/// \internal
/// <summary>Creates the audio context using the specified device.</summary>
/// <param name="device">The device descriptor obtained through AudioContext.AvailableDevices, or null for the default device.</param>
/// <param name="freq">Frequency for mixing output buffer, in units of Hz. Pass 0 for driver default.</param>
/// <param name="refresh">Refresh intervals, in units of Hz. Pass 0 for driver default.</param>
/// <param name="sync">Flag, indicating a synchronous context.</param>
/// <param name="enableEfx">Indicates whether the EFX extension should be initialized, if present.</param>
/// <param name="efxAuxiliarySends">Requires EFX enabled. The number of desired Auxiliary Sends per source.</param>
/// <exception cref="ArgumentOutOfRangeException">Occurs when a specified parameter is invalid.</exception>
/// <exception cref="AudioDeviceException">
/// Occurs when the specified device is not available, or is in use by another program.
/// </exception>
/// <exception cref="AudioContextException">
/// Occurs when an audio context could not be created with the specified parameters.
/// </exception>
/// <exception cref="NotSupportedException">
/// Occurs when an AudioContext already exists.</exception>
/// <remarks>
/// <para>For maximum compatibility, you are strongly recommended to use the default constructor.</para>
/// <para>Multiple AudioContexts are not supported at this point.</para>
/// <para>
/// The number of auxilliary EFX sends depends on the audio hardware and drivers. Most Realtek devices, as well
/// as the Creative SB Live!, support 1 auxilliary send. Creative's Audigy and X-Fi series support 4 sends.
/// Values higher than supported will be clamped by the driver.
/// </para>
/// </remarks>
private void CreateContext(string device, int freq, int refresh, bool sync, bool enableEfx, MaxAuxiliarySends efxAuxiliarySends)
{
if (!AudioDeviceEnumerator.IsOpenALSupported)
{
throw new DllNotFoundException("openal32.dll");
}
if (AudioDeviceEnumerator.Version == AudioDeviceEnumerator.AlcVersion.Alc1_1 && AudioDeviceEnumerator.AvailablePlaybackDevices.Count == 0) // Alc 1.0 does not support device enumeration.
{
throw new NotSupportedException("No audio hardware is available.");
}
if (context_exists)
{
throw new NotSupportedException("Multiple AudioContexts are not supported.");
}
if (freq < 0)
{
throw new ArgumentOutOfRangeException("freq", freq, "Should be greater than zero.");
}
if (refresh < 0)
{
throw new ArgumentOutOfRangeException("refresh", refresh, "Should be greater than zero.");
}
if (!String.IsNullOrEmpty(device))
{
device_name = device;
Device = Alc.OpenDevice(device); // try to open device by name
}
if (Device == IntPtr.Zero)
{
device_name = "IntPtr.Zero (null string)";
Device = Alc.OpenDevice(null); // try to open unnamed default device
}
if (Device == IntPtr.Zero)
{
device_name = AudioContext.DefaultDevice;
Device = Alc.OpenDevice(AudioContext.DefaultDevice); // try to open named default device
}
if (Device == IntPtr.Zero)
{
device_name = "None";
throw new AudioDeviceException(String.Format("Audio device '{0}' does not exist or is tied up by another application.",
String.IsNullOrEmpty(device) ? "default" : device));
}
CheckErrors();
// Build the attribute list
List <int> attributes = new List <int>();
if (freq != 0)
{
attributes.Add((int)AlcContextAttributes.Frequency);
attributes.Add(freq);
}
if (refresh != 0)
{
attributes.Add((int)AlcContextAttributes.Refresh);
attributes.Add(refresh);
}
attributes.Add((int)AlcContextAttributes.Sync);
attributes.Add(sync ? 1 : 0);
if (enableEfx && Alc.IsExtensionPresent(Device, "ALC_EXT_EFX"))
{
int num_slots;
switch (efxAuxiliarySends)
{
case MaxAuxiliarySends.One:
case MaxAuxiliarySends.Two:
case MaxAuxiliarySends.Three:
case MaxAuxiliarySends.Four:
num_slots = (int)efxAuxiliarySends;
break;
default:
case MaxAuxiliarySends.UseDriverDefault:
Alc.GetInteger(Device, AlcGetInteger.EfxMaxAuxiliarySends, 1, out num_slots);
break;
}
attributes.Add((int)AlcContextAttributes.EfxMaxAuxiliarySends);
attributes.Add(num_slots);
}
attributes.Add(0);
context_handle = Alc.CreateContext(Device, attributes.ToArray());
if (context_handle == ContextHandle.Zero)
{
Alc.CloseDevice(Device);
throw new AudioContextException("The audio context could not be created with the specified parameters.");
}
CheckErrors();
// HACK: OpenAL SI on Linux/ALSA crashes on MakeCurrent. This hack avoids calling MakeCurrent when
// an old OpenAL version is detect - it may affect outdated OpenAL versions different than OpenAL SI,
// but it looks like a good compromise for now.
