Info Request: ND Codecs and AVC; Target File Size Help

vbimport

#1

:confused:

Hi again. Can anyone point me to some info (another site, an old thread maybe, here or elsewhere) about just how many .mp4 codecs are actually in Nero Recode? I gather at least the two audio codecs (LC and HE) and maybe two video (normal<?> and AVC)? I see on the Nero (formely Ahead) web site that AVC is (I think<!>) a new standard for HiDef? How does this apply to the regular use of Recode for the average user?

I find that it takes about 25 minutes or so for Nero to turn a DVD9 ripped to the hard drive into a DVD5 on my system. I seem to be making .mp4’s just faster than real time. I tried the AVC codec profile (same file, same target size), but after 30 minutes it had only encoded 6 minutes or so of the movie. Why is it so much slower? What does this codec do? Is it better - I mean, same quality at smaller file size? Or just more compatible?

DVD’s are so cheap now, I’m wondering if going to .mp4 is even worth it.

I’ve been using the .mp4 abilities of Recode so far to back up my lesser favorite movies (ones I didn’t want cluttering my shelves, I guess). And I’ve been figuring that I get pretty good quality setting them to final file sizes of 1/3 a DVD5. But I honestly have no idea how to determine the most efficient file size. Heck, I made one movie that was 3:4 aspect ratio (i.e. full screen) the size of a cd and it looks pretty good, and almost everything I do is widescreen. Surely<?> a full screen movie requires more data per frame than a letterboxed one of equivalent resolution? I’ve got almost a terabyte of hard drive space now so I’ve never been much concerned about file size as far as a storage issue.

What I want to know is, say I have a 2 hour DVD movie and I want to make an .mp4 using Nero Digital, and keep the aparent quality of the original movie.
What size file gives Nero enough space to keep all the quality of the original but also just does this. I mean, if “x” mb’s equals DVD quality, then “x” + “y” doesn’t make it any better, so I don’t want any extra “y”.

I understand this is a tough question since all DVD’s are encoded at different compression rates. But I imagine there’s got to be some sort of a ratio I can use. For example, is ND .mp4 “x” times more efficient than mpeg-2? If it is twice as efficient, than I would imagine if the original disk held 4 gigs of data for the main title I wound want a 2 gig file for the .mp4. Does this make sense?

If I found out I gould have original quality in a much smaller size, it’d be kinda neat putting most of my collected movies on my computer for instant recall; just like my CD collection has migrated to the pc.

Thanks for staying with me.
Now, have you got any answers for me?

Thanks again!


#2

AVC (official name: MPEG-4 Part 10) is pretty much the next generation video standard, and will be used on the new HD-DVD formats. The problem is that right now, there isn’t much hardware nor software supporting it out yet. In fact, I think Nero is one of the very first to fully support it.

AVC is quite a bit slower but generally much more efficient than “normal” MP4 and “normal” DVD video (MPEG2). You can encode a long movie to 1CD with MP4 and then do the same with AVC and check the difference - it will be quite obvious how much better AVC is.

As a (very general very broad very inaccurate) guideline, if a DVD movie takes 100% space, you can encode to MP4 at 60% of that space, and to AVC at 40% of that space, without losing visible quality. Of course, since the original is in DVD format, that will always be better. Until the HD-DVD’s come out, at least…

I’m finding 1/4th DVD AVC encodes to look incredibly good, and you can fit 4x as much on 1 disk…


#3

So if 90 minutes of mpeg2 looks “DVD quality” when on a DVD5; then in .mp4 it would look good compressed to 60% of a DVD5? That doesn’t even let you get 3 hours of video in .mp4 on a DVD5. I guess by no loss of quality you mean even if you had a high def tv and zoomed in on the image, original and copy would still look the same…

But in practive, you will put, say, 6 hours of AVC on a DVD5? And you think it still looks incredibly good?

I’ve been putting about 3 movies per disk together, and been happy. I’ve only been using the standard codec though, not the AVC. Takes too long. I was wondering how others were doing it. I was considering forgetting about .mp4 backups altogether, at least until I get a standalone hardware player for it … Because I can recode to mpeg2 in at least a third of the time, and it only cost 50 cents a disk, and another $1 if I need a DVD keep case.

But I like the idea of keeping all my movies on the hard drive, so was wondering what a good target file size for each hour of .mp4 video should be.


#4

I go with 540mb’s per hour with the avc encoder. that includes audio, unless you go with over 128k audio.


#5

Yes. I can only recommend you test for yourself…

AVC really shines at lower bitrates, too, so you can do more than 6 hours easily. With MP4 you get blocks in the image if the bitrate is too low. AVC just looks a tiny bit less detailed.


#6

Thanks for the input.

Did you notice the much longer encoding time though, with AVC? If you are using it, you must have a monster of a machine.

Peace…


#7

I just let the machine run overnight :slight_smile:

BTW. There are some ways to speed up AVC encoding with almost no loss of quality. Check for the following settings:

Maximum reference frames: 1
Decision quality: Best (not extra)
Chroma Enhancement: Disabled

This can provide up to 50% speedup in AVC encoding, and the difference is basically never visible.