Capturing MPEG2 for DVD authoring... CBR or VBR?

[desertnocal]

Hi, I'm a newbie to this forum and the site, but I've already found this site VERY helpful. Big kudos to the ones working on this site.

I'm mainly looking to create DVDs out of my LD collection of anime (as well as my VHS collection of Hollywood movies). As seen in my profile, I use ATI AiW 9700 Pro for video capturing. I plan to capture MPEG2 files directly from the card, then use TMPGEnc for DVD authoring.

I understand that, to store two hours of video on one DVD+R disc, the corresponding CBR of the captured footage is roughly 5000 kbps of video, and I've been capturing files at that setting. But recently I've heard that VBR, if set correctly, can provide superior quality. And since I don't really have too much experience with VBR settings, I would like advice on the following: What are the good rule-of-thumb VBR settings (max, target, etc.) for a two-hour DVD-compliant footage? I'm basically looking to maximize the disc space (and the video quality) within the given time constraint. I realize that the final file size will depend on the kind of footage I capture (with respect to motion, etc.), but I'd like to get a good feeling on at least where to begin.

I've seen quite a few posts on the whole CBR vs. VBR issue on this forum, but I haven't found the ones specifically related to DVD authoring. Any tips that you experts could provide would be very much appreciated.

And one more thing: I've been using the 352 x 480 resolution with as high a bitrate as possible. The reason is that practically of my video sources have NTSC resolution (352 x 240, interlaced), and I thought expanding the capture resolution to 720 x 480 wouldn't provide me that much benefit, if any. Is there a good reason to capture at 720 x 480 with a high bitrate?

[housepig]

I may be wrong, but I don't think you can capture in VBR - the reasoning being, for Variable Bit Rate, the content and motion of the footage has to be analyzed by the software before it encodes it.

If you capture direct, it's not going to have the opportunity to analyze as it writes the file, so you are stuck with CBR.

If you want to use VBR, you should capture as an avi file and encode to mpeg-2 after the fact.

as far as 1/2 D1 (352x480) vs. Full D1 (720x480) you'll get a mixed bag of responses. I've tried both, and I find that coming from VHS sources (most of my captures) I get crisper detail and a sharper image with a Full D1 capture. Others here think it's overkill, and there's no benefit to capturing at such a high resolution. It's going to be a matter of individual taste.

[Sulik]

You definitely will get better quality capturing VBR. Yes you can do VBR encode in real time (it's called one-pass VBR - not to be confused with a multi-pass VBR).

I would personally suggest capturing at your current settings, but change the following:
- Enable VBR
- Set Maximum Bitrate to about 8Mbps
- Set target bitrate to 5Mbps

You'll end up with a file that's roughly the same size than a CBR encode at 5Mbps (or smaller), but with better quality, especially in high-motion scenes (CBR would be limited in quality by the bitrate).

The rough rule of CBR vs VBR is
CBR = constant bitrate, variable quality
VBR = constant quality, variable bitrate

[desertnocal]

Thanks for the input housepig.

I did try capturing identical 90-second clips in both CBR (4.6 Mbps) and VBR (4.6 Mbps target, 6 Mbps max) to test out the theory. (The source was an animated fight scene with a good amount of high-speed motion.) I could hardly tell the difference in quality with my own eyes, although two others who saw the clips said the VBR file had slightly better quality if they had to choose one or the other. And I did notice that the VBR file was about 7-8% smaller than the CBR file.

I'm just wondering if anyone else out there had conducted similar tests like that and can comment on it.

And speaking of VHS, my understanding is that its frame rate is 24 fps (as opposed to 29.97 for NTSC), and that the VCR player implements a "3:2 Pulldown" algorithm to make its TV output NTSC-compliant. And I noticed that the AiW has a "Inverse 3:2 pulldown" feature in the Capture Wizard, presumably to work with the VHS sources. Has anyone tried this? How effictive/useful is it?

Thanks again.

[desertnocal]

Thanks Sulik, for your input. I see that you replied while I was working on my second post.

So you can push the max rate all the way up to 8 Mbps and still get an equal or smaller size... I'll keep that in mind.

[lal]

Hi,

To extend the topic, can some body suggest me how to capture VBR MPEG2 with Camcorder thru firewire?

I have Scenalyzer and Ulead. Are there any suggested settings for these
software to capture MPEG2 with VBR?

Thanks.

[spiderman2k1]

CBR is better for captureing VBR is better for encoding. I do capture's from satellite dish and Laserdisc and VHS. Do your own test and see what you like better. When I encode I alway's use VBR but when capturing CBR is the way better

[next]

CBR is better for captureing VBR is better for encoding. I do capture's from satellite dish and Laserdisc and VHS. Do your own test and see what you like better. When I encode I alway's use VBR but when capturing CBR is the way better

My experience as well. The problem I have found with capturing using VBR is that there can be some pixelation in dark scenes. Especially if you are capturing a movie and the beginning credits have a black backround.

[aklendathu]

I think that the best way is to capture in MMJPEG AVI and then re-encode to MPEG-2 using 2-pass VBR. I leave max bitrate at 8000 and set average bitrate so that the movie fits the DVD. For my target of 90-some minutes per DVD that's usually around 5800 kbps.

Even in a in high-motion scene like a fight, there may not be sufficient motion to tell the difference between a 5800 kbps CBR and a 5800 kbps 2-pass VBR. One scene I have noticed where it does make a difference is in one of the initial scenes of LOTR-2 where Gandalf plunges into the abyss while fighting a monster. Also, some filmmaker logo (forgot the name) involving a winged horse also shows severe pixellation artifacts when the bitrate gets lower.

