Why AVI Is Bad for Multi-Stream DVD Archiving
Archiving DVDs requires a container format that reliably preserves multiple audio tracks, subtitle streams, and chapter markers without data loss or synchronization errors. While the Audio Video Interleave (AVI) format was once a multimedia standard, its outdated architecture makes it fundamentally inadequate for multi-stream DVD archiving compared to native VOB files or modern MKV containers. This article explains the technical limitations of AVI and why VOB and MKV are vastly superior choices for preserving DVD content.
Lack of Native Multi-Audio Support
The AVI format was introduced in 1992 based on the Resource Interchange File Format (RIFF). It was engineered with a simple structure designed primarily for a single video stream and a single audio stream. While hacks and non-standard extensions exist to mux multiple audio tracks into an AVI container, software and hardware decoders handle these implementations inconsistently. In contrast, DVDs regularly contain multiple audio formats (such as stereo commentary, 5.1 Dolby Digital AC-3, and DTS tracks). Both VOB and MKV natively support multiplexing unlimited audio tracks without playback conflicts or out-of-spec workarounds.
Inability to Handle Soft Subtitles
DVDs use bitmap-based subpicture streams for subtitles, allowing users to toggle them on or off or switch between languages during playback. The AVI container lacks a native, standardized specification for embedded text or bitmap subtitles. To preserve subtitles in an AVI file, users are forced to either "burn" (hardcode) the subtitles directly into the video frames—permanently altering the picture and limiting the viewer to a single language—or rely on external subtitle sidecar files (like .idx/.sub or .srt). MKV natively packages DVD VobSub streams directly alongside the video, maintaining switchability and original styling, while VOB preserves the original subpicture format natively.
Absence of Chapter and Menu Metadata
Navigation is an essential component of DVD preservation. The AVI container has no standard mechanism for storing chapter markers, title structures, or metadata. If you convert a DVD to AVI, you lose the ability to skip between chapters or view scene divisions. The MKV specification includes a robust chapter system that directly mirrors DVD chapter timestamps, and VOB files (when kept alongside their associated IFO files) retain the exact navigation logic of the original disc.
Inflexible Indexing and Timestamping
AVI uses a fixed frame-rate timing mechanism rather than per-frame timestamps. DVD video frequently incorporates variable frame rate mechanisms, such as 3:2 pulldown (telecine) for 24p film content encoded at 29.97i. Transmuxing or re-encoding this content into AVI often introduces audio-video sync drift over long durations. MKV uses a modern timecode-based architecture where every individual frame has a precise timestamp, ensuring that video, multiple audio tracks, and subtitles stay locked in sync regardless of frame rate variations.
Comparison with VOB and MKV
- VOB (MPEG-2 Program Stream): Because VOB is the native file format of the DVD-Video standard, keeping content in VOB format ensures a 1:1 bit-perfect archive. It retains the exact MPEG-2 video stream, all AC-3/DTS/LPCM audio channels, and all subpicture graphics with zero generational quality loss.
- MKV (Matroska): MKV is an open-standard, highly extensible container. It allows you to extract the raw streams from a DVD without re-encoding (remuxing) into a single, organized file. It effortlessly retains all video, audio, and subtitle streams, along with chapters and track-specific language tags, making it the premier choice for modern playback across virtually all media players.