Timeshifting video over HDMI capture device

[vlancer]

I have a cheap eBay HDMI-to-USB adapter that I am attempting to use it to turn my PC into a time-shifting video player.

I have tested it with the Windows built-in Camera App. It was able to record video at what appears to be full resolution (1080p 30fps) video. Regardless, the video quality is good enough for me.

I then try it with VLC. I am able to playback it back as Video Capture device with some success. I ran into some problem

1. Playback always default to 4:3 ratio
2. Resolution always default to 640x480
3. If I increase the resolution, frame rate will drop. So I have to change it manually.

Despite that, I was able to change the default manually, each time, to 16:9, 720p and 30 fps.

However, time-shifting only works when I press the pause button. I can only resume and not access another time. So I look into alternative which is to record in the background and playback the file simultaneously.

I first tried with the Windows Camera App. It records into .mp4 and VLC cannot playback until recording is complete. So that's a no-go.

I then tried using VLC to record. I ran into the same limitations I mentioned earlier. I tried many different encoding format and it seems all the advanced format will not let me restart video at random location. I eventually settled with .ts MPEG2 format. It worked. However, 720p video is very blocky.

I have a 10th Gen Intel i7 CPU, no discrete GPU, but I think it should be fast enough to record 720p. Perhaps it is the re-encoding causing issue? I tried selecting "Dump raw input" but it simply playback the video and not doing any recording. I am confused.

I feel that I am very close. All I need is to find a format that VLC playback can random access. Please share some ideas!