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https://gitlab.freedesktop.org/gstreamer/gstreamer.git
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- Mention that a new capability is required by "avtpsink" element; - Use "clockselect" element to change pipeline clock, instead of a gst-launch option that never saw the light of day. Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-bad/-/merge_requests/1443>
274 lines
10 KiB
C
274 lines
10 KiB
C
/*
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* GStreamer AVTP Plugin
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* Copyright (C) 2019 Intel Corporation
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later
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* version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the
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* Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
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* Boston, MA 02110-1301 USA
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*/
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/**
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* plugin-avtp:
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*
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* ## Audio Video Transport Protocol (AVTP) Plugin
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*
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* The AVTP plugin implements typical Talker and Listener functionalities that
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* can be leveraged by GStreamer-based applications in order to implement TSN
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* audio/video applications.
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*
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* ### Dependencies
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*
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* The plugin uses libavtp to handle AVTP packetization. Libavtp source code can
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* be found in https://github.com/AVnu/libavtp as well as instructions to build
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* and install it.
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*
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* If libavtp isn't detected by configure, the plugin isn't built.
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*
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* ### The application/x-avtp mime type
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*
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* For valid AVTPDUs encapsulated in GstBuffers, we use the caps with mime type
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* application/x-avtp.
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*
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* AVTP mime type is pretty simple and has no fields.
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*
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* ### gPTP Setup
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*
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* The Linuxptp project provides the ptp4l daemon, which synchronizes the PTP
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* clock from NIC, and the pmc tool which communicates with ptp4l to get/set
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* some runtime settings. The project also provides the phc2sys daemon which
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* synchronizes the PTP clock and system clock.
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*
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* The AVTP plugin requires system clock is synchronized with PTP clock and
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* TAI offset is properly set in the kernel. ptp4l and phc2sys can be set up
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* in many different ways, below we provide an example that fullfils the plugin
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* requirements. For further information check ptp4l(8) and phc2sys(8).
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*
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* In the following instructions, replace $IFNAME by your PTP capable NIC
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* interface. The gPTP.cfg file mentioned below can be found in /usr/share/
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* doc/linuxptp/ (depending on your distro).
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*
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* Synchronize PTP clock with PTP time:
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*
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* $ ptp4l -f gPTP.cfg -i $IFNAME
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*
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* Enable TAI offset to be automatically set by phc2sys:
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*
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* $ pmc -u -t 1 -b 0 'SET GRANDMASTER_SETTINGS_NP \
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* clockClass 248 clockAccuracy 0xfe \
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* offsetScaledLogVariance 0xffff \
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* currentUtcOffset 37 leap61 0 leap59 0 \
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* currentUtcOffsetValid 1 ptpTimescale 1 \
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* timeTraceable 1 frequencyTraceable 0 timeSource 0xa0'
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*
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* Synchronize system clock with PTP clock:
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*
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* $ phc2sys -f gPTP.cfg -s $IFNAME -c CLOCK_REALTIME -w
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*
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* The commands above should be run on both AVTP Talker and Listener hosts.
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*
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* With clocks properly synchronized, applications using the AVTP plugin
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* should use GstSytemClock with GST_CLOCK_TYPE_REALTIME as the pipeline
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* clock.
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*
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* ### Clock Reference Format (CRF)
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*
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* Even though the systems are synchronized by PTP, it is possible that
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* different talkers can send media streams which are out of phase or the
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* frequencies do not exactly match. This is partcularly important when there
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* is a single listener processing data from multiple talkers. The systems in
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* this scenario can benefit if a common clock is distributed among the
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* systems.
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*
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* This can be achieved by using the avtpcrfsync element which implements CRF
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* as described in Chapter 10 of IEEE 1722-2016. avtpcrfcheck can also be used
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* to validate that the adjustment conforms to the criteria specified in the
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* spec. For further details, look at the documentation for the respective
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* elements.
