Yet another Vision Client

Saw another post about a vision mixing client and thought I'd share our own client. Built for a customer to do mixing between live sources and pre-recorded media.
CasparVision.jpg (90.35 KiB) Viewed 8501 times
Fully animated GUI with volume faders and T-Bar control

Configuration is pretty self explanatory. All settings are made in the Config file. I have included 2 different config files. One for Decklink Quad card and one for demo purpose using the media files delivered with CasparCG 2.0.

Code: Select all

            <setting name="host" serializeAs="String">
            <setting name="port" serializeAs="String">
            <setting name="input1" serializeAs="String">
                <value>PLAY 1-1 DECKLINK DEVICE 1</value>
            <setting name="input2" serializeAs="String">
                <value>PLAY 1-2 DECKLINK DEVICE 2</value>
            <setting name="input3" serializeAs="String">
                <value>PLAY 1-3 DECKLINK DEVICE 3</value>
            <setting name="input4" serializeAs="String">
                <value>PLAY 1-4 DECKLINK DEVICE 4</value>
            <setting name="afv" serializeAs="String">
Simply edit the config to fit your needs. The last setting in the config file named "afv" stands for "Audio follow Video". This setting can be either True or False to set wether audio from each source should automatically cut or fade together with the corresponding video.

Download available here:

Re: Yet another Vision Client

aircooled76 wrote:Hi Guys,
Very exciting design... well done...

When mixing multiple inputs are there any issues with frame syncing, do you need genlocked cameras?

I read the BMD ATEM switcher has frame sync on each input to keep it locked...
It has an internal frame sync but that adds 1 frame of delay without regard to delay that's already on the line. In other words, the frame delays add up.

Re: Yet another Vision Client

Hi Guys,

Just trying to determine if I can build a vision switcher using BlackMagic cards and CasparCG (Similar to the one posted here) or get a BlackMagic ATEM Switcher...

If I have several HDMI inputs coming into CasparCG.... I assume that the frames would be arriving at slightly different times... Would there be any problems using Caspar to switch between them... Does Caspar sync the frames? How does it deal with the frames arriving at slightly different times?

Re: Yet another Vision Client

Frame sync doesn't really play any role here. Decklink cards automatically sync themselves to the source. Vision switchers need frame synchronisation to keep the aforementioned delay down. This way you can have minimal delay with synchronized cameras or add 1 frame delay for unsynchronized sources. With BMD Decklink you have so much processing delay in the card and the driver itself that frames arriving at different times don't change anything. Add to that the buffering CasparCG does at input (when playing a Decklink producer f.g.) and at output (when outputing through another Decklink card) and you get so much frame synchronization "space", that this stops being an issue.

This however means that you will have significant delay between what your camera operators see, then what you see on your computer monitor as incoming signal, then results of transitions, and then the signal actually output through your output decklink channel. Unless you have a specific reason (limited budget, unused Decklink cards laying around, the fun of it) or feature that you need (f.g. you want to do some complicated DVE, etc.) I suggest using a real video switcher. It will simply be more handy, robust, and do all the things you generally need out of the box.
Jan Starzak
CasparCG graphics designer, programmer and live CG operator - available for work
Lodz, Poland

Re: Yet another Vision Client

At this point I have a super low budget... and looking at a live event switcher for sports streaming... so the delay is not so critical...

Really appreciate your response though!!!

I was also thinking of building my own switcher using Decklink 4K cards to give me the ability to create a 1080p50fps switcher... The BlackMagic switchers (even the new one) don't seem to do 1080p50fps :(

Re: Yet another Vision Client

Bear in mind, that BMD cards also cost something - they are cheap compared to everything else available, but you need one per every input or output (you can use Decklink Duo or Quad, but the financial result is basically the same). An ATEM Television Studio costs $995, has 6 inputs and 6 outputs, a multiviewer and will introduce minimal delay. 3 inputs and 1 output using a Decklink Quad will cost you the same $995, but will offer much less features, introduce significant delay and will require you to do a lot of the work yourself. And this doesn't include the cost of the server, which will have to be substantial if you want to have the same level of reliability.

If sports is going to be your main application, remember that Caspar has some delay when it comes to processing your input through ACMP (performing transitions, etc.). So unless you're doing a sport with very little action, this is also an important factor to take under consideration. You won't get the "snappyness" of the switcher I for one would expect during a sports production.

It's true, there are no cheap 3G video switchers I heard of. What kind of 3G (1080p) video cameras do you want to use? Last time I checked, they weren't cheap as well...
Jan Starzak
CasparCG graphics designer, programmer and live CG operator - available for work
Lodz, Poland