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EVT_ACX_STREAM_FREE_RTPACKETS callback function (acxstreams.h)

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The EvtAcxStreamFreeRtPackets event tells the driver to free the RtPackets that were allocated in a previous call to EvtAcxStreamAllocateRtPackets. The same packets from that call are included.

Syntax

EVT_ACX_STREAM_FREE_RTPACKETS EvtAcxStreamFreeRtpackets;

void EvtAcxStreamFreeRtpackets(
  ACXSTREAM Stream,
  PACX_RTPACKET Packets,
  ULONG PacketCount
)
{...}

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.

Packets

A pointer to an array of ACX_RTPACKET structures that describes the location and size of the packets to be freed.

PacketCount

Specifies the number of packets to be freed. Valid values are 1 or 2.

Return value

None

Remarks

When work with the stream is complete, EvtAcxStreamFreeRtPackets is called after EvtAcxStreamReleaseHardware. This allows the release hardware phase to finish deallocating bandwidth, freeing DMA resources and any other associated cleanup, to occur before te allocated RT buffers are then freed.

Example

Example usage is shown below.

    // Init RT streaming callbacks.
    //
    ACX_RT_STREAM_CALLBACKS rtCallbacks;
    ACX_RT_STREAM_CALLBACKS_INIT(&rtCallbacks);
    rtCallbacks.EvtAcxStreamFreeRtPackets               = Dsp_EvtStreamFreeRtPackets;

    RETURN_NTSTATUS_IF_FAILED(AcxStreamInitAssignAcxRtStreamCallbacks(StreamInit, &rtCallbacks));

// Later in the code need to free the packets...
#pragma code_seg("PAGE")
VOID
Codec_EvtStreamFreeRtPackets(
    _In_ ACXSTREAM Stream,
    _In_ PACX_RTPACKET Packets,
    _In_ ULONG PacketCount
    )
{
    PCODEC_STREAM_CONTEXT ctx;
    ULONG i;
    PVOID buffer;

    PAGED_CODE();

    ctx = GetCodecStreamContext(Stream);

    for (i = 0; i < PacketCount; ++i)
    {
        if (Packets[i].RtPacketBuffer.u.MdlType.Mdl)
        {
            buffer = MmGetMdlVirtualAddress(Packets[i].RtPacketBuffer.u.MdlType.Mdl);
            IoFreeMdl(Packets[i].RtPacketBuffer.u.MdlType.Mdl);
            ExFreePool(buffer);
        }
    }

    ExFreePool(Packets);

    ctx->PacketsCount = 0;
    ctx->PacketSize = 0;
    ctx->FirstPacketOffset = 0;
}

ACX requirements

Minimum ACX version: 1.0

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

Requirements

Requirement Value
Header acxstreams.h
IRQL PASSIVE_LEVEL

See also