Low quality audio recorded when using USB C - USB A OTG adapter to connect audio interface

I recently purchased a UGreen USB-C to USB-A socket (so-called OTG adapter - see attached image) so that I can connect an external audio interface to my FP4 and record audio directly from an external source while recording video. Specifically, I want to video myself playing instruments in my small home studio and record the output from my mixer/DAW rather than using the internal mic on the FP4. While audio does indeed record along with the video footage, the quality is very much lower than I had hoped. It sounds muffled, almost as if there’s a low pass filter cutting all frequencies above approximately 10-12kHz.

I’ve tested multiple audio interfaces, including one with an internal power source so that it isn’t running on BUS power directly from the FP4 battery - I thought this might be under-powering the interface(s) and thus causing the drop in quality. I’ve also been using the Open Camera app due to the extra functionality, but the issue persists. The audio interfaces/devices I’ve connected to my FP4 via the OTG adapter are as follows:

Zoom H1n - tested with both internal battery power and running off BUS power via the FP4 battery

  • Audio such as vocals recorded via the H1n mic are muffled as explained above.
  • Audio from my mixer/DAW recorded via the line input of the H1n is similarly muffled.

Focusrite Scarlett 2i4 1st gen - will only run on BUS power

  • Audio from my mixer/DAW recorded via the line inputs of the Scarlett 2i4 is muffled.

M-Audio Fast Track Pro - can run on BUS or external power supply, but I don’t have the latter to test

  • Audio from my mixer/DAW recorded via the line inputs of the Fast Track Pro is muffled.

Allen & Heath Zone 43C DJ Mixer - runs only off mains power and can act as USB audio interface

  • Crashes the Open Camera or native camera app of the FP4.

I’ve also plugged the Zoom H1n into my Mac Mini using the same OTG adapter and I have been able to record audio without any drop in quality. I thought the OTG adapter might be the issue, but it clearly isn’t. My last “acid test” is to connect my PreSonus Studio 1810c directly to the FP4 as the interface is mains powered with USB C connectivity BUT that would prevent me from using it to record the instruments in my home studio, so it’s not really a practical solution.

I’m wondering if anyone has any experience with this issue, or knows of a work around to ensure audio from an external source connected to the FP4 via USB C is recorded without any impact on quality.


Have you tried with the builtin Soundrecorder app? It allows you to specify parameters of the recording quality…

Thanks for your reply. Unfortunately, the Sound Recorder app has no way for me to specify audio quality or audio input source. The version I have installed on my FP4 is super basic and only features a record button, a stop button and a menu for accessing previous recordings. I have a third party app called Audio Recorder which allows me to specify the audio file format I wish to record to (i.e., various bit/sample rates of M4a, Wav and 3gp) but again, it has no way to specify the audio input source so I assume it just defaults to the FP4 internal mic.

However, these are all somewhat moot points as my issue isn’t the ability to record high quality audio. I can accomplish that with my computer and home studio setup. The issue is recording video WITH high quality audio from an external source that inputs directly into my FP4 rather than using the FP4 internal microphone (apologies if I hadn’t made that super clear in my original post). Essentially, I want the video and audio to record simultaneously within one app like Open Camera or the native FP4 camera app. I can record both independently, but then I’ll have to edit them together afterwards which can be quite time consuming.

You don’t have the cog wheel button under the record button? That’s where quality is configured.


Also, your problem seems to be that you want to use an app that’s not designed for recording hifi audio to do exactly that (the camera app). Camera apps usually apply lots of postprocessing like wind removal etc and that is most probably the reason why your recordings are distorted.

Alternatively, you could try some of the apps that turn your phone into a webcam and do the recording on the computer. However, I’m not sure what would the latency be.

Or, wouldn’t it be easier to record the audio on the computer and merge it with the video in postprocessing?

This is the entirety of the app for me, there’s certainly no cogwheel to configure settings etc.

I appreciate that I’m trying to use a third party app, but that’s exactly the point as it’s the only app I’ve been able to find that allows the user to choose an audio input source from a list in the app settings (this is not the case with the native camera app). It even allows users to record audio “unprocessed” thus doing away with any noise reduction, post-processing etc that you mention. Furthermore, when I connect an audio interface to my FP4 and use the native camera app to record video with audio from an external source, I get the exact same results with poor quality audio.

I haven’t been able to find any tutorials for this process that don’t recommend using Open Camera (for Android phones at least) or typically, trying to get hold of an iPhone as they appear to work seamlessly with external microphones and audio interfaces - obviously that’s out of the question lol At this stage (and as you mention), I’m thinking of recording the audio and video separately and editing them together using something like CapCut or Canva to create a final video, but that’s actually what I wanted to avoid in the first place by trying this approach.