[Android] DisplayLink adopter worth for screen mirroring? CPU overhead? Latency?
 

Hi,

I have two Android devices (One with 1080p and another 2K ). Right now I'm using a Chromecast to mirror the screen of the devices, but the latency and image quality is pretty bad to use it for anything else than watching a movie from time to time. Also I travel a lot and having a good enough WiFi connection for Chromecast is not always possible, rendering the Chromecast useless for most of the time.

I've heard that DisplayLink works with some Android devices. I've been using DisplayLink devices in the past (3 or 4 years ago), but I was using it with PCs. I've just noticed that the CPU loved to spike when many things were going on on screen, which suggests to me that the image that is sent to the DisplayLink device is being rendered or processed on the CPU.

So going back to the original question. How does it look on Android? What devices are supported (Or what hardware is necessary) and what DisplayLink chip do I need to get at least a 1080p image to HDMI? How big is the CPU overhead, and how big is the latency when used with an Android device?

Greetings and thanks.

JUST AS EXTRA INFO IN CASE IT MATTERS:
The devices in question are:
- Motorola Moto G5 Plus (7.0)
- Lenovo Yoga Tab 3 Plus (7.1.1)

Hello RKK,

As far as I am aware, Android natively only does one device in clone at a max resolution of 1080p.
There's a presenter mode on some applications like PowerPoint to display something different without user interaction possible on that external display as there's no way with stock Android to handle mouse across displays or select which screen the app should be launched on.
We've done it to show it's possible, creating a specific ROM for that. The OS can be modified to do extended desktop with mouse support.

The Android device needs to support being a USB host (USB On The Go).
DisplayLink DL-1x5, DL-3000, DL-5000 and DL-6900 series all work.

No pixel comes from of any kind of computation.
Computation load and latency depends on content type, bandwidth available both on the computation and communication link.
It doesn't have the latency of casting as it would make it pretty useless for our core use case which is productivity. That's a different use case than screen casting.

I, every now and again, use my personal OnePlus 3T on my dock (with external mouse and keyboard) or on my miniRay pico projector to share presentations/photos
Today, you wouldn't be able to do protected video playback.

Kind regards,
Alban

Oh, that's great news!! Thank you for the information.

BTW. If I'm not wrong, the OnePlus 3T has USB 2.0 (As my devices). Does it supports 1080p@60 FPS or what resolution does works? I've seen in Amazon that the 3500 Chipset supports only 800x600 on USB 2.0. But on another device with a 5500 it was stated that it could go up to 1080p@60 on USB 2.0, while in the comments people were saying that they can go even higher on USB 2.0 and it still works. Any idea how this works? Is it possible to look up the right information somewhere for USB 2.0 and the supported resolution in USB 2.0 mode for each chipset?

Is there any chance the 3500 would be able to support 1080p@60 on Android?

Yes, it is USB 2.0. I initially wanted to use the USB plug to backup my phone on a drive, until I realise it was much faster to go through AC WiFi.
But USB 2.0 is not a bottleneck to getting FullHD at 60Hz because our algorithm is adaptative.
Obviously, if you're already maxing out the phone capacity without adding a display (RAM, CPU and GPU), then our algorithm will use what's left...
Unlike most computers, you have a limited power envelope available: no fan means if the phone gets warm, the computing power will be throttled not to burn your pocket.

If you tell me how you wish to use this, I can look deeper. I have 1080p60 displays on my desk (and we have gazillions of monitors in our office).

I would not advise the DL-1x5 for your application because it will never be able to do content protection as there's no hardware block for it, and cannot be field upgraded. It doesn't do audio either.
It works very well otherwise it wouldn't have been selling for years and keep doing so, it is just not "future-proof".

You can look at the table of the DisplayLink DL-3000 series with capability.
The DisplayLink DL-5000 series is an extension of the DL-3000 which can achieve 4K.

The key though is that DisplayLink sells chips! The manufacturer defines what the product does. For instance, you will find products using our DL-1x5 with audio, because an audio chip was added.
That's something we can look at if you have a few products in mind: I am likely to have the specifics of the implementation.

What would you show on the screen? That would give me an idea of what is realistic and test it myself.

