Stream

The main entry-point to the API is the VPIStream object. More...

Typedefs
typedef struct VPIStreamImpl *	VPIStream
	A handle to a stream.

Functions
VPIStatus	vpiStreamCreateWrapperCUDA (CUstream cudaStream, uint64_t flags, VPIStream *stream)
	Wraps an existing cudaStream_t into a VPI stream. More...
VPIStatus	vpiStreamCreate (uint64_t flags, VPIStream *stream)
	Create a stream instance. More...
void	vpiStreamDestroy (VPIStream stream)
	Destroy a stream instance and deallocate all HW resources. More...
VPIStatus	vpiStreamFlush (VPIStream stream)
	Submits all pending operations for execution. More...
VPIStatus	vpiStreamSync (VPIStream stream)
	Blocks the calling thread until all submitted commands in this stream queue are done (queue is empty). More...
VPIStatus	vpiStreamWaitEvent (VPIStream stream, VPIEvent event)
	Pushes a command that blocks the processing of all future commands submitted to the stream until the event is signaled. More...
VPIStatus	vpiStreamGetThreadHandle (VPIStream stream, VPINativeThreadHandle *handle)
	Returns OS-specific handle of the background stream processing thread. More...
VPIStatus	vpiStreamGetFlags (VPIStream stream, uint64_t *flags)
	Gets the VPIStream flags passed during its creation. More...

Memory creation flags.
These flags can be used when creating images, pyramids or arrays.
enum	VPIBackend
	VPI Backend types. More...

Stream-specific flags.
#define	VPI_STREAM_GREEDY   (1ULL << 63)
	Flushes operations to the backend at every submission.

Detailed Description

The main entry-point to the API is the VPIStream object.

This object represents a command queue (FIFO) storing a list of commands to execute. Commands might comprise running a particular CV algorithm or signaling an event in a particular backend. This allows the API functions to be executed asynchronously with respect to the calling thread. Invoking any CV function simply pushes a corresponding command to the command queue in the VPIStream instance and immediately returns. The queued commands then get consumed and dispatched to the associated backend device.

Enumeration Type Documentation

VPIBackend

enum VPIBackend

#include </opt/nvidia/vpi2/include/vpi/Types.h>

VPI Backend types.

Enumerator
VPI_BACKEND_CPU	CPU backend.
VPI_BACKEND_CUDA	CUDA backend.
VPI_BACKEND_PVA	PVA backend.
VPI_BACKEND_VIC	VIC backend.
VPI_BACKEND_NVENC	NVENC backend.
VPI_BACKEND_OFA	OFA backend.
VPI_BACKEND_INVALID	Invalid backend.

Definition at line 90 of file Types.h.

Function Documentation

vpiStreamCreateWrapperCUDA()

VPIStatus vpiStreamCreateWrapperCUDA	(	CUstream	cudaStream,
		uint64_t	flags,
		VPIStream *	stream
	)

#include </opt/nvidia/vpi2/include/vpi/CUDAInterop.h>

Wraps an existing cudaStream_t into a VPI stream.

CUDA algorithms are submitted for execution in the wrapped cudaStream_t. This allows to insert a VPI-driven processing into an existing CUDA pipeline. Algorithms can still be submitted to other backends.

The VPIStream doesn't own the cudaStream_t. It must be valid during VPIStream lifetime.

CUDA kernels can only be submitted directly to cudaStream_t if it's guaranteed that all tasks submitted to VPIStream are finished.

Parameters

[in]	cudaStream	The CUDA stream handle to be wrapped. Mandatory, it can't be NULL.
[in]	flags	Bit field specifying the desired characteristics of the stream. VPI_BACKEND_CUDA is always added internally. The field must be a combination of zero or more of the following flags: VPIBackend flags. Allows algorithms to be submitted to these backends. If no backend flags are passed, it'll consider all backends supported by the active VPIContext. Stream-specific flags. If flag VPI_REQUIRE_BACKENDS is given, user must pass at least one valid backend that is enabled in current context.
[out]	stream	Pointer that will receive the newly created VPIStream.

Return values

VPI_ERROR_INVALID_ARGUMENT	Output stream is NULL.
VPI_ERROR_INVALID_ARGUMENT	Input cudaStream is NULL.
VPI_ERROR_INVALID_ARGUMENT	No backend were given and VPI_REQUIRE_BACKENDS is set.
VPI_ERROR_OUT_OF_MEMORY	Not enough resources to create array.
VPI_ERROR_INVALID_OPERATION	Requested backend isn't enabled in current context.
VPI_ERROR_INVALID_CONTEXT	Current context is destroyed.
VPI_SUCCESS	Operation executed successfully.

vpiStreamCreate()

VPIStatus vpiStreamCreate	(	uint64_t	flags,
		VPIStream *	stream
	)

#include </opt/nvidia/vpi2/include/vpi/Stream.h>

Create a stream instance.

