Encoding and Authoring FAQ : Imperial Media

Encoding, Authoring & Menu Design

What are the different sizes for DVDs?

There are many variations on the DVD theme. Discs come in two physical sizes: 12 cm (4.7 inches) and 8 cm (3.1 inches), both 1.2 mm thick, made of two 0.6mm substrates glued together. These are the same form factors as a CD. A DVD can be single-sided or double-sided. Each side can have one or two layers of data. The amount of video a disc can hold depends on how much audio accompanies it and how heavily the video and audio are compressed. The oft-quoted figure of 133 minutes is apocryphal: a DVD with only one audio track easily holds over 160 minutes, and a single layer can actually hold up to 9 hours of video and audio if it's compressed to VHS quality.

What is the storage capacity of a DVD?

There are a number of different DVDs with various storage capacities, including DVD-5, DVD-9 and DVD-10.

DVD-5 - 4.7 Gigabytes capacity. It is single layer and single sided with up to 133 minutes of video.

DVD-9 - 8.54 Gigabytes capacity. It is dual layer and single sided with up to 240 minutes of video.

DVD-10 - 9.4 Gigabytes capacity. It is single layer and two sided. Conventional DVD printing is not an option for DVD-10s because both sides of the disc must be readable. This means only printing on the hub of the disc is available.

Acceptable formats for encoding, authoring & menu design?

Imperial Media Services accepts media in the following formats for DVD and Blu-ray authoring:

Video

Elementary MPEG2 streams
MPEG1 (Half-D1)
QuickTime-based Movies
H264
Apple Pro res

Audio:

AIFF 2-Channel (48000/96000)
AC-3 Mono through 5.1 Channel
DTS Audio 2.0/5.1
Wave Audio
PCM Audio
MPEG-1 Layer 2 Audio

Menu:

Any supported still or layered image
Any supported MPEG2
Any supported Audio
Any supported Application project

Image:

Adobe Photoshop Layered Images
TIFF Images
JPG (JPEG, must be hi res)

Project:

Motion (.motn)
LiveType (.ipr)

What is a 'Still Menu' or a 'Motion Menu'?

A DVD/Blu-ray menu is the display that appears at the beginning of a film listing all the features and functions available for selection by the user. The menu consists of buttons related to the features and may include scene selection, trailers, director's commentaries, subtitle options, and alternate audio tracks. A motion menu is a menu where the background is a video stream (hence motion) instead of a still menu, which consists of a background image without any movement. Motion menus have the same functionality as static menus, but with the added aesthetic appeal of employing motion graphics as the background. You can also add sound to a menu as background audio, which may or may not match the video.

How do the interactive features work?

DVD-Video players (and software DVD-Video navigators for computers) support a command set that provides rudimentary interactivity. The main feature is menus, which are present on almost all discs to allow content selection and feature control. Each menu has a still or motion background and up to 36 highlighted, rectangular "buttons" (only 12 if widescreen, letterbox, and pan & scan modes are used). Commands can also control player settings, jump to different parts of the disc, and control presentation of audio, video, sub-picture, camera angles, and so on. The command set enables relatively sophisticated discs, such as games or interactive educational programs.

I have a master. Can you just add a menu?

Yes, Imperial Media can author a new DVD or Blu-ray master with menus. We would use the video from your media that we would otherwise encode from tape. This will work best if you have locked picture and you are satisfied with the quality of the video on your project. Imperial can also go from the original source and encode everything for you.

Can I add a web link to my DVD?

Imperial Media can add web links, email links and links to files that are included on your DVD during the authoring process. However, these links will only be active when the DVD is viewed on a computer.

Can my DVD have surround sound?

Yes, Imperial Media can provide you with surround sound for your DVD project. Multi-channel or surround audio is supported via Dolby Digital in several configurations, most commonly 5.1. The 5.1 configuration consists of left, center, and right speakers in front, and left surround and right surround speakers placed on the sides of the listener. Imperial Media accepts WAV or AIFF files for authoring DVDs with surround audio.

What are alternate audio tracks or foreign language tracks?

Alternate audio tracks are audio channels included in DVDs that are separate from the primary dialogue and sound tracks. Directors, cast and crew frequently use alternate audio tracks for commentaries to supplement the primary audio. Also, foreign language dubs can be featured as alternative audio tracks.

