Class MFSample

The IMFSample interface represents a multimedia sample for a multimedia stream type. An typical example is a video frame, and a notable exception is audio where an IMFSample does not usually represent a single sample of audio, but rather a chunk of audio samples. Note that this allows us to reduce the overhead for representing audio in the pipeline.

A sample may consist of a multiple buffers as is the case of compressed audio or video samples received from the network or being sent to an ASF media sink or ASF multiplexer.

The IMFAttributes interface can be used to tag the sample with extra information that is not represented by the IMFSample methods. The MFSampleExtension_xxx GUIDs in mfapi.h define some standard attributes, but custom attributes are allowed and are preserved through the Media Foundation pipeline as well as possible.

Inheritance

object

DXComObject

MFAttributes

MFSample

Implements

IDisposable

Inherited Members

MFAttributes.MFAttributesGuid

MFAttributes.GetItemType(Guid)

MFAttributes.GetUINT32(Guid)

MFAttributes.GetUINT64(Guid)

MFAttributes.GetDouble(Guid)

MFAttributes.GetGUID(Guid)

MFAttributes.GetStringLength(Guid)

MFAttributes.GetString(Guid)

MFAttributes.GetUnknown(Guid, Guid)

MFAttributes.DeleteItem(Guid)

MFAttributes.DeleteAllItems()

MFAttributes.SetUINT32(Guid, uint)

MFAttributes.SetUINT64(Guid, ulong)

MFAttributes.SetDouble(Guid, double)

MFAttributes.SetGUID(Guid, Guid)

MFAttributes.SetString(Guid, string)

MFAttributes.SetUnknown(Guid, nint)

MFAttributes.LockStore()

MFAttributes.UnlockStore()

MFAttributes.GetCount()

MFAttributes.CopyAllItems(MFAttributes)

MFAttributes.GetAttributeUINT32(Guid, uint)

MFAttributes.GetAttributeUINT64(Guid, ulong)

MFAttributes.GetAttributeDouble(Guid, double)

MFAttributes.GetAttribute2UINT32asUINT64(Guid, out uint, out uint)

MFAttributes.SetAttribute2UINT32asUINT64(Guid, uint, uint)

MFAttributes.GetAttributeRatio(Guid, out uint, out uint)

MFAttributes.GetAttributeSize(Guid, out uint, out uint)

MFAttributes.SetAttributeRatio(Guid, uint, uint)

MFAttributes.SetAttributeSize(Guid, uint, uint)

DXComObject.Dispose()

DXComObject.AddRef()

DXComObject.Release()

DXComObject.QueryInterface(in Guid)

DXComObject.Handle

object.Equals(object)

object.Equals(object, object)

object.GetHashCode()

object.GetType()

object.MemberwiseClone()

object.ReferenceEquals(object, object)

object.ToString()

Namespace: JeremyAnsel.DirectX.MediaFoundation

Assembly: JeremyAnsel.DirectX.MediaFoundation.dll

Syntax

[SecurityCritical]
public class MFSample : MFAttributes, IDisposable

Remarks

MediaFoundation does not provide a synchronized (thread-safe) way to call the IMFSample methods. To guarantee thread-safety, the caller should obtain a lock while working with sample object to prevent access by other threads.

Constructors

MFSample(nint)

Initializes a new instance of the MFSample class.

Declaration

public MFSample(nint comPtr)

Parameters

Type	Name	Description
nint	comPtr

Fields

MFSampleGuid

The interface GUID.

Declaration

public static readonly Guid MFSampleGuid

Field Value

Type	Description
Guid

Methods

AddBuffer(MFMediaBuffer)

The AddBuffer method allows the caller to add a media buffer to the end of current list of buffers in the sample.

Declaration

public void AddBuffer(MFMediaBuffer pBuffer)

Parameters

Type	Name	Description
MFMediaBuffer	pBuffer	Pointer to a buffer object.

Remarks

The newly added buffer represents sample data at an offset equal to the previous total length of the sample.

ConvertToContiguousBuffer()

The GetContiguousBuffer method converts sample with multiple buffers into sample with single buffer and returns a pointer to this buffer.

