Preview during a live broadcast


#1

Hello,

I have a question.
Do you have any specific equipment or method to preview a graphic before sending it to AIR during a live transmission?

Thank you.


#2

I usually define a separate channel. Dependent of your system that can be an SDI out or a simple screen consumer.


#3

But how can set a PLAY command to execute only on a specific screen consumer for example?


#4

All commands have a “channel” argument. Dependent on your setup channel 1 is on air and channel 2 is preview.


#5

Hi, If it is for your operator the best thing is to dedicate a channel as screen consumer (that you can even embed it in your tv command program).
SO for instance at the clicking of a button “SUPER”
CG [video_channel:1]{-[layer:int]|-9999} ADD [cg_layer:int] [template:string] [play-on-load:1,1] {[data]}
Using channel 1 for the screen consumer as preview
and then apply the same command to another button that pops out after the channel 1 has something loaded to send the same super to fill and key in another channel…2 for example
CG [video_channel:2]{-[layer:int]|-9999} ADD [cg_layer:int] [template:string] [play-on-load:1,1] {[data]}
The channel 2 in this case it will be the one that pass trough the graphic card that sends fill and key.

Of course you can customize as much as you want the flow - preview and on air - this was just an example.

I usually use the screnn consumer of the preview showing in a different Layer the Program of the TV so I can see the preview directly on the program.


#6

a more newbie answer:
if you are using the standard client you start by going to the server page, there choose a server and open it and in the window you can choose preview and set the preview channel.
As it is already said here the channel can be a SDI or just a screen channel depanding on your need.
Remember that you cant preview (prerun) a video.
In your config-file setup your preview-channel just as a normal channel depending on how you run it, SDI and screenconsumer already mentioned the third opion that I can think of is running preview on a different client-pc. In that case you need to just add a channel without any consumers in yhe config-file. In this case you can see the preview-channel inside the client by choosing in the live-window your preview-channel(fill). either inside the client our windowed (this has a couple of seconds delay).
This is the basic setup, running the preview you just hit F8.
a small hint if your are running the preview (client) on the server-pc as a screenconsumer you can now in the 2.2.0 define both size and place where the screencomsumer will start (scroll down in the config-file to see how its done). I think its a very nice feature.


#7

I use Decklink Duo2 with two channels (1-preview, 2-onair) and after I send the command (ADD) for channel 1, I visually check the output and then I use the AMCP SWAP command and the contents of the preview channel is moved to the onair channel. I don’t know if this solution is better for system recources, but it is fully functional. You can use some “hide” action in JavaScript before You send the SWAP command and then you invoke a “show” JS function in the template which can start an intro animation for displaying in the onair channel


#8

Quite a complicate way of doing it. Playing the template on the preview channel, and after checking, playing it on-air is much simpler and does not use too much resources on a half way current system. And you are sure, that you don’t forget to issue the hide before you swap.


#9

For a CG custom client I use a dedicated lower-resolution channel for preview with an iVGA/NDI consumer.
The templates are prepared to scale and accept a “preview” field that actually shows the “completed” status that ignores all intro animations and updates texts instantly instead of replace animations like it should on the program output.
That preview stream is then embedded in the client and by default is shown that way when you edit a template.
When you add that template to the program channel it works with all the transitions in full resolution.
I use NDI instead of a standard screen consumers for server-client flexibility. You could launch the client from any PC in the local network and preview it without any extra latency. It also lets you show alpha channel with a checkerboard background easily. Oh and generate and save thumbnails too.