Benefits of DL-3X00 vs DL-195 over USB2 Macs, and font stretching bug

[miller5369]

I have a mid-2010 27" iMac with a second Apple 27" display. I have been using a Diamond DisplayLink BVU195 adapter to drive a third Dell 2709W monitor over USB2 in portrait mode at 1200x1920.

I have two questions about the benefits of the DL-3X00 hardware:

1. Can someone please tell me if there is an advantage to using a DL-3X00 device on a USB2 Mac like this? If I used a StarTech DisplayPort DL-3500 adapter or Diamond DL-3900 DV100 adapter, does it provide optimized video speed over a DL-195 device over USB2? Is there any advantage to upgrading using the same 1920x1200 monitor?

2. From what I understand, DL-3X00 devices allow resolutions up to 2560x1600. So instead of a Dell 2709W at 1920x1200, you could run a Dell U2711 or U2713 at 2560x1440 or U3011 or 2560x1600. For those of us stuck with USB2, is this the only advantage to upgrading to DL-3X00 chipset devices?

I've also experienced two issues with the alpha drivers:

1. Rotation works perfectly with the new 2.0a2 drivers. But I still get lots of display flickering when showing video or HTML5 content in Safari -- http://www.icloud.com is a perfect epileptic test for the flickering. It's all over the place using Safari, but doesn't happen in Firefox. This seems to be a known issue that may be fixed when 10.8.3 is released.

2. I see some horizontal screen stretching issues like the previous poster. See the attached image where the "r" in Worldwide and "m" in espn.com are stretched by one pixel. This happens in Firefox, but not Safari. Strange. This screen stretching behavior also happens when using Snapz Pro 2.5 -- the DisplayLink screen literally "jumps" and stretches 20 pixels horizontally when doing a screen capture.

Thanks for releasing this new 2.0 alpha -- you may hear a lot of complaints here, but the fact that I can run a third monitor over USB has helped extend the life of my mid-2010 iMac. It's been a great addition and I'm glad you continue to update the drivers.

[Wim]

Originally Posted by miller5369

1. Can someone please tell me if there is an advantage to using a DL-3X00 device on a USB2 Mac like this? If I used a StarTech DisplayPort DL-3500 adapter or Diamond DL-3900 DV100 adapter, does it provide optimized video speed over a DL-195 device over USB2? Is there any advantage to upgrading using the same 1920x1200 monitor?

Yes, there will be differences. The USB 3.0 DL-3000 devices use a completly different compression system, called DL3. USB 2.0 devices use the older compression called DL2.

From our testing, DL3 can give a better experience, especially if playing back video on a new Mac.

Originally Posted by miller5369

2. From what I understand, DL-3X00 devices allow resolutions up to 2560x1600. So instead of a Dell 2709W at 1920x1200, you could run a Dell U2711 or U2713 at 2560x1440 or U3011 or 2560x1600. For those of us stuck with USB2, is this the only advantage to upgrading to DL-3X00 chipset devices?

As I've said above, there are other advantages as it still uses the new compression on USB 2.0. 2560x1600 DisplayPort adapters based on the DL-3xxx are also supported on USB 2.0.

Originally Posted by miller5369

I've also experienced two issues with the alpha drivers:

1. Rotation works perfectly with the new 2.0a2 drivers. But I still get lots of display flickering when showing video or HTML5 content in Safari -- http://www.icloud.com is a perfect epileptic test for the flickering. It's all over the place using Safari, but doesn't happen in Firefox. This seems to be a known issue that may be fixed when 10.8.3 is released.

Yes, this does seem to be an OS issue and occurs with any driver that installs a Graphics kernel extension. Hopefully Apple will fix this in 10.8.3 as we have raised the bug with them months ago.

Originally Posted by miller5369

2. I see some horizontal screen stretching issues like the previous poster. See the attached image where the "r" in Worldwide and "m" in espn.com are stretched by one pixel. This happens in Firefox, but not Safari. Strange. This screen stretching behavior also happens when using Snapz Pro 2.5 -- the DisplayLink screen literally "jumps" and stretches 20 pixels horizontally when doing a screen capture.

Again, this appears to be an OS issue, but we'll check this.

Wim

[miller5369]

Thanks for the response Wim. I'm going to order a new DL-3X00 device to see if the new video compression algorithm is an improvement on my older DL-195 device. That brings up one more question. Is the StarTech adapter the only one that will go 2560x1600? All the other DL-3X00 devices listed on your site seem to max out at 2048x1152. Is there a reason for this, or do all DL-3X00 devices support the higher resolution?

StarTech USB3 to Displayport (USB32DPPRO)
Max Resolution: 2560x1600 (DL-3500 with DisplayPort)

StarTech USB3 to HDMI and DVI dual monitor adapter (USB32HDDVII)
Max Resolution: 2048x1152 (DL-3900)

Plugable USB3-HDMI-DVI USB 3.0 to HDMI/DVI Adapter
Max Resolution: 2048x1152 (DL-3500)

Plugable UGA-3000 USB 3.0 / 2.0 to VGA / DVI / HDMI Adapter
Max Resolution: 2048x1152 (DL-3100)

Plugable USB3-VGA USB 3.0 to VGA Graphics Adapter
Max Resolution: 2048x1152 (DL-3100)

StarTech USB32DVIPRO USB 3.0 to DVI Interface
Max Resolution: 2048x1152 (DL-3100)

Targus USB 3.0 SuperSpeed™ Dual Video Adapter
Max Resolution: 2048x1152 (DL-3900)

SIIG USB 3.0 to HDMI adapter with audio
Max Resolution: 2048x1152 (DL-3500)

Targus USB 3.0 SuperSpeed™ Video Adapter
Max Resolution: 2048x1152 (DL-3100)

[Wim]

To get 2560x1600, you need DisplayPort. This resolution is not supported out of any other output, as the pixel clock will not go that high.

Wim

[miller5369]

One additional bug I've found after using the 2.0a2 driver for a few days. When the cursor moves to the top of a window on a DisplayLink monitor, it "stops short" and switches from a pointer to a resize cursor. In the first two images, I'm trying to move my cursor to the top of the screen, but the cursor stops about 10 pixels before the top of the screen. It switches to the resize cursor instead of moving all the way to the top of the screen and then switching to the resize cursor. This behavior doesn't happen if the window is not positioned at the very top of the screen in the third image.

This only happens on my DisplayLink monitor using a DL-195 device, not on a monitor hooked directly to my iMac. It happens when the monitor display is rotated or in the default mode.

[mentalengine]

Just a note on the pixel stretching issue, I am using Mid 2012 MBP running OS X 10.8.3 (12D58) on the Pluggable USB3-HDMI-DVI, and when I go to the espn.com site, I can confirm there is no pixel stretching.