Home » Explore » Genlock, Timecode, Wordclock — What Are They? Do I Need Them? Are They Interchangeable?

Genlock, Timecode, Wordclock — What Are They? Do I Need Them? Are They Interchangeable?

Intro

Hey everyone, I wanted to take a little bit of time today and talk about a couple of topics that seem to be causing some confusion out there in the real world. What the differences are between timecode and genlock? And then I also want to do a brief mention of Wordclock at the end, because that’s kind of a similar concept, something you might encounter as you’re working on working with audio.

Genlock and timecode are not the same thing at all. And unfortunately, people confuse the two and not only confuse the two. Assuming that they might be the same thing, but also that one can take the place of the other. And they really can’t. They’re very different things. So even though they’re both synchronization signals, they have very different purposes and very different uses. Uh, so I’m trying to clear up some of that confusion here today.

What is Genlock

So I wanted to cover Genlock first and then I’ll get into timecode here in a little bit. But Genlock is basically a signal that’s used to tell video equipment specifically, usually cameras and playback devices like, uh, video media players or whatever. How often, how often and when to output the video information. So it’s a timing signal to basically make sure that all of your video devices that are going into a switcher are outputting their video simultaneously.  And the reason for that, well, originally had to do with the way we did things back in the analog days before a device called a frame. A frame sync was actually something that was very common. So what happened was your video switchers would, instead of buffering the video data coming in, you would make sure that all your cameras were timed the same, so that the same position on the screen from every camera was being received at the same time.

Therefore, when you needed to switch cameras or we needed to dissolve from one camera to another, you can just do that very cleanly. You don’t have to worry about where in the course of drawing the picture the camera is, because if you have the cameras genlock, they’re all outputting the same portion of the picture at the same time. Therefore, to switch from one to the other is very, very easy because they’re all timed and lined up exactly the same.

In the digital world that we have today. It’s not as necessary to do that, because most of the switchers that we have now actually have frame syncs built into them. And what happens with that is internally, the switcher will buffer will hold on to that picture data until it needs to output it. So if your cameras are not synchronized, the switcher will store that information temporarily in a buffer. And then the next time it needs to start drawing or outputting a video frame, it’s able to pull from the buffer instead of requiring the camera be at that exact same location as what it’s trying to output.

So if you’re outputting pixel zero comma zero, you don’t have to make sure that the cameras are all sending picture at zero comma zero the frame synchronization. Frame frame synchronizer that’s built into the switcher actually takes care of that. And on almost all video switchers that we have digital high definition actually do have frame syncs built into them.

So it’s much less necessary today to have Genlock cameras than it was back in the day. But there is still one very distinct advantage, and that is in reducing the amount of latency that there is from the time light enters the camera until it’s output out to the back of the switcher and sent to a display device like a television or a projector. So if you’re in a situation where you’re doing Imag image magnification, which is basically the terminology for displaying what’s going on live at an event on a projector screen within the venue, you want to minimize that delay as much as possible, because if it’s more than, say, 2 to 3 frames, people that are watching are going to see that and then notice it. And it’s kind of distracting to have what’s going on on screen be delayed by much compared to what’s actually happening in real life.

So going with a genlocked source allows you to eliminate that buffering that’s happening on the inputs of the switcher, and basically allows the video coming from the camera to be passed straight out to the back of the switcher in real time without that additional delay that’s required. When your frame information, your video frame information is not synchronized. What does it take to do this? Uh, we need a few pieces of equipment in order to do this. First of all, we need to have a device which generates a synchronization signal. And this signal is our genlock signal. So gen genlock means generator locked, which basically referring to the fact that our cameras and switcher are locked or synchronized to our video timing generator. So our genlock source and I happen to have one of those here in front of me.

What is Timecode

All right, with Genlock out of the way, let’s talk about timecode. This is another synchronization signal, but it’s very different. And people do tend to get the two confused. So what is timecode? It’s actually just a number which tells you how many hours, minutes, seconds and frames have elapsed from some arbitrary point in time.

