Squeezing more onto a DVD

[Scott Brickert]

The last big project I did, 24.0 GB of video (4 clips rendered out of Vegas 5 with project setting of NTSC [720x480]) fit into the 4.7GB of space on the DVD, with the bitrate set at 7Mbps, using one jpg for the main menu, plus 4 buttons with stills, all in DVDA2. The DVD project was also set at NTSC [720x480].

This time it's 24.6 GB of video (5 clips rendered out of Vegas 5 with project setting of NTSC widescreen [720x480]), plus a main menu jpg and no buttons. Using the Fit To Disc option results in a bitrate of 5.25Mbps, resulting in jerky motion within the frame. This DVD project is set at NTSC Widescreen [720x480].

What, if anything, can I do to get the bitrate up while still squeezing all the clips onto the DVD?

Does the NTSC Widescreen [720x480] compress differently i.e. less, than 4:3?



thanks,
Scott

[Edward Troxel]

Sounds like your project is about 1 hour 50 minutes based on the AVI size. The key is the length of time determines the necessary bitrate for the video to fit. For 1 hour 50 minutes, you would need a bitrate around 5,280,000 assuming you are using AC3 audio. A bitrate of 7,000,000 would only allow between 80 and 85 minutes assuming AC3 audio.

Personally, I always render the MPEG2 file from Vegas using the bitrates found in the bitrate chart in Vol 1 #7 of my newsletter. Rendering from Vegas gives you more control over all the various settings. You would also need to render the AC3 file from Vegas as well.

[Dan Euritt]

scott, the way to make it fit is to use two-pass variable bitrate encoding, with the average bitrate set at whatever ed calculated it at... but also set the peak vbr rate at ~8800, because scenes with fast motion will require a lot more bandwidth.

scenes with no motion, i.e., talking heads, will use a lot less bandwidth than what ed specified as the average, which leaves room on the dvd for the scenes that require a lot of bandwidth.

don't even try using cbr encoding for a program that's nearly two hours long.

[Edward Troxel]

I would not take the max over 8,000,000. Seen too many problems when it gets too high.

[Scott Brickert]

Thanks for the newsletter, Edward. It appears that in terms of average bitrate the formula provides similar results to clicking on Fit-To-Disc in the DVDA2 Optimize screen.

So I'm getting that if I use vbr in Vegas to render it results in smaller files.

Where could I find a practical explanation of the other variables in the Customize menu e.g. I-frames, B-frames, Profile, Level, and video quality?

In terms of workflow, would you recommend combining the 5 clips into one long clip with e.g. a 1sec pause between each, then rendering in Vegas using vbr. So when I create the menu in DVDA2 I link each button to the same clip, just choosing different in/out points to correspond to the menu item?

Regarding audio, I also have to render the audio to AC3, then in DVDA2 I associate the resulting AC3 file with the MPEG2 file, and if they both start at zero on the timeline they will be synced?

thanks,
Scott

[Edward Troxel]

So I'm getting that if I use vbr in Vegas to render it results in smaller files.

No. In means that it can use a higher bitrate when needed and a lower bitrate when needed to maintain the given average to attempt to make your video look better. It won't make smaller files. It's supposed to make your files look BETTER at smaller sizes.

Where could I find a practical explanation of the other variables in the Customize menu e.g. I-frames, B-frames, Profile, Level, and video quality?

Generally speaking, you should use one of the DVDA presets and NOT touch these. You definitely want the "Video Quality" on 31 (for some reason, the "default" preset has it at 15). However, for more info:
http://www.sonymediasoftware.com/dow...p2.asp?DID=391


In terms of workflow, would you recommend combining the 5 clips into one long clip

Depends. Do you want them to all play through as one file? If yes, definitely give DVDA ONE file. If they are totally independent, you can give DVDA 5 files. Just make sure the encoding average bitrate settings are for the TOTAL length of ALL files.


