| CompositionOffsetBox Class |
This box provides the offset between decoding time and composition time.
Inheritance HierarchySystemObject
StreamCoders.Container.MP4Box
StreamCoders.Container.MP4FullBox
StreamCoders.Container.MP4CompositionOffsetBox
StreamCoders.Container.MP4Box
StreamCoders.Container.MP4FullBox
StreamCoders.Container.MP4CompositionOffsetBox
Namespace: StreamCoders.Container.MP4
Assembly: MediaBase (in MediaBase.dll) Version: 2.0.5.0 (2.0.5.0)
SyntaxThe CompositionOffsetBox type exposes the following members.
Constructors| Name | Description | |
|---|---|---|
 | CompositionOffsetBox(Byte) | Initializes a new instance of the CompositionOffsetBox class |
| CompositionOffsetBox(Box) | Initializes a new instance of the CompositionOffsetBox class |
Properties| Name | Description | |
|---|---|---|
 | BoxSize |
Gets the content + header size of a single box (without children) in bytes.
(Inherited from Box.) |
| ContentSize | (Overrides BoxContentSize.) |
| FullTreeSize |
Gets the boxes size including all children and header sizes (in bytes).
(Inherited from Box.) |
| HeaderSize | (Inherited from FullBox.) |
Methods| Name | Description | |
|---|---|---|
| AddChild |
Adds a child.
(Inherited from Box.) |
| DebugWriteToFile | (Inherited from Box.) |
| FindChild(BoxType) |
Finds a child of this item.
(Inherited from Box.) |
| FindChild(BoxType) |
Finds a child of this item.
(Inherited from Box.) |
| FindChildT |
Finds the first occurance of a child immediate to the current box.
(Inherited from Box.) |
| FindChildFullT |
Finds child of type T in full tree.
(Inherited from Box.) |
| FindChildFullSubClassedT |
Finds first child subclassed from type T in full tree.
(Inherited from Box.) |
| FindChildrenT |
Finds multiple Children of the same type immediate to the current box.
(Inherited from Box.) |
| FindChildrenFullSubClassedT |
Finds object derived subclassed from T in full tree.
(Inherited from Box.) |
| FindParentT |
Traverses up until root node until an immediate parent is found.
(Inherited from Box.) |
| FindParentOrChildT |
Traverses Parent and immediate children up to root node for a specific box type.
(Inherited from Box.) |
| GetCompositionOffset | |
| Parse |
Parses this object.
(Inherited from Box.) |
| ReadDebugData |
Reads the debug data.
(Inherited from Box.) |
| SetDirty |
Marks box and its children as dirty. Initially all boxes are dirty.
(Inherited from Box.) |
| Skip |
Skips the remaining bytes of the box by reading them.
(Inherited from Box.) |
| Update |
Updates the box and it's children. The box must be set dirty.
(Inherited from Box.) |
| VerifyDebugData |
Verify debug data.
(Inherited from Box.) |
| VerifyDebugData(String) |
Verify debug data.
(Inherited from Box.) |
| WriteInto |
Writes the box and its children to a destination stream.
(Inherited from Box.) |
Events| Name | Description | |
|---|---|---|
 | OnBeforeWrite |
Event to be raised before a Box is written to an output stream using Box.WriteInto
(Inherited from Box.) |
Fields| Name | Description | |
|---|---|---|
 | BoxType |
Contains the type of the box.
(Inherited from Box.) |
| BoxValueType |
The value representation of the box type.
(Inherited from Box.) |
| CompositionOffsetEntries | |
| Flags | (Inherited from FullBox.) |
| SizeExcludingHeader |
The size of the box without header.
(Inherited from Box.) |
| SizeIncludingHeader |
The size of the current box including header.
(Inherited from Box.) |
| UserType |
Custom Box type (uuid).
(Inherited from Box.) |
| Version | (Inherited from FullBox.) |
Extension Methods| Name | Description | |
|---|---|---|
 | Copy | Overloaded.
Creates a copy of the object.
(Defined by ObjectExtensions.) |
| Copy(Object) | Overloaded.
Creates a deep copy of the object using the supplied object as a target for the copy operation.
(Defined by ObjectExtensions.) |
Remarks
In version 0 of this box the decoding time must be less than the composition time, and
the offsets are expressed as unsigned numbers such that CT(n) = DT(n) + CTTS(n) where
CTTS(n) is the (uncompressed) table entry for sample n. In version 1 of this box, the
composition timeline and the decoding timeline are still derived from each other, but the
offsets are signed. It is recommended that for the computed composition timestamps, there
is exactly one with the value 0 (zero). For either version of the box, each sample must
have a unique composition timestamp value, that is, the timestamp for two samples shall
never be the same. It may be true that there is no frame to compose at time 0; the
handling of this is unspecified (systems might display the first frame for longer, or a
suitable fill colour). When version 1 of this box is used, the CompositionToDecodeBox may
also be present in the sample table to relate the composition and decoding timelines.
When backwards-compatibility or compatibility with an unknown set of readers is desired,,
version 0 of this box should be used when possible. In either version of this box, but
particularly under version 0, if it is desired that the media start at track time 0, and
the first media sample does not have a composition time of 0, an edit list may be used to
‘shift’ the media to time 0. The composition time to sample table is optional and must
only be present if DT and CT differ for any samples.
See Also