EVT_ACX_AUDIOENGINE_RETRIEVE_BUFFER_SIZE_LIMITS callback function (acxelements.h)

Artikel
10/03/2023

The EVT_ACX_AUDIOENGINE_RETRIEVE_BUFFER_SIZE_LIMITS callback is implemented by the driver and is called when the buffer size limits for a given data format are requested for the specified audio engine.

Syntax

EVT_ACX_AUDIOENGINE_RETRIEVE_BUFFER_SIZE_LIMITS EvtAcxAudioengineRetrieveBufferSizeLimits;

NTSTATUS EvtAcxAudioengineRetrieveBufferSizeLimits(
  ACXAUDIOENGINE AudioEngine,
  ACXDATAFORMAT Format,
  PULONG MinBufferSizeInBytes,
  PULONG MaxBufferSizeInBytes
)
{...}

Parameters

AudioEngine

The ACXAUDIOENGINE object for which the buffer size limits have been requested. For more information about ACX objects, see Summary of ACX Objects.

Format

The ACXDATAFORMAT for which the callback is determining the min and max buffer sizes the audio engine can accommodate it with.

MinBufferSizeInBytes

The minimum size of buffer that the hardware audio engine can support for the given data format, at the instance when it is called. The buffer size is specified in bytes.

MaxBufferSizeInBytes

The maximum size of buffer that the hardware audio engine can support for the given data format, at the instance when it is called. The buffer size is specified in bytes.

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

Example

Example usage is shown below.

EVT_ACX_AUDIOENGINE_RETRIEVE_BUFFER_SIZE_LIMITS CodecR_EvtAcxAudioEngineRetrieveBufferSizeLimits;

NTSTATUS
CodecR_EvtAcxAudioEngineRetrieveBufferSizeLimits(
    _In_    ACXAUDIOENGINE  AudioEngine,
    _In_    ACXDATAFORMAT   DataFormat,
    _Out_   PULONG          MinBufferBytes,
    _Out_   PULONG          MaxBufferBytes
    )
{
    PAGED_CODE();

    ULONG bytesPerSecond = AcxDataFormatGetAverageBytesPerSec(DataFormat);

    *MinBufferBytes = (ULONG) (MIN_AUDIOENGINE_BUFFER_DURATION_IN_MS * bytesPerSecond / 1000);
    *MaxBufferBytes = (ULONG) (MAX_AUDIOENGINE_BUFFER_DURATION_IN_MS * bytesPerSecond / 1000);

    return STATUS_SUCCESS;
}

ACX requirements

Minimum ACX version: 1.0

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

Requirements

Requirement	Value
Header	acxelements.h
IRQL	PASSIVE_LEVEL

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