DVD Authoring Or How to Burn a DVD Without Getting Burned
by Bob Hudson
Confused about DVD authoring and how to easily burn a DVD of your favorite
home videos or client videos? The hardware and software for DVD authoring
and DVD burning can now be purchased for as little as a few hundred
dollars, but in some respects the process of successful DVD burning can
seem as mysterious as it did in 2000 when a low-end DVD authoring system
would have added perhaps $20,000 to the price of your computer.
No
matter how much you spend for a DVD authoring system, though, the basics
are the same:
-
Acquire and edit your source video
-
Put
the video and audio in the required formats for DVD
-
"Author" the video and audio into the required structure for a DVD,
including menus, chapters and other bells and whistles, and
-
Burn the authored project to DVD or send the completed project to a DVD
duplicator or replicator
LAST
THINGS FIRST - BURNING A DVD
Let's
talk about that last step first. "DVD burning" gets its name from the
laser beam used to etch the data into a chemical layer on a recordable
DVD. "DVD burning" also describes what some people feel like doing to the
pile of unusable DVD-R's they accumulated while trying to learn DVD
authoring and production. Hopefully we can save you from some of their
mistakes.
After
completing the DVD authoring process, most of us will burn DVD's on a DVD
recorder installed in our computer or connected to the computer by
Firewire or USB. This process differs significantly from the way they
produce those DVD's of our favorite movies that we rent or buy. Those
DVD's are "replicated" and the data is actually stamped into the DVD's
during a complicated manufacturing process. However, the same chemical
burning process used by our desktop DVD burners is also used by some
companies that will make mass copies of your DVD project: instead of
replicating them with the stamping process, they duplicate them in
machines that can burn several copies at once. The difference between
burning - or duplication - and replication can be critical.
Burned/duplicated DVD's are produced on recordable DVD's including DVD-R,
DVD-RW, DVD+R and DVD+RW. The "R" stands for "recordable." "RW" DVD's are
re-writable so you can erase them and record on them again. The plus and
minus signs indicate the two primary formats of recordable DVD's. There
has been a lot of debate about which is best, but the few impartial tests
of each format seem to indicate that there really is not a lot of
difference between DVD-R and DVD+R. The big difference is between DVD
recordables and the replicated - stamped - DVD's. In this article we'll
use "DVD-R" to represent all types of DVD recordables.
Replicated disks are pretty much 100% compatible with all DVD players.
DVD-R's, meanwhile, are at best compatible with something like 80-90% of
players. That means if you want to author and distribute a DVD that will
play on any player, it has to be replicated. But, replication can be quite
expensive unless you need hundreds of copies. Later on in this article
we'll discuss ways to make your burned DVD's as compatible as possible.
A
couple more quick items regarding DVD recordables:
The
DVD burners we use with our computers are designed only for DVD-R for
General disks. There is also something called DVD-R for Authoring disks
but almost no one uses them, even though they have a much better
compatibility rate than DVD-R General disks. The disks themselves are
generally much more expensive, and there is only one burner on the market
which supports them - the Pioneer DVR-S201 which costs about $4,300.00 the
last time I checked. You may also encounter DVD-RAM, a type of disk
designed for recording data much the same as a floppy disk does. It has
been used in some standalone DVD recorders (which function much like a
VCR) but it is not compatible with the DVD-Video specification that
governs the types of DVD's we use to watch movies on conventional DVD
players.
When
you buy a box of DVD-R disks it will say "4.7GB" (gigabytes) capacity. Now
try to fit 4.7GB of computer files on one of them. You can't do it. DVD's,
as with hard drives, have their advertised sizes computed in the decimal
system, while your computer counts in the binary system. Thus a 4.7GB DVD
will hold only 4.37GB of computer data.
PLAN
FOR DVD BEFORE YOU SHOOT
Which
brings us to the first of the basics of DVD authoring we outlined above:
acquiring and editing your source video.
If
you are going to author a DVD project you really want to start planning
for it even before you shoot or edit your video, if for no other reason
than the limits imposed by the 4.37GB of storage space on DVD's.
4.37GB DVD's are called DVD-5 and it is said their capacity was determined
by Hollywood's desire to be able to fit a 135 minute movie on a single
disk (at the time that covered 99% of movies). Today most Hollywood movies
are no longer distributed on DVD-5 disks, but instead are on dual layer
DVD-9 disks which can hold almost twice as much data, but which have to be
replicated - you cannot burn a DVD-9 (a dual layer DVD+R that can be
burned was pending at the time this article was written but it will likely
require a new generation of DVD burners and revised DVD authoring
software). There are DVD disks that can be burned on both sides, but that
means very long projects would have to be divided into two parts and users
have to flip the DVD to the other side when one side finishes playing.
