IP-VFC and Genlock

The IP-VFC card is ultra-low latency and to achieve this it relies on being genlocked. The IP-VFC and interacts with genlock uniquely to other VFC cards and has additional capabilities and considerations.

The IP-VFC can be genlocked in 2 modes and 1 fallback mode:

PTP (Precision Time Protocol) mode - with a PTP clock on the network.
EXT (External) mode - with a traditional genlock source.
DP (Display Port) mode - fallback with the output from the GPU.

The IP-VFC behaves differently to other VFC cards in that it will produce it’s own genlock signal to lock the GPU in both PTP and EXT modes. In these modes, the incoming PTP network timestamps, or the incoming external genlock signal will be used to time a new genlock signal that the first-installed IP-VFC will generate and send to the Sync card on the GPU to lock it. This allows for a lower-latency workflow with the IP-VFC.

In DP mode, the IP-VFC receives timing sync from the DP signal output by the GPU and does not generate a genlock signal.

PTP mode

PTP (Precision Time Protocol) mode is exclusive to the IP-VFC and allows the IP-VFC to not only lock itself but also the media server an an incoming PTP clock. PTP mode is available ONLY when outputting ST 2110 network video.

PTP is a high precision protocol for sharing time between machines over a network. This page will not explain how to configure PTP in general but will explain how to use the IP-VFC in a network with PTP to apply genlock to your machine.

When PTP is available on the network and it is configured in with ST 2110 SFPs, the first installed IP-VFC card will automatically detect the PTP signal and can be configured to generate it’s own traditional genlock signal which is sent to the sync card in the media server. On Nvidia machines this is always a TTL genlock signal and on AMD machines this is always a Tri-level genlock signal at 1080p at 30Hz and below and 720p above 30Hz.

PTP does not run at a “Refresh Rate” like a traditional genlock signal. As a result, before applying feed settings, the GPU will see NO genlock signal present. Once you set the project refresh rate and apply feeds, the IP-VFC will then be configured to output a genlock signal at the project refresh rate. A card that has previously been configured to output at a particular rate will retain this configuration through reboots.

There are various flavours of PTP, these are the ones the IP-VFC supports:

The IP-VFC card uses the SMPTE 2059-2 profile for PTP. Access the SMPTE specification here.
The IP-VFC only supports PTPv2 (PTP version 2). Access a tutorial here.
the IP-VFC supports both multicast and mixed PTP operating modes.

To apply PTP genlock follow these steps:

Make sure you select PTP sync mode in the Feed View before you configure genlock for the IP-VFC. If you leave it at EXT mode when trying to lock to a traditional genlock signal it will not apply properly.
Set your desired project refresh rate.
Configure your output heads to be all the same resolution.
Press Apply Feed Settings to configure the IP-VFC card to generate the correct genlock signal. (This will work even if Designer reports no genlock signal is present before pressing Apply Feed Settings).

After genlock is visible and feeds have been applied, this configuration will stick through reboots and project re-launches. To change Refresh rates simply change the project refresh rate and apply feeds again.

Under the Sync Status dropdown you can find a range of additional read-only information about the existing clock source:

PTP Clock ID: MAC address of the PTP Grandmaster.
PTP Port Number: Probably always 0 and can be ignored.
PTP State: Whether we are locked to PTP, Locking, or not locked.
PTP Lock Distance: Nanoseconds between the PTP clock for the Port and the Grandmaster (Anything < 100 nanoseconds indicates good PTP Lock).

EXT mode

EXT (External) mode most closely resembles a traditional genlock setup and indeed locks to a traditional genlock signal. EXT mode is available both when outputting SDI and when outputting ST 2110 network video signals from the IP-VFC.

When an external genlock source is connected to the genlock BNC the IP-VFC will automatically detect it and can be configured to generate it’s own genlock signal which is sent to the sync card in the media server. On Nvidia machines this is always a TTL genlock signal and on AMD machines this is always a Tri-level genlock signal at 1080p at 30Hz and below and 720p above 30Hz.

To configure EXT genlock follow these steps:

Make sure you select EXT sync mode in the Feed View before you configure genlock for the IP-VFC. If you leave it at PTP mode when trying to lock to a traditional genlock signal it will not apply properly.
Set your desired project refresh rate.
Configure your output heads to be all the same resolution.
Press Apply Feed Settings to configure the IP-VFC card to generate the correct genlock signal. (This will work even if Designer reports no genlock signal is present before pressing Apply Feed Settings).

DP fallback mode

DP (Display Port) sync is the mode that the IP-VFC enters if no PTP or external genlock sync is present. It can be be forced on manually by internally locking the GPU. In this mode the timing of the card is driven directly by the output of the GPU. This is the highest latency mode. DP mode is available both when outputting SDI and when outputting ST 2110 network video signals from the IP-VFC.

If feed settings fail to be applied, sometimes we will fallback to DP sync mode automatically. This can then appear like the card is not locked or lockable, but often it is simply that the incoming genlock signal from the external genlock source does not match the project refresh rate.