High Profile Encoding - What are the benefits and drawbacks?

[greggerm]

With the release of a functional Nero Digital HP encoder, I have a general set of questions about 8x8 / High Profile encoding. I'm asking for the newbies out there who don't necessairily know the details and inner workings of video encoding technology. I asked the same question in a thread a few weeks ago, and with no offense to DVD_Maniac who answered me, the technical brief provided flew over my head by a wide margin. :)

Simply put, what benefits do 8x8 High Profile encoding bring to the table for folks using Nero (or any other encoder)?

How about a true/false session! If you are kind enough to answer, feel free to elaborate on any of the subjects you see fit. But like Nero Recode itself, try to keep it on a level that is good for a beginner.

* 8x8 allows the encoder to subdivide the screen image into smaller chunks to improve motion detection, and that's about it (T/F)

* 8x8 tends to benefit higher resolution encodes (HDTV) more than low (DVD/SDTV). (T/F/Benefits Equally/Not Applicable)

* 8x8 tends to benefit higher bandwidth encodes (+1mbps) more than low (T/F/Benefits Equally/Not Applicable)

* Given you want a desired file size, turning on 8x8 will improve, if only slightly, the image quality of your encode irregardless of resolution or bitrate (T/F)

* If you had the opportunity to use 8x8 in your everyday DVD/SDTV encoding, would you turn it on? (Y/N)

Thanks!
Hopefully some of these questions will help us luddites without an intimate knowledge of how encoders work decide upon using the Nero 8x8 HP implementation. I've been a little confused with it since most of the talk about 8x8 is in the context of HDTV encodes, and I am personally only encoding DVD and standard def. programming.

Perhaps the answer can end up in the Nero Digital guides here on Doom9 next time it is updated.

Your input is greatly appreciated!
-Greg

[check]

8x8 allows the encoder to subdivide the screen image into smaller chunks to improve motion detection, and that's about it
When encoding with h264, the screen is divided into 16x16 Macroblocks (MBs). These blocks can be subdivided further into partitions of various sizes (16x8, 8x16, 8x8, 4x4). 8x8 DCT (which is what you are referring to) is simply another way of subpartioning a macroblock. Motion estimation is better with smaller subpartitions, but the overhead for such information is similarly increased.

8x8 tends to benefit higher resolution encodes (HDTV) more than low (DVD/SDTV).
Very little difference would be observed.

8x8 tends to benefit higher bandwidth encodes
Couldn't say.

Given you want a desired file size, turning on 8x8 will improve, if only slightly, the image quality of your encode irregardless of resolution or bitrate
Yes

If you had the opportunity to use 8x8 in your everyday DVD/SDTV encoding, would you turn it on?
I use x264, so I've already had access to it for well over 2 years (?) now :). 8x8dct is enabled in everything I do that isn't a baseline profile encode for my pocket pc.

[akupenguin]

8x8 DCT (which is what you are referring to) is simply another way of subpartioning a macroblock.
DCT block size is separate from motion block ("partition") size. The DCT has a choice of 8x8 or 4x4. Motion partitions have a choice of 16x16, 16x8, 8x16, 8x8, 8x4, 4x8, or 4x4. Each (inter-) macroblock has both a DCT block size and some motion partition size(s). The only restriction on combining the two is that partitions can't be smaller than their DCT blocks.
Small partitions provide better prediction but cost more bits. There is no overhead one way or the other for DCT block size, but also one isn't always better compression than the other, so that decision is based just on which one is more appropriate to the given image region.
That said, high profile also introduced a new intra partition, "i8x8". Intra partition sizes now have a choice between 16x16, 8x8, and 4x4, which is decided based on prediction quality vs bit cost just like motion partitions are.
In x264, --8x8dct enables high profile, and x264 allows i8x8 partitions if high profile is enabled, but they should not be confused as being the same feature.

8x8dct tends to benefit higher resolution encodes (HDTV) more than low (DVD/SDTV)?
benefits equally
8x8dct tends to benefit higher bandwidth encodes (+1mbps) more than low?
benefits equally

[Manao]

BTW, sometimes, I wonder if a mode "only 8x8 dct" would please the ringing-and-grain/noise addicts that still prefer XviD over x264. Did you ever try it ?

[Blue_MiSfit]

Loving your nomenclature there Manao. I need my fix!!! GRAIN!!! :D

~MiSfit (in good humor)

[greggerm]

Might I say thanks Check and AKU for your guidance. I thought that is what DVD_Maniac was getting at when he sent me the info and wrote a little bit about it, but for some reason I couldn't get my hands around it.

-Greg

[Sharktooth]

BTW, sometimes, I wonder if a mode "only 8x8 dct" would please the ringing-and-grain/noise addicts that still prefer XviD over x264. Did you ever try it ?
That's interesting...