In This Topic ▼

SampleFrequency Property

Summary

Gets the audio format sample frequency, in hertz.

Syntax

C++

public int SampleFrequency {get;}

Public ReadOnly Property SampleFrequency As Integer

public: 
property int SampleFrequency { 
   int get(); 
}

Property Value

The sample frequency, in hertz.

Remarks

This is the number of audio samples received in one second. The AudioFormats object contains all the audio formats available for the current capture device. The AudioFormats object contains an AudioFormat object for each of the supported audio formats. The properties of each AudioFormat object, obtained using the [] indexer, contains information for the specific audio format. This information includes the BitsPerSample property, Channels property, and the SampleFrequency property.

The AudioFormat.Channels property is the number of channels for the audio format. The AudioFormat.BitsPerSample property is the number of bits per sample for the audio format

Example

using Leadtools; 
using Leadtools.MediaFoundation; 
using LeadtoolsMediaFoundationExamples.Fixtures; 
 
public CaptureCtrlForm _form = new CaptureCtrlForm(); 
public bool _result = false; 
 
public void AudioFormatExample() 
{ 
   try 
   { 
      int count, freq = 0, bits = 0, channels = 0; 
      int found, selected = -1; 
 
      // reference the capture control 
      CaptureCtrl capturectrl = _form.CaptureCtrl; 
 
      // set an audio device, use the name of your device here 
      if (capturectrl.AudioDevices["USB"] == null) 
         throw new Exception("No USB audio device available"); 
 
      capturectrl.AudioDevices["USB"].Selected = true; 
 
      // get count of available audio formats 
      count = capturectrl.AudioCaptureFormats.Count; 
 
      // reset the current selection to -1 
      capturectrl.AudioCaptureFormats.Selection = -1; 
 
      // reference the audioformats property 
      AudioFormats audioformats = capturectrl.AudioCaptureFormats; 
 
      // enumerate formats and select one 
      foreach (AudioFormat af in audioformats) 
      { 
         freq = af.SampleFrequency; 
         bits = af.BitsPerSample; 
         channels = af.Channels; 
 
         // select the format if it matches some criteria 
         if (freq == 8000 && bits == 16 && channels == 2) 
         { 
            af.Selected = true; 
            break; 
         } 
      } 
 
      // get the currently selected format 
      selected = audioformats.Selection; 
 
      // find a format based on frequency, bits/channel and number of channels 
      found = audioformats.IndexOf(8000, 8, 2); 
 
      // our found format is not selected, so select it 
      if (found != selected) 
         audioformats.Selection = found; 
 
      // get the new selected format 
      selected = audioformats.Selection; 
 
      // set our result based on what we expect 
      _result = (count > 0 && selected == found); 
   } 
   catch (Exception) 
   { 
      _result = false; 
   } 
}

Imports Leadtools 
Imports Leadtools.MediaFoundation 
Imports LeadtoolsMediaFoundationExamples.Fixtures 
 
Public _form As CaptureCtrlForm = New CaptureCtrlForm() 
Public _result As Boolean = False 
 
Public Sub AudioFormatExample() 
   Try 
      Dim count As Integer, freq As Integer = 0, bits As Integer = 0, channels As Integer = 0 
      Dim found As Integer, selected As Integer = -1 
 
      ' reference the capture control 
      Dim capturectrl As CaptureCtrl = _form.CaptureCtrl 
 
      ' set an audio device, use the name of your device here 
      If capturectrl.AudioDevices("USB") Is Nothing Then 
         Throw New Exception("No USB audio device available") 
      End If 
 
      capturectrl.AudioDevices("USB").Selected = True 
 
      ' get count of available audio formats 
      count = capturectrl.AudioCaptureFormats.Count 
 
      ' reset the current selection to -1 
      capturectrl.AudioCaptureFormats.Selection = -1 
 
      ' reference the audioformats property 
      Dim audioformats As AudioFormats = capturectrl.AudioCaptureFormats 
 
      ' enumerate formats and select one 
      For Each af As AudioFormat In audioformats 
         freq = af.SampleFrequency 
         bits = af.BitsPerSample 
         channels = af.Channels 
 
         ' select the format if it matches some criteria 
         If freq = 8000 AndAlso bits = 16 AndAlso channels = 2 Then 
            af.Selected = True 
            Exit For 
         End If 
      Next af 
 
      ' get the currently selected format 
      selected = audioformats.Selection 
 
      ' find a format based on frequency, bits/channel and number of channels 
      found = audioformats.IndexOf(8000, 8, 2) 
 
      ' our found format is not selected, so select it 
      If found <> selected Then 
         audioformats.Selection = found 
      End If 
 
      ' get the new selected format 
      selected = audioformats.Selection 
 
      ' set our result based on what we expect 
      _result = (count > 0 AndAlso selected = found) 
   Catch e1 As Exception 
      _result = False 
   End Try 
End Sub

Requirements

Target Platforms

Reference

AudioFormat Class

AudioFormat Members

AudioCaptureFormats Property

Download our FREE evaluation

Help Version 20.0.2020.4.2

Leadtools.MediaFoundation Assembly

Introduction

Getting Started

Namespaces

Leadtools.MediaFoundation Namespace

Leadtools.MediaFoundation.Common Namespace

Assemblies