if (AudioDeviceEnumerator.AvailablePlaybackDevices.Count > 0)
{
MakeCurrent();
}
CheckErrors();
device_name = Alc.GetString(Device, AlcGetString.DeviceSpecifier);
lock (audio_context_lock)
{
available_contexts.Add(this.context_handle, this);
context_exists = true;
}
}
// Loads all available audio devices into the available_*_devices lists.
static AudioDeviceEnumerator()
{
IntPtr dummy_device = IntPtr.Zero;
ContextHandle dummy_context = ContextHandle.Zero;
try
{
Debug.WriteLine("Enumerating audio devices.");
Debug.Indent();
// need a dummy context for correct results
dummy_device = Alc.OpenDevice(null);
dummy_context = Alc.CreateContext(dummy_device, (int[])null);
bool dummy_success = Alc.MakeContextCurrent(dummy_context);
AlcError dummy_error = Alc.GetError(dummy_device);
if (!dummy_success || dummy_error != AlcError.NoError)
{
throw new AudioContextException("Failed to create dummy Context. Device (" + dummy_device.ToString() +
") Context (" + dummy_context.Handle.ToString() +
") MakeContextCurrent " + (dummy_success ? "succeeded" : "failed") +
", Alc Error (" + dummy_error.ToString() + ") " + Alc.GetString(IntPtr.Zero, (AlcGetString)dummy_error));
}
// Get a list of all known playback devices, using best extension available
if (Alc.IsExtensionPresent(IntPtr.Zero, "ALC_ENUMERATION_EXT"))
{
version = AlcVersion.Alc1_1;
if (Alc.IsExtensionPresent(IntPtr.Zero, "ALC_ENUMERATE_ALL_EXT"))
{
available_playback_devices.AddRange(Alc.GetString(IntPtr.Zero, AlcGetStringList.AllDevicesSpecifier));
default_playback_device = Alc.GetString(IntPtr.Zero, AlcGetString.DefaultAllDevicesSpecifier);
}
else
{
available_playback_devices.AddRange(Alc.GetString(IntPtr.Zero, AlcGetStringList.DeviceSpecifier));
default_playback_device = Alc.GetString(IntPtr.Zero, AlcGetString.DefaultDeviceSpecifier);
}
}
else
{
version = AlcVersion.Alc1_0;
Debug.Print("Device enumeration extension not available. Failed to enumerate playback devices.");
}
AlcError playback_err = Alc.GetError(dummy_device);
if (playback_err != AlcError.NoError)
{
throw new AudioContextException("Alc Error occured when querying available playback devices. " + playback_err.ToString());
}
// Get a list of all known recording devices, at least ALC_ENUMERATION_EXT is needed too
if (version == AlcVersion.Alc1_1 && Alc.IsExtensionPresent(IntPtr.Zero, "ALC_EXT_CAPTURE"))
{
available_recording_devices.AddRange(Alc.GetString(IntPtr.Zero, AlcGetStringList.CaptureDeviceSpecifier));
default_recording_device = Alc.GetString(IntPtr.Zero, AlcGetString.CaptureDefaultDeviceSpecifier);
}
else
{
Debug.Print("Capture extension not available. Failed to enumerate recording devices.");
}
AlcError record_err = Alc.GetError(dummy_device);
if (record_err != AlcError.NoError)
{
throw new AudioContextException("Alc Error occured when querying available recording devices. " + record_err.ToString());
}
#if DEBUG
Debug.WriteLine("Found playback devices:");
foreach (string s in available_playback_devices)
{
Debug.WriteLine(s);
}
Debug.WriteLine("Default playback device: " + default_playback_device);
Debug.WriteLine("Found recording devices:");
foreach (string s in available_recording_devices)
{
Debug.WriteLine(s);
}
Debug.WriteLine("Default recording device: " + default_recording_device);
#endif
}
catch (DllNotFoundException e)
{
Trace.WriteLine(e.ToString());
openal_supported = false;
}
catch (AudioContextException ace)
{
Trace.WriteLine(ace.ToString());
openal_supported = false;
}
finally
{
Debug.Unindent();
// clean up the dummy context
Alc.MakeContextCurrent(ContextHandle.Zero);
if (dummy_context != ContextHandle.Zero && dummy_context.Handle != IntPtr.Zero)
{
Alc.DestroyContext(dummy_context);
}
if (dummy_device != IntPtr.Zero)
{
Alc.CloseDevice(dummy_device);
}
}
}