Blackmagic Forum

Hey all -

I'm thinking about buying the ATEM Television Studio for live webcasting. I'm not a *total* newbie, but I'm also not an expert when it comes to this stuff. I was hoping I could post the set up I have in mind, and let you guys tell me if it makes sense, or if I should reconsider anything.

I want to input 3 cameras (Gh2, T2i, 7D) in a ATEM Television Studio, which will go into my computer via a mini-recorder.

My concerns right off the bat are:

1. Whether or not these cameras will all be able to output to a mutual usable format for the ATEM.

2. Audio latency. The Mini-Recorder causes a 3-4 frame delay in the video. Can I just output my audio from my Apollo to the ATEM with XLR cables, and then it will be in sync with the cameras after both go through the Mini-Recorder together? If that won't do the trick, what are common solutions for audio latency with the Mini-Recorder?

Thanks!

Brian

1. Probably not, maybe, you need to test it. I wouldn't use DSLRs (especially not low/mid-end like T2i / T3i) live, due to rolling shutter issues, ergonomics, overheating (T3i can only film for 12 minutes before shutting down due to heat) etc. Probably fine for static shots where you can break when you need to.

2. The Mini Recorder delays the entire input signal, and the ATEM embeds the audio as part of the video. In general, the only place you will have sync issues, is where the audio is embedded to the video, in this case when you input it in your switcher. This means that your 3-4 frames from the mini recorder won't be a problem, just the inherent delay of frame sync in the ATEM.

I.e. you will probably need a box that is capable of delaying audio before it enters the ATEM, unless your software is capable of doing it. You need something like 30-120ms depending on cameras, switcher settings etc.

To clarify a little. The ATEM TVS adds in maximum (!) on frame delay (I don't know, if there may be a second frame when/while using DVE). One frame delay is not noticeable. So, the by XLR inserted audio is nearly in sync, there would be no reason for using an audio delay unit to keep audio in sync, but .....

Most of the video delay comes from cameras which were not designed for live video. They have delay at their output caused in signal processing. This is not noticeabe when play back files from camera memoy - but when comparig live video with live audio.

So you get at least 3,4 or maybe 5 frames delay in total at recorders input, maybe different delay with different cameras. So i don't think it it is o good idea mixing different camera brands and models.

This delay is really noticeable and to solve this issue, an audio-delay unit is recommended - maybe a digital audio console or a digital audio effects generator. There is also a cheep box sold by "Lindy", doing such delay. (A Little) Audio after video is no problem, this is a normal situation for humans, because of different speed of light and sound in the air

Also other vision mixers have such delay, not only Blackmagig !

When I worked with Tricaster, I had the same issue, when recording video from the vision mixer together with direct audio from a mixing console bypassing the vision mixer. This shows, that there allways will be delay, but maybe other (and more expensive) vision mixers have an audio delay inserted. So some bucks that you save buying an ATEM must be invested in additional equpiment....

Thomas Seewald wrote: (I don't know, if there may be a second frame when/while using DVE).

I believe one frame if you are using the frame syncs (no reference), and one frame extra when using DVE.