For example, you’re shooting a music video. You could use Timecode to represent how far into the song you are. So at that point, when you’re pulling all your footage together and you want to sync it up for editing, it’s able to use the timecode to make sure that you’re always lined up so that whatever portion of the song the artist is singing at any given portion of time is exactly what you’re seeing on screen. So. But that’s that’s really all the time code is timecode is not used to adjust the timing of anything inside of the camera other than a clock that’s displayed, and that time is recorded as part of the beginning of each frame of video.

Timecode caveats

But this is where I have to kind of point out some of the caveats associated with using timecode. Because Timecode is not adjusting the video timing within the camera, they will still get out of sync. If you got a camera that, instead of outputting exactly 29.97 frames per second, or recording 29.97 frames per second, it does 29.98 frames per second. Over time, it’s still going to drift out of sync with your other cameras, so timecode allows you to line up the beginning of video clips in your editor, but it doesn’t do anything whatsoever for making sure that over time they they stay in sync.

What is Wordclock

They’re both synchronization signals, but they serve very different purposes, and one is not a substitute for the other. Very often, if you really want to have signal stay in sync, you want both. Let me mention one other type of technology that’s used associated with synchronization. And this is specific to audio. And this is called Wordclock. So when we have digital audio like AES, EBU or AS3, and when you have audio going between multiple different devices, you need for all of those devices to be synchronized one with one another. Otherwise you find that when a bit comes in, it’s not lined up with when the device is expecting it to to come in, and all of a sudden the data gets distorted and you end up with actual audio distortion and or complete loss of signal.

The solution for this is something called Wordclock. So you’ll have one device in your audio setup which generates a Wordclock signal. And then you connect that to the Wordclock input of all the other devices that have it. That way, everything on your in your audio setup, all your all your audio equipment is transmitting and receiving all your audio data, your digital audio data at the same time stays in sync. No distortion, no drift. You start recording on one device at one time and another device at the same time. Hours later. Those those samples will line up perfectly. If you’re able to use Wordclock, we’re seeing fewer and fewer devices actually support Wordclock these days. A lot of times, devices are actually able to derive Wordclock from having a digital input.

When you have multiple digital audio devices communicating digitally, this only applies to digital communication and logic doesn’t doesn’t come into play at all. But we have audio devices communicating digitally and they support Wordclock. You probably should actually connect up the Wordclock connections between your different devices. And what I’ve got here is I have this is a MOTU mark of the unicorn audio interface for computer, and it happens to have a Wordclock output on it. So I’m going to show you what that signal actually looks like.

How are they related

Now, how do these actually relate to one another? Well, in a fully functioning studio, you’ll have either one device that’s generating all of these signals your Genlock, your Timecode and or Wordclock, or devices that are synchronized with one another that are doing so. That way it doesn’t matter what device you’re recording on, whether it’s audio or video or whatever, when it comes time to actually sync those things up in editing, there’s no trouble doing so because everything was recording at the same rate frames last the exact same amount of time.

The amount number of frames recorded over a period of time is exactly the same across all your devices. Your audio doesn’t drift. Your video doesn’t drift. Everything lines up perfectly So in a broadcast facility, that’s very much the way that they handle that. They’ll have a master sync device master clock that generates those signals, and then those are distributed to all the equipment. So for those who have the budget to do so, it’s a great thing to do. But if you don’t, you may find yourself running into signal drift issues.

Conclusion

If you need your cameras to always stay exactly lined up, you still need Genlock. And then timecode can be used to line up the positions on the timeline of the different clips, so that you’re seeing the same video from the same point in time when it was recorded. So in that way, timecode is very useful for editing, but it does absolutely nothing for making sure that over time, cameras and whatnot stay in sync. So they actually work separately and together in order to make sure that your timing on your device is your video, your audio, etc., actually lines up.

Darren

Filmmaking tips & tricks, camera gear reviews, cinematography breakdowns, and other training-based content to help you level up your filmmaking.

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