Some simple DVD questions

[Leif G]

The first question is probably best answered by Ken Berry.
What is a "hybrid disk" and what is the purpose of making one?

I am fairly new to DVD,and one problem I've had is how to burn more than one video
on a disk. So far I have only made tests,to see what quality I can get,and have not created
any menus. I have deleted the previous burning each time. But it seems a waste,since the files
are less than ten minutes.
I am using Movie Factory 7 and standard DVD-RW disks. I found the option "do not close disk"
(why it's hidden under a link "I " I don't understand). Is that the one I should select?

Another thing I like to hear comments on is that "normalize audio" option.
It seems to me a bit risky to use,because you do not know what exactly it is doing.
After all if the audio level is varying in your video,it is usually because it should,
because you have filmed in different situations. And one need to have some control,
so I prefer to normalize my video in an audio editor,where I can select the level and what parts
to apply it to,before DVD burning.

Leif G.

[Ken Berry]

A hybrid disc is a high definition disc using AVCHD video, burned in a Blu-Ray folder, but on a standard definition DVD. It can only be played on a Blu-Ray player rated to play such discs (most can these days). And the main purpose of making them is to get around the still incredibly high cost of Blu-Ray discs. For instance, I buy my DVDs these days for less than 30 cents each, yet a single Blu-Ray disc will cost me around $25! Admittedly, you can burn more on a Blu-Ray disc, and only about 20 minutes of HD video on a standard, single layer DVD using the highest quality settings. But it is still much cheaper. And the hybrid discs play in my PlayStation 3 just fine!

Burning more than one video onto a standard DVD is simple. Using the burning module in X2 or Movie Factory 7 SE, for instance, all you do is insert as many separate, edited video clips in the burning timeline as you might want (though respecting the fact that a standard single layer DVD will only allow 4.3 GB to be burned to it. Using high quality settings with a bitrate of 8000 kbps, this means about one hour of video, or a little more if you use Dolby audio.) Then you can make a menu if you want one. Each video clip will have a separate thumbnail or title on the menu, depending on which type of menu you choose. However, you don't need to make a menu if you don't want one. And then you just burn the several clips to disc. It is best, of course, to ensure that your video clips are in the DVD-compatible mpeg-2 format.

As for normalising audio, I agree with you 100%. If I do it -- and that is rare -- I prefer to do it using third party audio software. I have only ever used Video Studio's normalise command once, several years ago, and didn't like the result at all. Now I simply ignore it. Others, however, will obviously have their own views on its value.

[BrianCee]

The 'do not close disc' option will allow you to add extra files to your disc later - But a disc which is not closed will only play on a computer - it will not play in any stand alone DVD player.

[Leif G]

Thanks Ken and Brian
If I understand it correctly,this means that to be able to judge the changes I have done,I have to
make the different editing and then burn the altered projekts all at the same time. It's possible of course.

As for the hybrid disk,it sounds interesting,since I have a Blu-ray player. But I wonder how much will I gain
in quality? I mean I can play standard DVDs (even the ones I have burned) in my Blu-ray player,
and they are somehow upgraded to HD,and it looks very good. Almost too good some times. I believe
there may be som adjustments I can make,if I think the effect is too strong.

When it comes to normalizing,I realize that it's a difficult subject. I have used it only because it's been
recommended,without really understanding the excact difference between "normalize" and "amplify".
In the end I have to rely on my own hearing to judge if the audio sounds right.

Leif G.

[BrianCee]

It is not necessary to burn a disc just to see how your video looks after making changes - if in the burn module you uncheck 'burn disc' and check 'Create DVD folders' you will produce a Video_TS folder which can be played on your computer using a software player such as WinDVD - you can then see the full effect without wasting a disc.

[Ken Berry]

As for hybrid discs, if you maintain the properties of the original high definition video in the burning process, you will get true high definition AVCHD on the hybrid disc. There is no upscaling involved. You get high definition quality because it *is* high definition.

Of course, in saying this I am assuming that you are using high definition video in the first place. If, however, you are using standard definition video and converting it to high definition, you cannot get video which is equivalent to video produced on a high definition camcorder. As the old saying goes, you can't make a silk purse from a sow's ear....

