Time Protocols and Synchronization on the Digital Media Players

This section includes the following topics:

■ Network Time Sources for the Digital Media Players

■ PTP Master and Members

■ DMP-to-DMP Content Synchronization

■ Zone-Based Video Wall Synchronization

■ Use Cases for Video DMP-to-DMP Synchronization with PTP

Network Time Sources for the Digital Media Players

The DMP supports two different network time sources under the global DMP settings:

■Network Time Protocol (NTP)—This is the default.

■Precision Time Protocol (PTP)—Required for video wall synchronization feature and for DMP-to-DMP synchronization.

NTP and PTP settings are provisioned globally for all digital media players. The Cisco Vision Dynamic Signage Director server is provisioned as the default NTP source for all media players.

Note: When PTP is configured, only the DMP PTP master derives its clock using NTP.

For the most accurate synchronization for video playback across DMP devices, the time on the target media players must be almost the same. NTP does not provide this level of time synchronization and accuracy, so PTP is also required.

PTP Master and Members

The DMP is capable to serve as a PTP master or as a PTP member, where members obtain their time from the master. The PTP master, in turn, will get its time from an NTP server.

By default, all DMP devices are designated as eligible master candidates.

DMP-to-DMP Content Synchronization

The DMP-to-DMP Content Synchronization feature for the digital media player synchronizes content rendering of playlist items on the displays.

This synchronization includes transitioning from one item to the next (such as for still images), and more accurate playback and rendering of local video content. For local video, this serves as the foundation for implementing video ribbon boards and video walls. This requires cabling of a single media player per display.

Note: Widgets, external URLs, and multicast video tuning synchronization are outside the scope of this feature.

Improved content synchronization was first introduced in Cisco Vision Director Release 3.2 through the use of the Network Time Protocol (NTP).

Cisco Vision Director Release 4.0 and later supports enhanced content synchronization methods for the DMPs only, with close synchronization of playlist item transition using the Precision Time Protocol (PTP).

Zone-Based Video Wall Synchronization

Zone-based video wall synchronization is an alternative form of synchronization available for DMP devices participating in a video wall. It makes use of a mechanism native to the DMPs that helps a group of media players stay in content sync with a leader device over multicast.

The primary benefit of this form of synchronization is that if any DMP device that is not the leader in the video wall reboots, it will “catch up” to play whatever content item that the rest of the video wall is currently playing.

If a DMP device reboots in a video wall that is not using zone-based video wall synchronization (using normal DMP-to-DMP synchronization), the trade-off is that the rebooting device synchronizes with the rest of the video wall at the next content item in the playlist, or at replay of a single-item playlist.

The general guideline is to use zone-based video wall synchronization for dedicated video walls that are playing video content longer than 15 minutes. While you can use this form of synchronization for all video walls, the synchronization benefit is best seen with longer-playing video wall content.

Use Cases for Video DMP-to-DMP Synchronization with PTP

PTP is particularly beneficial for the following use cases in the Cisco Vision Dynamic Signage Director network:

■Using video background for Dynamic Menu Boards (DMBs) that show primary and secondary regions of the event.

■Sponsored moment of exclusivity.

■When a team scores a goal, a secondary video using the luma key feature can be shown on screen overlaying a full screen video showing the live event.

■Video-based ads.

■Ads in region 2 or 3 (or L-wraps) can now be video content. For L-wraps, use the luma key so that the live multicast video displays.

How to Configure NTP and PTP on the Digital Media Players

By default, both NTP and PTP services are automatically enabled for digital media players. The digital media players use PTP to achieve optimal synchronization. However, an NTP source also must be used to provide initial clocking to the devices that are elected PTP masters in the network.

This section includes the following topics:

■ Restrictions for PTP on the Digital Media Players

■ Guidelines for NTP and PTP on the Digital Media Players

■ Modifying the PTP and NTP Configuration on the Digital Media Players

■ Verifying PTP Operation for the Digital Media Player

Restrictions for PTP on the Digital Media Players

Before you configure PTP on the Series 2 and Series 3 media players, consider the following restrictions:

■By default, PTP messages will not cross VLANs and PTP master candidates need to be identified for each VLAN and configured in the Management Dashboard.

■The system supports a configurable Precision Time Protocol (PTP) Time To Live (TTL) setting in the Management Dashboard. The PTP TTL specifies the number of VLANs that can be crossed for selection of a PTP master. The default value of 1 (recommended) means that each VLAN will elect its own PTP master.