The
question then might be, "So a DVD-R or +R can hold two hours and 15
minutes of video, right?" Yes and no. You can put three hours or even four
hours of video on a 4.37GB disk, but realistically it can be very hard to
get good quality with just two hours of video and some DVD authoring and
encoding software can barely produce a one hour DVD with acceptable
quality. Whether you are shooting and producing a new video, such as a
wedding, or editing together a bunch of short home movies into one
project, it's a good idea to have a target of perhaps 90 minutes of video
for a DVD authoring project, unless you have a high quality MPEG encoder,
and even then you might want to think about how many people will actually
sit through a long production (unless you are one heck of an editor and
story teller).
During editing you also want to keep in mind that certain kinds of video
can be much harder to encode to MPEG, such as fast motion, fancy
transitions and title effects and noisy low light video. Surprisingly, one
of the hardest things to encode are simple fades to and from black.
A
popular use of DVD is to archive those old analog tapes, such as VHS and
Hi8 tapes, by using a DV camcorder or analog-to-DV converter box to import
them into the computer before editing and encoding to MPEG-2. That analog
video can look much better if you connect a
video processing amplifier (proc amp) and/or
timebase corrector (TBC) between the analog source and the DV converter.
Some imperfections in the analog tape will be reduced or eliminated and,
if needed, you can adjust the color and brightness so your DVD's may end
up actually looking better than the source tapes. (For more information on
authoring analog-to-DVD projects, click here:
Convert VHS to DVD
Article).
MPEG ENCODING IS CRITICAL STEP
The most critical
stage of DVD authoring is compressing the video with an MPEG encoder.
The DVD Video
specification requires that the video be encoded as MPEG-1 or MPEG-2, but
MPEG-1 is almost never used for DVD's. The specification also requires
that the video be a certain size: for NTSC, such as is used in North
America, the frame size (resolution) must be 704x480, 720x480, 352x480 or
352x240 and the frame rate must be 23.976 or 29.97 frames per second.
For PAL video (the
European standard) it's 720x576, 704x576, 352x576 or 352x288 at 25fps.
If you work in the
popular DV format (which includes mini DV, Digital 8 and DVCAM), your
source video will be 720x480 at 29.97 fps for NTSC and 720x576 at 25fps
for PAL. This is something to keep in mind during editing, because some
editing programs work in other resolutions, for instance NTSC 640x480, and
in order to encode non-standard resolutions to MPEG-2 the source video
would have to be converted and that often results in a loss of quality.
Some video editing programs produce video that is 720x486: an advanced
MPEG encoder will crop off the extra lines to make it 720x480 and there is
no loss of quality.
Any loss of quality
in your source video is likely to be multiplied after encoding to MPEG-2,
which is a highly compressed format. You may have noticed that when you
capture an hour of DV video (which is considered to be compressed 5:1) to
your computer, it takes up almost 14GB of hard drive space. When you
author a DVD project and burn that same hour to a DVD it has to fit in
less than 4.37GB of space: that's a lot of compression. If you have two
hours of video on a DVD it is compressed to just two percent the size of
so-called "uncompressed video."
We often see the
phrase "DVD quality," but that is somewhat misleading. Encoding your video
to MPEG-2 and burning it to DVD will not make it better than the original.
At best it will preserve much more of the quality of the original than
would, for example, a VHS tape copy, but if there are flaws in the
original they may get noticeably worse. The notion of "DVD quality" is due
in large part to those Hollywood movies which cost millions to produce on
the highest quality 35mm film equipment, the film is digitized (scanned)
at extremely high resolutions as progressive scan images and processed and
encoded on some very expensive systems. It's a far cry from using a $1,500
camcorder shooting interlaced video that is compressed even before it gets
to the MPEG-2 encoding stage.
But even the
Hollywood productions would not look so impressive had they not been
encoded with a good MPEG encoder and the quality of the MPEG encoder you
use can make a vast difference in the final quality of your burned (or
replicated) DVD. If you are shopping for DVD authoring software, you
should consider getting a DVD authoring program that allows you to decide
which MPEG encoder you use. Some DVD authoring programs, such as Apple's
popular iDVD, have a built MPEG-2 encoder and you cannot use other
encoders. The built-in encoders may be okay for home movies or, depending
upon the software, some simple commercial projects, but they generally
don't do a very good job if you want to get more than 60 minutes of video
on one DVD and some, quite frankly, don't do a very good job on any length
of video.