[Leif G]

Yes Brian, you are right. But it has been mostly that I have wanted to see the quality of
video and audio after burning. Particularly the audio have been a problem. For some reason the sound
has come out too low. It's probably the originals.I may have to raise the input level of the camera mic in some
situatons. But then I also have to see if I can use some wind noise filter.The one in the camera is not good
enough.
I am experimenting a little with various material,but it's very difficult to fasten something in front of the
small microphone. I will probably go for an external microphone eventually.
I had not expected so much trouble with sound. I am sure I have spent more time working with the sound
then I have with the video.

And yes Ken,I am working with HD video. I have a new blu-ray player,so I will definitely try
the hybrid disk aternative.
The standard DVDs I make are for others,I don't need them myself naturally.

Leif G.

[Leif G]

Half an hour after I wrote the above, I have burned an AVCHD hybrid disk,and with a very good result.
I see the difference in quality. I won't say it's huge, but when I compare I don't see the
flickering wich is noticable in the standard DVD played on the blu-ray player.
Just as you say Ken, it is hardly worth to go for blu-ray burning.
It's not only the disks, but I need a new burner too don't I ?

Leif G.

[Ken Berry]

To burn a full Blu-Ray disc, yes you will need a Blu-Ray burner. An SD burner won't recognise a Blu-Ray disc.

I am surprised you only noticed minor improvement in quality over an SD DVD... even with the upscaling of the latter. Did you maintain high property settings in the AVCHD e.g. bitrate of 18 Mbps (which is the maximum allowable for a hybrid disc)? To me, the difference is like between chalk and cheese, though I acknowledge that upscaling of SD commercial DVDs can be pretty good. My PS3 can do it, for instance. But when it upscales my home-made DVDs, even though they used high quality SD settings, then even with upscaling, the difference in a hybrid disc stands out considerably.

[DVDDoug]

Some thoughts on audio...

In the end I have to rely on my own hearing to judge if the audio sounds right.

That's usually best! Although, there are things (like normalizing) that are more-easily done (and better-done) entirely by software.

I am sure I have spent more time working with the sound

I think audio glitches & defects are often more annoying than video gltiches/defects. Even with the editing, we're kind-of used to hard-splicing and instant scene changes, but something like a sudden change in background noise or background music cutting in-and-out can be distracting/annoying. I think audio edits need to be "smoother".

When it comes to normalizing, I realize that it's a difficult subject. I have used it only because it's been recommended,without really understanding the excact difference between "normalize" and "amplify".

If I recall correctly, Corel doesn't know what it means either... I think, at one point it meant one thing during editing, and another thing during DVD authoring...

In audio jargon (with an audio editor), normalize means to increase the volume of the whole file as much as possible* without clipping (without getting distorted flat-topped waves). It's as-if you turn-up the volume control (if possible) and leave the same volume setting through the whole file/program. Quiet parts remain relatively quiet, and loud parts remain loud.

Normalization is not automatic volume control, where quiet parts are turned-up and loud parts turned-down for more-constant volume. The important thing is that the volume adjustment is bassed on the loudest part of the file. If you have one clip/file some very-loud and very-quiet parts, and another with fairly constant volume and you normalize both, the constant-volume clip is going to sound louder.

With music files it's generally best to leave the loud & quiet parts, but with video (dialog etc.) it can be a problem (if not intended). If it's a problem it can be fixed manually, or with some kind of automatic-volume-control, dyamic compression, etc.

But then I also have to see if I can use some wind noise filter.

Noise is always a challenge. Wind noise is just about impossible to remove in post-production, except between dialog where you can mute the sound. Automatic-volume-control & dynamic compression make it worse because they turn-up the volume (noise) when the audio is quiet.

An external mic (with a wind sock), near the subject for a strong signal-to-noise ratio will help. But, be aware that most (professional) movie dialog is re-recorded in the studio. It's just to difficult to prevent or eliminate location-noise.


* With digital audio files the maximum is 0dBFS (decibels full-scale). For example, with 16- bit audio, 0dB is the biggest number (positive & negative) that you can hold in 16-bits. Some audio guys like to "normalize" to nearly 0dB... Maybe -1dB, etc. If you try to go higher (with an integer format like WAV), you get clipping.