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*
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* ### Traffic Control Setup
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*
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* FQTSS (Forwarding and Queuing Enhancements for Time-Sensitive Streams) can be
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* enabled on Linux with the help of the mqprio and cbs qdiscs provided by the
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* Linux Traffic Control. Below we provide an example to configure those qdiscs
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* in order to transmit a CVF H.264 stream 1280x720@30fps. For further
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* information on how to configure these qdiscs check tc-mqprio(8) and
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* tc-cbs(8) man pages.
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*
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* On the host that will run as AVTP Talker (pipeline that generates the video
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* stream), run the following commands:
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*
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* Configure mpqrio qdisc (replace $MQPRIO_HANDLE_ID by an unused handle ID):
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*
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* $ tc qdisc add dev $IFNAME parent root handle $MQPRIO_HANDLE_ID mqprio \
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* num_tc 3 map 2 2 1 0 2 2 2 2 2 2 2 2 2 2 2 2 \
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* queues 1@0 1@1 2@2 hw 0
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*
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* Configure cbs qdisc (replace $CBS_HANDLE_ID by an unused handle ID):
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*
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* $ tc qdisc replace dev $IFNAME parent $MQPRIO_HANDLE_ID:1 \
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* handle $CBS_HANDLE_ID cbs idleslope 27756 sendslope -972244 \
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* hicredit 42 locredit -1499 offload 1
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*
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* Also, the plugin implements a transmission scheduling mechanism that relies
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* on ETF qdisc so make sure it is properly configured in your system. It could
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* be configured in many ways, below follows an example.
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*
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* $ tc qdisc add dev $IFNAME parent $CBS_HANDLE_ID:1 etf \
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* clockid CLOCK_TAI delta 500000 offload
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*
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* No Traffic Control configuration is required at the host running as AVTP
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* Listener.
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*
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* ### Capabilities
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*
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* The `avtpsink` and `avtpsrc` elements open `AF_PACKET` sockets, which require
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* `CAP_NET_RAW` capability. Also, `avtpsink` needs `CAP_NET_ADMIN` to use ETF.
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* Therefore, applications must have those capabilities in order to successfully
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* use these elements. For instance, one can use:
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*
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* $ sudo setcap cap_net_raw,cap_net_admin+ep <application>
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*
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* Applications can drop these capabilities after the sockets are open, after
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* `avtpsrc` or `avtpsink` elements transition to PAUSED state. See setcap(8)
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* man page for more information.
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*
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* ### Elements configuration
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*
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* Each element has its own configuration properties, with some being common
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* to several elements. Basic properties are:
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*
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* * streamid (avtpaafpay, avtpcvfpay, avtpaafdepay, avtpcvfdepay,
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* avtpcrfsync, avtpcrfcheck): Stream ID associated with the stream.
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*
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* * ifname (avtpsink, avtpsrc, avtpcrfsync, avtpcrfcheck): Network interface
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* used to send/receive AVTP packets.
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*
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* * dst-macaddr (avtpsink, avtpsrc): Destination MAC address for the stream.
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*
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* * priority (avtpsink): Priority used by the plugin to transmit AVTP
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* traffic.
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*
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* * mtt (avtpaafpay, avtpcvfpay): Maximum Transit Time, in nanoseconds, as
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* defined in AVTP spec.
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*
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* * tu (avtpaafpay, avtpcvfpay): Maximum Time Uncertainty, in nanoseconds, as
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* defined in AVTP spec.
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*
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* * processing-deadline (avtpaafpay, avtpcvfpay, avtpsink): Maximum amount of
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* time, in nanoseconds, that the pipeline is expected to process any
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* buffer. This value should be in sync between the one used on the
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* payloader and the sink, as this time is also taken into consideration to
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* define the correct presentation time of the packets on the AVTP listener
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* side. It should be as low as possible (zero if possible).
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*
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* * timestamp-mode (avtpaafpay): AAF timestamping mode, as defined in AVTP spec.
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*
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* * mtu (avtpcvfpay): Maximum Transmit Unit of the underlying network, used
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* to determine when to fragment a CVF packet and how big it should be.
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*
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* Check each element documentation for more details.
