Table of Contents

Class MPEG4ParseBlock

Namespace
VisioForge.Core.MediaBlocks.Parsers
Assembly
VisioForge.Core.dll

Parses MPEG-4 Part 2 (MPEG-4 Visual) bitstreams for VOP boundary detection and codec parameter extraction.

public class MPEG4ParseBlock : MediaBlock, IMediaBlock, IDisposable, IMediaBlockInternals

Inheritance

Implements

Inherited Members

Extension Methods

Remarks

The MPEG4ParseBlock processes MPEG-4 Part 2 encoded video streams, parsing Visual Object Sequences (VOS), Visual Object Layer (VOL) headers, and Video Object Planes (VOPs) to ensure proper frame boundaries. MPEG-4 Part 2 includes profiles like Simple Profile, Advanced Simple Profile (ASP), and others used in formats like DivX, Xvid, and early MP4 videos.

Key features: - Visual Object Sequence (VOS) header parsing for profile/level detection - Visual Object Layer (VOL) processing for resolution and timing info - Video Object Plane (VOP) boundary detection and type identification (I, P, B, S) - Support for rectangular and arbitrary shaped video objects - Handles packed bitstream mode and B-frame processing - Interlaced content support with field-based processing - Sprite (S-VOP) and GMC (Global Motion Compensation) support

Common use cases: - Streaming: Processing MPEG-4 content for adaptive streaming - Muxing: Packaging MPEG-4 Visual into MP4, AVI, or MKV containers - Transcoding: Providing properly parsed VOPs to MPEG-4 decoders - Legacy support: Handling DivX/Xvid content in media players - Video analysis: Extracting codec parameters and stream properties

The parser handles various MPEG-4 Visual profiles including Simple Profile (SP), Advanced Simple Profile (ASP), Core Profile, and Main Profile, automatically detecting stream characteristics and ensuring compliance with ISO/IEC 14496-2.

Constructors

MPEG4ParseBlock()

Initializes a new instance of the VisioForge.Core.MediaBlocks.Parsers.MPEG4ParseBlock class.

public MPEG4ParseBlock()

Remarks

Creates input and output pads configured for video media type. The parser will automatically detect the MPEG-4 Visual profile and features (packed bitstream, B-frames, GMC, etc.) upon receiving the VOS/VOL headers.

Properties

Input

Gets the primary input pad for receiving MPEG-4 Visual bitstream data.

public override MediaBlockPad Input { get; }

Property Value

MediaBlockPad

Inputs

Gets all input pads available on this block.

public override MediaBlockPad[] Inputs { get; }

Property Value

MediaBlockPad[]

Output

Gets the primary output pad that provides parsed MPEG-4 VOPs.

public override MediaBlockPad Output { get; }

Property Value

MediaBlockPad

Outputs

Gets all output pads available on this block.

public override MediaBlockPad[] Outputs { get; }

Property Value

MediaBlockPad[]

Type

Gets the type of this media block.

public override MediaBlockType Type { get; }

Property Value

MediaBlockType

Methods

Build()

Builds and initializes the MPEG-4 Visual parser element within the media pipeline.

public override bool Build()

Returns

bool

true if the parser was successfully created and configured; false if initialization failed or required plugins are missing.

Remarks

This method creates the GStreamer MPEG-4 parser element, initializes it within the pipeline context, and connects the input/output pads. The parser will begin processing VOPs once the pipeline transitions to the playing state.

CleanUp()

Performs cleanup of the parser resources and resets the build state.

public void CleanUp()

Remarks

This method disposes of the GStreamer element and resets internal state. It is called during disposal to ensure proper resource cleanup.

Dispose(bool)

Releases unmanaged and - optionally - managed resources.

protected override void Dispose(bool disposing)

Parameters

disposing bool

true to release both managed and unmanaged resources; false to release only unmanaged resources.

GetCore()

Gets the core GStreamer element wrapper.

public BaseElement GetCore()

Returns

BaseElement

The base element wrapper providing access to common GStreamer functionality.

GetElement()

Gets the underlying native GStreamer element.

public Element GetElement()

Returns

Element

The native GStreamer element instance used for MPEG-4 Visual VOP parsing.

IsAvailable()

Determines whether the MPEG-4 Visual parser is available in the current GStreamer installation.

public static bool IsAvailable()

Returns

bool

true if the MPEG-4 parser plugin is available; otherwise, false. This requires the GStreamer bad plugins to be installed.

Remarks

The MPEG-4 Visual parser is provided by the GStreamer bad plugins collection. Ensure the appropriate VisioForge SDK redistribution package is included in your project.

IMediaBlockInternals.SetContext(MediaBlocksPipeline)

Sets the media pipeline context for this block.

void IMediaBlockInternals.SetContext(MediaBlocksPipeline pipeline)

Parameters

pipeline MediaBlocksPipeline

The media pipeline that will contain this parser block.

See Also