms of the non-silence segment of the signal in pcm, which 21 is of numSamples length, and sampled at sampleRate. pcm is assumed to 22 consist of silence - signal - silence, as might be logged during a 23 speech recognition attempt. The stimulus signal in this case should 24 be approximately a 3-second burst of pink noise presented at a level 25 comparable to normal speaking level. The RMS is measured using 25ms 26 duration non-overlapping windows. These are averaged over the whole 27 non-silence part of pcm, and the result is returned in rms. The 28 standard deviation of this measurement over all frames is returned in 29 stdRms, and the estimated duration of the non-silence region, in 30 seconds, is returned in duration. The target signal is taken to be 31 that segment that is onsetThresh dB above the background, and is 32 expected to be continuous, once the onset has been found. If 33 onsetThresh < 0.0, simply make the measurememt over the entire pcm 34 signal. In both cases, the mean of the entire signal is returned in 35 mean. */ 36 void measureRms(short* pcm, int numSamples, float sampleRate, 37 float onsetThresh, float* rms, float* stdRms, 38 float* mean, float* duration); 39 40 41 #endif /* MEASURE_RMS_H */ 42