Unfortunately, many capture cards and DVD burners come with software that only lets you capture MPEG-2 (sometimes not even VBR) or uncompressed AVI. Sonic MyDVD OEM comes to mind. So, unless you are willing to make an additional (modest) investment (say, PicVideo MMJPEG codecs and iuVCR) to be able to capture in MMJPEG AVI, I suggest capturing as 8000kbps MPEG-2 and then re-encode in TMPGEnc using 2-pass VBR with an average bitrate suited to your movie size.

Hope this helps.

[onetrueday]

I think we're all forgetting something. VBR is best used for encoding into a vcd, where bitrates and size are an issue. I would have to question how much it really matters when we're talking about converting with a range of 5000-8000 video br.

VBR really helps when you're making a xvcd with an average br of 800, with those specs using a dual pass vbr is almost a necessity.

[jamawass]

For capture from vhs you probably don't need resolution higher than 352 x 240. Increase the bitrate for better quality and use video soap light comb filter around 20% to reduce your file size by at least 20%. Also capture via the s-video in the quality is much better.

aklendathu said:I think that the best way is to capture in MMJPEG AVI and then re-encode to MPEG-2 using 2-pass VBR. I leave max bitrate at 8000 and set average bitrate so that the movie fits the DVD. For my target of 90-some minutes per DVD that's usually around 5800 kbps.

With the latest MMC 8.5 and a clean video input this is no longer necessary for DVD caps. AVI caps are only better if you are capturing from analog cable. Since getting digital cable through s- video hookup to my AIW Radeon the DVD capture quality is outstanding. When burned to DVD and viewed on my TV there is NO difference with commercial DVDs. My cap settings are 720x480, vbr- target 6mb, max 8mb, 96% motion estimation and video soap light- comb filter 20%. A two hr capture this morning was 3.2 Gb

[spectroelectro]

In my experienc eht efile size difference between 1-pass VBR and CBR is not that great unless the CBR is set to some very high level, like 8000.
The true advantages of VBR only arise when you use 2-passs VBR. In that case, my experience shows that a 2-pass VBR MEG-2 file is nearly half the size of a CBR file with the same target bitrate.
Example: A 45-minute TV show encoded into 2-pass VBR with settings min 2000 av 5000 max 8000 typically uses around 1.6 gigs, while CBR 6000 typically burns up about 2.4 gigs for the exact same source mateiral. That's a whopping big difference, but you only get that size reduciton if you go to 2-pass VBR, not 1-pass VBR.
If I were you, I would try to preserve as much of the superb video quality from laserdisc as possible. Laserdisc is ag reat video format, as good as analog video gets. I have a bunc hof laserdiscs and I 've captured from laserdisc all the time. I get great results, but only by caputring to DV format AVI files, then encoding with 2-pass VBR using MTPG.
The results are worth it. I see no visible difference twixt the original laserdisc and the DVD, but get about 90 minutes of video per DVD-R.
HINT: Encode your audio into AC-3 using BeSweet with the AC3machine front end GUI (download it as freeware at www.doom9.org).
By encoidng hte audio as AC-3 instead of a WAV file, you save about 370 megabytes of DVD-R space which can be better spent on video.

[lordsmurf]

I'm just wondering if anyone else out there had conducted similar tests like that and can comment on it.

And speaking of VHS, my understanding is that its frame rate is 24 fps (as opposed to 29.97 for NTSC), and that the VCR player implements a "3:2 Pulldown" algorithm to make its TV output NTSC-compliant. And I noticed that the AiW has a "Inverse 3:2 pulldown" feature in the Capture Wizard, presumably to work with the VHS sources. Has anyone tried this? How effictive/useful is it?

Yes, if your system can handle it, a VBR capture is better than a CBR capture. I capture from tv all the time, with 352x480 MPEG2, using VBR with a 3.42 average and 4.00 max. The VBR is better, and the quality is excellent. Cannot distinguish original satellite source from DVD.

Out of the two systems I have armed with ATI AIW cards, only one can do it without dropping frames. The other system is forced to do CBR at 3.50, otherwise it drops. Celeron issues.

As far as capturing tv or VHS, in the USA or in a NTSC country or with NTSC source, only, I repeat only, capture 29.97 and interlaced and use 352x480 resolution. The ATI AIW cards come setup crappy, and is the primary reason my guide (now working itself into a full site) was created. I have on clue why it's set to inverse 3:2 and deinterlace with blur filters. That's just plain wrong, and I only wish I had known that when I first got the card. Took months to get good captures.

Read my guide for more info on settings. It needs an update, as it was made from MMC 7.5 with some older preferences, but follow it, and merely alter the guide settings for what I just told you.[/u]

[onetrueday]

short reply...

to see the difference with VBR, you need a longer segment. The whole idea is that your bitrate is cached from slower scenes, to the faster moving scenes that need the higher bitrate.

so, you wouldnt see any difference in a short 90 second action scene. Plus, the video soap probably clears up any problems you're facing in those actions scenes anyway.

[pixel]

Definitely use VBR if it is real-time encoding for a DVD (You will probably be able to squeeze a few minutes more on the DVD than you expected).
If you plan to re-encode the video use CBR (or just capture in AVI).

If you know your source video has lots of high-motion scenes (eg. sports, action movie) don't set your maximum bitrate too high or the file size may run over the limit you want.

@lordsmurf the new site is looking great. Can't wait to see the new guides.