Introduction to DVD Authoring and Burning
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 and 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 ImgBurn.
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 really 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||Video specs||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 usually 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 352×240 MPEG-1 between 1150k and 1856k and MPEG-2 at either 352×480 or 720×480 with bit-rates of up to 8000k for the video. It does not allow 352×240 or 704×480 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 – 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.
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.
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.
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
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 720×480 16:9 ratio MPEG-2 video, the disc bonus can be smaller 352×480 4:3 MPEG-2 and the trailers can be 352×240 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.
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