5.2 KiB
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
gst::ClockExt, gst::ObjectExt, glib::object::ObjectExt
Create a new NetClientClock 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
gst::ObjectExt, glib::object::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, gst::ClockExt, gst::ObjectExt, glib::object::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
gst::ClockExt, gst::ObjectExt, glib::object::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
Returns
A new gst::Clock