Kind regards,
Alban

Thank you Alban for the useful information.
I was looking at this device from Amazon (https://www.amazon.de/gp/aw/d/B076SX...7oL&ref=plSrch). It has a DL-3500 chipset which supports 1080p@60 which is perfect for what I need by now.

I'm searching for a small device that I can take with me when I'm traveling, to connect my phone to the TV via HDMI. The main thing I would use it for would be to watch mainly self-encoded (unprotected) videos that are all being hardware decoded by my mobile device (so the CPU usage is really minimal and should not be a problem). Although I would really like to make use of some mobile IDEs and editors like Word, which was never feasible to do on a Chromecast due to the latency, setup hassle and blurriness. Also I'd like to run sporadically some game or emulator (this probably will use more CPU, although the highest impact will be on CPU) though the last one is not really a big requirement.

All my equipment is Bluetooth enabled anyway (keyboard, mouse and even joystick).

Do you think that the DL-3500 would be enough to get the 1080@60 for the 3 use cases I mentioned on an android device?

Hello,

When you watch a film, you are effectively asking your phone to do transcoding from whatever the film is encoded in to the DisplayLink DL3 format.
If the codec used to encode the film is not available as a hardware decoder on the phone, this means the CPU has to do both decode and encode, that can be a bit taxing for a phone, especially at it takes place full screen.

The text editor use case is much easier, as there's nothing to decode first, and not much to encode then, even if you type fast!

I will try this and get back to you. I'll use some random DivX, a similar adapter and plug this to a Full HD TV similar to what you're likely to find in hotels.

Kind regards,
Alban

Thank you for taking the time to try it out. I'm looking forward for the results.

Hello RKK,

I've used a Plugable USB3-3900DHE on my Oneplus 3T on Oreo with a Dell P2414H display.
The Dell monitor is synchronised at 1920 x 1080 at 60 Hz.
For media, I used a rather old .avi file encoded almost a decade ago.

When using VLC for video, the application seems to recognise our solution as, instead of displaying on both screens, VLC shows an icon on the native display and the video on the external display.
No video pause, no video tearing. To me, it plays smoothly like on the mobile phone.

I also tried the picture-in-picture (PIP) feature you have on Oreo, and it works too (it is a real duplicate here, and full screen duplicate when exiting PIP)
In that case, performance is spotless too, but that's an easier job as the video is smaller.

I'll try at home on my TV later, to make sure the sound matches the image!

Kind regards,
Alban

RKK,

I have now checked with a television.
The audio is in-synch with the video.
I've also found a recent 1080p AVI which plays just as well as my old one.
The quality is good, very good even, especially if I compare to the usual quality I get in hotel rooms... I mean it's Full HD on a Full HD screen, instead of blurry sub-576i on a 1080p display.
If I wasn't using my phone for messaging and all from the bed when putting the TV on as background noise, I would use it myself from now on.

Kind regards,
Alban

Amazing!! Cannot thank you enough Alban for testing this out!

I'm pretty sure this thread will be also helpful for other people searching for a Chromecast replacement.

I'll buy myself the device with a DL-3900 chipset and report back once I get my hands on it and test it out.

Greetings and thank you again!

So I finally got my device and tested it out a bit, and I have to say I'm very positively surprised how well the device is performing most of the time. The image quality is super crisp, no way near to the blurry and blocky Chromecast quality.

Although my first impression didn't go too smooth at first, as I had the DisplayLink Presenter and DisplayLink Desktop (Demo) installed at the same time, and eider these two or some other app I had installed on my phone clashed with the system when I connected the DisplayLink device, leaving all my 8 CPU cores maxed out at full speed during the whole time, draining huge amount of battery (It used up more than 50% in 10 to 20 minutes) and heating up the phone tremendously. But things changed quite drastically when I removed the DisplayLink Desktop (Demo) app and restarted my phone.

Once the conflict got solved, it was a huge surprise to see how efficiently the DisplayLink software was working. The CPU usage drops to near zero when nothing is changing on the Display, but even when you play a Video or a Game, I haven't seen any performance drops so far.

