The Failover Channel has been specifically designed for the Live Events feature. As part of this channel, you can select multiple sources and define which one is the Slate source, and from the remaining selected channels which one is the preferred (primary) and which one is not preferred (secondary).

Failover channels are like Pass-Through channels in that they do not involve any actual processing to the stream, but rather creates redundancy by defining parallel streams from multiple Sources as a single entity. This ensures that if one Source becomes inactive the stream will be automatically transmitted from the parallel Source.

How priorities influence the failover process

A failover occurs when a current source has a malfunction and is no longer able to stream or that a high-priority source that went went into error has resumed streaming. This means that the priority level hierarchy can influence on when a failover occurs, and if it occurs, to which of the sources it will failover to. In a Failover Channel the priority is as follows:

Preferred – high
Non-preferred – medium
Slate – low

So, the channel will play the preferred source by default. If the preferred source becomes unavailable, it will failover to a non-preferred stream (if one exists). If there is no non-preferred stream of it becomes unavailable (while the preferred stream is still unavailable), Zen Master will failover to the Slate.

How the failover process is overridden by a Live Event

The Failover behavior can be overridden by Live Event configuration. There are some stages of the event, where the Slate is the source that will be streamed. For example, in Pre-live the Live Event is configured to select the Slate source. In the Live event, it will automatically select the preferred source and if the preferred source is not available, it will fall back to a non-preferred source. If neither the non-preferred nor a preferred source is available, it will fall back to a Slate. For more information, see Live Events.

The following procedure describes how to add a Failover Channel in ZEN Master. In addition, an explanation of each of the configuration parameters is given in the table below.

To add a Failover channel:

In the main navigation, click Channels.
Click + Add.
The Create New Channel selection menu is displayed.
Click on Failover Channel.
The Create New Failover Channel window is displayed.
In the Info section, in the Name field, enter a logical name for the Channel.
In the Tags field, select one or more of the predefined Tags from the drop-down list.
Tags are used for access control. By selecting an Tag, you are relating this Channel to that Tag. Tags are associated with certain roles (through the Users & Roles screen), and roles, in turn, are associated with users and user groups. If you would like to create a new Tag, see Creating a Tag.
In the Events Configuration Profile field, select from the dropdown list the profile that you would like to apply to this Channel. By default, the Default profile is applied.

Events Profiles consist of a series of rules that determine precisely how various types of Events are logged and what results they trigger.
In the Input section, in the Processing Cluster field, select from the drop-down list one of the Channel Processing clusters that has been configured in ZEN Master. The selected cluster will be used to process this Channel.

If the Source does not exist in the cluster, then the cluster will pull the Source automatically.
-In the Target Broadcaster/s field, elect your broadcaster preference. Either select a specific broadcaster to be used OR specify your preference for using primary vs. backup broadcasters, options are: Prefer Primary Broadcasters, Primary Broadcasters only, Backup Broadcasters only or Prefer Backup Broadcasters.
- If you want to configure an alternative path for disaster recovery, in the Alternative Channel (Disaster Recovery) field, select the Channel that will be used as the alternative path. For more details, see Disaster Recovery (Alternative Path).
In the Sources section, add one or more Sources to the Channel and specify whether they should be a Preferred Source (select the Preferred checkbox), a Non-preferred Source (do not select anything) or a Slate Source (select the Slate checkbox. This is done as follows:
1. Find the Source that you would like to add either by scrolling through the list of available Sources or by entering a search word into the Filter If the Source that you would like to add is not yet configured in ZEN Master, see Sources.
2. Add a Source by clicking the + button next to the Source.
  Selected Sources are shown above the Filter box.
3. Do one of the following:
  1. Select the Preferred checkbox if you would like to designate the Source as preferred source.
  2. Select the Slate checkbox if you would like to designate the source as a Slate.
  3. Do not select any checkbox if you would like to designate the source as a Non-preferred source.
4. Repeat the above procedure for each Source that you would like to add to the Channel.
If you would like to remove the selected Secondary Source, click on the ‘X’ in the Secondary Source textbox.

All Access Tags that are assigned to the selected Sources are added by default to the Channel.
If you would like to apply a PID Mapping profile to this Channel, then in the PID Mapping Profile field, select the desired profile from the drop-down list.
In the Initial State section, select the Disabled checkbox if you would like to disable this Channel upon initial configuration.
Select the Muted checkbox if you would like to disable error/recovery notifications for this Channel upon initial configuration.