The highest quality
encoding is usually "two-pass, variable bitrate (VBR)" encoding. That
means the MPEG encoder goes through your video twice: on the first pass it
analyzes each frame to determine how much data should be allocated to each
frame, and then on the second pass it encodes it (there are VBR encoders
that can do more than two passes for even higher quality).
The bitrate is also
referred to as the data rate or bandwidth and in DVD encoding it is
expressed as megabits per second, or Mbps. A typical bitrate would be
6Mbps. In VBR encoding there would be an average of six megabits of data
allocated for each one-second of video, but some complex sections might be
encoded at 8Mbps, while some easier sections (for instance those with
little movement) might be encoded at 4Mbps, but for the whole video the
average would work out to 6Mbps. VBR MPEG encoders usually let you set the
average bitrate as well as minimum and maximum rates.
There is also
constant bitrate (CBR) encoding. The bitrate never varies, so the tricky
stuff (fast motion, transitions, etc.) gets encoded with the same amount
of data as the easy stuff. CBR encoders can be considerably faster than
VBR encoders, but the speed comes at the expense of quality and you might
have to use a higher bitrate than you would with a two-pass VBR encoder.
In addition to
software MPEG encoders there are also hardware encoders, some of which
will only work from videotape sources and others which will also encode
files from your hard drive. Hardware encoders can vary in price from a
couple of hundred dollars to several thousand. The growth in MPEG encoding
for things like Tivo has led to development of a new generation of
inexpensive MPEG encoder chips that can deliver very good results. While a
software encoder might take, for instance, 10 hours to encode one hour of
video using VBR, a hardware MPEG encoder would do it one hour, in "realtime."
Some hardware encoders have inputs for your VCR's and camcorders so you
can capture and do MPEG encoding in realtime. However, because the video
is captured as MPEG, you cannot do any real editing to it because of the
nature of MPEG files. You can cut out some parts of the video you don't
want, but that's about it. If you want to do any fancy editing, do that
before you feed your video to an MPEG encoder.
SELECTING AN MPEG-2
BITRATE
With both hardware
and software MPEG encoders, the bitrate you select for your video will
determine not only the quality of the video, but also how much you can fit
on a DVD. If you are going to burn your project to DVD-R or +R, it may
also affect how compatible your disks are with various DVD players.
Video bitrates
usually fall into the range of 4Mbps to 8Mbps. At 4Mbps you could get 135
minutes of video on a single DVD, but at 8Mbps you could only get 70
minutes on a DVD. The lower the bitrate the harder it is to get good
quality and some encoders simply cannot deliver acceptable quality at 4 or
even 5Mbps.
The amount of video
you can get on a DVD also depends on the audio bitrate.
On Video DVD's the
audio uses one of three basic formats: compressed Dolby Digital (AC3),
uncompressed PCM, or compressed MPEG audio. For NTSC DVD's, MPEG audio is
an optional part of the specifications, so not all DVD players will play
the MPEG audio. Unfortunately this is often the only type of compressed
audio provided in many DVD authoring programs, so if you are creating
DVD's for other than personal use, you should use uncompressed PCM audio
or Dolby Digital. There is also a "DTS" audio format which uses very
expensive encoders.
Stereo PCM audio has
a bitrate of over 1.5Mbps, while compressed Dolby Digital and MPEG audio
can have a bitrate that is as low as 10% of PCM audio. This can make a big
difference in how much video you can get on a disk or how high of a video
bitrate you can use. In the example above I said that at 4Mbps you could
get 135 minutes of video on a DVD - that's by using audio compressed to
224Kbps (.224Mbps). If you used PCM audio and a 4Mbps video bitrate you
would only be able to get about 115 minutes of video on the DVD.
The best choice for
audio is Dolby Digital. It can have very good quality at low bitrates and
is compatible with all NTSC and PAL DVD players. It requires a special
encoder and authoring software that will support it
DVD AUTHORING
SOFTWARE
You've produced
clean source video and audio and properly encoded it (if your authoring
program accepts pre-encoded video), now how do you get it on disk ready to
pop into a DVD player?
That's where the DVD
authoring software comes in. In its simplest form DVD authoring could
involve importing an MPEG-2 movie and its audio file into the DVD
authoring program and then setting the options so that as soon as someone
pops the DVD into a player, that one movie starts playing - no menu, no
chapters, nothing but the movie.
Usually though, we
want a menu with at least one button for the viewer to click. Menus can
have still or moving images in the background, even sound. Not all DVD
authoring programs have every option and not all of them allow you to
customize the look of the menu. With some DVD authoring software you may
be limited to certain design templates while others give you have free
reign to import your own backgrounds and create cheesy buttons if you so
desire. The more advanced DVD authoring software lets you create some
rather complex navigation schemes for having users move about through your
DVD. Again, keep the viewer in mind: in this era of technology overload,
most folks are happy to just be able to figure out which button to click
to play the movie.