Note: For ease of configuration for venues with multiple VLANs, the system is configured by default to list all Series 2 and Series 3 devices as eligible PTP master candidates. However, be aware that although this simplifies configuration, the time that it takes for the devices to arbitrate a master device in each network will vary, and depends on the number of eligible devices in each network.

■Content synchronization for video playback on the Series 2 and Series 3 media player relies on precise time across DMPs using PTP. If the DMPs are playing video and one of the devices reboots, the rebooting unit will restart video playback from the beginning and will only synchronize with the other players when the next item in the playlist is rendered.

■If Series 2 and Series 3 devices are participating in zone-based content synchronization for video walls, with some enhanced synchronization capability, the rebooting unit will synchronize with the current item being played by the device leader in the video wall. For more information, see “Working with Video Walls” in Cisco Vision Dynamic Signage Director Operations Guide.

Guidelines for NTP and PTP on the Digital Media Players

Before you configure NTP and PTP on the Series 2 and Series 3 media players, consider the following guidelines:

■For new installations of Cisco Vision Dynamic Signage Director, PTP is the default time source for the Series 2 and Series 3 media players, with NTP as the default time source for the elected PTP master.

NTP Guidelines

■Each Series 2 and Series 3 media player designated as PTP master (per VLAN) will use NTP as its time source. The other devices in the network operate using a PTP reference clock from the elected PTP master.

■When PTP is disabled (not recommended), all Series 2 and Series 3 devices use NTP to set their local clock.

Note: For synchronized video playback, NTP alone cannot be relied upon for Series 2 and Series 3 devices and PTP must be used.

■The default NTP synchronization interval with the host time server is one hour and is configurable.

■An NTP source must be configured in Cisco Vision Dynamic Signage Director. By default, the Cisco Vision Dynamic Signage Director server is configured as the Series 2 and Series 3 NTP host.

PTP Guidelines

■PTP version 2 is supported only for the Series 2 and Series 3 media players and applies globally to all devices in the Cisco Vision Dynamic Signage Director network when configured.

■PTP configuration includes a PTP domain and a set of master candidates:

–PTP domain—Default is 0.

Be sure that this domain does not conflict with any other PTP domain (and multicast addressing) in use in your network, and revise as needed. See table “Global DMP Settings—PTP Property Values” for more information.

–PTP master candidates—Default is *.

This specifies that all Series 2 and Series 3 devices in the network are eligible as master candidates and will go through arbitration to designate a master for their respective subnets.

■If you revise the default PTP master candidates configuration, you must configure one or more Series 2 and Series devices as master candidates in a semicolon-separated list of IP addresses for each VLAN.

A minimum of two master candidates per network is recommended.

■If there is an in-house PTP master for your network, leave the “PTP master candidates” property value blank. However, this configuration is only supported for venues without multiple subnets.

Modifying the PTP and NTP Configuration on the Digital Media Players

By default the NTP and PTP services are automatically enabled and configured for Series 2 and Series 3 media players. Use this task if you need to modify the default settings described in Table 2 and Table 3.

To modify the standard NTP and PTP configuration on all Series 2 and Series 3 DMPs:

1. Log into the Cisco Vision Dynamic Signage Director server as an administrator.

2. Go to Tools > Management Dashboard.

3. Go to Dynamic Signage Director Configuration > System Configuration > Global DMP Settings > Time Source (Figure 1).

Figure 1 Global DMP Settings for NTP and PTP on the Series 2 and Series 3

4. (Optional) Change the global PTP properties as required for your network. Refer to Table 2.

5. (Optional) Change the global NTP properties as required for your environment. Refer to Table 3.

6. Click the disk icon to Save changes.

7. Reboot the Series 2 and Series 3 devices.

Verifying PTP Operation for the Digital Media Player

This section describes how to verify the PTP configuration and also the operation of PTP for your Series 2 and Series 3 devices.

To verify the PTP operation for the Series 2 and Series 3 media player:

1. Open your browser and navigate to one of the DMPs:

http:// sv4k-ip-address /ptp.html

2. Identify the PTP master by finding the unit that has an “offsetFromMaster” value of 0.0.

Figure 2 highlights the PTP master and shows a network where PTP is operating successfully with 12 members.

Figure 2 Successful PTP Clock Operation