Latency Measurement API

Detailed Description

Defines an API for measuring latency in modules.

Data Structures
struct	_NvDsMetaSubCompLatency
	Holds information about latency of the given subcomponent. More...
struct	_NvDsMetaCompLatency
	Holds information about latency of the given component. More...
struct	NvDsFrameLatencyInfo
	Holds information about the latency of a given frame. More...

Macros
#define	MAX_COMPONENT_LEN   64
#define	nvds_enable_latency_measurement   (nvds_get_enable_latency_measurement())
	Defines a pseudo-variable whose value is the return value of nvds_get_enable_latency_measurement(). More...

Typedefs
typedef struct _NvDsMetaSubCompLatency	NvDsMetaSubCompLatency
	Holds information about latency of the given subcomponent. More...
typedef struct _NvDsMetaCompLatency	NvDsMetaCompLatency
	Holds information about latency of the given component. More...

Functions
NvDsUserMeta *	nvds_set_input_system_timestamp (GstBuffer *buffer, gchar *element_name)
	Sets the system timestamp when the Gst Buffer arrives as input at the component. More...
gboolean	nvds_set_output_system_timestamp (GstBuffer *buffer, gchar *element_name)
	Sets the system timestamp when a Gst Buffer that is pushed to the downstream component. More...
guint	nvds_measure_buffer_latency (GstBuffer *buf, NvDsFrameLatencyInfo *latency_info)
	Measures the latency of all frames present in the current batch. More...
gboolean	nvds_get_enable_latency_measurement (void)
	Indicates whether the environment variable NVDS_ENABLE_LATENCY_MEASUREMENT is exported. More...
void	nvds_add_reference_timestamp_meta (GstBuffer *buffer, gchar *element_name, guint frame_id)
	Adds the reference timestamp metadata for this buffer Note: element_name == "audiodecoder" and "nvv4l2decoder" will be used for latency measurement calculations where the timestamp will be used by API: nvds_measure_buffer_latency() to calculate the latency of buffers downstream relative to the decoder. More...

Macro Definition Documentation

MAX_COMPONENT_LEN

#define MAX_COMPONENT_LEN   64

Definition at line 34 of file nvds_latency_meta.h.

nvds_enable_latency_measurement

#define nvds_enable_latency_measurement   (nvds_get_enable_latency_measurement())

Defines a pseudo-variable whose value is the return value of nvds_get_enable_latency_measurement().

It indicates whether latency measurement is enabled.

Definition at line 172 of file nvds_latency_meta.h.

Typedef Documentation

NvDsMetaCompLatency

typedef struct _NvDsMetaCompLatency NvDsMetaCompLatency

Holds information about latency of the given component.

NvDsMetaSubCompLatency

typedef struct _NvDsMetaSubCompLatency NvDsMetaSubCompLatency

Holds information about latency of the given subcomponent.

Function Documentation

nvds_add_reference_timestamp_meta()

void nvds_add_reference_timestamp_meta	(	GstBuffer *	buffer,
		gchar *	element_name,
		guint	frame_id
	)

Adds the reference timestamp metadata for this buffer Note: element_name == "audiodecoder" and "nvv4l2decoder" will be used for latency measurement calculations where the timestamp will be used by API: nvds_measure_buffer_latency() to calculate the latency of buffers downstream relative to the decoder.

Parameters

[in]	buffer	A pointer to the arriving Gst Buffer.
[in]	element_name	A pointer to the name of the component for which latency is to be measured.
[in]	frame_id	The id/number of this frame/buffer produced by the component that produces this buffer.

nvds_get_enable_latency_measurement()

gboolean nvds_get_enable_latency_measurement

(

void

)

Indicates whether the environment variable NVDS_ENABLE_LATENCY_MEASUREMENT is exported.

Returns

True if the environment variable is exported, or false otherwise.

nvds_measure_buffer_latency()

guint nvds_measure_buffer_latency	(	GstBuffer *	buf,
		NvDsFrameLatencyInfo *	latency_info
	)

Measures the latency of all frames present in the current batch.

The latency is computed from decoder input up to the point this API is called. You can install the probe on either pad of the component and call this function to measure the latency.

Parameters

[in]	buf	A pointer to a Gst Buffer to which NvDsBatchMeta is attached as metadata.
[out]	latency_info	A pointer to an NvDsFrameLatencyInfo structure allocated for a batch of this size. The function fills it with information about all of the sources.

nvds_set_input_system_timestamp()

NvDsUserMeta* nvds_set_input_system_timestamp	(	GstBuffer *	buffer,
		gchar *	element_name
	)

Sets the system timestamp when the Gst Buffer arrives as input at the component.

Parameters

[in]	buffer	A pointer to the arriving Gst Buffer.
[in]	element_name	A pointer to the name of the component for which latency is to be measured.

Returns

A pointer to a NvDsUserMeta structure which holds an NvDsMetaCompLatency as NvDsUserMeta.user_meta_data.

nvds_set_output_system_timestamp()

gboolean nvds_set_output_system_timestamp	(	GstBuffer *	buffer,
		gchar *	element_name
	)

Sets the system timestamp when a Gst Buffer that is pushed to the downstream component.

This is a corresponding function to nvds_set_input_system_timestamp().

Parameters

[in]	buffer	A pointer to a Gst Buffer to be pushed to the downstream component.
[in]	element_name	A pointer to the name of the component for which latency is to be measured.

Returns

TRUE if the timestamp is attached successfully, or FALSE otherwise.