VideoFilter | play and save video with gpu filter | Video Utils library

I'm trying to adapt Apple's AVCamFilter sample to MacOS. The filtering appears to work, but rendering the processed image through Metal gives me a framerate of several seconds per frame. I've tried different approaches, but have been stuck for a long time.

This is the project AVCamFilterMacOS - Can anyone with better knowledge of AVFoundation with Metal tell me what's wrong? I've been reading the documentation and practicing getting the unprocessed image to display, as well as rendering other things like models to the metal view but I can't seem to get the processed CMSampleBuffer to render at a reasonable framerate.

Even if I skip the renderer and send the videoPixelBuffer to the metal view directly, the view's performance is pretty jittery.

Here is some of the relevant rendering code I'm using in the controller:

Trying to record audio on android with gstreamer(enable permission of audio record already), I prefer gstreamer but not the java api because there are more functions need to be added in the future, like convert the audio to specific format(S16LE, channels=1, rate=16000 etc), encode as wav, separate video/audio and so on

The pipeline I am using are

in my uwp app I am getting video files from KnownFolder.VideoLibrary and I am using QueryOptions to get them, so taking advantage of that I am trying to use AdvancedQuerySyntax so that I only get video files, but I am actually getting subtitle files like srt as well. what am I doing wrong here? is the AQS syntax I wrote wrong? I think subs files are also considered as video files according to this syntax, is there a way I can narrow it down to getting only video files excluding subtitle files? or can I get a link to docs where I can know what is the list of extension types, this syntax actually will return? So I can manage it accordingly?

CODE

Searching for an alternative as OpenCV would not provide timestamps for live camera stream (on Windows), which are required in my computer vision algorithm, I found ffmpeg and this excellent article https://zulko.github.io/blog/2013/09/27/read-and-write-video-frames-in-python-using-ffmpeg/ The solution uses ffmpeg, accessing its standard output (stdout) stream. I extended it to read the standard error (stderr) stream as well.

Working up the python code on windows, while I received the video frames from ffmpeg stdout, but the stderr freezes after delivering the showinfo videofilter details (timestamp) for first frame.

I recollected seeing on ffmpeg forum somewhere that the video filters like showinfo are bypassed when redirected. Is this why the following code does not work as expected?

Expected: It should write video frames to disk as well as print timestamp details.
Actual: It writes video files but does not get the timestamp (showinfo) details.

Here's the code I tried: