IMFPMediaItem::SetStartStopPosition method (mfplay.h)

發行項
12/05/2018

[The feature associated with this page, MFPlay, is a legacy feature. It has been superseded by MediaPlayer and IMFMediaEngine. Those features have been optimized for Windows 10 and Windows 11. Microsoft strongly recommends that new code use MediaPlayer and IMFMediaEngine instead of DirectShow, when possible. Microsoft suggests that existing code that uses the legacy APIs be rewritten to use the new APIs if possible.]

Sets the start and stop time for the media item.

Syntax

HRESULT SetStartStopPosition(
  [in] const GUID        *pguidStartPositionType,
  [in] const PROPVARIANT *pvStartValue,
  [in] const GUID        *pguidStopPositionType,
  [in] const PROPVARIANT *pvStopValue
);

Parameters

[in] pguidStartPositionType

Unit of time for the start position. See Remarks. This parameter can be NULL.

[in] pvStartValue

Start position. The meaning and data type of this parameter are indicated by the pguidStartPositionType parameter. The pvStartValue parameter must be NULL if pguidStartPositionType is NULL, and cannot be NULL otherwise.

[in] pguidStopPositionType

Unit of time for the stop position. See Remarks. This parameter can be NULL.

[in] pvStopValue

Stop position. The meaning and data type of this parameter are indicated by the pguidStopPositionType parameter. The pvStopValue parameter must be NULL if pguidStopPositionType is NULL, and cannot be NULL otherwise.

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	Invalid argument.
MF_E_OUT_OF_RANGE	Invalid start or stop time. Any of the following can cause this error: Time less than zero. Time greater than the total duration of the media item. Stop time less than start time.

Remarks

By default, a media item plays from the beginning to the end of the file. This method adjusts the start time and/or the stop time:

To set the start time, pass non-NULL values for pguidStartPositionType and pvStartValue.
To set the stop time, pass non-NULL values for pguidStopPositionType and pvStopValue.

The pguidStartPositionType and pguidStopPositionType parameters give the units of time that are used. Currently, the only supported value is MFP_POSITIONTYPE_100NS.

Value	Description
MFP_POSITIONTYPE_100NS	100-nanosecond units. The time parameter (pvStartValue or pvStopValue) uses the following data type: Variant type (vt): VT_I8 Variant member: hVal To clear a previously set time, use an empty PROPVARIANT (VT_EMPTY).

The adjusted start and stop times are used the next time that IMFPMediaPlayer::SetMediaItem is called with this media item. If the media item is already set on the player, the change does not happen unless you call SetMediaItem again.

Examples

HRESULT PlayMediaClip(
    IMFPMediaPlayer *pPlayer,
    PCWSTR pszURL,
    LONGLONG    hnsStart,
    LONGLONG    hnsEnd
    )
{
    IMFPMediaItem *pItem = NULL;
    PROPVARIANT varStart, varEnd;

    ULONGLONG hnsDuration = 0;

    HRESULT hr = pPlayer->CreateMediaItemFromURL(pszURL, TRUE, 0, &pItem);
    if (FAILED(hr))
    {
        goto done;
    }

    hr = GetPlaybackDuration(pItem, &hnsDuration);
    if (FAILED(hr))
    {
        goto done;
    }

    if ((ULONGLONG)hnsEnd > hnsDuration)
    {
        hnsEnd = hnsDuration;
    }

    hr = InitPropVariantFromInt64(hnsStart, &varStart);
    if (FAILED(hr))
    {
        goto done;
    }

    hr = InitPropVariantFromInt64(hnsEnd, &varEnd);
    if (FAILED(hr))
    {
        goto done;
    }

    hr = pItem->SetStartStopPosition(
        &MFP_POSITIONTYPE_100NS,
        &varStart,
        &MFP_POSITIONTYPE_100NS,
        &varEnd
        );
    if (FAILED(hr))
    {
        goto done;
    }

    hr = pPlayer->SetMediaItem(pItem);

done:
    SafeRelease(&pItem);
    return hr;
}

Requirements

Requirement	Value
Minimum supported client	Windows 7 [desktop apps only]
Minimum supported server	Windows Server 2008 R2 [desktop apps only]
Target Platform	Windows
Header	mfplay.h

共用方式為