Ok, got it working! Did like this:
public void ConvertAudioAddSilence(string inpFile, string outputFile, TimeSpan silenceLenght)
{
int _stream = Bass.BASS_StreamCreateFile(inpFile, 0, 0, BASSStream.BASS_STREAM_DECODE);
lameTooLame = new EncoderTooLAME(_stream);
lameTooLame.InputFile = null;
lameTooLame.OutputFile = outputFile + ".MP2";
lameTooLame.TOO_Bitrate = 256;
lameTooLame.Start(null, 0);
_fileName = outputFile + ".MP2";
if (!lameTooLame.EncoderExists)
{
}
byte[] encBuffer = new byte[65536]; // our dummy encoder buffer (32KB x 16-bit - size it as you like)
while (Bass.BASS_ChannelIsActive(_stream) == (int)BASSActive.BASS_ACTIVE_PLAYING)
{
Bass.BASS_ChannelGetData(_stream, ref encBuffer[0], encBuffer.Length);
}
float _dur = (float)silenceLenght.Seconds;
int _bytesLength= (int)Bass.BASS_ChannelSeconds2Bytes(_stream, _dur);
byte[] silentBuffer = new byte[_bytesLength];
Un4seen.Bass.AddOn.Enc.BassEnc.BASS_Encode_Write(_stream, ref silentBuffer[0], _bytesLength);
lameTooLame.Stop();
Console.WriteLine("DONE!");
}