Going a bit more into details, the Motorola Moto G 5 Plus has the littleBIG architecture, which basically has two quad core CPUs inside, one low energy one that goes from 0,6GHz to 1,6GHz, and another one which is high performant but is less energy efficient one and goes up to 2GHz. These CPUs are enabled and disabled depending on the system need, so if the system needs a lot of processing power it would wake up the fast CPU.

So I played a 1080p movie with VLC (Hardware decoded), and it didn't even wake up the high performance CPU!! Even better, it was using the energy efficient CPU at only 1.4Ghz most of the time, which is nearly the same as it was without using the DisplayLink device. And the image quality was just super sharp like with a regular Blue Ray player.

Also for the sake of completeness, I wanted to see how much of a performance hit the DisplayLink device would have during Gaming and graphical intensive tasks. And I sincerely could barely see any performance hit. I tried with emulators like N64 and PSX, each of them rendering at native 1080p, and it was just smooth as butter during most of the time. I even tried GTA San Andreas which is pretty much a GPU monster, with the same settings I was using without DisplayLink and it was running as smooth as without the device. In the worst cases there would be some minor artifacts or glitches or some sporadic frame drops, which anyway just happen pretty rarely and only when the CPU gets maxed out.

It seems like DisplayLink priorizes the running application over itself, resulting in small graphical glitches and artifacts or sometimes even frame drops when the CPU is maxed out, but the app that is running doesn't seems to perform any slower. I think that's a really neat way of working.

So all in one, I'm really happy with the device, and surprised how efficiently it works. It works perfectly for what I need it to, from simple browsing and document editing, to movie watching and even quite intensive gaming.


The only device that didn't work so well was my tablet device with the 2K screen, which I guess uses a lot of CPU for downscaling the image, or something else is going on, because I only get the screen with a lot of artifacts and cracking sound. But sincerely I barely tried it out during 5 minutes, so maybe there was also something conflicting. But I will look into that later on.

Once again, thank you @AlbanRampon for all the help. The device was a total hit for me. I just hope that some day there will be a mobile targeted DisplayLink device that would allow to charge the mobile device while using the DisplayLink screen, altough I guess that the DL docking station is as close to that as it can get by now.

Displaylink chip support
 

Will the Displaylink chipset DL-165 support Android OnePlus 3T to mirror on a screen using this adapter?

Plugable UGA-165 USB 2.0 to VGA/DVI/HDMI Graphics Adapter for Windows Multiple Monitors up to 1920x1080 / 1600x1200 Each (DisplayLink DL-165 Chipset)
https://www.amazon.in/dp/B004AIJE9G/..._C5FbBb93XM15R

Yes, it does work the same way.

what about lag during gaming?

thanks in advance

I don't perceive any lag (if there is any it is barely noticeable for me). The only thing I see is that it is unable to send all 60fps to the device, while on the phone screen graphics are smooth at 60fps on my TV it seems like it's 30 - 45 fps (perceived), but that might be due to my phone's limited processing power (Moto G 5 Plus).

J'ai entendu dire que DisplayLink fonctionne avec certains appareils Android. J'utilisais des appareils DisplayLink par le passé (il y a 3 ou 4 ans), mais je l'utilisais avec des PC. Je viens de remarquer que le processeur aimait faire des pics lorsque de nombreuses choses se passaient à l'écran, ce qui me suggère que l'image envoyée au périphérique DisplayLink est en cours de rendu ou de traitement sur le processeur.

Where can I find the OS changes necessary to support multiple screens? I build my own ROM for my phone, and I'd like to include this feature.

This hint really helped me a lot! I have the problem that my phone has a 2:1 (resp. 16:8) screen ratio instead of standard fullHD 16:9. So I get 1/18 black bars top and bottom. This is not too annoying while surfing or writing on my phone but for videos it is. Especially when I watch a 16:9 video "fullscreen" on my phone as it adds black bars on the left and right side. So when streaming directly from the web browser on the phone a video "fullscreen", I am getting black bars all around the video.

BUT as you mentioned VLC is able to directly access the displaylink hardware. With the Firefox extension "External Video Player" I can easily play my video with VLC instead of Firefox itself and voila: I am getting fullHD streaming without any black bars from my phone to my external monitor. Awesome! :D