Regarding audio, I also have to render the audio to AC3, then in DVDA2 I associate the resulting AC3 file with the MPEG2 file, and if they both start at zero on the timeline they will be synced?

Yes, if you render the same area for the MPEG2 and AC3, they will both be in sync in DVDA.

[Dan Euritt]

Originally Posted by Edward Troxel

I would not take the max over 8,000,000. Seen too many problems when it gets too high.

i have sold thousands of dvd-r's that were set at 8700-8800 peak vbr, as have a number of other people... no issues at all, those numbers are within the legal dvd bitrate spec.

i would suggest that you examine your workflow to find the real source of your problems... perhaps you are using cheap media, for instance, that does not read well... many tests have proven that quality media can be burned faster than cheap media.

and yes scott, you are correct, vbr most certainly does result in smaller files! that's the whole purpose of it... if you needed 6500 cbr to get acceptable quality, but a long program requires 5000 to fit on the disc, you use 5000 with a peak vbr, and the end result is most definitely a smaller file with good picture quality.

always export one long mpeg file whenever possible, and be sure to put a black leader on the front of the clip.

[Bill Binder]

Two comments:

(1) I've also seen a DVD player choke on bit rates above 8000.

(2) This probably isn't an option, but if you render out 24p, when done right, you can squeeze more video at the same bit rate onto a single DVD.

[Edward Troxel]

Originally Posted by Dan Euritt

i have sold thousands of dvd-r's that were set at 8700-8800 peak vbr, as have a number of other people... no issues at all, those numbers are within the legal dvd bitrate spec.

I'm glad you've had good success with those numbers. I've seen many other people that have not. I still do not recommend going over 8,000,000 as the max but will not say that it won't work.

Originally Posted by Dan Euritt

i would suggest that you examine your workflow to find the real source of your problems... perhaps you are using cheap media, for instance, that does not read well... many tests have proven that quality media can be burned faster than cheap media.

My workflow is fine. My media is Verbatim 8x printable surface DVD-R. I've had very good success with them with my workflow. Burn rate is usually 4x.

Originally Posted by Dan Euritt

and yes scott, you are correct, vbr most certainly does result in smaller files! that's the whole purpose of it... if you needed 6500 cbr to get acceptable quality, but a long program requires 5000 to fit on the disc, you use 5000 with a peak vbr, and the end result is most definitely a smaller file with good picture quality.

No, VBR does NOT result in smaller files. The lower AVERAGE BITRATE results in smaller files. VBR gives you BETTER QUALITY in those smaller files. Better Quality in Smaller Files is the purpose of VBR but the VBR setting alone will not give you smaller files.

[Dan Euritt]

verbatim 8x burned at 4x?? why so slow? is your burner old? or are you scared to use the rated burn speed with that inferior media?

i burn 16x taiyo-yuden media at 12x, at 8700-8800 peak vbr, with zero errors and no compatability problems... if i and many others can do it, so can you :-) try it, you won't be hearing any more complaints about how your product isn't compatible.

bill, your observations need to be qualified as either 1)cbr or 2)vbr... dvd players have buffers that pre-read the data off of the disc before it gets sent to the screen... how full the buffer stays is critical to playback.

vbr definitely DOES result in smaller files, WITH RESPECT TO the pq(picture quality)... everything is ALWAYS wrt pq!

[Edward Troxel]

Originally Posted by Dan Euritt

verbatim 8x burned at 4x?? why so slow? is your burner old? or are you scared to use the rated burn speed with that inferior media?

First of all, my media is not inferior. Secondly, the burner in my laptop burns at 4x. Thirdly, it does a good job so there's no need for me to buy an external burner just to get a higher speed. If I was trying to burn 50 a day, that might be a different story. I don't need to burn anywhere near that many.

Originally Posted by Dan Euritt

vbr definitely DOES result in smaller files, WITH RESPECT TO the pq(picture quality)... everything is ALWAYS wrt pq!

