Pull the Voice Activity Detector out from the AGC

webrtc/modules/audio_processing/agc/standalone_vad.cc

-/*
- *  Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
- *
- *  Use of this source code is governed by a BSD-style license
- *  that can be found in the LICENSE file in the root of the source
- *  tree. An additional intellectual property rights grant can be found
- *  in the file PATENTS.  All contributing project authors may
- *  be found in the AUTHORS file in the root of the source tree.
- */
-
-#include "webrtc/modules/audio_processing/agc/standalone_vad.h"
-
-#include <assert.h>
-
-#include "webrtc/modules/interface/module_common_types.h"
-#include "webrtc/modules/utility/interface/audio_frame_operations.h"
-#include "webrtc/typedefs.h"
-
-namespace webrtc {
-
-static const int kDefaultStandaloneVadMode = 3;
-
-StandaloneVad::StandaloneVad(VadInst* vad)
-    : vad_(vad),
-      buffer_(),
-      index_(0),
-      mode_(kDefaultStandaloneVadMode) {}
-
-StandaloneVad::~StandaloneVad() {
-  WebRtcVad_Free(vad_);
-}
-
-StandaloneVad* StandaloneVad::Create() {
-  VadInst* vad = WebRtcVad_Create();
-  if (!vad)
-    return nullptr;
-
-  int err = WebRtcVad_Init(vad);
-  err |= WebRtcVad_set_mode(vad, kDefaultStandaloneVadMode);
-  if (err != 0) {
-    WebRtcVad_Free(vad);
-    return nullptr;
-  }
-  return new StandaloneVad(vad);
-}
-
-int StandaloneVad::AddAudio(const int16_t* data, int length) {
-  if (length != kLength10Ms)
-    return -1;
-
-  if (index_ + length > kLength10Ms * kMaxNum10msFrames)
-    // Reset the buffer if it's full.
-    // TODO(ajm): Instead, consider just processing every 10 ms frame. Then we
-    // can forgo the buffering.
-    index_ = 0;
-
-  memcpy(&buffer_[index_], data, sizeof(int16_t) * length);
-  index_ += length;
-  return 0;
-}
-
-int StandaloneVad::GetActivity(double* p, int length_p) {
-  if (index_ == 0)
-    return -1;
-
-  const int num_frames = index_ / kLength10Ms;
-  if (num_frames > length_p)
-    return -1;
-  assert(WebRtcVad_ValidRateAndFrameLength(kSampleRateHz, index_) == 0);
-
-  int activity = WebRtcVad_Process(vad_, kSampleRateHz, buffer_, index_);
-  if (activity < 0)
-    return -1;
-  else if (activity == 0)
-    p[0] = 0.01;  // Arbitrary but small and non-zero.
-  else
-    p[0] = 0.5;  // 0.5 is neutral values when combinned by other probabilities.
-  for (int n = 1; n < num_frames; n++)
-    p[n] = p[0];
-  // Reset the buffer to start from the beginning.
-  index_ = 0;
-  return activity;
-}
-
-int StandaloneVad::set_mode(int mode) {
-  if (mode < 0 || mode > 3)
-    return -1;
-  if (WebRtcVad_set_mode(vad_, mode) != 0)
-    return -1;
-
-  mode_ = mode;
-  return 0;
-}
-
-}  // namespace webrtc
-