[Leif G]

I am surprised you only noticed minor improvement in quality over an SD DVD....

I had a second look at the videos,and I have to maintain my view that there is not a big difference.
The quality of (my burned) SD DVD played on the blu-ray player is surprisingly good.
Maybe the player is doing a very good job. I have only had it 4 months,a Panasonic DMP-BDT100.

But there is that flickering I was mentioning. It's the kind you may be familiar with,wich can be seen
on straight lines when there is panning in the video. I don't know what causes this, I have seen it
before in video I have edited. I had a look on the internet,the discussions is mostly about problem in
players or monitors,wich is something different.
I suspect it could be that the straight lines are not exactly vertical or horizontal but at a slight angle,
wich causes some problem because the pixels on your screen is square or rectangular.
But this is only my guessing. This is probably not a unique problem. It is difficult to avoid filming
straight lines in a city environment.

Leif G.

[Ken Berry]

That effect is generally described as "jaggies", and is usually caused either by changing the Field Order of the original video during editing, or else, with HD video, or even SD, by panning horizontally too fast. Regarding the latter, if you look at professional HD landscapes, pans are generally verrrrry slow and tend not to cover a particularly wide angle. I try to follow suit nowadays, and wherever possible I now also use a tripod with a semi-professional floating head.

As for field order, just about all HD camcorders of which I am aware film using Upper Field First. Some of the templates used by VS use Lower Field First by default, so if you edit and just apply one of these default templates, you will end up with video whose field order has been reversed. This causes the jaggies effect since in effect you are getting a second part of a frame -- and its slightly lower embedded image -- coming before the first part (or vice versa if your oriignal video is Lower Field First). Hence one of the basic rules of video editing is to make sure you use the same Field Order throughout a project. This does not apply to embedded photographs, since they are one solid frame per image, or HD "p" for progressive videos, which also use one full image per frame. But the majority of consumer-level video cameras currently on the market still use "i" for interleaved video i.e. two half images (Upper and Lower fields) which together make up a full frame.

[Leif G]

Hello DVDDoug
Audio is an interesting subject,and difficult. Before I started using a film camera
I knew hardly anything about it. I've had to learn a lot.
One thing that surprised me was the incredible amount of noise and unwanted sounds
there was in my video,wich I had not noticed at the time of filming.
I've had to learn to use an audio-editor. And many hours have been spent to try to remove or clean up
disturbing sounds that does not fit in. But as you say, wind-noise is impossible to get rid of.
Depending on the content it is sometimes possible to use one part of a file to replace another.

To come back to "normalising" again.I have read som very good explanations of it,and have now I
think a good enough understanding of what it means. It seems that the difference between amplify
and normalize is mostly in how it's used. But don't ask me to explain it.
I don't know what the "audio jargon" you refered to means. After all normalising can also be used
to lower the audio,I often do it on some parts.
By the way,why is the deciBel given as negative figures? 0 -6 -12 -24 etc.in my editor.

Leif G.

[Leif G]

It's interesting Ken that you mention that about panning. Because one of the important lessons
I've learned from my early ettempts with a film camera is "avoid long panning" and even short ones
should not be used too often. Not only for the problems it can cause, but for the audience it can be
tiring too.
There is another thing that surprised me when burning to DVD. In my editing,after rendering I play
the clip in a player and watch it on my computer. And I can see in some panning scenes a slight
jerkiness. But in the DVD as by some miracle it is gone! It plays smooth and evenly.

So the problem can not be in the video file,because it would have been visible in the DVD too.
There remains my player. But no,it looks the same in any of the three players I can use.

Now I am beginning to wonder if my computer is NOT after all good enough,and if so where is the
weak link. Processor? Graphics card? Memory? The whole system?
Of course as long as the end result is good all is good ? Not really,I want it to look good even on my
computer monitor. So what do I do,where should I look? Some tests I can do ?
I remember some years ago there was a program wich could be downloaded and by wich you could test
your whole system,everything you had connected. It was a sofisticated program. But they had a
free version with some limitations. I believe it was an English program. But I can't remember the
name and can't find it.
Does anyone recognize it? It may have gone out of the market

Leif G.