What formats do you accept for subtitles?

For purposes of subtitling, Imperial Media supports files that conform to the following formats:
STL: The Spruce Technologies subtitle format
SON: The Sonic Solutions bitmap-based format
TXT: A plain text file
SCR: The Daiken-Comtec Laboratories Scenarist bitmap-based format

Files in these formats should all contain multiple subtitle text or graphics images tied to time code values, ensuring they are placed properly within the timeline.

What is a 'Slideshow' for a DVD?

A 'Slide show' is a compilation of still photos and graphic images complete with transitions, music and text. A slideshow can have it's own button on the DVD menu which launches the presentation. You can choose to add professional "Pan & Zoom" effects to your slides, as well as touch up, crop and add text to the photos in your slide shows.

How do I put a PowerPoint presentation on a DVD?

There's not yet a feature in PowerPoint to export directly to video on DVD, but you can convert a PowerPoint presentation to stills or video for import into a DVD authoring program. Recent versions of PowerPoint allow you to save your slides as graphic images (JPEG or PNG files) that can be imported into a DVD authoring program that supports slideshows. The advantage of using the slideshow feature is that you can have the DVD player pause indefinitely on each still until you press the Enter or Play key on the remote control. The disadvantage of using stills is that you won't get animations and other fancy PowerPoint effects. Alternatively you can record the PowerPoint presentation as a video file and import the video file into the DVD authoring program. This preserves the full visual effect but locks you into the timing you used when recording the presentation.

What are 'closed captions'?

Closed captions are a text version of the spoken part of a video, movie, or computer presentation. Closed captioning was developed to aid hearing-impaired people, but it's useful for a variety of situations. For example, captions can be read when audio can't be heard, either because of a noisy environment, such as an airport, or because of an environment that must be kept quiet, such as a hospital.

Closed captioning information is encoded within the video signal. The text only becomes visible with the use of a decoder, which may be built into a television set or available as a set-top box. In general, an onscreen menu on newer televisions allows you to turn closed captioning on or off.

What is video compression?

Video compression refers to reducing the quantity of data used to represent video images and is a straightforward combination of image compression and motion compensation. Video Compression algorithms take advantage of the fact that there is minimal difference from "one" frame to the next. The first frame is encoded and then the sequence of differences between frames. This is also known as "inter-frame" coding. For DVDs, the original video is compressed and rendered in the MPEG-2 format that is the industry standard.

What is MPEG-2 video?

MPEG stands for "Motion Picture Experts Group", which is named after the standards committee that established the compression algorithm. MPEG-2 is the standard compression technology used for DVD video. Video must be highly compressed so longer programs can fit on a single disc. The longer the program, the greater the amount of compression required to fit the material on a disc. Higher compression rates result in poorer video quality. At Imperial Media we always use the optimal compression rate to provide the highest quality end product.

What is anamorphic?

If the picture on your screen appears squished, you are watching an anamorphic picture intended for display only on a widescreen TV. You need to go into the player's setup menu and tell it you have a standard 4:3 TV, not a widescreen 16:9 TV. It will then automatically letterbox the picture so you can see the full width at the proper proportions. Some discs are labeled with widescreen on one side and standard on the other. In order to watch the full-screen version you must flip the disc over.

Do all videos use Dolby Digital? Do they all have 5.1 channels?

Most DVD-Video discs contain Dolby Digital soundtracks. However, it's not required. Some discs, especially those containing only audio, have PCM tracks. Don't assume that the Dolby Digital label is a guarantee of 5.1 channels. A Dolby Digital soundtrack can be mono, dual mono, stereo, Dolby Surround stereo, etc.

What's a hybrid DVD?

A hybrid DVD is a broad category that encompasses all of the following:

A disc that works in both DVD-Video players and DVD-ROM PCs is called an enhanced DVD.
A DVD-ROM disc that runs on Windows and Mac OS computers is called a cross-platform DVD.
A DVD-ROM or DVD-Video disc that also contains Web content for connecting to the Internet is called a Web DVD or enhanced DVD.
A disc that contains both DVD-Video and DVD-Audio content is called a universal or AV DVD.
A disc with two layers, one that can be read in DVD players and one that can be read in CD players, is called a legacy or CD-compatible disc.
A disc with two layers on one side and one layer on the other is called a DVD-14.
A disc with an embedded memory chip for storing custom usage data and access codes is called a chipped DVD.
A disc that has a foreign language dubbed audio track and also has subtitles in that language.

