gstreamer-rs/docs/gstreamer-net/docs.md
2017-12-16 14:53:48 +02:00

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NetClientClock implements a custom gst::Clock that synchronizes its time to a remote time provider such as NetTimeProvider. NtpClock implements a gst::Clock that synchronizes its time to a remote NTPv4 server.

A new clock is created with NetClientClock::new or NtpClock::new, which takes the address and port of the remote time provider along with a name and an initial time.

This clock will poll the time provider and will update its calibration parameters based on the local and remote observations.

The "round-trip" property limits the maximum round trip packets can take.

Various parameters of the clock can be configured with the parent gst::Clock "timeout", "window-size" and "window-threshold" object properties.

A NetClientClock and NtpClock is typically set on a gst::Pipeline with gst::Pipeline::use_clock.

If you set a gst::Bus on the clock via the "bus" object property, it will send gst::MessageType::Element messages with an attached gst::Structure containing statistics about clock accuracy and network traffic.

Implements

ClockExt, ObjectExt, ObjectExt

Create a new GstNetClientInternalClock that will report the time provided by the NetTimeProvider on remote_address and remote_port.

name

a name for the clock

remote_address

the address or hostname of the remote clock provider

remote_port

the port of the remote clock provider

base_time

initial time of the clock

Returns

a new gst::Clock that receives a time from the remote clock.

This object exposes the time of a gst::Clock on the network.

A NetTimeProvider is created with NetTimeProvider::new which takes a gst::Clock, an address and a port number as arguments.

After creating the object, a client clock such as NetClientClock can query the exposed clock over the network for its values.

The NetTimeProvider typically wraps the clock used by a gst::Pipeline.

Implements

ObjectExt, ObjectExt

Allows network clients to get the current time of clock.

clock

a gst::Clock to export over the network

address

an address to bind on as a dotted quad (xxx.xxx.xxx.xxx), IPv6 address, or NULL to bind to all addresses

port

a port to bind on, or 0 to let the kernel choose

Returns

the new NetTimeProvider, or NULL on error

Implements

NetClientClockExt, ClockExt, ObjectExt, ObjectExt

Create a new NtpClock that will report the time provided by the NTPv4 server on remote_address and remote_port.

name

a name for the clock

remote_address

the address or hostname of the remote clock provider

remote_port

the port of the remote clock provider

base_time

initial time of the clock

Returns

a new gst::Clock that receives a time from the remote clock.

GstPtpClock implements a PTP (IEEE1588:2008) ordinary clock in slave-only mode, that allows a GStreamer pipeline to synchronize to a PTP network clock in some specific domain.

The PTP subsystem can be initialized with gst_ptp_init, which then starts a helper process to do the actual communication via the PTP ports. This is required as PTP listens on ports < 1024 and thus requires special privileges. Once this helper process is started, the main process will synchronize to all PTP domains that are detected on the selected interfaces.

PtpClock::new then allows to create a GstClock that provides the PTP time from a master clock inside a specific PTP domain. This clock will only return valid timestamps once the timestamps in the PTP domain are known. To check this, you can use gst::ClockExt::wait_for_sync, the GstClock::synced signal and gst::ClockExt::is_synced.

To gather statistics about the PTP clock synchronization, gst_ptp_statistics_callback_add can be used. This gives the application the possibility to collect all kinds of statistics from the clock synchronization.

Implements

ClockExt, ObjectExt, ObjectExt

Creates a new PTP clock instance that exports the PTP time of the master clock in domain. This clock can be slaved to other clocks as needed.

If gst_ptp_init was not called before, this will call gst_ptp_init with default parameters.

This clock only returns valid timestamps after it received the first times from the PTP master clock on the network. Once this happens the GstPtpClock::internal-clock property will become non-NULL. You can check this with gst::ClockExt::wait_for_sync, the GstClock::synced signal and gst::ClockExt::is_synced.

name

Name of the clock

domain

PTP domain