You can Enable/Unmute the Channel at any time.
Under the Source section, select the Automatically switch to Preferred Source, if you want the stream to switch automatically to the configured preferred source. This feature requires Broadcaster version 17 or newer.
For Failover Mode, select the desired mode for failing over/merging the streams. Options are:
- Stream Switch – ZEN Master treats the streams as different and does not try to merge them. If packets are missing from one stream, ZEN Master will switch to the alternate stream. If the payload is not binary identical it will fall back to Stream Switch.
- SMPTE 2022-7 Hitless Merge - if the Sources use RTP, and the RTP headers were maintained, Zixi can use the SMPTE 2022-7 to compare and merge the two streams. This option uses the sequence and the timestamp in the packets to compare which packets are missing, providing optimal results.
- Content Hitless Merge - if the Sources do not have RTP headers, Zixi will merge the streams using the MPEG-TS payload content itself. This method uses Zixi's patented DNA like sequencing algorithm to fill in the missing packets.
If you have selected the Content Hitless Merge or the SMPTE-2022-7 Hitless Merge option, in the Merge Search Window [ms] field, enter the time frame for which the system will search for the relevant packets in a matching stream. (Default: 1000)

If there is a latency difference between the streams, the Search Window value should be higher than the latency difference between the streams.

If Merge Mode is Disabled, the time period specified in the Search Window field defines how long the stream will wait for packet before attempting to switch between streams.
If you have selected the Stream Switch option, in the Zero Bitrate/Offline Detection Window [ms] field, enter the time frame with zero bitrate or offline state after which the system will perform the failover
Failover Rules allow you to set rules for what type of error and how often they occur to change to the failover stream. If you would like to change the rules, use the following procedure (supported for Broadcasters v15+):
1. Select the Checkbox next to the error for which you would like to change the error rules. Options are: P1 Transport Errors, Frozen Video, Blank Picture, Silent Audio, and Low Bitrate. (Zero Bitrate/Offline is set as selected on a fixed basis.)
2. Set the parameters for:
  - Sample Duration - the duration (in seconds) of the window of each sample.
  - Samples - the number of samples that you check in each sampling.
  - Samples Threshold - the number of error results (within a sampling) that trigger the failover.
  - PID - scopes the rule to a specific PID in the transport stream (e.g., if you have multiple audio programs it will only apply the rule to the specified one).
    For example, if you set Sample Duration=10, Samples=6, Samples Threshold=2: then if during a 60 second time period an error occurs during 2 out of the 6 ten-second windows, failover will be triggered.
    
    When the payload is binary identical Failover Rules are ignored in favor of Hitless merge of the sources.
    
    Mentioned PID(s) must be present on all participating streams.
    
    Broadcasters older than version 15 only support Zero Bitrate/Offline failover.
    
    Broadcasters older than version 16.6 do not support PID based rules.
If you would like to enable Content Analysis (CQA), verify that the Enable Content Analysis checkbox is selected (default).

It is generally recommended to enable Content Analysis unless it is causing technical problems. If Content Analysis is disabled, the system won't detect errors in the video and audio content of the stream and won't generate warnings for such events. Even when Content Analysis is disabled the system will still detect TR101 errors in the stream.
If you would like to adjust the Enable Content settings, click the Enable Content Analysis field.
Under Error Concealment, click the Enable Error Concealment checkbox to enable the following error concealment mechanisms that can correct transport stream for downstream IRDs:
1. Continuous Timeline - corrects errors that are related to timeline jumps in the source. This mechanism will normalize the timeline by creating a variant of the input (the input is doubled) and normalizing the timeline of the doubled input.
2. Replace Frames - If there are frames with CC errors, it replaces them with skip frames. This solves issues such as an IRD that lost synchronization when it received broken frames. This mechanism also creates a variant of the input (doubling the input).
3. Renumber CC - The Continuity Counter is part of the TS encapsulation. When there are CC errors in TR101 analysis it means that the counter has a gap due to lost frames. This mechanism can re-write the CC counter for the downstream devices, so they will see a continuous increase of the counter.
4. Delay -
5. CBR Padding - enter a value for the rate at which padding will be added to maintain a specific output transport bitrate.
6. PCR Interval - select the frequency at which Program Clock Reference is inserted into the outputs Transport stream. Options include:
  - ATSC standard - 100 ms
  - DVB standard - 40 ms
If you would like to adjust the advanced settings, click Advanced.
The Advanced settings fields are displayed:
20.If you would like to track usage for this Source, enter your Billing Code details. See Billing Codes.

