Ask Chromus

Post by **beyonder** » Sat Jan 22, 2005 12:14 pm

In Windows, there are two basic methods used for decoding video. One is DirectShow and does NOT allow you to take screenshots of the video overlay. The other, VFW interface, allows screenshots to be taken... DirectShow is faster, however may cause some problems so MS allowed for a way to disable it. Basically what you're doing by setting the acceleration to half is disabling video overlay, forcing the codec to either use VFW(very slow) or DirectShow but not in overlay mode(slower than overlay).
The video overlay is produced by your video card. Windows doesn't know what's there. How does this work? Well, windows has your CPU decompress the video, but then it sends it to your video card for color space conversion(MPEG2/4, including XviD/DivX is all done in the YV12 colorspace, but you need RGB16/24 or RGBA32 to display it!). When your video card is done with this it just slaps it up on the screen. If you set it to no acceleration it may disable DShow entirely...I haven't checked into that. Of course the video will play back at the same speed, as long as your computer is fast enough to still decode it, otherwise you'll get a big choppy mess. For taking shots of a video, I recommend using VirtualDub which has a function to save a frame of video. And you don't have to crop it.... as for DVD screenshots, I'd just decrypt the VOB files to my harddrive and take the shots from there... again in VirtualDub. Note that you may need an MPEG2 VFW codec, as VDub does not use DShow. If you have installed any software DVD player, you probably already have one...

The reason for DVDs is *basically* the same as the reason for AVIs except that some video cards (and add-on cards. example: hollywood2) can actually help in decompressing the MPEG2 stream from the DVD as well, meaning the video is sent to the card for processing even BEFORE the videocard does colorspace conversion!

Post by **beyonder** » Sat Jan 22, 2005 12:20 pm

Oh, one more thing. Color space conversion is slightly lossy. Taking shots in virtualdub will result in slightly higher quality screens. Why? DShow is going to be going for the speed of display over complete accuracy. VDubs color space conversion will just be more accurate, although a little slower. Not that most people would notice...

Phred · Post by **Phred** » Sat Jan 22, 2005 8:40 pm

ok, let's see if you can picture this:
there's a Computer, with two network cards, and a Laptop
The Cable Modem plugs into the computer, and the laptop also plugs into the computer with a crossover cable.
Like this the Laptop can access the computer's files, printer and internet.
But the crossover cable is too short, so a router is aquired, the internet goes into the router, and the computer plugs in with a regular cable, while the laptop connects wirelessly to the router. But this doesn't allow for filesharing (unless you can figure out a way that it does)
so why doesn't file sharing work when the laptop and computer are plugged in again with the crossover cable? (low conectivity warning)
does that make any sense at all?

chromus · Post by **chromus** » Sun Jan 23, 2005 6:49 pm

Leave it to Beyonder to know all there is to know about computer video techniques. Are these some of the skills you have to use when you do translation/distribution for your anime group?

chromus · Post by **chromus** » Mon Jan 24, 2005 7:35 am

Whoops. Sorry Phred. I totally didn't notice that you posted a question.

First of all, a hard connection (with wires) can't have low connectivity. Also, file-sharing shouldn't have been disabled just by installing a wireless card on the laptop. This suggests to me that software was installed that may have disabled some things. Did you install any special software?

Phred · Post by **Phred** » Mon Jan 24, 2005 4:44 pm

actualy, the laptop came with wireless powers

chromus · Post by **chromus** » Mon Jan 24, 2005 9:12 pm

Did you install any software (like Windows XP SP2) before/after the switch without testing file sharing on the cross-over cable?

Phred · Post by **Phred** » Mon Jan 24, 2005 10:57 pm

nope, I'm not sure what was wrong
Beyonder acutually helped out, but to no avail
except for now the computers show up on the network places, they just can't be accessed
<_<
it's confusing

chromus · Post by **chromus** » Tue Jan 25, 2005 10:59 pm

What did he do to help you? It might help me figure out what is going on.

Phred · Post by **Phred** » Wed Jan 26, 2005 11:11 pm

we turned off firewalls
...I think that was mostly all we did...
but after it didn't work, I turned them all back on

chromus · Post by **chromus** » Wed Feb 02, 2005 11:29 pm

It may be that the Windows firewall has problems with Windows filesharing. Turn off the firewall, make sure Simple Filesharing is turned on (by going to Folder Properties in any explorer window), and make sure Guest account is enabled on both computers.

drekikona · Post by **drekikona** » Thu Feb 03, 2005 9:15 pm

Is it possible for someone to have a heart attack after a disturbance in the REM of dreaming?

chromus · Post by **chromus** » Sun Feb 06, 2005 12:46 am

Since I don't have any medical training, I can't say if it's possible or not. I have done quite a bit of research, and there does seem to be a link between reduced sleep and heart attacks in women. Here are some sources:
http://www.cnn.com/2003/HEALTH/conditio ... ttacks.ap/
http://sleepdisorders.about.com/cs/slee ... nheart.htm
http://my.webmd.com/content/Article/59/66895.htm

drekikona · Post by **drekikona** » Sun Feb 06, 2005 12:50 am

hmm, ok, thanks alot.

chromus · Post by **chromus** » Sun Feb 06, 2005 1:38 am

The best way to get a good answer to this question is to ask your doctor, since your doctor should know who to contact or where to look up the statistics on something like this.