这是Using UWP monitor live audio and detect gun-fire/clap sound
的扩展问题感谢Dernis，我终于获得了可以监视实时音频并在分贝数超过一定范围时触发事件的代码。
当我们在办公室/封闭/安静的区域中运行它时，这非常理想。
但是当我带着该应用打开道路时，会出现交通声音，风声，人们说话的声音以及其他噪音，并且BLOW事件无法正确识别。
对于从何处开始的任何帮助，我们将不胜感激。
OnNavigatedTo
protected override async void OnNavigatedTo(NavigationEventArgs e)
{
//other logic
await CreateInputDeviceNodeAsync(_deviceId);
}
CreateInputDeviceNodeAsync
public async Task<bool> CreateInputDeviceNodeAsync(string deviceId)
{
Console.WriteLine("Creating AudioGraphs");
// Create an AudioGraph with default settings
AudioGraphSettings graphSettings = new AudioGraphSettings(AudioRenderCategory.Media)
{
EncodingProperties = new AudioEncodingProperties
{
Subtype = "Float",
SampleRate = 48000,
ChannelCount = 2,
BitsPerSample = 32,
Bitrate = 3072000
}
};
CreateAudioGraphResult audioGraphResult = await AudioGraph.CreateAsync(graphSettings);
if (audioGraphResult.Status != AudioGraphCreationStatus.Success)
{
_rootPage.NotifyUser("Cannot create graph", NotifyType.ErrorMessage);
return false;
}
_audioGraph = audioGraphResult.Graph;
AudioGraphSettings audioGraphSettings =
new AudioGraphSettings(AudioRenderCategory.GameChat)
{
EncodingProperties = AudioEncodingProperties.CreatePcm(48000, 2, 32),
DesiredSamplesPerQuantum = 990,
QuantumSizeSelectionMode = QuantumSizeSelectionMode.ClosestToDesired
};
_frameOutputNode = _audioGraph.CreateFrameOutputNode(_audioGraph.EncodingProperties);
_quantum = 0;
_audioGraph.QuantumStarted += Graph_QuantumStarted;
LoudNoise += BlowDetected;
DeviceInformation selectedDevice = null;
if (!string.IsNullOrWhiteSpace(_deviceId))
selectedDevice = await DeviceInformation.CreateFromIdAsync(_deviceId);
if (selectedDevice == null)
{
string device = Windows.Media.Devices.MediaDevice.GetDefaultAudioCaptureId(
Windows.Media.Devices.AudioDeviceRole.Default);
if (!string.IsNullOrWhiteSpace(device))
selectedDevice = await DeviceInformation.CreateFromIdAsync(device);
else
{
_rootPage.NotifyUser($"Could not select Audio Device {device}", NotifyType.ErrorMessage);
return false;
}
}
CreateAudioDeviceInputNodeResult result =
await _audioGraph.CreateDeviceInputNodeAsync(MediaCategory.Media, audioGraphSettings.EncodingProperties,
selectedDevice);
if (result.Status != AudioDeviceNodeCreationStatus.Success)
{
_rootPage.NotifyUser("Cannot create device output node", NotifyType.ErrorMessage);
return false;
}
_selectedMicrophone = selectedDevice.Name;
_deviceInputNode = result.DeviceInputNode;
_deviceInputNode.AddOutgoingConnection(_frameOutputNode);
_frameOutputNode.Start();
_audioGraph.Start();
return true;
}
Graph_QuantumStarted
private void Graph_QuantumStarted(AudioGraph sender, object args)
{
if (++_quantum % 2 != 0) return;
AudioFrame frame = _frameOutputNode.GetFrame();
float[] dataInFloats;
using (AudioBuffer buffer = frame.LockBuffer(AudioBufferAccessMode.Write))
using (IMemoryBufferReference reference = buffer.CreateReference())
unsafe
{
// Get the buffer from the AudioFrame
// ReSharper disable once SuspiciousTypeConversion.Global
((IMemoryBufferByteAccess) reference).GetBuffer(out byte* dataInBytes,
out var capacityInBytes);
var dataInFloat = (float*) dataInBytes;
dataInFloats = new float[capacityInBytes / sizeof(float)];
for (var i = 0; i < capacityInBytes / sizeof(float); i++)
{
dataInFloats[i] = dataInFloat[i];
}
}
double decibels = dataInFloats.Aggregate<float, double>(0f, (current, sample) => current + Math.Abs(sample));
decibels = 20 * Math.Log10(decibels / dataInFloats.Length);
_decibelList.Add(decibels);
if (double.IsInfinity(decibels) || decibels < _threshold) return;//-45
if (_watch != null && _watch.Elapsed <= TimeSpan.FromSeconds(1)) return;
LoudNoise?.Invoke(this, decibels);
_watch = Stopwatch.StartNew();
}
答案 0 :(得分：1)
这只是统计信息。您可能需要收集至少50帧（1秒）的数据，然后才能使其真正起作用（也许让用户通过按住并释放按钮来决定）。然后，您可能需要确定分贝级别通常在哪里。我可以想到3种方法。
private void Graph_QuantumStarted(AudioGraph sender, object args)
{
...
double decibels = dataInFloats.Aggregate<float, double>(0f, (current, sample) => current + Math.Abs(sample)); // I dislike the fact that the decibels variable is initially inaccurate, but it's your codebase.
decibels = 20 * Math.Log10(decibels / dataInFloats.Length);
if (scanning) // class variable (bool), you can set it from the UI thread like this
{
_decibelList.Add(decibels); // I assume you made this a class variable
}
else if (decibels == Double.NaN)
{
// Code by case below
}
else if (decibels > _sensitivity) //_sensitivity is a class variable(double), initialized to Double.NaN
{
LoudNoise?.Invoke(this, true); // Calling events is a wee bit expensive, you probably want to handle the sensitivity before Invoking it, I'm also going to do it like that to make this demo simpler
}
}
maxDecibels + Math.Abs(maxDecibels* 0.2)（分贝可能为负） ，因此是Abs。）double maxDecibels = _decibelList.OrderByDescending(x => x)[0];
_sensitivity = maxDecibels + Math.Abs(maxDecibels* 0.2);
sensitivity = _decibelList.OrderByDescending(x => x)[24]; // If you do a variable time you can just take Count/4 - 1 as the index
int greatestChange, changeIndex = 0;
double p = Double.NaN; // Previous
for (int i = 0; i < _decibelList.Count(); i++)
{
if (p != Double.Nan)
{
change = Math.Abs(_decibelList[i] - p);
if (Math.Abs(change > greatestChange)
{
greatestChange = change;
changeIndex = i;
}
}
p = _decibelList[i];
}
int i = changeIndex;
p = Double.NaN; // reused
double c= Double.NaN; // Current
do
{
p = c != Double.NaN ? c : _decibelList[i];
c = _decibelList[++i];
} while (c < p);
_sensitivity = ((3 * c) + _decibelList[changeIndex]) / 4;