21. Click Save.

Failover Channel Configuration Parameters Table

*Info*
Parameter	Description
Name	Specify a name for the Failover Channel in ZEN Master.
Tags	Select one or more of the predefined Tags from the drop-down list. Tags are used for access control. By selecting an Tag, you are relating this Channel to that Tag. Tags are associated with certain roles (through the Users & Roles screen), and roles, in turn, are associated with users and user groups. If you would like to create a new Tag, see Creating a Tag.
Events Configuration Profile	Select from the dropdown list the profile that you would like to apply to this Channel. By default, the Default profile is applied. Note: Events Profiles consist of a series of rules that determine precisely how various types of Events are logged and what results they trigger.
*Input*
Processing Cluster	Select from the drop-down list one of the Channel Processing clusters that has been configured in ZEN Master. The selected cluster will be used to process this Channel. Note: If the Source does not exist in the cluster, then the cluster will pull the Source automatically.
Target Broadcaster/s
Alternative Channel (Disaster Recovery)	Enables reverting an entire path after the Source (i.e., Channel/Broadcaster to the Target) to go through an alternative path, which is usually hosted on an alternative cloud/region. The redirection to the alternative path is manual. So, in case of a fault, if there is no time to troubleshoot a problem, this mechanism allows the user to select the feed that has an issue, click a button and revert the stream to go through a pre-configured alternative path. For example, if you have a Channel and a Broadcaster on GCP and a secondary Channel and Broadcaster on Azure. If something goes wrong with the GCP path, you can click the Go to Alternative button and failover everything to Azure.
Sources	Add one or more Sources to the Channel by clicking the + button next to the Source and select the checkboxes if you would like to designate them as a Preferred Source or as a Slate. If you would like to designate the Source as non-preferred, leave the checkboxes empty. If you would like to remove a Source from the Channel, click on the - button next to the Source.
PID Mapping Profile	If you would like to apply a PID Mapping profile to this Source, then select the desired profile from the dropdown list.
Initial State
Disabled	Select this checkbox if you would like to disable this Channel upon initial configuration.
Muted	Select this checkbox if you would like to disable error/recovery notifications for this Channel upon initial configuration.
Source
Automatically switch to Preferred Source	If the primary fails and it switches over to the secondary and later the primary returns, if the box is selected, it will switch back to the primary even if the secondary is good. However if it it is not selected, it will stay on the secondary until the secondary is no longer available.
Failover Mode	Select the desired mode for failing over/merging the streams. Options are: Stream Switch – ZEN Master treats the streams as different and does not try to merge them. If packets are missing from one stream, ZEN Master will switch to the alternate stream. If the payload is not binary identical it will fall back to Stream Switch. SMPTE 2022-7 Hitless Merge - if the Sources use RTP, and the RTP headers were maintained, Zixi can use the SMPTE 2022-7 to compare and merge the two streams. This option uses the sequence and the timestamp in the packets to compare which packets are missing, providing optimal results. Content Hitless Merge- if the Sources do not have RTP headers, Zixi will merge the streams using the MPEG-TS payload content itself. This method uses Zixi's patented DNA like sequencing algorithm to fill in the missing packets.
Merge Search Window [ms]	Specify the time frame for which the system will search for the relevant packets in a matching stream. (Default: 1000) Note: If there is a latency difference between the streams, the Search Window value should be higher than the latency difference between the streams.
Zero Bitrate/Offline Detection Window [ms] (for Stream Switch option)	Enter the time frame with zero bitrate or offline state after which the system will perform the failover.
Failover Rules	Failover Rules allow you to set rules for what type of error and how often they occur to change to the failover stream. If you would like to change the rules, use the following procedure (supported for Broadcasters v15+): Select the checkbox next to the error for which you would like to change the error rules. Options are: P1 Transport Errors, Frozen Video, Blank Picture, Silent Audio, and Low Bitrate. Set the parameters for: Sample Duration – the duration (in seconds) of the window of each sample. Samples – the number of samples that you check in each sampling. Samples Threshold – the number of error results (within a sampling) that trigger the failover. PID - scopes the rule to a specific PID in the transport stream (e.g., if you have multiple audio programs it will only apply the rule to the specified one) Note: For example, if you set Sample Duration=10, Samples=6, Samples Threshold=2: then if during a 60 second time period an error occurs during 2 out of the 6 ten-second windows, failover will be triggered.
Enable Content Analysis	If you would like to enable Content Analysis (CQA), verify that this checkbox is selected (default). Note: It is generally recommended to enable Content Analysis unless it is causing technical problems. If Content Analysis is disabled, the system won’t detect errors in the video and audio content of the stream and won’t generate warnings for such events. Even when Content Analysis is disabled the system will still detect TR101 errors in the stream.
Error Concealment
Enable Error Concealment	Select this checkbox to enable the error concealment mechanisms listed below to correct transport stream for downstream IRDs.
Continuous Timeline	Corrects errors that are related to timeline jumps in the source. This mechanism will normalize the timeline by creating a variant of the input (the input is doubled) and normalizing the timeline of the doubled input.
Replace Frames	If there are frames with CC errors, it replaces them with skip frames. This solves issues such as an IRD that lost synchronization when it received broken frames. This mechanism also creates a variant of the input (doubling the input).
Renumber CC	The Continuity Counter is part of the TS encapsulation. When there are CC errors in TR101 analysis it means that the counter has a gap due to lost frames. This mechanism can re-write the CC counter for the downstream devices, so they will see a continuous increase of the counter.
Delay (ms)
CBR Padding (kbps)	Enter a value for the rate at which padding will be added to maintain a specific output transport bitrate.
PCR Interval (ms)	Select the frequency at which Program Clock Reference is inserted into the outputs Transport stream. Options include: ATSC standard - 100 ms DVB standard - 40 ms
Advanced
Billing Codes	If you would like to track usage for this Source, enter you Billing Code details, see Billing Codes. (Supported for Broadcasters v14.8+)
Billing Password	Enter the password that corresponds to this billing code.
External ID	The ID that is used when integrating ZEN Master with an external ESNI/ESAM server. For more detail, contact your Zixi representative.

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