Hi, I was wondering if anyone can help? I have just been looking at some tips for the Happauge 250, and I have found that changing the GOP size to 12 is the best for PAL users. Well i'm a PAL user but i'm not sure how to do this, can anyone help. This is the link http://www.cask-of-amontillado.com/pvr_reg.html#_Change_Gopsize_to Its asking to create a new config entry first, but i'm not sure what this is. Can anyone help? Thanks
The easy way: Go to Start > Run > and type in regedit. Navigate down to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Globespan\Parameters\ivac15\Driver\GOPSize. Right click, select Modify. Change the entry to read 1203
Thanks for the reply, The value that you gave, thats in decimal, yeah? What is the difference between your way and the other way? Ive not changed it yet but what will happen? I mean will I get the option of picking GOP size 12 in the settings of wintv or will it automatically go to 12? Because at the moment there are already 2 options in the settings. I just don't want to mess anything up so i'm being extra cautious. Your help is much appreciated. Thanks
This sets it to 12 (decimal/hex, 12 is 12), period. You won't see any option to change it anywhere, and if you try, it won't work, even with the tweak tool.
Thanks reebootjim, Its all sorted now, I can't notice a huge difference but GOP 12 is slightly better that 15. Do you keep the GOP size at one setting or do you change it depending on what you are capturing? Does changing the GOP size affect the colour of the captured file, e.g the quality of it? Thanks Pez
GOP size affects quality. Because each GOP contains 1 "I" frame, and the rest are P and B frames, the more I frames (true, full image frames) per GOP, the better the quality. I have mine set to 5.
Thanks for clearing that up, sorry but i have another question regarding this, how do you know which is the best GOP size then? i.e which GOP size has the most I frames? Is there a standard that states GOP 12 will result to so many I frames? Thanks Pez
There is always 1 "I" frame per GOP. The bigger the GOP, the lower the picture quality (usually...it's slightly more complicated than that, but this is basically true). A GOP can be anything, from over 5000 (take a look at the KDVD templates) to 1. A GOP of 1 results in huge files of superb quality. A GOP of 5000 results in very small files of very poor quality. Other tricks are used to maintain some quality in KDVD. Lower the GOP to 15, 12, or even 5, and you get better quality video, without a substantial increase in filesize. eg. 1.) A 6000kbps video, GOP 15, would be deemed average, about 3.2 gig in size for 2 hours. 2.) A 6000kbps video, GOP 12, would be slightly better, about 3.5 gig in size for 2 hours. 3.) A 6000kbps video, GOP 5, would be noticably better, about 3.9 gig in size for 2 hours. 4.)A 12000kbps video, GOP 15, would be better yet, but about 9 gig in size for 2 hours. 5.) A 12000kbps video, GOP 1, would be perfect, but wouldn't fit on your hard drive Viewed on a 20" TV, #1 would appear identical to the original. Viewed on a 36" TV, #1 would appear horrible, about VHS quality. Viewed on a 20" TV, #3 would appear identical to the original. Viewed on a 36" TV, #3 would appear identical to the original. Viewed on a 36" TV, #4 would appear identical to the original, but at double the filesize. The last thing to consider, only about 1 in 100 GOOD DVD players can handle bitrate above 9000kbps, so why bother recording at that, especially when you have to re-encode it anyhow, to fit an hour on a disk?
Thanks for this info, I also looked at the previous posts and now I actualy understand what GOP is. I realy appreciate it. I also just tried my dvd out on my new philips dvd player and the quality is excellent just like the original copy. I was actually very suprised. They were captured in GOP 12, which suprised me a little. I'm very happy with that GOP. I'll try the next few in GOP 5 and see how I go. cheers
If your source is very good, then a GOP of 5 gives just that extra little bit of quality one would expect from a DVD. It's like the difference between a VHS master, and a remastered DVD of the same film.
Thanks, Is there any way you can check to see what GOP a clip is after I have captured it? Like a program or something? Thanks Pez
Open it (the mpg) in virtualdubmod. Skip through the video, one frame at a time. In the information bar at the bottom, it tells you if a frame is I, P, or B.
Help, I can't believe this. I have just checked my clips in VirtualMod and I get a 'I' frame every 15 frames! so that means I have been capturing in 15 all this time, when I thought I was capturing in 12! I must have done something really wrong. I managed to create loads of new configs in winTV, one for each GOP I was testing e.g 12,5 etc. And I thought it was working, but obviously not. In WinTV the area where I can select which GOP I want to use, a blank field is already pre-selected so I just leave that alone. But it still only captures in GOP 15. Am I going something wrong? Pez
Me again, I have also just went back and changed GOP Size the way you asked me to the first time, which still did not work as I still get an 'I' frame every 15 frames. I'm out of options. Thanks Pez
Ok I have managed to change the gop to 12, I modified the GOPSize value to read 'c03', 'c'hex = '12'dec. I don't actually know what the 03 is used for. The value that you gave originally (1203) changed the GOP Size to 18 (when checked through virtualMod). So I assumed that to get a GOP Size of 1 for example would mean changing the value to read '103' as '1' is the same whether its in hex or dec. But for some reason this did not work and it still captured in GOP 15. I also had to reboot the PC after each change. I have all the latest drivers, but still no luck. Any ideas?
There are more than one place to change the setting. Search the registry for "GOPSize" and change them all. If you only changed the currentcontrolset, and for some reason it get's messed up, windows will try currentcontrolset1, then 2 etc, or backup your current one to currentcontrolset1 and create a new one with the defaults.