I repeat, VBR - by itself does not result in smaller size. You must use the proper bitrate to get the files the proper size. I ran a test just confirm this:

Test using 6,500,000 Average, 8,000,000 max, 2,000,000 min:

CBR - 369 Meg
VBR 1 pass - 366 Meg
VBR 2 pass - 367 Meg

If you multiply by 10 to get to 3.7 Gig, you're looking at 20 to 30 Meg smaller in size - an insignificant amount.

Test using 4,000,000 Average, 8,000,000 max, 2,000,000 min:

CBR - 232 Meg
VBR 1 pass - 230 Meg
VBR 2 pass - 230 Meg

Multiplied to full DVD size, you're looking at 10 to 40 Meg in size difference only by changing to VBR. What really changed the file size was adjusting the bitrate. VBR simply lets the video look BETTER at the lower bitrate.

[Scott Brickert]

I'm sitting here whining about having to render out five video files plus five AC3 files, then add up the total and see if it will fit on the DVD.

Does DVDA3 have VBR, either per track or per DVD render?

Using 5.25Mbps CBR the quality was right on the edge, so maybe using VBR it would be OK. But I have to render out each file separately. Seems like a hassle. And only once it's done can I check to see the total GB.

Or am I missing something?

thanks for the good argument. It's illuminating.

Scott

[Edward Troxel]

Add up the total length of the 5 pieces first. Then render all 5 pieces at the bitrate appropriate for the total length of video. That should make sure the total size is small enough to fit.

As for DVDA, it uses VBR. Even in Vegas, I use VBR and, now that it has it, usually use 2-pass VBR (but it takes twice as long to render)

[Matt Howell]

Just a couple of tips/notes on this subject.

1. taiyo yuden (ty) media is indeed the best in the world, both CD-R and DVD-R/+R. (I just wish I knew a way to get ty media at retail in NC.)

2. Laptop DVD burners are generally slower and produce poorer quality discs than full size desktop computer DVD drives. Burn on a laptop for convenience, burn on a desktop for quality and speed.

3. Generally, and I say this loosely because there are many factors in play, a slower burn like 4x, will be higher quality than a faster (8x-16x) burn on a given DVD burner.

4. There is a huge range of DVD media quality. Most DVD media sold in the USA is poor quality at best, and horrid at worst.

5. (MOST IMPORTANT TIP!!!) Bitsetting DVD+R media to booktype DVD-ROM is a best practice when producing DVD's for pay. You will see a huge increase in DVD player combatibility if you always burn DVD+R discs with the booktype set to DVD-ROM. Even most ancient DVD players from 1997-99 can play these discs! Only DVD+R and DVD+RW media can set booktype to DVD-ROM. Please google on bitsetting and booktype and try it if you want to see for yourself what I am saying about DVD booktype.

[Dan Euritt]

matt, you can mail order genuine ty at supermediastore.com... they have been reliable for me... i have also not seen ty at any retail store :-(

ed, he's right about burning with a laptop drive... it's only a matter of time before it fails on you, and it'll cost a lot more to replace than a desktop dvd burner... step up to the plate and get yourself a pioneer internal dvd burner, and stick it into one of those $25 external cases... and yes, verbatim media is inferior to media that's made in japan.

your test was interesting, because it proved that the average vbr rate on that particular encoder is constrained very well, as compared to the cbr rate from the same encoder... now go encode a 2.5-hour program with both vbr and cbr, small enuf so it'll fit onto a dvd disc, *at the same picture quality level*, and tell us which file is smaller.

scott... if you insist on encoding out 5 seperate clips(why??), at least put 'em together as one long clip afterwords, before authoring the dvd... if you go to www.womble.com, i believe that you can download a working trial version of that mpeg editor, it handles ac3 as well, and it makes dvd-legal files *without re-encoding*, as long as all the source files are the same bitrates/framerates.