[SOLVED] Getting Usb Vga To Work

[Fishbong]

What framerate do you get? And can it load back data from the SGX? I highly doubt that the framerate is any good and that you can use the default 3D hw on the external display without loosing a good bit of performance.
Imo, a VGA-Box is the way to go, but lets see your results first..

Don't know, and don't know. Framerate doing what? and how would I measure it? I've only been looking at mostly static images so far (as that's what I'm trying to use). The Image is not very sharp, which is fine for a projector but maybe not really great for desktop use.

A VGA-box might work well, but I'd need to wait for / sort out a TV-out cable first.

The framerate should be very low when using such a USB VGA "adaptor". Those things work like this: The driver converts all the video output as a video stream and sends it over USB to the actual "adaptor" who then converts the video stream into RGB HV video for the VGA output.
So the Pandora has to do realtime video encoding while displaying anything when using this method, meaning there's a heavy strain on the CPU. So everything on the Pandora should run very slow.

Of course if you just look at still images, that would not be a problem.

 

[WizardStan]

Don't know, and don't know. Framerate doing what? and how would I measure it? I've only been looking at mostly static images so far (as that's what I'm trying to use). The Image is not very sharp, which is fine for a projector but maybe not really great for desktop use.

Two things: try doing playback of a video; something low quality (around 320x200 would be adequate, I think) that isn't necessarily going to tax the CPU would be fine. Try making it full screen, even.
Second, you can try running some of the OpenGLES demo programs that reside on the NAND somewhere and drag the window onto the USB screen; someone else will have to tell you where, since I don't know where they might be, but I know they're there.
For a more difficult test, try a higher quality video, something like a 480p (or even 720p, if you're feeling bold) XVid file.

 

[rv6502]

The framerate should be very low when using such a USB VGA "adaptor". Those things work like this: The driver converts all the video output as a video stream and sends it over USB to the actual "adaptor" who then converts the video stream into RGB HV video for the VGA output.
So the Pandora has to do realtime video encoding while displaying anything when using this method, meaning there's a heavy strain on the CPU. So everything on the Pandora should run very slow.

that's not how they work.

1600x1200 16bpp takes only 4MB of RAM, 8MB for 32bpp.

they have just enough internal memory to hold the video picture, they don't stream the image over the USB bus, that would not work due to timing issues.
the only thing that gets sent on the USB bus are updates to the frame buffer, and the driver can send only the updated region, not the whole screen.
and some devices support hardware blitting and video overlays with hardware scaling & decoding further reducing the CPU and USB strain.

showing a static image will not use any CPU processing at all.

 

[petelewin]

However, I'm sure this has been discussed several times on here, with the general opinion being OpenOffice is way too much of a memory hog to run reasonably on Pandora. I started looking into building it (maybe just the presentation part), but I have not yet found the time and probably don't have the ability...

As Alerino noted, it may be worth you taking a look at Stuckie's "Debian In An Extend" thread. I gather that this should give you the ability to install items from the Debian ARM repository (although I haven't used it myself, so do take that with a pinch of salt).

That may well be a good idea, thanks. I have read that thread, but haven't got my head round how it works yet. So much stuff to try, so little time!

 

[seb64]

The framerate should be very low when using such a USB VGA "adaptor". Those things work like this: The driver converts all the video output as a video stream and sends it over USB to the actual "adaptor" who then converts the video stream into RGB HV video for the VGA output.
So the Pandora has to do realtime video encoding while displaying anything when using this method, meaning there's a heavy strain on the CPU. So everything on the Pandora should run very slow.

that's not how they work.

1600x1200 16bpp takes only 4MB of RAM, 8MB for 32bpp.

they have just enough internal memory to hold the video picture, they don't stream the image over the USB bus, that would not work due to timing issues.
the only thing that gets sent on the USB bus are updates to the frame buffer, and the driver can send only the updated region, not the whole screen.
and some devices support hardware blitting and video overlays with hardware scaling & decoding further reducing the CPU and USB strain.

showing a static image will not use any CPU processing at all.

Actually this particular device is a real GPU (a Sis 315) with 2D, 3D and video acceleration (though it is an old GPU and roughly equivalent to a Geforce 2 MX)

 

[mtaylor]

Has anyone tried doing this with a displaylink based usb-dvi adapter? There seems to be an opensource effort already, over here.

The displaylink chipset is used in a large number of devices, including usb-based docks and usb monitors.

Displaylink has been mentioned in the forum, but I haven't seen anyone actually try and make it work yet.

Anyways, I won't get my pandora any time soon (somewhere around 2k in the queue), or I would be trying to get this working myself, right now!

 

[petelewin]

However, I'm sure this has been discussed several times on here, with the general opinion being OpenOffice is way too much of a memory hog to run reasonably on Pandora. I started looking into building it (maybe just the presentation part), but I have not yet found the time and probably don't have the ability...

As Alerino noted, it may be worth you taking a look at Stuckie's "Debian In An Extend" thread. I gather that this should give you the ability to install items from the Debian ARM repository (although I haven't used it myself, so do take that with a pinch of salt).

That may well be a good idea, thanks. I have read that thread, but haven't got my head round how it works yet. So much stuff to try, so little time!

Well, I've now got OpenOffice running under Stuckie's Debian chroot! Unfortunately it is too slow and unresponsive to be useful for running presentations :-( Still, the whole Debian-in-an-extend is really neat, and well worth the time playing with just for fun!