 If you use OBS Studio virtual camera for online meetings and you have noticed a lag between your audio and your video, then this video is for you. OBS Studio is a great tool for creating engaging content for your online meetings. You can create complex scenes that combine camera and other sources like this and project them in Zoom or other platforms such as Microsoft Teams, Google Meet etc. This is achieved by using the virtual camera feature of OBS Studio. However, there can be a problem with this approach. If you create a complex scene with many sources, you may observe a lag between the audio and the video. To demonstrate an example of lag, here is a short clip of a recent training I conducted using OBS and Zoom. Tools and Waffa has already done something similar right? Waffa has used a kind of a simulation of a flip chart. As you may have noticed, there was a significant lag between my lips moving and the actual audio. To understand why this happens, we need to look at how Zoom and OBS work together. As you can see from this illustration, we have a microphone that is connected directly to Zoom. The video, on the other hand, goes through a slightly convoluted process. The image is first captured by OBS which you can see here and we can add other elements such as video, images to create a scene in OBS. This scene is then projected as virtual camera and Zoom uses this virtual camera to project it to the audience. All this processing takes time and the time taken will depend upon two factors. First, the complexity of the scene. That means the more elements you put in your scene, the longer it takes OBS to assemble it. And second, the speed of your computer. If you have a very fast computer, then the delay may be insignificant. At the end of the day, there will be a delay. This means your audio reaches the audience before the video and this is what we call the lag. Can we solve this problem? Let's find out. What should ideally happen is both the microphone as well as the camera should go via OBS. This gives us the added advantage of applying audio filters such as compression, noise gates, equalizers to really enhance our audio. Similar to how we enhance the video with scenes. If there is any mismatch between these two signals, the audio and the video, OBS allows us to correct it using what is called the audio sync offset. This is accessible through the advanced audio properties. Once both the signals are synchronized, then we can create a virtual camera and a virtual microphone and use that in Zoom so that the audience gets to hear both the signals at the same time and everyone is happy. Unfortunately, Zoom currently doesn't support virtual microphones. Perhaps in a future release, they will add the support and it will be amazing. For now, we have to look for other alternatives. The alternative available as of now is to add another software layer called NDI, short for Network Device Interface. NDI is a technology developed by Nutek and it allows computers to exchange low latency video over high-speed network connections. In our case, we have not going to use multiple computers but run it on the same computer and the way it works is as follows. We capture both the microphone and camera in OBS, process both the video and the audio, apply any sync offset and then send the signals to NDI. The NDI software picks up both the signals from OBS and creates a virtual camera and a virtual microphone that can be used by Zoom or any other software. You may have to fine tune the audio signal by adding a gain to the signal before sending it to Zoom. I will show you how. And now everyone is happy. Before you jump and install NDI tools on your computer, I want to highlight few important points. 1. Choose this route only if you feel comfortable tinkering with software. With so many layers of software involved, there are multiple points of failure. When something goes wrong, you will struggle to pinpoint the source of the problem. This is not for the weak of heart. Your computer should have decent processing power and I mean decent. With so much processing happening, you can imagine your computer stretching to its limits. This can result in crashes and you don't want a crash in the middle of an important presentation. Now that we have the theory out of the way, let's see how we can add NDI to our OBS studio. Step number one, download and install the NDI plugins, which is available for free to install the NDI add-on for OBS. Search for OBS NDI and it should take you to this page. I have added the link in the video description. Go to download. Depending on whether you have Windows or Mac or Linux, click on the appropriate link, download the program and install it on your PC. Once you have installed the NDI add-on for OBS, you can open OBS and go to tools. You will find a new setting called NDI output settings. Click on it. Make sure the main output is enabled and give a name to your output. In my case, I have simply called it OBS NDI and click. Okay. And that's all there is to it. OBS is now broadcasting both the audio as well as the video over NDI. And when we are using NDI, we don't have to worry about starting the virtual camera because the output is automatically getting transmitted over NDI. But we are not done yet because Zoom doesn't understand NDI. We need another layer of software between OBS and Zoom that can convert the signals into virtual camera and virtual microphone. To install the next bit of software, we head over to the NewTek website. I did tell you this is not for the weak of heart, didn't I? On the website, you will find the option NDI and NDI tools. Click on this and this will take you to a separate page called NDI tools. To download the tools, you will have to scroll all the way down till you find the option called NDI tools for Windows or for Mac. And depending upon your system, you can download the appropriate package. The download process is not very straightforward. When you click on the download button, you will be asked to give your details, your name, your country and more importantly, your email. And when you click on the submit button, an email will be sent to you with the link to download. So make sure you go to your email inbox and check the email from NewTek and click on the link and download the software and install it on your laptop or PC. Once you have downloaded the NDI tools, you will find them in your download folder. Double click on it. Click on I accept the agreement and choose a folder. The NDI tools has many features, but the one that we are interested in is the webcam input. That's the one that will grab the NDI output created by OBS. Click next and install the program. That's all there is to it. Once you complete the installation, you can go to programs and scroll down till you find NDI. Click on webcam input. At this point, it looks like nothing is happening. But if you go to the system tree, you will find that it has installed the NDI virtual input. Right click on it and you will notice that NDI tools is now detecting that there is an output coming over NDI. This is the name of my computer and it has detected the name OBS NDI that I gave in OBS. Click on it and the NDI tools is now capturing both the audio and video and creating virtual camera and virtual microphone. Now let's see how we can use that in Zoom. This is my Zoom window. If I click on settings, let's first go to audio and in the microphone, let me choose new tech NDI audio. Testing, testing one, two, three. Test, test. As you can see, the audio levels are moving, which means the audio coming from the microphone to OBS through NDI into Zoom is working. Isn't that amazing? If I go to video, also I will find a virtual camera called new tech NDI video. Let's click on it and see what happens and it works. The scene that is there in OBS is now being captured as a camera in Zoom. And now we have the ideal scenario of the microphone and the camera coming through OBS all the way through NDI into Zoom. There are two points I would like you to consider. The first is related to the audio. If you click on the system tray and select NDI and right click on it and click audio. For some reason, the audio when it goes through NDI seems to be lower in volume compared to OBS. And you can correct it by adding either 6 dB or 10 dB or 20 dB. dB means decibels of volume to the audio levels. And you can experiment and test and see what works well for you. But do check it and ensure that your audio levels are correct. The final and the most important part and the reason why we made this entire video is the lag or the sync between the audio and video. Even with the new process that we have implemented of taking both the camera and the microphone into OBS and then into NDI into Zoom, there is still a possibility of a sync offset or a lag between the audio and video. And the way we fix that is very simple. We do it in OBS. If you look at the microphone, right click on the settings and select Advanced Audio Properties. I can see 3 active audio inputs. But the one I am interested in is the microphone. And if we look here, we have something called a sync offset. And a sync offset is a way of telling OBS that you want the audio to be ahead or behind by set number of milliseconds. So in my case, I have set it to 100 milliseconds. It can be a positive or negative value depending on whether the audio is going ahead or behind the video. You need to experiment with this. And a simple experiment that we can do is once everything is set up, use the clapping method. And if you can see the clap and hear the clap at the same time, that means they are in sync. You can always connect to a friend over Zoom and ask them to check the sync. And once you have dialed in the right sync offset, you are good to go. So there we have it. The microphone and the camera going into OBS. Apply the sync offset in case there is any delay between the audio and video. Output it to NDI using the NDI plugin. Capture the NDI output using the NDI tools and create a virtual camera and virtual microphone using NDI and use both in Zoom. I hope you found this video useful and I wish you all the best.