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IMFASFIndexer::GetSeekPositionForValue method (wmcontainer.h)

  • Article

Given a desired seek time, gets the offset from which the client should start reading data.

Syntax

HRESULT GetSeekPositionForValue(
  [in]  const PROPVARIANT    *pvarValue,
  [in]  ASF_INDEX_IDENTIFIER *pIndexIdentifier,
  [out] QWORD                *pcbOffsetWithinData,
  [out] MFTIME               *phnsApproxTime,
  [out] DWORD                *pdwPayloadNumberOfStreamWithinPacket
);

Parameters

[in] pvarValue

The value of the index entry for which to get the position. The format of this value varies depending on the type of index, which is specified in the index identifier. For time-based indexing, the variant type is VT_I8 and the value is the desired seek time, in 100-nanosecond units.

[in] pIndexIdentifier

Pointer to an ASF_INDEX_IDENTIFIER structure that identifies the stream number and index type.

[out] pcbOffsetWithinData

Receives the offset within the data segment of the ASF Data Object. The offset is in bytes, and is relative to the start of packet 0. The offset gives the starting location from which the client should begin reading from the stream. This location might not correspond exactly to the requested seek time.

For reverse playback, if no key frame exists after the desired seek position, this parameter receives the value MFASFINDEXER_READ_FOR_REVERSEPLAYBACK_OUTOFDATASEGMENT. In that case, the seek position should be 1 byte pass the end of the data segment.

[out] phnsApproxTime

Receives the approximate time stamp of the data that is located at the offset returned in the pcbOffsetWithinData parameter. The accuracy of this value is equal to the indexing interval of the ASF index, typically about 1 second.

  • If the index type specified in pIndexIdentifier is GUID_NULL (time indexing), this parameter can be NULL.
  • For all other index types, this parameter must be NULL.
If the approximate time stamp cannot be determined, this parameter receives the value MFASFINDEXER_APPROX_SEEK_TIME_UNKNOWN.

[out] pdwPayloadNumberOfStreamWithinPacket

Receives the payload number of the payload that contains the information for the specified stream. Packets can contain multiple payloads, each containing data for a different stream. This parameter can be NULL.

Return value

The method returns an HRESULT. Possible values include, but are not limited to, those in the following table.

Return code Description
S_OK
 The method succeeded.
MF_E_ASF_OUTOFRANGE
 The requested seek time is out of range.
MF_E_NO_INDEX
 No index exists of the specified type for the specified stream.

Requirements

Requirement Value
Minimum supported client Windows Vista [desktop apps only]
Minimum supported server Windows Server 2008 [desktop apps only]
Target Platform Windows
Header wmcontainer.h
Library Mfuuid.lib

See also

ASF Index Object

IMFASFIndexer

MFTIME