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DanH
02-18-2004, 03:14 PM
I am in the midst of editing a massive curriculum that will consist of 16 modules. Each module contains four 56-minute lessons. I would like to make this available on as few DVDs as possible, yet with decent quality. Is it reasonable to fit 112 minutes on a dvd? I currently own Sonic Foundry's DVD Architect.
Thank You,
Dan

Steve Thompson
02-18-2004, 04:40 PM
Hi Dan,

I too burn DVD's and this is what I have learned from one of the experts; Eugene Kosarovich.

You can burn up to 62 minutes of MPEG2 video on a 4.7GGB DVD. Unless of course you have a lot of money to buy the systems that can do dual layers like the DVD movies you buy in the store.

If you have to go over the 62 minute limit then hopefully someone like Eugene can jump in.

Eugene wrote in one of his artilces that 'there are ways to calculate the data rates for a two hour DVD' but then the audio data rate comes into play and it all becomes rocket science to me so no thanks.

You can lower data rates down to as much as 7Mb's at CBR but below that I believe the quality starts to show.

I know that there are some threads out there that may go into more detail but hopefully this will cover some of your questions.

Respectfully,
Steve

Ivan
02-18-2004, 05:09 PM
I created a DVD that had about 129 minutes on with no real problems. The quality was pretty good because it was mostly talking heads. I think I encoded it at about 4MB/s using variable bit rate. There are calculaters out there that will do the math for you. You will need to use AC3 audio because it will save you almost 1 gig of space over PCM audio. You will also want to do multipass VBR to get the best quality.

Keep in mind that on a 4.7 gig disk you don't really get 4.7 gigs, more like 4.3. Long story short 4.7 gigs is the marketing measure of the disk.


Ivan

lucca65
02-18-2004, 05:14 PM
It depends on what software you are using to author and burn your dvd's.

If your authoring software can compress your audio to Dolby Digital or AC3 (it is the same thing different names) then that will leave you much more room for more video.

Also, if you using CBR constant bit rate then you are pretty much locked to how much you can fit on a DVD. If you use VBR variable bit rate encoding, then more bits are used for busier scenes, less bits for less busier scenes (still photos etc.)

I used TMPGENC and SONIC MYDVD PE and squeezed over 90 minutes of content with better than VHS quality.

Now I used PROCODER and ADOBE ENCORE DVD and get the same amount of time with better quality.

There are websites dedicated to DVD encoding

Just do a search and start there.

The best advice is to play with the settings until you like what you see.

ScorpioProd
02-18-2004, 09:07 PM
Hi Dan, looks like my cue to join the conversation. :)

First of all, the 4.7GB is based on base 10, in other words, a gigabyte actually being a billion bytes, which it would be in base 10... But computers are really base 2, binary. The base 10 size is a big number, and marketing people like big numbers, so that's why that's the size used. The actual size in bytes of a 4.7GB DVD is 4.37GB in the real sense.

As for your question, you don't mention what your curriculum is, as in is it a lot of talking head shots or is there a lot of motion, but either way you can fit 120 minutes on a single layer 4.7GB DVD and maintain great quality.

The key as mentioned is how you encode the MPEG-2 files.

I don't have the authoring application you mention, but I can comment on what I do for such things. I use TMPGEnc for my MPEG-2 encoding and Ulead DVD Workshop AC-3 for my authoring. You may be able to set the settings I'm about to describe in your software, but I don't know for sure.

Basically, as has already been mentioned, up to 62 minutes you can do at a Constant Bit Rate of 8000kb/s and you'll be at the maximum quality that a DVD can legally be. I also agree that down to 7000kb/s, I would stick with CBR as well.

When you need to go lower than that, I switch to 2-pass Variable Bit Rate encoding. 120 minutes of video will fit fine at an average data rate of 4500kb/s and AC-3 encoding of the audio at 192kb/s. You're going to always want to use AC-3 audio, it's the only compressed audio standard that's part of the NTSC DVD spec.

I have a published article on all of this in the now defunct NewtekPro magazine, and it will give you more details. You can find it at:

http://www.professionaleventvideo.com/tmpdirections.htm

As for going beyond two hours, if it is for talking head kind of stuff without lots of fast action, you can go as far as 2.5 hours and still maintain decent quality. This would be an average video data rate of about 3500kb/s with 2-pass VBR. Again, all my subjective quality here is based on the really good encoding engine of TMPGEnc, not all encoders are created equal.

Beyond this, there is the question of how much quality do you really need... If it is for lessons that students are going to be watching play on their PCs, it can be a lot lower quality than something that's going to be projected on a screen or on a TV.

If you need to go to three hour length on one DVD, you would need to cut your horizontal resolution in half, called "Half D1", this would drop your resolution from video's 720X480 to 352X480. Going over four hours on one DVD, you would need to go to "Quarter D1", 352X240, which is actually the resolution of the VCD format, so it's not unheard of even to watch this resolution on a TV.

But again, personally, I would only use these reduced resolutions if it was only for PC playback.

But as for two hours on one DVD at high quality? No problem thanks to 2-pass VBR encoding.

xerxesnon
02-18-2004, 10:00 PM
Here's a killer little app that's come in quite handy when determining the bitrate vs. how much almost any type of media (consumer DVD/Pro DVD/CDR/you name it)

http://videoproductions.com.au/dvd-lab/BITCALC106.ZIP

RayLarson
02-19-2004, 08:47 AM
We use both a Pioneer A04 and a Panasonic Standalone T3040 DVD Burners. I have foound that for long form where intricate menues are not an issue, the standalone Panasonic can do awesome quality even in the 4 hours mode, at 6hr mode (ep) the video is passable...I also use DVD workshop and find that 2 hours is entirely possible is great quality.

Just my .02 and worth every penny