What are wide-screen, full-screen, and letterbox?

In some DVDs released by the major studios today, there may be both a full-screen and widescreen version of the movie on the same disc. Full-screen has an aspect ratio of 4:3 and widescreen has an aspect ration of 16:9. Letterbox means the video is presented in its theatrical aspect ratio, which is wider than standard or widescreen TV. Black bars, called mattes, are used to cover the gaps at the top and bottom. DVD was designed to make movies look as good as possible on TV. Since most movies are wider than standard TVs, letterboxing preserves the format of the theatrical presentation. (Nobody seems to complain that the top and bottom of the picture are cut off in theaters.) DVD is ready for TVs of the future, which are widescreen. For these and other reasons, many movies on DVD are only available in widescreen format.

How do the parental control and multi-rating features work?

DVD includes parental management features for blocking playback and for providing multiple versions of a movie on a single disc. Players (including software players on PCs) can be set to a specific parental level using the onscreen settings. If a disc with a rating above that level is put in the player, it won't play. In some cases, different programs on the disc have different ratings. The level setting can be protected with a password.

What's a dual-layer disc?

A dual-layer disc has two layers of data, one of them semi-transparent so that the laser can focus through it and read the second layer. Since both layers are read from the same side, a dual-layer disc can hold almost twice as much as a single-layer disc, typically 4 hours of video. Many discs use dual layers. The advantage of two layers is that long movies can use higher data rates for better quality than with a single layer.

What are "regional codes," "country codes," or "zone codes"?

Motion picture studios want to control the home release of movies in different countries because theater releases aren't simultaneous. Therefore they required that the DVD standard include codes to prevent playback of certain discs in certain geographical regions. Each player is given a code for the region in which it's sold. The player will refuse to play discs that are not coded for its region. This means that a disc bought in one country may not play on a player bought in another country.

Regional codes are entirely optional for the maker of a disc. Discs without region locks will play on any player in any country. It's not an encryption system, it's just one byte of information on the disc that the player checks. Region codes don't apply to DVD-Audio, DVD-ROM, or recordable DVD.

Seven regions (also called locales or zones) have been defined, and each one is assigned a number, 1 -7, plus 8 for airlines & cruise ships. Technically there is no such thing as a region zero disc or a region zero player. There is such thing as an all-region disc. There are also all-region players. Imperial Media Services can code your DVD for specific zone codes or create all-region discs. It is just a matter of the customer's specific needs.

What is a DVD-Audio discs or a DVD-Music discs?

DVD-Music isn't actually an official DVD format, but it has become a commonly used name for a DVD-Video disc that contains primarily music. A DVD-Music disc plays in any standard DVD player with video or still pictures that accompany the audio. As DVD-Audio disc contains special high-fidelity audio tracks that can only be played in DVD-Audio players.

What about animation on DVD? Doesn't it compress poorly?

Some people claim that animation, especially hand-drawn cell animation such as cartoons and anime, does not compress well with MPEG-2 or even ends up larger than the original. Other people claim that animation is simple so it compresses better. Neither is true.

Because of the way MPEG-2 breaks a picture into blocks and transforms them into frequency information it can have a problem with the sharp edges common in animation. This loss of high-frequency information can show up as "ringing" or blurry spots along edges. However, at the data rates commonly used for DVDs this problem does not usually occur. By employing optimal data rates, Imperial Media can assure our clients of the highest quality DVD authoring for their animation projects.

Why do some discs require side flipping?

Even though DVD's dual-layer technology allows over four hours of continuous playback from a single side, some movies are split over two sides of a disc, requiring that the disc be flipped partway through. Most "flipper" discs exist because of producers who are too lazy to optimize the compression or make a dual-layer disc. Better picture quality is a cheap excuse for increasing the data rate; in many cases the video will look better if carefully encoded at a lower bit rate. Very few players can automatically switch sides, but it's not needed since most movies less than 4 hours long can easily fit on one dual-layer (RSDL) side.

