Is there a special app needed on my iPhone XR for the video camera to sync an external microphone?
I have all the TRS/Lightning connections correct, but no voice is recording with the video.
IPhone App for External Microphone
iphonemac-appstoremicrophone
Related Solutions
If security is a major concern, I'd assume that a software hack is not the solution. There still is a chance of malicious software importing code which re-enables the audio functionality.
I read NSA guidelines for Mac OS X 10.6 about disabling iSight on Macs where is was recommened to physically remove the webcam for absolute security.
If you do not want to physically remove your iPhone's microphone, I would try to distort the audio as good as possible - that would leave a spy with imprecise mumbling noises. The iPhone 4 can be muted quite effectively by just closing the hole at the bottom. There is a good chance that closing the hole of the microphone has the same effect. You could apply prestik or hot glue for example.
Both Filmic Pro and MoviePro lets you select which mic to use for recording.
Best Answer
No, there's no special app needed.
It sounds like you're using some kind of adapter/dongle for converting between the Lightning interface and a simple TRS. You do not mention what dongle or microphone, you're using.
It sounds likely that you are using incorrect cables. The TRS plug comes in two versions - the CTIA version used on iPhone (and most Android phones), and the OMTP version used on some Android phones and especially older equipment. If you have the incorrect verison, you'll get no voice recorded.