hope you can help. I am recording audio from a microphone and streaming it live across a network. The quality of the samples is 11025hz, 8 bit, mono. Although there is a small delay (1 second), it works great. What I need help with is I am trying to now implement noise reduction and compression, to make the audio quieter and use less bandwidth. The audio samples are stored in a C# array of bytes[], which I am sending/receiving using Socket.
Could anyone suggest how, in C#, to implement compression and noise reduction? I do not mind using a third party library as long as it is free (LGPL license, etc) and can be utilized from C#. However, I would prefer actual working source code examples. Thanks in advance for any suggestion you have.
UPDATE:
I changed the bit size from 8 bit audio to 16 bit audio and the noise problem is fixed. Apprarently 8 bit audio from mic had too low signal-to-noise ratio. Voice sounds great at 11khz, 16 bit mono.
The requirements of this project have changed since I posted this, however. We are now trying to add video as well. I have a callback setup that receives live images every 100ms from a webcam. I need to encode the audio and video, mux them, transmit them on my socket to the server, the server re-transmits the stream to the other client, which receives the stream, demuxes the stream and decodes the audio and video, displays the video in a picture box and outputs the audio to the speaker.
I am looking at ffmpeg to help out with the (de|en)coding/[de]muxing, and I am also looking at SharpFFmpeg as a C# interop library to ffmpeg.
I cannot find any good examples of doing this. I have scoured the Internet all week, with no real luck. Any help you can provide is much appreciated!
Here's some code, including my call back function for the mic recording:
private const int AUDIO_FREQ = 11025; private const int CHANNELS = 1; private const int BITS = 16; private const int BYTES_PER_SEC = AUDIO_FREQ * CHANNELS * (BITS / 8); private const int BLOCKS_PER_SEC = 40; private const int BUFFER_SECS = 1; private const int BUF_SIZE = ((int)(BYTES_PER_SEC / BLOCKS_PER_SEC * BUFFER_SECS / 2)) * 2; // rounded to nearest EVEN number private WaveLib.WaveOutPlayer m_Player; private WaveLib.WaveInRecorder m_Recorder; private WaveLib.FifoStream m_Fifo; WebCam MyWebCam; public void OnPickupHeadset() { stopRingTone(); m_Fifo = new WaveLib.FifoStream(); WaveLib.WaveFormat fmt = new WaveLib.WaveFormat(AUDIO_FREQ, BITS, CHANNELS); m_Player = new WaveLib.WaveOutPlayer(-1, fmt, BUF_SIZE, BLOCKS_PER_SEC, new WaveLib.BufferFillEventHandler(PlayerCB)); m_Recorder = new WaveLib.WaveInRecorder(-1, fmt, BUF_SIZE, BLOCKS_PER_SEC, new WaveLib.BufferDoneEventHandler(RecorderCB)); MyWebCam = null; try { MyWebCam = new WebCam(); MyWebCam.InitializeWebCam(ref pbMyPhoto, pbPhoto.Width, pbPhoto.Height); MyWebCam.Start(); } catch { } } private byte[] m_PlayBuffer; private void PlayerCB(IntPtr data, int size) { try { if (m_PlayBuffer == null || m_PlayBuffer.Length != size) m_PlayBuffer = new byte[size]; if (m_Fifo.Length >= size) { m_Fifo.Read(m_PlayBuffer, 0, size); } else { // Read what we can int fifoLength = (int)m_Fifo.Length; m_Fifo.Read(m_PlayBuffer, 0, fifoLength); // Zero out rest of buffer for (int i = fifoLength; i < m_PlayBuffer.Length; i++) m_PlayBuffer[i] = 0; } // Return the play buffer Marshal.Copy(m_PlayBuffer, 0, data, size); } catch { } } private byte[] m_RecBuffer; private void RecorderCB(IntPtr data, int size) { try { if (m_RecBuffer == null || m_RecBuffer.Length != size) m_RecBuffer = new byte[size]; Marshal.Copy(data, m_RecBuffer, 0, size); // HERE'S WHERE I WOULD ENCODE THE AUDIO IF I KNEW HOW // Send data to server if (theForm.CallClient != null) { SocketAsyncEventArgs args = new SocketAsyncEventArgs(); args.SetBuffer(m_RecBuffer, 0, m_RecBuffer.Length); theForm.CallClient.SendAsync(args); } } catch { } } //Called from network stack when data received from server (other client) public void PlayBuffer(byte[] buffer, int length) { try { //HERE'S WHERE I WOULD DECODE THE AUDIO IF I KNEW HOW m_Fifo.Write(buffer, 0, length); } catch { } }
So where should I go from here?