How do the parental control and multi-rating features work?

How does MPEG-4 affect DVD?

MPEG-4 is a video encoding standard designed primarily for low-data rate streaming video, although it's actually more efficient than MPEG-2 at DVD and HDTV data rates. DVD uses MPEG-2 video encoding. Standard DVD players don't recognize the MPEG-4 video format. MPEG-4 files can be stored on DVD-ROM for use on computers.

What's Web DVD or Enhanced DVD?

Web DVD is the simple but powerful concept of combining DVD content with Internet technology. It combines the best of DVD (fast access to high-quality video, audio, and data) with the best of the Internet (interactivity, dynamic updates, and communication). In general, Web DVD refers to enhancing a DVD with HTML pages, links and scripting, or enhancing a Web site with content from a local DVD drive. It's not a new idea --it's been done with CD-ROM for years-- but the differences with DVD are that the quality of the audio and video are finally better than TV, and the discs can be played in low-cost set top players.

What is Dolby Digital, Surround, Pro Logic, and DTS?

Almost every DVD contains audio in the Dolby Digital (AC-3) format. DTS is an optional audio format that can be added to a disc in addition to Dolby Digital audio. Dolby Digital and DTS can store mono, stereo, and multi-channel audio (usually 5.1 channels).

Every DVD player in the world has an internal Dolby Digital decoder. The built-in 2-channel decoder turns Dolby Digital into stereo audio, which can be fed to almost any type of audio equipment (receiver, TV, etc.) as a standard analog stereo signal using a pair of stereo audio cables or as a digital PCM audio signal using a coax or optical cable.

A standard audio mixing technique, called Dolby Surround, "piggybacks" a rear channel and a center channel onto a 2-channel signal. A Dolby Surround signal can be played on any stereo system, in which case the rear- and center-channel sounds remain mixed in with the left and right channels.

The improved decoding technique, Dolby Pro Logic, also extracts the center channel. A brand new decoding technology, Dolby Pro Logic II, extracts both the center channel and the rear channel and also processes the signals to create more of a 3D audio environment.

Unlike Dolby Surround, Dolby Digital encodes each channel independently. Dolby Digital can carry up to 5 channels (left, center, right, left surround, right surround) plus an omni-directional low-frequency channel.

What is interlaced or progressive video?

There are basically two ways to display video: interlaced scan or progressive scan. Progressive scan, used in computer monitors and digital televisions, displays all the horizontal lines of a picture at one time as a single frame. Interlaced scan, used in standard television formats (NTSC, PAL, and SECAM), displays only half of the horizontal lines at a time. Interlacing relies on phosphor persistence of the TV tube to blend the fields together over a fraction of a second into a seemingly single picture. The advantage of interlaced video is that a high refresh rate (50 or 60 Hz) can be achieved with only half the bandwidth. The disadvantage is that the vertical resolution is essentially cut in half, and the video is often filtered to avoid flicker and other artifacts.

DVDs are specifically designed to be displayed on interlaced-scan displays, which represent 99.9 percent of the more than one billion TVs worldwide. However, most DVD content comes from film, which is inherently progressive. To make film content work in interlaced form, the video from each film frame is split into two video fields 240 lines in one field, and 240 lines in the other and encoded as separate fields in the MPEG-2 stream. A complication is that film runs at 24 frames per second, whereas TV runs at 30 frames (60 fields) per second for NTSC, or 25 frames (50 fields) per second for PAL and SECAM. For PAL/SECAM display, the simple solution is to show the film frames at 25 per second, which is a 4 percent speed increase, and to speed up the audio to match. For NTSC display, the solution is to spread 24 frames across 60 fields by alternating the display of the first film frame for 2 video fields and the next film frame for 3 video fields. This is called 2-3 pull-down.

What is edge enhancement?

When films are transferred to video in preparation for DVD encoding, they are commonly run through digital processes that attempt to clean up the picture. These processes include digital video noise reduction (DVNR) and image enhancement. Enhancement increases contrast but can tend to overdo areas of transition between light and dark or different colors, causing a "chiseled" look or a ringing effect. Video noise reduction is a good thing, when done well, since it can remove scratches, spots, and other defects from the original film.

