Table of Contents

Class DVDMultichannelAudioAttributes

Namespace
VisioForge.Core.Types.MediaInfo
Assembly
VisioForge.Core.dll

Represents the attributes for DVD multichannel audio streams, providing detailed information about channel mixing and downmixing coefficients for surround sound playback.

public class DVDMultichannelAudioAttributes

Inheritance

Inherited Members

Remarks

DVD-Video supports sophisticated multichannel audio formats, primarily 5.1 and 7.1 surround sound configurations. This class contains the metadata necessary for proper audio channel management, including downmixing coefficients for playback on systems with fewer speakers than the source material.

The multichannel audio system in DVD uses the following standard channel configurations: - 5.1: Front Left, Front Right, Center, LFE (Low Frequency Effects), Surround Left, Surround Right - 6.1: Adds a Rear Center channel - 7.1: Adds Surround Back Left and Surround Back Right instead of single Rear Center

Downmixing is the process of converting multichannel audio to fewer channels (e.g., 5.1 to stereo). The coefficients define how each source channel contributes to the output channels, ensuring proper balance and preventing clipping while maintaining the artistic intent of the mix.

DVD players use these attributes to: - Properly route audio to available speakers - Calculate downmix matrices for stereo or Pro Logic output - Apply dynamic range compression when requested - Maintain proper phase relationships between channels

Properties

Coeff

Gets or sets an array of DVDMUACoeff objects containing the mixing coefficients for channel downmixing.

public DVDMUACoeff[] Coeff { get; set; }

Property Value

DVDMUACoeff[]

Remarks

These coefficients define the mathematical relationships for downmixing multichannel audio to stereo or other reduced channel configurations. Each coefficient specifies: - The contribution of each source channel to the left output - The contribution of each source channel to the right output - Any phase inversions or delays required - Attenuation levels to prevent clipping

Common downmix scenarios include: - 5.1 to Stereo: Typically uses coefficients like C→L/R: 0.707 (-3dB), Ls/Rs→L/R: 0.707 - 5.1 to Pro Logic: Maintains surround encoding with specific phase relationships - 7.1 to 5.1: Combines rear channels into existing surround channels

The DVD specification includes standard downmix coefficients (e.g., ITU-R BS.775), but content creators can specify custom coefficients to preserve their artistic intent when the audio is played on systems with fewer speakers.

Coefficients are typically expressed as: - Linear values (0.0 to 1.0) - Or in decibels (-∞ to 0 dB) - May include phase information (0° or 180°)

Info

Gets or sets an array of DVDMUAMixingInfo objects containing mixing information for each audio channel.

public DVDMUAMixingInfo[] Info { get; set; }

Property Value

DVDMUAMixingInfo[]

Remarks

Each element in this array corresponds to one audio channel and contains: - Channel position identifier (e.g., front left, center, surround right) - Phase relationship information - Channel grouping for related channels - Special processing flags (e.g., LFE channel indicators)

The array typically contains: - Index 0: Front Left (L) - Index 1: Front Right (R) - Index 2: Center (C) - Index 3: LFE/Subwoofer (.1) - Index 4: Surround Left (Ls) - Index 5: Surround Right (Rs) - Index 6-7: Additional surround channels for 6.1/7.1 configurations

The mixing information is crucial for maintaining proper soundstage and imaging when the audio is played back on various speaker configurations.