AUTHORING
GUIDES -> Introduction to DVD authoring (and FAQ)
The authoring process is best described as the organizing and burning stage of making a
DVD. This is when you make menus and arrange the video and audio files.
The authoring software then takes all your
audio/video/subtitles/menus creates the VOB, BUP and IFO files found on
DVDs. This is followed by the final burning stage.
Because most authoring programs include a burning engine, it is normally streamlined into a single process. Most authoring guides on this site also give information on how to burn in the same program.
However, I prefer to author DVD files to a folder on the hard drive for testing. Testing is done in PowerDVD using DVD-on-HDD mode. After testing verifies,
then the authored folder is burned to disc in Nero.
This guide has four parts:
(1) Authoring Basics, (2) Video/Audio DVD Specs,
(3) Audio
FAQ, and (4) Multiple VTS FAQ
Authoring
basics
What is a VOB file?
IFO/BUP files? A DVD uses VOB files as containers that hold the video and
audio data and IFO (InFOrmation files) store the navigation
data. The BUP is a BackUP of the IFO files, and must be on
the discs. The discs are composed of a VIDEO_TS folder and
an AUDIO_TS folder, although the audio folder is unused.
Both the audio and video are stored in the VOB files that
are present in the VIDEO_TS folder.
Your video and audio files are often "imported"
into an authoring application and referred to as
"assets".
ENCODE
YOUR FILES SEPARATELY!!!
Authoring applications were never meant to encode audio
or video. They were meant to author a disc. The encoding
function found in most authoring programs is not very good
and was an afterthought. It only exists for lazy newbies.
Never let an authoring package encode
your video.
It is an authoring application, not an
encoder. While many authoring programs have the ability to
encode your video for you, it is often not good quality and
gives you no control over the size, resolution, bit-rates
and important factors that determine the quality of the
disc. Bad authoring encoders include DVDit!, DVD Workshop,
NeoDVD, MyDVD, and several other Ulead products, just to name a
few.
Never let an authoring package encode non-AC3 audio. With
few exceptions, the same rules for video apply to audio.
Again, authoring applications were meant to author, not
encode. The only exception I find acceptable is when using TMPGEnc
DVD Author to convert VCD to DVD, it is easier to allow the
program to convert the 44.1kHz MPEG Layer-II audio to 48kHz, for
fear of losing audio sync. Although TMPGEnc is not the best
audio encoder, in this situation, this is the lesser of two
evils.
If the program has a true AC3 encoder, like DVDit! PE or DVD
Workshop AC3, then feel free to let it encode the AC3.
Video
and audio specifications for DVD
Video files must
conform to MPEG specifications allowed by the DVD format. This means you can ONLY use MPEG-1 or MPEG-2 files that meet
the specifications, not AVI or Divx or whatever else
non-MPEG files you may have. And even then, the MPEG must
have an allowed resolution, bit-rate, GOP size and sequences
headers as required.
| Video
format |
File
Format |
Resolutions |
Video
bit-rates |
Audio
specs |
| DVD-Video |
MPEG-2,
sequence headers at each GOP, 4:2:0, MP@ML |
=
NTSC (4:3): 352x240, 352x480, 704x480, 720x480
= NTSC (16:9 widescreen): 704x480, 720x480
= PAL (4:3) 352x288, 352x576, 704x576, 720x576
= PAL (16:9 widescreen): 704x576, 720x576 |
Up
to 10.08Mb/s total combined bitrate. Up to 9.8Mb/s max
video bit-rate. CBR, CVBR, or VBR |
=
(1) AC3 Dolby Digital stereo or surround. Average AC3
stereo is 192-384k. Average surround is 448k or
higher.
= (2) LPCM uncompressed 1536k WAV/AIFF.
= (3) DTS, same bit-rate as AC3.
= (4) MPEG Layer II (MP2) stereo, 192-256k
bit-rate, not officially supported in the spec |
| DVD-Video |
MPEG-1,
sequence headers at each GOP, 4:2:0, MP@ML |
=
NTSC (4:3): 352x240
= PAL (4:3): 352x288 |
Between
1.150Mb/s and 1.856Mb/s CBR video bitrate |
Same
audio spec as MPEG-2 version |
The video must also be all PAL or all NTSC.
Multi-format discs are not supported, and most authoring
applications prevent this mistake from being made. DVD
players do not support playback of such discs.
Authorware variances.
Each authoring program has it's own preferences and rules
regarding the file types that are required and/or allowed
for use. Your video and audio files must conform to the
rules of the program, and this information is often found in
the program manual or help files. It is imperative that you read the help files and manual
of your authoring program.
- Example One: DVDit! PE.
The DVDit! line of software
requires that all files be the same resolution and format.
This program does not support multiple VTS (see the multiple
VTS authoring guide for more information on this topic). It
only support 352x240 MPEG-1 between 1150k and 1856k and
MPEG-2 at either 352x480 or 720x480 with bit-rates of up to
8000k for the video. It does not allow 352x240 or 704x480
video. It does not allow MPEG audio, only AC3 and PCM (WAV
or AIFF only) sound files. It also requires closed GOP for
the MPEG. It will not accept non-MPEG files. It requires
video and audio to be imported separately.
-
Example Two: TMPGEnc DVD Author: This program allows
pretty much anything in the MPEG specification. It will not
accept non-MPEG files. This program also allows multiple VTS.