What about the new HD formats?

Next-generation DVD was actually under development before DVD came out but didn't begin to emerge until 2003, and the formats were not used for movies until 2006. Some high-definition versions of DVD use the original DVD physical format but depend on new video encoding technology such as H.264 and VC-1 to fit high-definition video in the space that used to hold only standard-definition video. High-density formats use blue or violet lasers to read smaller pits, increasing data capacity to around 15 to 30 GB per layer. High-density formats use high-definition MPEG-2 video and also use advanced encoding formats, supporting 720p and 1080p video. Originally, there were a number of different competing formats. The winning format of this 'competition' (and now the industry standard) is Blu-Ray. Blu-Ray Disc has a data depth of 0.1mm, handles video in MPEG-2, H.264, & VC-1, and audio in PCM, Dolby Digital+, & DTS HD.

What is Blu-ray Disc (BD)?

Blu-ray is the new industry standard High Definition DVD format. It is a high-density physical format that holds 25 GB per layer and up to 2 layers per disc for a total possible capacity of 50GB. Recording capacity on a single layer is about 2 hours of HD video (at 28 Mbps) or about 10 hours of standard-definition video (at 4.5 Mbps).

Can I play DVD movies on my computer?

Yes, if your computer has the right stuff. Almost all Windows and Mac OS computers with DVD drives come with software to play DVDs.

The computer operating system or playback software must support regional codes and be licensed to descramble copy-protected movies.

Can I play DVD-Audio discs on my computer?

Usually not. DVD-ROM drives can read DVD-Audio discs, but as of 2005 only the Sound Blaster Audigy 2 card includes the software needed to play DVD-Audio on a computer. Part of the reason for general lack of support is that very few computers provide the high quality audio environment needed to take advantage of DVD-Audio fidelity.

It's possible that Microsoft could add DVD-Audio playback to a future version of Windows, in which case you would only need to download some inexpensive decoding software to get DVD-Audio playback.

What are .IFO, .VOB, . AOB, and .VRO files?

The DVD-Video and DVD-Audio specifications define how audio and video data are stored in specialized files. The .IFO files contain menus and other information about the video and audio. The .BUP files are backup copies of the .IFO files. The .VOB files (for DVD-Video) and .AOB files (for DVD-Audio) are MPEG-2 program streams with additional packets containing navigation and search information.

Can I put DVD-Video content on a CD-R or CD-RW?

Copying from DVD to CD is impractical, since it takes 7 to 14 CDs to hold one side of a DVD. Also, most DVD movies are encrypted so that the files can't be copied without special software. However, there are many advantages to creating a DVD-Video volume using inexpensive recordable CD rather than expensive recordable DVD. The resulting "cDVD" (sometimes called a "miniDVD") is perfect for testing and for short video programs. Unfortunately, you can put DVD-Video files on CD-R or CD-RW media, or even on pressed CD-ROM media, but almost no set-top player can play the disc. Computers are more forgiving. DVD-Video files from any source with fast enough data rates, including CD-R or CD-RW, with or without UDF formatting, will play back on most DVD-ROM PCs as long as the drive can read the media.

How do I put other data files on a DVD I make?

DVDs can store any type of data file (PowerPoint, PDF, text, JPEG, etc.) in addition to video. The files can be viewed by putting the disc in a computer and opening the disc. They can be put pretty much anywhere on the disc other than in the VIDEO_TS folder. However, the software you're using to create the DVD has to support adding data files. Check the feature list for the software to see if it can add extra files.

How can I copy a DVD?

First, please understand that copying a commercial DVD may be illegal, depending on what country you live in and what you do with the copy. Copying video for your own personal use may be legal, but making copies of copyrighted discs for friends is not. Second, be aware that almost all DVD movies are protected from casual copying. Third, realize that many movies come on dual-layer discs (DVD-9s), which can only be directly copied on a dual-layer recordable drive. Fourth, understand that simply copying the computer files from a DVD to a recordable DVD often produces a disc that won't play in a set-top DVD player, since the files have to go in specific order and specific places on the disc.

If you have a legitimate need to copy a DVD, such as a disc you made yourself, Imperial Media Services can do the job for you. Whether you need 50 copies or 50,000 copies, Imperial Media can handle your project.