I have a presentation which contains professionally recorded narrations from a studio (very high quality).
These are being used to narrate a fairly complex presentation with lots of storyboard sequencing (animation).
When I export the file as the highest quality 1920x1080 video in MP4 format on the PC version of PowerPoint 2016 (Office 365, 16.0.7167.2060) I am getting audio glitching in random places which includes phasing, noise spikes and missing syllables. I've tried embedding the audio narrations in the PowerPoint deck in various formats such as WAV, MP3 and Microsoft's recommended M4a and while the results differ, none produce perfect audio quality compared with the source audio played during the slide show or outside of PowerPoint in a standalone media player. I tried exporting the video on a very different spec PC and got the same result.
The source audio has been produced at 44.1kHz, 16 bits using the codec corresponding to the file container : WAV/PCM, MP3/MP3, M4a/MPEG2/4.
I then tried on OSX (Yosemite 10.10.5) with PowerPoint:mac 2016 (Office 365, 15.26.160910) to see if the performance was better with the exact same PPTX file. The time to create the file was incredibly quick compared to the PC but to my surprise, the exported MP4 video doesn't contain an audio track at all. I made sure the relevant options were set as follows:
How can I create a video from PowerPoint (PC or Mac) with perfect audio?
Finally, as an aside, I had to scrap my initial AV sync method of using bookmarks in the audio files to trigger animations as they did not always work in the exported video from the PC version of PowerPoint 2016 although they do work in 2013!
It looks like the video export feature of PowerPoint is far from stable!