- Example Three: Ulead DVD Workshop: This program will
take MPEG source without transcoding it, and will accept
multiplexed MPEG streams, a rarity for mid-level to
high-level authoring software. It does motion menus and
multi VTS. It will accept some non-MPEG files and will
transcode them to MPEG-2 format.
Audio
FAQ: AC3 vs. PCM vs. MP2
The DVD format
supports three types of audio: Dolby Digital (AC-3),
uncompressed PCM, and MPEG Layer II. Each of them has
advantages and disadvantages. All audio must be a minimum
48hz and stereo. It can also be surround sound.
The most popular of them is AC3, as it is a small file that
retains high quality. Dolby sound also allows for surround
sound, most commonly the Dolby Digital 5.1 sound scheme.
AC3 audio
Dolby Digital Audio is a highly
compressed audio format stored in an AC3 file. Dolby can
be stereo or surround, and has allowable stereo
bit-rates from 128k to 384k. Most commercials DVDs using
stereo use 192k or 224k audio, having come from perfect
sources and using hardware encoding. For home use, I suggest the 256k bit-rate in order to
retain rich sound, especially if it is converted from AVI or
MPEG captures. Surround sound must have at least 6 separate source
channels. Do not use 5.1 unless you have a surround
source. Taking a stereo or mono audio file and forcing
it into Dolby 5.1 format will only waste space and provide
no advantages. Most surround systems are able to emulate
surround by translating the audio and feeding it to all the
speakers, which is essentially the same as converting a 2/0
file into a 5/1 file.
Advantage: size and quality.
Disadvantage: none, really.
PCM audio
Uncompressed PCM
audio is often stored as WAV or AIFF sounds files. PCM is
merely uncompressed audio, and is enormous in size, often 10
times the file size of MP2 or AC3. Do not let the term "uncompressed" fool you,
as most of the compression is being done on frequencies
and information outside the range of human hearing.
Compressed AC3 and MP2 audio can sound just as good as PCM,
at a lower cost (in terms of disc space).
In general, much like AVI video, the PCM audio format is
honestly only good for editing. Final DVD audio should be
AC3 if at all possible. Only leave it as PCM if final disc
size is unimportant or if unusual distortion occurs from AC3
or MP2 compression.
The bit-rate of PCM sound is set at 1536k or a close
approximate.
Advantage: quality
Disadvantage: size
MPEG Layer II audio
The MPEG Layer II
format (commonly using the .MP2 or .MPA file extension) is
not the same as the MPEG Layer III (MP3) audio format. While
both forms of MPEG audio, they are not the same. DVD and
CD-based video does not use MP3 audio.
For NTSC video, MPEG audio is not officially supported.
This being said, also realize most DVD players can playback
the MPEG audio. If the player can play S/X/VCD formats, then
it will most likely playback the MPEG Layer II. Most MPEG
video chips are also hard-coded to play the audio.
For PAL users, MPEG Layer II is currently supported, though
recent shifts in the DVD Forum has hinted that this will
change in the future.
The biggest advantage to leaving the audio as MP2 is to
preserve it's quality, assuming it was clean sounding from
the beginning. Encoding to PCM merely makes the file larger
and encoding to AC3 can potentially harm the quality,
especially if the MP2 was a low bitrate.
In general, using 256k 48hz is optimal. And 192k is
minimum. Most X/S/VCD formats used 224k.
Advantage: size and ease of
conversion from XVCD/SVCD/CVD/VCD
Disadvantage: quality and player support
Multiple VTS
The VOB and IFO
files on a DVD are stored with a VTS naming structure. VTS
stands for Video Title Set, though it is often referred to
as "tracks".
Example:
VTS_01_0,
VTS_01_1,
VTS_01_2,
VTS_02_0,
VTS_02_1,
VTS_03_0,
VTS_03_1, etc
The first number following the VTS, as in "VTS_xx"
is the VTS identification number, whereas VTS_01_05 would be
VTS one part five. Each VTS can only hold one video format.
All video within that VTS must have the same aspect ratio,
resolution and MPEG type.
Why is this important, you ask? Well, most consumer
authoring software only allows one VTS for the whole disc.
This means you are more limited in what your project can
contain. It is important to remember this if your discs will contain
multiples video, as they must all have the same specs.
Multiple VTS does not require such limitations.
Advantages of multiple VTS. The advantages of multiple VTS are
simple: it allows greater control over the content of the
disc. The main movie can be 720x480 16:9 ratio MPEG-2 video,
the disc bonus can be smaller 352x480 4:3 MPEG-2 and the
trailers can be 352x240 MPEG-1 video. Or an episode disc can
use several sources at different size and format. Or VCD
material can be added to an existing DVD with no conversion
being required.
The possibilities of using multiple VTS are great.
This also allows MPEG-1 and MPEG-2 to be put on the same
disc.
Multiple
VTS software. The general rule is
that professional software supports multiple VTS and that
consumer software does not.
- Home software. Most home-use software is single
VTS software. The only real exception is TDA,
which calls these "tracks". All you have to do is
add a track and then a new VTS is created. Some of the
newest mid-level authoring software like DVD Workshop 2 and
DVDit! 5 also supports multi VTS.
- Professional software. Most professional software,
like DVD Studio Pro, Sonic Scenarist, Sonic Maestro,
SpruceUp and others, supports multiple VTS.
Please read the manual, the software help files or online
support file in order to learn whether or not your software
supports multiple VTS.
Page Last Updated: May 17th 2005
|
Print
this guide:  |
|
