DVD/mpeg2 Quality? Could I be doing better?!

[James Binder]

Greetings –

I’m burning to DVD several business conference speakers. Most are about one hour, one is two hours.

I edited a two camera shoot in Vegas, and exported (rendered as) MainConcept mpeg2 using the DVD NTSC template – which reads in the description:

Audio: 224 Kbps, 48,000 Hz, Layer 2
Video: 29.97 fps, 720x480
Use this setting to create an MPEG-2 file with an NTSC DVD-compliant video stream, and an MPEG layer 2 audio stream.

Question(s) –

• Is this a good choice? Could I be doing better in terms of quality with some other setting(s)?

I did a test burn (I burned using Ulead DVD Workshop 2, with no further rerendering or compression). The results were pretty good, not as snappy as within Vegas, but not too bad either.

I should mention that I have the capacity to do a dual layer burn – which I plan on taking advantage of because I have approximately eight to ten hours of speakers in which to burn to DVD.

• Second question -- Audio: with the above template, the audio is combined with the video file. Why in other templates (example; render for DVD Architect), is the audio separate? Does that allow for higher quality video and audio files? Pardon my inexperience, and glaringly obvious newbie question – but if somebody could explain the difference regarding why and when you would separate the audio, I would appreciate it.

Again the audio sounds fine on my test burn – there’s nothing fancy going on, just boring business presentations.

So… Am I on the right track? And again, could my quality be better without dramatically increasing the size of the final mpeg2?

1 hour, five minutes (final mpeg2) presently = 2.87GB.

I’ve spent countless hours searching around the internet to educate myself – but nevertheless, I return here because of the great people and advice that I find.

Thanks in advance to everyone!

[Dan Euritt]

you aren't planning on selling d/l media disks to the public, are you? do your homework on that first!

since your content is talking heads, you should be able to easily get at least two hours of content on a dvd... i would use dolby audio created by vegas, the quality will be better than the mpeg audio created by the mainconcept encoder.

[James Binder]

Thanks for the reply --

Nope, not selling -- just internal use...

Why Dolby? To be honest, the original audio isn't all that great. I had to do a fair amount of work to remove AC hum/buzz. Wouldn't I just end up with a highly polished audio turd in Dolby? The last thing I want to do is accentuate any of the flaws in the audio. I would think that the mpeg audio in this situation would suffice – and really, the mpeg audio sounds pretty decent considering its original shape.

As to my other questions -- anyone else? I could really use the input... Thanks

[Joshua Provost]

You might try other encoders, such as TMPGenc or CCE. They are generally considered to turn out better-looking video.

Also, dig a little deeper into those templates. Do you have options for controlling the bitrate? An hour of video at max bitrate of around 8000kbps will be around 4.5GB and fill a single layer DVD. It will look a lot better than what you have now, which is probably around 4000kbps.

If you are going to use less than the max bitrate, look for variable bitrate (VBR) settings. These will analyze the video thoroughly on a first pass, then encode on the second pass. It takes longer, but results in better video.

There are other advanced settings, such as DC component precision (usually configurable from 8 to 10, 10 is better, takes longer), and motion search precision (which can be increased for better quality, and, again, slower encoding).

[Bogdan Vaglarov]

Everything sounds right to me.

You can increase the average bitrate (default is 6000 avg, 8000 max) but for talking heads wouldn't change much.
If you have a lot of motion it is recomended higher bitrate but don't set maximum over 10 000 as some DVD players can't coop with such a high demand for decoding. Combined (video + audio) max peak bitrate is something like 10,500 kbps.

Vegas with DVD architect includes AC3 plugin that allows you to use AC3 stereo and 5.1 channel. In that case you have to render video and audio separately and author with DVD-A to preserve the Dolby Digital AC3.

If you have AC3 plug-in with Ulead Workshop - check if you can use AC3 - it allows a bit more compressed file size with a bit higher quality than MPEG audio.
But again - for just 'talking' audio 224kbps MPEG1 - layer 2 is more than sufficient.

