Can LPCM Audio Be Multiplexed into a VOB File?

Yes, an uncompressed Linear PCM (LPCM) audio track can be multiplexed into a VOB (Video Object) file. Because VOB is based on the MPEG-2 Program Stream standard and serves as the core container format for DVD-Video, the official DVD specification fully supports uncompressed LPCM audio alongside compressed formats like AC-3 (Dolby Digital) and DTS. This article explains how LPCM functions inside a VOB container, the format's technical constraints, and how the multiplexing process is handled.

LPCM Support in the DVD-Video Standard

The DVD-Video specification explicitly includes LPCM as a mandatory audio standard. In a VOB file, LPCM audio is packaged inside MPEG-2 private stream packets (Private Stream 1, identifier 0xBD), utilizing specific sub-stream IDs ranging from 0xA0 to 0xA7 to support up to eight distinct audio tracks.

Because LPCM is entirely uncompressed, it provides bit-for-bit audio fidelity identical to the master recording, making it ideal for music releases and high-fidelity video projects on DVD.

Technical Constraints and Specifications

When multiplexing LPCM into a VOB container, the audio must comply with strict DVD-Video standard parameters:

• Sampling Rate: Supported rates are strictly limited to 48 kHz and 96 kHz. Standard 44.1 kHz CD audio must be resampled to 48 kHz or 96 kHz prior to multiplexing.
• Bit Depth: Quantization supports 16-bit, 20-bit, or 24-bit resolution.
• Channel Configuration: While the format mathematically supports up to 8 channels, channel count is restricted by bandwidth. Standard configurations are almost exclusively 2.0 stereo. At 96 kHz / 24-bit, stereo alone requires 4.608 Mbps.
• Bitrate Limits: The DVD-Video specification caps the maximum audio bitrate at 6.144 Mbps, and the total multiplexed bitrate (combining video, all audio tracks, and subtitles) cannot exceed 10.08 Mbps.

How to Multiplex LPCM into VOB

Multiplexing involves combining the elementary video stream (typically MPEG-2 video, .m2v) and the raw LPCM track (commonly provided as an uncompressed .wav or .pcm file) into the .vob container.

Common tools for this process include:

• FFmpeg: A command-line utility capable of muxing directly into DVD-compliant VOB files. A typical command looks like: ffmpeg -i video.m2v -i audio.wav -target ntsc-dvd -acodec pcm_dvd output.vob Using pcm_dvd ensures the LPCM stream is structured with the correct DVD header headers and packet boundaries.
• Dedicated DVD Authoring Software: Tools such as MuxMan, DVDAuthor, or Scenarist directly accept elementary MPEG-2 video and 48 kHz WAV files, correctly setting the sub-stream headers and navigation packets required for proper playback in standard hardware players.