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*
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*
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* ### Running a sample pipeline
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*
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* The following pipelines uses debugutilsbad "clockselect" element to force
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* the pipeline clock to be GstPtpClock. A real application would
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* programmatically define GstPtpClock as the pipeline clock (see next section).
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* It is also assumes that `gst-launch-1.0` has CAP_NET_RAW and CAP_NET_ADMIN
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* capabilities.
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*
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* On the AVTP talker, the following pipeline can be used to generate an H.264
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* stream to be sent via network using AVTP:
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*
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* $ gst-launch-1.0 clockselect. \( clockid=ptp \
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* videotestsrc is-live=true ! clockoverlay ! x264enc ! \
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* avtpcvfpay processing-deadline=20000000 ! \
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* avtpcrfsync ifname=$IFNAME ! avtpsink ifname=$IFNAME \)
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*
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* On the AVTP listener host, the following pipeline can be used to get the
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* AVTP stream, depacketize it and show it on the screen:
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*
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* $ gst-launch-1.0 clockselect. \( clockid=ptp avtpsrc ifname=$IFNAME ! \
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* avtpcrfcheck ifname=$IFNAME ! avtpcvfdepay ! \
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* vaapih264dec ! videoconvert ! clockoverlay halignment=right ! \
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* queue ! autovideosink \)
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*
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* ### Pipeline clock
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*
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* The AVTP plugin elements require that the pipeline clock is in sync with
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* the network PTP clock. As GStreamer has a GstPtpClock, using it should be
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* the simplest way of achieving that.
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*
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* However, as there's no way of forcing a clock to a pipeline using
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* gst-launch-1.0 application, even for quick tests, it's necessary to have
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* an application. One can refer to GStreamer "hello world" application,
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* remembering to set the pipeline clock to GstPtpClock before putting the
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* pipeline on "PLAYING" state. Some code like:
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*
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* GstClock *clk = gst_ptp_clock_new("ptp-clock", 0);
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* gst_clock_wait_for_sync(clk, GST_CLOCK_TIME_NONE);
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* gst_pipeline_use_clock (GST_PIPELINE (pipeline), clk);
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*
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* Would do the trick.
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*
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* ### Disclaimer
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*
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* It's out of scope for the AVTP plugin to verify how it is invoked, should
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* a malicious software do it for Denial of Service attempts, or other
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* compromises attempts.
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*
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* Since: 1.18
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*/
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#ifdef HAVE_CONFIG_H
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#include <config.h>
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#endif
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#include <gst/gst.h>
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#include "gstavtpaafdepay.h"
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#include "gstavtpaafpay.h"
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#include "gstavtpcvfdepay.h"
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#include "gstavtpcvfpay.h"
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#include "gstavtpsink.h"
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#include "gstavtpsrc.h"
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#include "gstavtpcrfsync.h"
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#include "gstavtpcrfcheck.h"
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static gboolean
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plugin_init (GstPlugin * plugin)
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{
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if (!gst_avtp_aaf_pay_plugin_init (plugin))
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return FALSE;
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if (!gst_avtp_aaf_depay_plugin_init (plugin))
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return FALSE;
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if (!gst_avtp_sink_plugin_init (plugin))
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return FALSE;
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if (!gst_avtp_src_plugin_init (plugin))
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return FALSE;
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if (!gst_avtp_cvf_pay_plugin_init (plugin))
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return FALSE;
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if (!gst_avtp_cvf_depay_plugin_init (plugin))
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return FALSE;
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if (!gst_avtp_crf_sync_plugin_init (plugin))
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return FALSE;
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if (!gst_avtp_crf_check_plugin_init (plugin))
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return FALSE;
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return TRUE;
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}
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GST_PLUGIN_DEFINE (GST_VERSION_MAJOR, GST_VERSION_MINOR,
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avtp, "Audio/Video Transport Protocol (AVTP) plugin",
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plugin_init, VERSION, GST_LICENSE, GST_PACKAGE_NAME, GST_PACKAGE_ORIGIN);
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