Recording audio in C#

Initialize the device
Next, we need to initialize the actual recording device. In the constructor of the RecordUtil place the following code snippet.

By initializing with the device 0, we will use the first recording device found by the Bass api. 

Next, we're going to create the recording stream. You will need to set the sampling rate, the number of channels, BASSRecord flags, a callback function, and a user. The following code accomplishes this.

The first parameter is the sampling rate. This is the rate at which the analog wave is sampled (41000 times per second). The second parameter is the number of channels: 1 is mono, 2 is stereo. The third parameter is either the resolution (BASS_DEFAULT 16-bits, BASS_SAMPLE_8BITS 8-bit, BASS_SAMPLE_FLOAT - all of these choices will start the recording) BASS_RECORD_PAUSE starts the recording paused. Lastly, the fourth parameter is the callback function on each sample and the last parameter is the user associated with the recording.

Automatic versus manual recording
BASS has two methods of recording audio. When you do not specify null for the RECORDPROC callback function you must obtain the actual channel data using the BASS_ChannelGetData method. This is known as manual recording. Manual recording allows lower latency for full-duplex recording (i.e. playing the data as it's being recorded). 

In an overloaded method for the BASS_RecordStart function, the third parameter is actually the period. The period defines the interval (in milliseconds) between calls to the callback function. The default is 100ms. (Minimum is 10ms, Maximum is 500ms). 

If you do specify a callback to the RECORDPROC parameter, you are implementing automatic recording. All the data is obtained for you.

Then create the callback function and within the method you can simply return true. For the sake of this tutorial I will go into detail at a later post to explain the neat things you can access with the data.

LAME Encoder
In order to start recording with the parameter we chose, we need to use Channel_Play. But before we do that we are going to use the LAME encoder to stream the recording to an output file. Add the following code snippet:

I have added a field in the class called encoder. The EncoderLame class is in the Un4seen.Bass.Misc namespace. The first line simply constructs the encoder with the streaming channel (in our case the recording stream). Next, we set the OutputFile to the given path denoted output. The last lines of code are LAME specific variable configurations.

Aside from the bitrate and sample rate, Mode defines the encoding channel mode as in mono, stereo, join stereo.. etc. There are plenty of variables that you can configure, I have just configured the basics in this example. We want to sample at the same rate we created our recording channel at, use the default mode, encode according to quality, and have our bitrate at 192kbps (kilobits/sec).

Next, I have added four methods to handle different states in our recording program. They start out as the following: The code here is pretty straight forward. When we call encoder.Start(null, 0) we are passing it a callback function and the associated user. The callback function allows us to work the encoding byte stream at each interval ourselves. This is very useful for us when we want to send the stream elsewhere like over a network.

The only thing left for us to do in this class is add the code for the Bass.Channel functions like we did in the previous tutorial on streaming audio. When you have that part done the final code should look like the following.
And there you go, the only missing piece is creating an interface the utilize this nice little recording utility. I've thrown a simple interface together to demonstrate this. When you're done with yours simply call the appropriate functions in the order: constructor, Initialize, Encode (with the output file), and setup a play, pause, and stop function.

Once you have your interface ready, you can make the calls to the functions you just created. When you're done your code should look something like the following code snippet.