I want to do a recording of radio news with background music which fades in and fades out while I am reading. I don't have proper device, so I decide to enable loopback mode, so that I can record directly from my microphone to audacity, and at the same time play music in the background with VLC. I am using the volume control of the VLC to fade the music out when I am speaking, and I fade it back in when I pause the speaking.
After some experimentation I realized that at the moments when I adjust the volume, there is no smooth fade-in or fade-out of the music, but instead there is some pops or some distortion. After this happens, an unwanted echo appears in the voice recording, which gradually increases as I fade-in and fade-out many times. After a few minutes of recording, the echo may become unbearable. This echo or the fade-in/out distortion are not audible during the recording. There is something on the way the sound is delivered from the audio driver to audacity.
I tried to increase the latency on the microphone (this is not an issue for me) and I think the problem with the echo was reduced, but it still remained in overall.
Would somebody please think of a solution?