Declaration

public MFMediaBuffer ConvertToContiguousBuffer()

Returns

Type	Description
MFMediaBuffer

Remarks

This method copies the content of the sample into a contiguous media buffer, and should be used with care.

CopyToBuffer(MFMediaBuffer)

The CopyToBuffer method allows the caller to copy the sample data to the buffer object provided.

Declaration

public void CopyToBuffer(MFMediaBuffer pBuffer)

Parameters

Type	Name	Description
MFMediaBuffer	pBuffer	Pointer to a buffer object.

GetBufferByIndex(uint)

The GetBufferByIndex method returns a pointer to the IMFMediaBuffer object at a specified index in the sample.

Declaration

public MFMediaBuffer GetBufferByIndex(uint dwIndex)

Parameters

Type	Name	Description
uint	dwIndex	32 bit value specifying the index of the buffer object requested.

Returns

Type	Description
MFMediaBuffer

GetBufferCount()

The GetBufferCount method returns the count of the buffers in that are currently associated with this sample.

Declaration

public uint GetBufferCount()

Returns

Type	Description
uint

Remarks

It is valid to have a sample with a buffer count of zero. This is considered to be an empty sample.

GetSampleDuration()

The GetSampleDuration method returns the duration of the sample.

Declaration

public ulong GetSampleDuration()

Returns

Type	Description
ulong	If the method succeeds, it returns S_OK. If no the sample does not have a duration MF_E_NO_SAMPLE_DURATION is returned. If this method fails otherwise it returns an error code.

Remarks

The duration is specified in 100ns interval units. If the duration is zero, then the sample duration is unknown. In such cases, it is possible that it can be derived from the media type e.g. video frame rate. Application should avoid calculating duration of presentation as sum of sample durations because of possible cumulative error. For example cumulative error for 60fps video on 24 hours interval is 0.1728 seconds. For 60fps, there are 5184000 frames * 166667 100ns/frame = 24 hours + 0.1728 seconds

GetSampleTime()

The GetSampleTime method returns the presentation time associated with the sample.

Declaration

public ulong GetSampleTime()

Returns

Type	Description
ulong	If the method succeeds, it returns S_OK. If no the sample does not have a sample time MF_E_NO_SAMPLE_TIMESTAMP is returned. If this method fails otherwise it returns an error code.

Remarks

The presentation time is stored in 100ns interval units.

GetTotalLength()

The GetTotalLength method returns the total length of all buffers objects in the sample.

Declaration

public uint GetTotalLength()

Returns

Type	Description
uint

Remarks

The total length of the sample is tracked when buffers are added (via AddBuffer), removed (via RemoveBufferByIndex and RemoveAllBuffers).

RemoveAllBuffers()

The RemoveAllBuffers method allows the caller to remove all buffer objects associated with the sample.

Declaration

public void RemoveAllBuffers()

Remarks

After this call, the buffer count of the sample is zero i.e. it is an empty sample.

RemoveBufferByIndex(uint)

The RemoveBufferByIndex method allows the caller to remove a buffer object at a specified index within the list of available buffer objects in the sample.

Declaration

public void RemoveBufferByIndex(uint dwIndex)

Parameters

Type	Name	Description
uint	dwIndex	32 bit value specifying the index.

Remarks

The total length of the sample is reduced by the length of the removed buffer, and the offsets of all buffer objects that were at indices greater than dwIndex are shifted up by the length of the removed buffer.

SetSampleDuration(ulong)

The SetSampleDuration method allows the caller to set the duration of the sample.

Declaration

public void SetSampleDuration(ulong hnsSampleDuration)

Parameters

Type	Name	Description
ulong	hnsSampleDuration	64 bit value specifying the sample duration.

Remarks

The duration is specified in 100ns interval units. This value should be set wherever possible to aid in the processing of samples in a multimedia pipeline.

SetSampleTime(ulong)

The SetSampleTime method allows the caller to set the presentation time associated with the sample.

Declaration

public void SetSampleTime(ulong hnsSampleTime)

Parameters

Type	Name	Description
ulong	hnsSampleTime	64 bit value specifying the presentation time.

Remarks

The presentation time is stored in 100ns interval units.

Implements

IDisposable