Using a RaspberryPi as a Display Adapter | Hacker News Reader

Using a RaspberryPi as a Display Adapter

gwolf.org

52 pointspabs39 comments

I've wasted some time on trying to get multicast RTP working for various purposes and I don't recommend it. Software on the receiving end often isn't equipped to deal with it, so it falls flat. E.g. ffmpeg based software can connect to multicast RTP, but you need to explicitly state that you want multicast. A lot of software that uses ffmpeg doesn't even allow you to set those options.

About VNC, yes, it is slow and laggy... on a raspberry pi 3. ;)

It depends on the encoding and implementation, really. For example, I see that Mr. Wolf is using raw encoding for the RTP stream, so bandwidth is hardly a problem. Thus, I would be surprised if VNC with raw encoding would be any slower than that. In fact, it should be even faster because WayVNC will only send the parts of the image that actually changed, whereas wf-recorder will send the whole image every time. Of course, it also depends on the client. I recommend tigervnc.

I would also like to mention that VNC has, recently, gained support for H264 encoding and WayVNC can do zero-copy h264 encoding on the GPU/VPU using VAAPI. Clients that support h264 so far are: tigervnc and wlvncc. However, only wlvncc does it using hardware decoding and hardware rendering. It really falls short, when it needs to touch the CPU. When that happens, you're better off with Tight encoding.

Edit: I should mention that h264 does not work on Raspberry Pi yet. It needs hardware specific encoder and decoder.

Edit 2: Actually, I misremembered about RTP. My troubles were with multicast RTSP.

I was blown away by this great high quality post... Oh, it's from @any1, author of wayvnc!

> Edit: I should mention that h264 does not work on Raspberry Pi yet. It needs hardware specific encoder and decoder.

So Raspberry Pi HW h.264 encode & decode are not usable for this purpose?

I've seen several people on HN say that VNC can be just as good as RDP but I've never found that to be true myself, would you say H264 make a significant difference? Is there anything else that makes VNC closer to RDP? Any recommendation for Windows server?

While I sincerely appreciate the user, I often find we in Linux/OSS/FOSS are complicating our lives. Anyone wanting decent batterylife please get some JasperLake or GeminiLake refresh notebooks. These are available in eBay or retail for $200 - $300. I have a Dell latitude 3190 (fanless/HD screen), and Acer Swift 314 (fanless/IPS/FHD), and Acer Aspire 317 (FHD - 17 inches) - has decent HDMI (but barrel charger) 2 X USB. Close to 1.3 kg. Battery life - seems at least 12 hours. Sure I usually ssh and work remote.

I did something simalar with one or four kindles (eink). https://hackaday.com/2021/01/08/old-kindle-shows-hdmi-video-...

Instead of 'cutting out' a part of your screen to export via VNC/RTP, you could use EVDI to create a virtual DisplayOutput, that can be bound to one of the available rendering heads of your graphics card (so with HW-Accel), and then exported either through VNC or RTP. That way you can extend your desktop onto nearly any external display surface.

This is an awesome "hack".

The easiest way is to run an xserver on it. Why do things have to be so unnecessarily inconvenient these days?

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