I made instructional video recently where I use my own music from .wav files 44.1kHz. Authored to 384kbps, 48kHz MPEG audio it still sounds very good.

[James Binder]

Thanks Dan, Joshua, bogdan -- you guys are great. I must say, this is one of the nicest, most informative boards I have ever visited...

Yes, I need to figure out how to ‘dig deeper’ into the templates. Right now, it (Vegas) does not allow me to change the default setting. I know I read somewhere recently how to get in there -- I just need to find the info again and dig in…

Why is AC3 better and why does it have to be rendered separately? I’m really curious about that. My guess is that mpeg is mpeg, both audio and video – and as such, can be rendered together. Since the AC3 algorithm is different than the mpeg compression algorithm, it must have to be processed separately – yes, no?

Also, I plan to burn to dual layer disks – any advice there? Will most players be able to read a dual layer disk at the current compression levels that I mentioned above? I’d go with a little higher quality, but I’d like to get as many speakers on a DVD as I can – otherwise, I’ll end up with about 10 standard DVDs!

I'd love to hear more if anyone else cares to chime in!

Thanks again everybody...

[Moe Belli]

Wow, you cover a lot of ground here.

First of all, when you burn DVD-R/+R's for maximum compatibility with desktop DVD players, you should be using moderate bitrates and AC3 audio.

Lower datarates in both video and audio, give players a better chance to error correct disc problems and so result in reduced skipping and stuttering. Some will argue with me on this, but it's something I firmly believe.

So encoding at CBR 6,000 kbps or VBR 2-pass 4,000-6,000 kbps is a good way to go. With good DV source material and a good encoder, you should get good video. AC3 can be set to whatever, 192 or 256 kbps is what's used in most cases.

Another thing, don't deliver any other audio format on DVD but AC3, don't go PCM which is what you're doing now and don't got MPEG. AC3 is so efficient it allows more room for video on the disc, and it's a universal standard. Most DVD players at home are hooked up properly for it, either through optical cables or RCA jacks which convert AC3 to analog.

I submitted a DVD-R to a producer/duplication house 2-years ago and it was rejected because I didn't use AC3 but PCM. It's a standard, so always go AC3 (by the way, because AC3 is compressed, it actually is not of the same quality as PCM).

The problem with Vegas from what I remember with it's templates was that I wasn't able to adjust my datarate so if you leave it alone, it will encode at the highest video bitrate possible. Again, with very high spikes, this could be problematic on some DVD players in some scenes.

My recommendation for serious authoring is to invest in a quality encoder, Canopus Procoder and CCE are two very good choices. These suckers will give extremely high quality video at low to average datarates compared to others. At high datarates (example over 7,500 kbps) there's little diff with these or anything else on the market.

When preparing DVD assets you can go program stream (includes audio in the MPEG) or elementary stream (video and audio are seperate).

What I do is encode with Procoder elementary streams (mpg2 plus WAV audio) then encode with TMPGenc AC3 encoder my WAV to AC3. Then I import these into DVD Workshop and author (DVDWS does not re-encode, so the quality I get from Procoder/TMPenc AC3 remains the same).

You could reduce your workflow and just use program streams and not split MPEG2 and audio. Todays DVD authoring tools can use either method. Elementary streams is just the way I like to work and I'm able to monitor/quality check my audio tracks even before I go to my authoring software.

Hope this helps.


MB

[Dan Euritt]

james, you have 8-10 hours of video, which is only 5 single layer dvd-r's... i don't understand what your fixation is with d/l disks? they are expensive, and they have lousy compatibility with desktop players.

dolby audio at 192kbps should sound better than the 224kbps audio that you have now... which leaves you more room to increase the video bitrate... be sure to use two-pass mpeg2 video encoding.

try to understand the importance of compatibility when it comes to dvd's... moe is exactly right about ac3 being the better choice when it comes to desktop players.

