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MESourceStarted event

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Raised when a media source starts without seeking.

Event values

Possible values retrieved from IMFMediaEvent::GetValue include the following.

VARTYPE Description
VT_EMPTY
 No event data. The start time was from the current position.
VT_I8
 The starting time, in 100-nanosecond units, relative to the time stamps on the samples.

Attributes

The following attributes are defined for this event.

Attribute Description
MF_EVENT_SOURCE_ACTUAL_START
 Start time. The media source sets this attribute if it restarts from its current position.
MF_EVENT_SOURCE_FAKE_START
 Specifies whether the current segment topology is empty. The sequencer source sets this attribute.
MF_EVENT_SOURCE_PROJECTSTART
 Start time for a segment, relative to the start of the presentation. The sequencer source sets this attribute.

Remarks

A media source raises this event when it starts from a stopped state, or starts from a paused state at the same position in the source. The event is raised if the IMFMediaSource::Start method returns S_OK.

If the media source starts from the current position and the source's previous state was running or paused, the event data can empty (VT_EMPTY). If the event data is VT_EMPTY, the media source might set the MF_EVENT_SOURCE_ACTUAL_START attribute with the actual starting time.

If the media source starts from a new position, or the source's previous state was stopped, the event data must be the starting time (VT_I8).

If the Start method causes a seek, the media source sends the MESourceSeeked event instead of MESourceStarted.

Requirements

Requirement Value
Minimum supported client
 Windows Vista [desktop apps only]
Minimum supported server
 Windows Server 2008 [desktop apps only]
Header
Mfobjects.h (include Mfidl.h)

See also

Media Foundation Events