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Windows Driver Kit DDI reference (nc-acxstreams-evt_acx_stream_run)

Description

The EvtAcxStreamRun event tells the driver to transition the stream state from Pause to Run.

Parameters

`Stream`

An ACXSTREAM object represents an audio stream created by a circuit. The stream is composed of a list of elements created based on the parent circuit's elements. For more information, see ACX - Summary of ACX Objects.

Return value

Returns STATUS_SUCCESS if the call was successful. Otherwise, it returns an appropriate error code. For more information, see Using NTSTATUS Values.

Remarks

An AcxStream supports different states. These states indicate when audio is flowing (RUN state), audio is not flowing but audio hardware is prepared (PAUSE state), or audio is not flowing and audio hardware is not prepared (STOP state).

The EvtAcxStreamRun event will transition the stream state from the Pause state to the Run state. Once the stream is in the Run state, the driver may receive the EvtAcxStreamPause event to transition to the Pause state.

ACX Events are analogous to KS states as described in this table.

Start State	End State	ACX Driver Event Called	Notes
STOP	ACQUIRE	PrepareHardware	Driver performs hardware allocations and preparations
ACQUIRE	PAUSE	(No Call)
PAUSE	RUN	Run
RUN	PAUSE	Pause
PAUSE	ACQUIRE	(No call)
ACQUIRE	STOP	ReleaseHardware	Driver releases hardware allocations

Example

Example usage is shown below.

    ACX_STREAM_CALLBACKS streamCallbacks;
    ACX_STREAM_CALLBACKS_INIT(&streamCallbacks);
    streamCallbacks.EvtAcxStreamRun = EvtStreamRun;
    ...
    status = AcxStreamInitAssignAcxStreamCallbacks(StreamInit, &streamCallbacks);

_Use_decl_annotations_
PAGED_CODE_SEG
NTSTATUS
EvtStreamRun(
    _In_ ACXSTREAM Stream
    )
{
    PSTREAM_CONTEXT ctx;
    NTSTATUS        status;

    PAGED_CODE();

    ctx = GetStreamContext(Stream);

    status = TransitionStreamToRun(Stream);

    if (NT_SUCCESS(status))
    {
        ctx->StreamState = AcxStreamStateRun;
    }

    return status;
}

ACX requirements

Minimum ACX version: 1.0

For more information about ACX versions, see ACX version overview.

EVT_ACX_STREAM_RUN - NtDoc