[James Binder]

Dan, Moe --

Thank you very much for the great info... it has really helped me to understand some of the particularities of DVD authoring.

Along those lines:

I'm not really fixated on using DL disks; I just want to be able to fit as many speakers/presentations on one disk (at the best quality) as I can. I thought DL disks might be a good option. But if as you mention, it comes at the price of DVD player incompatibility, then I suppose it's not a good choice!

So...

How much time/video can I expect to fit onto a DVD at very good quality? (I keep hearing two hours...?)

And.. what is the bit rate (for mpeg2) that would best facilitate that?

Say for instance I have a 1:15 presentation and a 1:00 presentation that I would like to fit onto a standard disk... That's more than two hours -- how do I fit the extra 15 mins on there? I suppose adjusting the bit rate, but being so new to this, I'm not exactly sure what that would be.

Again, I really appreciate all of your patients and help with my newbie questions. I am searching the dvinfo.net archives, and the net in general for as much information as possible in order to educate myself. If anyone has any good suggestions for a site that covers this (and maybe geared to newbies), I would certainly appreciate it!

Oh... one more thing:

<be sure to use two-pass mpeg2 video encoding.>

Why?

*edited to include the below info*:

Just found the answer to the two pass question -- does this sound right?:

[In 2-pass VBR mode, the compressor will make two passes. In the first pass, it will compress the footage while trying to keep a constant quality, regardless of bitrate. It will then use the resulting bitrate (scaled to fit within the user-selected values) to do the final encoding. This results in the best relationship between compression and quality. It is, however, rather slow. If you use CBR at 8 Mb/s, you will end up with more or less the same quality, but the compression will not be as efficient. This means that the resulting file will be bigger, and you will not be able to fit as much video into one disc. If your movie has less than 1 hour, and you don't have any use for the extra space on the disc, you should use CBR to save on the encoding time.]


Thanks again –

[James Binder]

From another site:

<<Generally, a value of 6000 for average and 8000 for maximum will produce good results and allow you to fit about 90 minutes into a 4.7 GB disc (assuming you will use compressed sound; if you use uncompressed sound, then you will only be able to fit about 75 minutes into one disc at that bitrate).>>

So...

How do you fit two hours (with sound) onto a standard disk -- without greatly sacrificing quality? Maybe I've got the "you should be able to fit two hours on a disk" thing wrong. I thought that's what I've heard -- somebody please correct me if that is wrong!

I guess all of this boils down to the fact that I have an enormous amount of material to burn to DVD (over ten hours of mind-numbing speakers/presentations). I would like to not have to burn a ten DVD set of this stuff!!

Are DL DVDs really that incompatible with the players currently out there?

My head is spinning -- gotta go now...

Thanks!

[Dan Euritt]

it's good to see that you are doing the research on this stuff! some people can't be bothered to make the effort.

dig up some of the freebie bitrate calculators, they will tell you what to set the average bitrate at so that it'll fit on a single disc.

if you are concerned about the quality, simply select a short section of your footage that is the worst-case scenario for encoding... do a test encode with it at the bitrate the calculators recommended, and burn it to an r/w disc to check the results.

[James Binder]

Thanks again Dan --

Found this caculator -- is this what you were talking about, or is there a better one somewhere?

http://www.angelfire.com/az2/asw/programs/bitratecalc/bitratecalc.html


Thanks!

[Bill Keen]

Dan is right about using AC3 at 192 kbps. Though this article http://www.kenstone.net/fcp_homepage..._warmouth.html is told from the Apple products point of view, the basics still apply whatever program(s) you're using.

[Dan Euritt]

that looks like the dvd bitrate calculator i use... take a look at http://www.videohelp.com for a bunch of stuff as well.

[James Binder]

Great links...

Thanks again Dan, Bill and the others -- your help has been great!