Parameters

[in]	flags	Bit field specifying the desired characteristics of the stream. The field must be a combination of zero or more of the following flags: VPIBackend flags. Allows algorithms to be submitted to these backends. If no backend flags are given and VPI_REQUIRE_BACKENDS is not set, it'll consider all backends supported by the active VPIContext. Stream-specific flags. Common object flags. If flag VPI_REQUIRE_BACKENDS is given, user must pass at least one valid backend that is enabled in current context.
[out]	stream	Pointer to memory that will receive the created stream handle.

Return values

VPI_ERROR_INVALID_ARGUMENT	Output stream handle is NULL.
VPI_ERROR_INVALID_ARGUMENT	flags is invalid.
VPI_ERROR_INVALID_ARGUMENT	No backend were given and VPI_REQUIRE_BACKENDS is set.
VPI_ERROR_OUT_OF_MEMORY	Not enough resources to allocate image.
VPI_ERROR_INVALID_CONTEXT	Current context is destroyed.
VPI_ERROR_INVALID_OPERATION	Requested backend isn't enabled in current context.
VPI_SUCCESS	Operation executed successfully.

vpiStreamDestroy()

void vpiStreamDestroy

(

VPIStream

stream

)

#include </opt/nvidia/vpi2/include/vpi/Stream.h>

Destroy a stream instance and deallocate all HW resources.

This operation will implicitly synchronize the stream to guarantee that all operations submitted to it are completed.

Parameters

[in]

stream

Stream handle to be destroyed. Passing NULL is allowed, to which the function simply does nothing.

vpiStreamFlush()

VPIStatus vpiStreamFlush

(

VPIStream

stream

)

#include </opt/nvidia/vpi2/include/vpi/Stream.h>

Submits all pending operations for execution.

Parameters

[in]

stream

Stream handle. Mandatory, it can't be NULL.

Return values

VPI_ERROR_INVALID_ARGUMENT	stream is NULL or doesn't represent a VPIStream instance.
VPI_SUCCESS	Operation executed successfully

vpiStreamSync()

VPIStatus vpiStreamSync

(

VPIStream

stream

)

#include </opt/nvidia/vpi2/include/vpi/Stream.h>

Blocks the calling thread until all submitted commands in this stream queue are done (queue is empty).

This function call is equivalent to atomically calling vpiEventRecord followed by vpiStreamWaitEvent.

The operation will implicitly flush the stream.

Parameters

[in]

stream

Stream handle. Mandatory, it can't be NULL.

Return values

VPI_ERROR_INVALID_ARGUMENT	stream is NULL or doesn't represent a VPIStream instance.
VPI_SUCCESS	Operation executed successfully

vpiStreamWaitEvent()

VPIStatus vpiStreamWaitEvent	(	VPIStream	stream,
		VPIEvent	event
	)

#include </opt/nvidia/vpi2/include/vpi/Stream.h>

Pushes a command that blocks the processing of all future commands submitted to the stream until the event is signaled.

Parameters

[in]	stream	Stream handle. Mandatory, it can't be NULL.
[in]	event	Event handle.

Return values

VPI_ERROR_INVALID_ARGUMENT	Output event is invalid.
VPI_ERROR_INVALID_ARGUMENT	stream is NULL or doesn't represent a VPIStream instance.
VPI_SUCCESS	Operation executed successfully

vpiStreamGetThreadHandle()

VPIStatus vpiStreamGetThreadHandle	(	VPIStream	stream,
		VPINativeThreadHandle *	handle
	)

#include </opt/nvidia/vpi2/include/vpi/Stream.h>

Returns OS-specific handle of the background stream processing thread.

Parameters

[in]	stream	Stream handle. Mandatory, it can't be NULL.
[out]	handle	Stream processing thread handle.

Return values

VPI_ERROR_INVALID_ARGUMENT	stream is NULL or doesn't represent a VPIStream instance.
VPI_ERROR_INVALID_ARGUMENT	Output handle pointer is NULL.
VPI_SUCCESS	Operation executed successfully.

vpiStreamGetFlags()

VPIStatus vpiStreamGetFlags	(	VPIStream	stream,
		uint64_t *	flags
	)

#include </opt/nvidia/vpi2/include/vpi/Stream.h>

Gets the VPIStream flags passed during its creation.

Parameters

[in]	stream	Stream handle. Mandatory, it can't be NULL.
[out]	flags	Pointer to variable where the flags will be stored into.

Return values

VPI_ERROR_INVALID_ARGUMENT	stream is NULL or doesn't represent a VPIStream instance.
VPI_ERROR_INVALID_ARGUMENT	Output flags pointer is NULL.
VPI_SUCCESS	Operation executed successfully.