Some advanced DVD
authoring options have more utility, such as adding additional soundtracks
in other languages or closed captioning. Multi-angles can have some
interesting uses: you could shoot the same event with two or more cameras
and at the click of a button, the viewer could switch between the
different viewpoints while watching the DVD.
Of more use perhaps
is "chapters." Chapters are basically markers within a movie and each
chapter can have a button so a viewer can instantly jump to a point within
a movie without having to fast forward or rewind. This can be handy with,
for example, wedding videos where a viewer might want to skip over the
ceremony and jump straight to that point in the reception where Uncle
Louie dances a torrid tango with Aunt Tillie.
DVD authoring can
take 20 minutes or several days, but no matter how simple or complex the
project, before burning it to disk all the elements, including video
files, audio tracks, menu and button graphics and the instructions on how
it is to be played, have to be assembled into a rather strict file
structure required for video DVD's. Some programs call it "compiling,"
others call it the "build," and some just do it when you click a button
that says "Burn DVD."
It can take quite a
while and during this stage you may get an error message if you did
something wrong in an earlier stage. For instance, the DVD Video
specifications say that the maximum combined bitrate for audio and video
must be 9.8Mbps or less. Well, if you encoded your video at 8.5Mbps and
used PCM audio (which is over 1.5Mbps) you will be over the limit and
during compiling your DVD authoring software may stop and tell you that
the data rate is too high. Or you may have encoded two hours of video at
7Mbps and the total files for your DVD project exceed the 4.37GB capacity
of the DVD so the program stops compiling and gives an error message about
that.
At the end of the
compiling stage your authoring software will have created two new files,
folders actually, called "VIDEO_TS" and "AUDIO_TS." Again, depending upon
your software, you may have an option to not only burn a disk but to also
save these folders to your hard drive, or to just save the folders but not
burn them to disk. The "VIDEO_TS" folder contains all of the compiled
files, while the "AUDIO_TS" folder is empty (we won't get into that). If
the DVD player on your computer allows it, you can select the "VIDEO_TS"
folder from your hard drive and play it exactly as you would a burned DVD.
If everything looks and works as it should, you can then burn the two
folders to DVD, either using your authoring program or some disk utility
programs which, while they may not be able to author DVD's, will burn the
"VIDEO_TS" and "AUDIO_TS" folders to DVD in the proper manner (if you want
several copies of the DVD, this can be the best way to do it).
A warning here about
hard drive space: have lots of it. If you encode video and audio files and
associated menus and buttons that will fill up most of a DVD that means
you will need about 4.37GB of disk space for those. Then you will need
another 4.37GB for the compiled files, so plan on setting aside close to
10GB of hard drive space for each DVD project you author. You can always
reclaim much or all of it after you've burned and tested your DVD and
found everything to be okay.
When buying DVD
authoring software make sure it will have all of the features you deem
essential, whether it's chapters, Dolby Digital audio encoding, the
ability to accept MPEG2 files encoded by other software, the ability to
create custom menus with background images of your choice, etc. Again,
some DVD authoring software will only allow you to use the menu choices
that come with the software and some will only let you use the MPEG
encoder included with the software.
DVD-R PLAYBACK
PROBLEMS AND SOLUTIONS
Have you spent many
hours encoding video, using DVD authoring software, burning the project to
DVD-R and then when play your disk it has glitches such as blocky video,
audio out of sync, pauses and freezes?
If you know that the
video looked good after being encoded but before being burned to disk,
then chances are the above symptoms all relate to the pitfalls of DVD-R
and DVD+R (this also include RW disks and we'll just lump all of these
under the name DVD-R). These kinds of problems show up when a player has a
problem with a DVD-R. It's the compatibility issue we discussed earlier in
Part 1.
Some players,
usually older ones, will have problems no matter what you do and some just
will not even load a DVD-R. But to improve compatibility there are a few
basic steps to follow.
The first is to keep
your video bitrate below 7Mbps. Then, if at all possible, use compressed
audio. Many DVD-R playback problems can be solved just by using compressed
audio instead of uncompressed PCM audio.
Use "name brand"
recordable DVD's: some brands just work better than others. Maxell, TDK,
MAM-A (formerly Mitsui) and Verbatim have done well in published tests and
generally get good reports from users. Some cheaper DVD's may work well on
your personal player or for data storage or backup, but don't count on
them for DVD's you produce for clients or sell to others. After all the
hard work you did producing a video and authoring a DVD, it's not worth
trying to save a buck or two on a blank DVD-R if it increases the chances
someone may not be able to play it.
