protected void ProcessFrameReceived(object sender, NDI.AudioFrameReceivedEventArgs e)
{
if (!_BufferAllocated || (e.Frame.NumChannels * e.Frame.NumSamples * sizeof(short)) > _BufferSize)
{
if (e.Frame.NumChannels != _NumChannels)
{
_Log.Error($"--audio-channel-count argument doesn't match what's being received. Configured: {_NumChannels} Received: {e.Frame.NumChannels}");
}
if (e.Frame.SampleRate != _SampleRate)
{
_Log.Error($"--audio-clock-rate argument doesn't match what's being received. Configured: {_SampleRate} Received: {e.Frame.SampleRate}");
}
AllocateBuffer(e.Frame.SampleRate, e.Frame.NumSamples, e.Frame.NumChannels);
}
// Populate buffer with NDI frame data
Marshal.Copy(e.Frame.AudioBuffer, _Buffer.DataBuffer.Data, 0, e.Frame.NumChannels * e.Frame.NumSamples * sizeof(short));
// rusty.clarkson: Due to int rounding we might be losing samples...
int duration = (1000 * e.Frame.NumSamples) / e.Frame.SampleRate;
RaiseFrame(new AudioFrame(duration, _Buffer));
}
// the receive thread runs though this loop until told to exit
void ReceiveThreadProc()
{
while (!_exitThread && _recvInstancePtr != IntPtr.Zero)
{
// The descriptors
NDIlib.video_frame_v2_t videoFrame = new NDIlib.video_frame_v2_t();
NDIlib.audio_frame_v2_t audioFrame = new NDIlib.audio_frame_v2_t();
NDIlib.metadata_frame_t metadataFrame = new NDIlib.metadata_frame_t();
switch (NDIlib.recv_capture_v2(_recvInstancePtr, ref videoFrame, ref audioFrame, ref metadataFrame, 1000))
{
// No data
case NDIlib.frame_type_e.frame_type_none:
// No data received
ReceivingFrames = false;
break;
// frame settings - check for extended functionality
case NDIlib.frame_type_e.frame_type_status_change:
// check for PTZ
IsPtz = NDIlib.recv_ptz_is_supported(_recvInstancePtr);
// Check for recording
IsRecordingSupported = NDIlib.recv_recording_is_supported(_recvInstancePtr);
// Check for a web control URL
// We must free this string ptr if we get one.
IntPtr webUrlPtr = NDIlib.recv_get_web_control(_recvInstancePtr);
if (webUrlPtr == IntPtr.Zero)
{
WebControlUrl = String.Empty;
}
else
{
// convert to managed String
WebControlUrl = NDI.UTF.Utf8ToString(webUrlPtr);
// Don't forget to free the string ptr
NDIlib.recv_free_string(_recvInstancePtr, webUrlPtr);
}
break;
// Video data
case NDIlib.frame_type_e.frame_type_video:
Connected = true;
ReceivingFrames = true;
// if not enabled, just discard
// this can also occasionally happen when changing sources
if (!_videoEnabled || videoFrame.p_data == IntPtr.Zero)
{
// alreays free received frames
NDIlib.recv_free_video_v2(_recvInstancePtr, ref videoFrame);
break;
}
VideoFrameReceivedEventArgs videoArgs = new VideoFrameReceivedEventArgs();
videoArgs.Frame = new VideoFrame(videoFrame);
VideoFrameReceived?.Invoke(this, videoArgs);
// free frames that were received AFTER use!
NDIlib.recv_free_video_v2(_recvInstancePtr, ref videoFrame);
break;
// audio is beyond the scope of this example
case NDIlib.frame_type_e.frame_type_audio:
Connected = true;
ReceivingFrames = true;
// if no audio or disabled, nothing to do
if (!_audioEnabled || audioFrame.p_data == IntPtr.Zero || audioFrame.no_samples == 0)
{
// alreays free received frames
NDIlib.recv_free_audio_v2(_recvInstancePtr, ref audioFrame);
break;
}
// we're working in bytes, so take the size of a 16 bit sample into account
int sizeInBytes = (int)audioFrame.no_samples * (int)audioFrame.no_channels * sizeof(short);
// NDI uses planar, but we'll return interleaved which Pcm uses by default.
// create an interleaved frame and convert from the one we received
NDIlib.audio_frame_interleaved_16s_t interleavedFrame = new NDIlib.audio_frame_interleaved_16s_t()
{
sample_rate = audioFrame.sample_rate,
no_channels = audioFrame.no_channels,
no_samples = audioFrame.no_samples,
timecode = audioFrame.timecode
};
// we need a managed byte array to add to buffered provider
byte[] audBuffer = new byte[sizeInBytes];
// pin the byte[] and get a GC handle to it
// doing it this way saves an expensive Marshal.Alloc/Marshal.Copy/Marshal.Free later
// the data will only be moved once, during the fast interleave step that is required anyway
GCHandle handle = GCHandle.Alloc(audBuffer, GCHandleType.Pinned);
// access it by an IntPtr and use it for our interleaved audio buffer
interleavedFrame.p_data = handle.AddrOfPinnedObject();
// Convert from float planar to 16 bit interleaved audio
NDIlib.util_audio_to_interleaved_16s_v2(ref audioFrame, ref interleavedFrame);
AudioFrameReceivedEventArgs audioArgs = new AudioFrameReceivedEventArgs();
audioArgs.Frame = new AudioFrame16bpp(interleavedFrame);
AudioFrameReceived?.Invoke(this, audioArgs);
// release the pin on the byte[]
// never try to access p_data after the byte[] has been unpinned!
// that IntPtr will no longer be valid.
handle.Free();
// free the frame that was received
NDIlib.recv_free_audio_v2(_recvInstancePtr, ref audioFrame);
break;
// Metadata
case NDIlib.frame_type_e.frame_type_metadata:
// UTF-8 strings must be converted for use - length includes the terminating zero
//String metadata = Utf8ToString(metadataFrame.p_data, metadataFrame.length-1);
//System.Diagnostics.Debug.Print(metadata);
// free frames that were received
NDIlib.recv_free_metadata(_recvInstancePtr, ref metadataFrame);
break;
case NDIlib.frame_type_e.frame_type_error:
Connected = false;
break;
}
}
}
