IWMProfile3::GetExpectedPacketCount method (wmsdkidl.h)

Article
4/26/2023

[The feature associated with this page, Windows Media Format 11 SDK, is a legacy feature. It has been superseded by Source Reader and Sink Writer. Source Reader and Sink Writer have been optimized for Windows 10 and Windows 11. Microsoft strongly recommends that new code use Source Reader and Sink Writer instead of Windows Media Format 11 SDK, when possible. Microsoft suggests that existing code that uses the legacy APIs be rewritten to use the new APIs if possible.]

The GetExpectedPacketCount method calculates the expected packet count for the specified duration. The packet count returned is only an estimate, and it is based upon the settings of the profile at the time this call is made.

Syntax

HRESULT GetExpectedPacketCount(
  [in]  QWORD msDuration,
  [out] QWORD *pcPackets
);

Parameters

[in] msDuration

Specifies the duration in milliseconds.

[out] pcPackets

Pointer to receive the count of packets expected for msDuration milliseconds.

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.
E_INVALIDARG	pcPackets is NULL.
E_OUTOFMEMORY	One of the internal objects required by the method could not be initialized.
E_NOTIMPL	The profile in the profile object is not compatible with this method.

Remarks

Problems will arise if the value passed in msDuration is not a positive number of milliseconds. The method will return S_OK as normal, but the packet count returned will not be correct.

It is impossible for this method to give exact counts, because there is no way to account for interleaved data in an encoded file. The packet count returned is most accurate for files with one audio stream. The more complicated the profile, the less accurate the packet count will be.

Requirements

Requirement	Value
Minimum supported client	Windows 2000 Professional [desktop apps only],Windows Media Format 9 Series SDK, or later versions of the SDK
Minimum supported server	Windows 2000 Server [desktop apps only]
Target Platform	Windows
Header	wmsdkidl.h (include Wmsdk.h)
Library	Wmvcore.lib; WMStubDRM.lib (if you use DRM)

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