DVD-Video & Audio
From image to sound format: everything that makes DVDs a movie disc – codecs, channels, aspect ratios, television standards.
Here you will find everything about the cinematic side of DVD: how a Video-DVD is structured, which audio formats exist, what aspect ratio means, and how MPEG-2 compresses the data so that 2 hours of film fit on one disc.
📋 Content of this page
Video-DVD
The DVD-Video builds on the DVD-ROM (physical and logical structure) and adds an Application Layer that regulates, among other things:
- MPEG-2 video in high quality – approx. 2 hours of film on a DVD-5
- Up to 8 audio tracks with up to 8 channels each
- Up to 32 subpicture tracks (subtitles, karaoke, menus, animations)
- Seamless branching of the plot
- Variable playback (fast forward/rewind, slow motion, single frame)
- Interactive menus and seamless switching of camera perspective
- Parental control
Structural Hierarchy
A DVD-Video is much more structured than the old Video-CD. From smallest to largest:
- Pack — raw data in 2 KB blocks (corresponds to logical sector)
- Video Object Unit (VOBU) — Group of Pictures (GOP) from 0.4 to 1.2 seconds
- Cell — Collection of VOBUs, individually or randomly accessible
- Program (PG) — Collection of Cells (typically a scene)
- Chapter — Collection of Programs, accessible from the menu
- Program Chain (PGC) — Several chapters, possibly with their own age rating
- Title — the individual movie
- Video Title Set (VTS) — up to 99 movies per DVD
- Volume — the individual DVD
🎮 Commands that DVD players recognize
From title selection via chapter/time search, fast forward/rewind, pause, stop, menu, resume, change language, change audio track, turn subtitles on/off, change camera perspective, switch aspect ratio to karaoke activation – all standard. But: DVD creators can block individual functions – which is why on some discs, FBI warnings or commercials cannot be skipped.
DVD-Audio
Approved in March 1999 – with a delay because the music industry was waiting for effective copy protection. It was not meant to repeat the MP3 debacle.
The result was a separate format with "DVD-Audio zones" – which can hardly be read by a normal DVD-Video player. This made DVD-Audio a niche format – as CD-I and Photo-CD had shown before: normal consumers don't buy dozens of players for dozens of formats.
LPCM as mandatory
LPCM is the prescribed format: uncompressed, up to 8 channels, 48–96 kHz, 16/20/24 bits. The data rate is limited to 6144 Kbps – at 96 kHz and 24 bits, it's only enough for 2 channels.
Optional: Dolby Digital (mandatory for video on DVD-Audio), MPEG-Audio, DTS. Plus: up to 16 graphics per track on the player's display.
Aspect Ratio — Image Formats
Aspect ratios are the proportions of the image. Widescreen cinema film: 2.35:1. Classic television: 1.33:1 (4:3). Modern devices: 1.78:1 (16:9).
DVD videos are stored in 4:3 or 16:9. Players can generate the following output formats from them:
A 16:9 video is scaled down until it fits on a 4:3 TV – black bars appear at the top and bottom. The film remains in its original format, just smaller. Ideal if the film is already 1.8:1 (fits perfectly on 16:9 TVs).
Cuts off the sides of a 16:9 video so that a full image is output on a 4:3 TV. More common with old VHS videos, less on DVDs – loss of part of the image is not for everyone.
Post-processed widescreen films so that the material fills the screen on a 4:3 TV. Some DVDs contain both versions – widescreen for 16:9, full frame for 4:3.
Original aspect ratio of the cinema film. Ideal for 16:9 screens for 1.8:1 films. For 2.38:1, thin black bars remain. On 4:3 TVs, it is scaled down like letterbox.
The image is stored horizontally compressed and stretched horizontally again during playback. The player can convert it to letterbox or pan & scan – if intended by the DVD producer.
Television Standards: PAL, NTSC, HDTV
PAL/SECAM & NTSC
PAL/SECAM is the European television standard, NTSC is the American one – and both are mutually incompatible:
| PAL/SECAM | NTSC | |
|---|---|---|
| Resolution | 720 × 576 | 720 × 480 |
| Framerate | 25 fps | 29.97 fps |
| Audio (old DVDs) | MPEG-Audio | AC-3 |
| Region | Europe | USA, Japan |
Generally, a player bought in Europe can handle it – problems are more likely with decoder cards on the TV.
HDTV — High Definition Television
Standard with 16:9 screen and five times higher resolution:
- 720p — 1280 × 720
- 1080i / 1080p — 1920 × 1080
- HD Ready — 1366 × 768
- 4K UHD — 3840 × 2160 (four times Full HD)
First German HD channels launched in October 2005, 4K followed later.
Audio Formats on DVD
Possible audio formats on a DVD: LPCM, Dolby Digital, MPEG-2 Audio, DTS, SDDS. The formats used are usually listed on the back of the DVD cover.
As on a CD, but with 48 or 96 kHz and 16/20/24 bits. 1–8 channels. Data rate limited to 6144 KBps – fewer channels possible with higher quality.
Before 1995 still called AC-3. Almost every DVD uses Dolby Digital 5.1. Excellent sound quality despite compression. Mandatory on NTSC DVDs.
1–5.1 or 7.1 channels, backward compatible with MPEG-1. Initially a quasi-standard in Europe, now replaced by AC-3.
Similar to Dolby Digital, similar results. Requires an external decoder or modern receiver. On pure audio discs, DTS also works in normal DVD players (disguised as PCM).
Sony Dynamic Digital Sound. Technology from the MiniDisc, optional. Did not catch on for DVDs.
5.1 Channel — what the numbers mean
Of the possible 8 channels, usually 6 are used: front left/right, center, rear left/right plus a separate subwoofer channel. Called 5.1 because the subwoofer channel only transmits bass signals – it's not counted as a full channel.
MPEG-2 Compression
Standard image data rate of the digital video standard: 167 Mbit/s. Uncompressed, a DVD-5 (4.7 GB) would only hold 4 minutes of video. Solution: MPEG-2 compression.
How it works
MPEG-2 utilizes the fact that up to 96% of the digital data in a video consists of repetitions. These can be compressed without visible deterioration.
Two passes
- First pass: The video signal is analyzed for complexity.
- Second pass: More complex images receive higher bit rates (lower compression), simpler images lower bit rates. Variable bitrate.
On average 4 Mbit/s, in extreme cases up to 10 Mbit/s. MPEG-2 is the successor to MPEG-1 from the Video CD.
Audio and Video Quality
Audio Quality
The sound quality of a DVD generally surpasses that of a CD. But: poor compression processes can still ruin the sound. Films with poor original soundtracks remain poor – even on DVD.
Video Quality
For a long time, the DVD surpassed all other home display systems – Laserdisc, and computer monitors in any case. Factors that can reduce enjoyment:
- Compression strength — with bit rates below 3 Mbit/s, the inferior quality becomes visible. From 6 Mbit/s, the probability is close to zero.
- MPEG artifacts — partial blur, color errors, swallowed details. In extreme cases: floating foreground motifs.
💡 By the way: Newer codecs such as MPEG-4, h.264, and h.265 are significantly superior to MPEG-2. Not to mention Blu-ray, HD-DVD, or 4K.
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