Interpolation of audio for new frames I am trying to upsample a video by existing frame interpolation techniques. In the process, I realize that I also need to interpolate the audio signal for the new frames so that the audio signal is in sync with the frames of the new video. 

The new upsampled video should have the same frame rate as the original input video, and will be a slowed down version of the input video.

Is there any way I can proceed to do the part of the audio interpolation?
If the frame rate is F and the audio sampling rate is Fs, then Fs/F audio samples are associated with each frame of the original video.

Any insight on how to proceed regarding this idea would be helpful.
When upsampling the number video frames to allow playing a video in slow motion, rather than for a frame rate increase for smoothness, you will likely need to modify the audio using a time-pitch stretching/shifting algorithm to stretch the audio out (increase the number of samples) for a longer play duration (to match the increase in slow motion video playback time), and to do so without distorting vocal or musical pitches.

If you just interpolate or resample audio without time-pitch correction, you will mess up all the pitch frequencies in the audio.

See this Wikipedia article for a description of several possible time-pitch stretching/scaling algorithms. There are multiple commercial and open source applications and libraries that can accomplish time-pitch modification/correction with varying degrees of quality and artifacts.