I-Frame Only??

[neomaine]

Hello folks,

When setting the digital vcr in MMC (I use 7.5 on an AIW Radeaon) it has a choice for I-Frames Only...or at least something similar. I use it mostly for capturing tv shows and didn't know if this could help or hurt. I've looked around here but couldn't find anything too specific. What I'm looking for is:

- A short version of what an I-Frame is (maybe what a P or B one is in contrast.
- A short version of how it is used.
- Would it help? Help/Not help shorten file size...Help/Not help quality...

Have a good one,
neomaine

[JimJohnD]

- A short version of what an I-Frame is (maybe what a P or B one is in contrast.

An “I Frame” is an actual picture (as much information as can be stored), “P Frame” is predicted bases on the difference between the last frame (only the difference so it’s less information), and “B Frame” is a bi-directionally predicted frame (is even less information).

- A short version of how it is used.

Myself, I capture to “I Frame” at 8meg video using 480X480 Mpeg 2. This gives me a source file I can use for XSVCD and VCD output with GREAT quality. You SHOULD use “I Frame” only for capture if you are planning on editing your video (like removing commercials). You can only get good cuts on an “I Frame” frame.

- Would it help? Help/Not help shorten file size...Help/Not help quality...

Use “I Frame” only for capture and the standard IBP GOP structure for rendering to make a video disc. An all “I Frame” video will take the most disk storage as it has as much information per frame on video as you can get with “IP” and “IPB” giving you smaller file sizes. You might think that if an “I Frame” is the actual picture you should always use it. Not so, at the lower data rates an “I Frame” only video will be REAL BLOCKY because there just isn’t enough video data rate to go around. My DVD player will loose sound sync with an all “I Frame” XSVCD, but play fine with a 4:2 GOP and looks Near DVD quality.

I record using ATI 6.3 TV application, and edit and render with Ulead Media Studio Pro 6.5 with DVD MovieFactory. I am very happy with the quality of the resulting videos from this setup.

[misteray]

In order to remember those I,P & B terms, my trick is to associate it to visual terms. So "I" stand for Image, "P" for pixels and "B" for block. I know this is not the right definition and the above message was more precise but got reason to beleive anyone would understand.

Good day

[katzenkreis]

@JimJohnD: Do you use CBR or VBR. Thanx