Burn your DVD's at
slower speeds - the theory is that you get a cleaner burn and better data
integrity at slower speeds. I still use 1X for all of my DVD's and many
experienced DVD producers say that even burning at 2X greatly increases
the chances that your DVD-R will have compatibility problems. Those 4X
DVD's you see in the store - burn them at 1X.
Do not use paper
labels. They work fine on CD's but not DVD's. For a professional look
there are now lots of printers that will print directly to DVD's.
I also use
re-writable DVD-RW's lot. Well, actually I have just one DVD-RW but is has
been erased and re-used dozens of times. I had to buy a DVD player than
would handle DVD-RW disks, but the savings in not having to use one-time
only DVD-R's for everything has more than paid for the player. When
starting out in DVD authoring it is inevitable that you will burn disks
which, for various reasons, will not work. Get a DVD-RW so you don't see
dollar signs floating away every time you burn a disk that is usable only
as a coaster. DVD-RW is also handy to use for testing and experimenting.
Practice, practice,
experiment
Video compression
and DVD authoring is a bit of art and science and I encourage you to do a
lot of experimenting. I often run across pleas for help that say something
to the effect of, "I just bought X Brand DVD authoring software yesterday
and promised a client I'd have a two-hour DVD project ready in three days,
but the video looks terrible, I can't fit it all on one disk and my menu
buttons go to the wrong places!"
Your first lesson
should be to find out how well your MPEG encoder works (or doesn't).
Create a three to five minute test movie with lots of different types of
video (including fast motion, fades to black and cross-dissolves) and
encode that at several different bitrates and, if your encoder has them,
with various option quality settings. Then burn that to disk and watch it
on a few different DVD players including the one on your computer. Since
the disk will also require a menu as well as buttons to click between the
different versions of the movie, this is also a good way to learn the
basics of creating a DVD navigation scheme.
Unless you plan to
use only the menu templates and canned artwork included with many DVD
authoring programs, you'll also want to practice creating the graphics for
DVD menus. You'll find that designs and colors that look great on a
computer screen look lousy on a television. Skinny lines, narrow fonts,
vivid colors and gradients should be avoided. Also be aware that there are
issues of image size and resolution that must be considered when designing
DVD menus. For instance, if you create a DVD menu in a graphics program,
you typically would create it at 720x534, 72dpi. After it's finished you
would then re-size it to 720x480 and save that as the file you use for
your menu. Because of differences in the "aspect ratio" of pixels, this
process ensures that your menu (or other still image, such as a
photograph) will not be distorted. If you had, for example, a perfect
circle in your design and you did not use this process, the circle would
look like an oval in your DVD menu. Some graphics programs and some DVD
authoring programs now have shortcuts for streamlining this process.
If you really don't
need fancy menus nor do you want to spend a lot of time waiting for your
computer to encode, compile and burn DVD's, then maybe you should consider
the standalone DVD recorders that work like a VCR. You can edit your
movie, save it back to tape, plug the tape deck or camcorder into the DVD
recorder, press a couple of buttons, and have it turn out a DVD-R in
realtime. You can do chapters on these, record from your DV camcorder's
Firewire connection for better quality, and the hardware encoders in some
of these DVD recorders are quite decent. You don't have as much control
over the look and layout of the DVD as would using authoring software, but
it's the simplest and fastest way to burn videos to DVD-R. There are also
now some hybrid hardware/software solutions for your computer that work in
a similar manner: plug your tape source into the hardware and it gets
encoded and burned to disk on your computer's DVD burner in realtime.
(As an aside here,
you can also use standalone DVD recorders and mix them with VCRs to
simultaneously mass duplicate DVD's and VHS tapes. All you have to do is
to hook them all up with some relatively inexpensive
video duplication gear.)
Before purchasing
any DVD authoring and encoding software, or hardware DVD recorders, search
out the various DVD user forums on the Internet to find out how the
products you're considering are actually performing in the real world.
There are a lot "reviews" that are really nothing more than re-writes of
manufacturer's press releases and they only tell you what a product is
supposed to do, not how it really performs. Again, look for the real world
user reports.
One last thought:
when you visit the online DVD forums you will read a lot of reports from
people who said something went wrong and they have "burned a lot of
coasters." Well, truth be told, faulty DVD's make lousy coasters. They
have that big hole in the middle so the condensation from your drink ends
up making a ring on the table.
Now if someone would
just start marketing a cork hole plug...
Article copyright © 2004 by
Bob Hudson |
