PAR encoding with XviD

[Tropican]

Should I be making PAR encodes? Is there a large perceptual quality advantage in XviD? If so, how would I then go about selecting a resolution? Then I guess an aspect ratio error doesn't do anything as the video is resized to the proper AR?

Thanks,
Tropican

[SeeMoreDigital]

Whether to generate anamorphic encodes as apposed to square pixelled encodes often depends on your intended end use.

For example, will you be watching your encodes on a stand-alone player for viewing via a large or small screen. Or will you be watching your encodes on a PC for viewing via a PC monitor (17" is the most popular size).

Given the bit-rate, the more pixels you encode with, the better looking the encode will be. However (arguably) very little can be gained by exceeding the quantity of pixels as used in the source!

There are many of us on the forum who generate Mpeg4 DVD back-ups using either 720x480 or 720x576 pixels (ie: the same quantity as the source).


Cheers

[Tropican]

Interesting...Does the bitrate have to be high to avoid a resize? Does that affect the overall size of the film?

[SeeMoreDigital]

Originally posted by Tropican
Interesting...Does the bitrate have to be high to avoid a resize? Does that affect the overall size of the film? As with all encoding, the bit-rate you'll require will depend on how much activity there is in the source!

As you know an NTSC 720x480 DVD source contains 354,600 pixels. A PAL 720x576 DVD source contains 414,720 pixels. So if you've been used to generating say, 640x272 square pixelled encodes containing just 174,080 pixels, as you can see... there is quite a difference in the quantity!

On a positive note... if you head over to DivX's High-Def site (http://www.divx.com/hd/) you will find some high-def trailers which have been encoded using more than 900,000 pixels (ie: twice that of an PAL DVD) and at bit-rates of no more than 4000Kbps!

Which kinda makes you wonder why we need the massive capacity of Blu-Ray and HD-DVD disc's ;)


Cheers

[Shinigami-Sama]

Originally posted by SeeMoreDigital

Which kinda makes you wonder why we need the massive capacity of Blu-Ray and HD-DVD disc's ;)


Cheers
to increase the grapical quality while still neglecting the story line of movies and games perhaps?

back on topic
I personaly find resizing to square pixels looks better on my tv
but agais it;s up to you

[Tropican]

I think I'm finding myself more lost the more you guys post :) So why do the guides on doom9 (extensively) recommend resizing then?

When I was talking about bitrate and size I was referring to the bits/pixel ratio and how it affects movie quality and undersized films.(Arguably, not for this thread) What I meant to ask was as choosing too small a resolution can result in undersized and sub-optimal quality movies, can choosing to large one cause movies to tend to be oversized, causing the codec to choose lower bitrates?

Thanks,
Tropican

[SeeMoreDigital]

Originally posted by Tropican
I think I'm finding myself more lost the more you guys post :) So why do the guides on doom9 (extensively) recommend resizing then? It can be rather confusing can't it... because you have so much choice ;)

Like I mentioned earlier, try to consider how you'll be viewing your encodes... not just today but in the future!

You never know, at some time in the future you might decide to splash out on an big screen/display (if you haven't already got one)... and you'll be glad you encoded with more pixels!


Cheers

[unskinnyboy]

Originally posted by Tropican
I think I'm finding myself more lost the more you guys post :) So why do the guides on doom9 (extensively) recommend resizing then?

When I was talking about bitrate and size I was referring to the bits/pixel ratio and how it affects movie quality and undersized films.(Arguably, not for this thread) What I meant to ask was as choosing too small a resolution can result in undersized and sub-optimal quality movies, can choosing to large one cause movies to tend to be oversized, causing the codec to choose lower bitrates?

Thanks,
Tropican
Resizing is recommended depending on the kind of movie you have, the compressibility of the movie, the length of the movie etc, etc, etc...

Undersizing can happen if you choose too small a resolution, but for any decent resolution (i.e. 640x272) undersizing shouldn't happen if all other factors are OK (i.e. not too short a movie etc). But oversizing definitely should not occur even if you choose higher resolutions. Codec will choose lower bitrates and the bits/pixel will be very low, yes. But the target size would be honored if you have chosen a 2-pass target size encode.

[Neo Neko]

Originally posted by Tropican
[B]I think I'm finding myself more lost the more you guys post :) So why do the guides on doom9 (extensively) recommend resizing then?

The guides may not be absolutely up to date. PAR/DAR support is still rather fresh for most MPEG4 tools. Some like Divx IIRC don't even support it encoding wise. So for absolute compatability resizing is a good idea. Not doing so and then trying to play back a clip on a persons computer with Divx or old filters installed could lead to undesired playback issues. Also some systems might not be able to decode and handle resize in real time.

[Tropican]

Thank you SeeMoreDigital, unskinnyboy, and Neo Neko. I think for the moment I will stick with resizing, as I do 1-cd rips often. I'll do my own tests of anamorphic encodes this weekend. If I start encoding from an HD source to a large storage space such as my harddisk, I'll forego resizing

Thanks,
Tropican