How to fix audio delay on OBS
If you’ve ever tried watching a movie where the audio and video don’t sync up properly, you’ll know the feeling. Sounds play a split-second before or after you see their sources on screen, and it becomes all you can focus on. For creators too, the pesky issue of audio delay is no less frustrating. Many OBS Studio users reading will be familiar with the disheartening moment when you’ve recorded a video or started streaming, only to find that the video is lagging behind the audio.
Fortunately, you don’t have to experience the dreaded audio desync any longer! In this article, we’ll explain exactly what is going on when you experience sound delay in OBS, and provide you with a few solutions to fix it. This guide is tailored to the specific tools and features available in OBS, but don’t worry, we have audio syncing tips for other broadcasting or recording software too.
Generally speaking, video takes longer to process and encode within OBS than audio. This can mean that on occasion the audio comes out ahead of or out of time with the video, resulting in an annoying delay that makes the viewing experience a bit uncomfortable.
As with most technical issues, there can be any number of reasons why a computer would struggle with this process, but one thing to look out for is that all the sound devices on your system are set to either 48 kHz, or 44.1 kHz, which are the two sample rates that OBS supports. Find out the sample rate that you’re using in the Audio Settings section of OBS and make sure everything else matches up in your computer’s sound settings panel.
As is the case with most annoying technical blips, it’s not uncommon for people to find themselves blaming everything in sight when they realize their audio and video are out of sync.
It’s unlikely that the problem is your HDMI cable, however. Audio is sent interleaved with video in a signal transmission through HDMI, and it's the latter that consumes the majority of the data. So if you had a dodgy cable, you would most likely notice issues with the video before any problems with the audio.
Audio lag can occur when using HDMI, but the causes are typically either an issue causing video processing delay or a sync problem in your broadcasting program, which we’ll look into next.
Everyone’s recording setup is different – some have multiple audio sources from cameras and mics, while others opt for a more minimal configuration of one video and one audio source.
With this in mind, your first task when experiencing audio delay in OBS is to locate the audio source that’s out of sync. This means muting channels in the audio mixer until you can pinpoint exactly which source is the main offender. Even a cursory glance at the volume levels in the control panel while speaking into your microphone will give you a sense of how bad the delay is.
Once you’ve isolated the sound source that is out of sync with your video, click the gear icon to access the Advanced Audio Properties menu. From here, you can change the sync offset amount, which is the amount of milliseconds you need to offset the audio against the video to make them match. This can be a negative or positive figure, and will take a bit of fiddling to figure out.
As well as recording video, OBS is a live streaming platform, and the same issue with audio delay can occur during a live stream. OBS uses the best open source video encoding library available, x264, to encode video, but it can be taxing for computers. It’s not uncommon for the audio and video to go out of sync while streaming if the CPU is overloaded, so make sure to have a look at your system resources monitor to see if the usage isn’t too high.
When carrying out any tests to check your audio settings or computer performance, it’s advisable to record a short clip on OBS, rather than carrying out your experiments on a live stream. You don’t really want to broadcast yourself floundering around adjusting settings to your streaming audience, do you?
As mentioned above, you can alter the sync offset amount in the Advanced Audio Properties menu in OBS to make sure your stream’s audio and video are running in tandem. A more precise way to do this than testing out different time values is to use a hand clap or clapper board. By recording a short, sharp sound like a clap you can more easily sync the audio to the exact moment the sound is made.
In the Controls menu on OBS, click Start Recording and capture a video clapping your hands together – if you have a clapper board, that’s great, otherwise your hands will do just fine.
Once you’ve recorded the clip, open it up in a video editing software program. Any program will work as long as it has a clip timeline, but we recommend DaVinci Resolve as it is stacked with great features and has a free version! Zoom in on the timeline as far as you can go (because we’re going to examine the video frame by frame), and locate the audio spike in the sound file where the clap was recorded. You’ll see that the audio spike doesn’t match with the clap in the video preview.
After comparing your audio with the video frames, you can take a measurement that will help you get rid of the delay. Starting one frame before the moment of the clap in the recording, count the number of frames there are before your hands come together on screen. The reason why you should start a frame ahead of the sound is that as humans we see things before we hear them, so it’s more natural for the audio to be ever so slightly behind the video.
Now for some maths. Find out what frame rate you are recording in on OBS by clicking Settings under the Video tab. There are a thousand milliseconds in a second. Divide this by your frame rate value; for example, if you’re recording in 60 FPS, 1,000 divided by 60 = 16.666. Multiply the result of this sum by the number of frames between audio and video that you counted previously. The number that you get is the figure you should put in the sync offset box on OBS to fix the audio delay!
Audio bitrate in OBS is connected to a number of things, including video frame rate and CPU power. This means recommended audio bitrates will be different for every system, so it’s important to play around with yours before you commit to any hard and fast streaming settings.
Remember, the lower the bitrate, the more compressed the audio will be, meaning less detail and quality in the sound. The higher the audio bitrate, the clearer the sound will be. You can use the handy OBS plug–in OBS bitrate calculator to calculate the best resolution or frame rate for a target bitrate, or use this general guide below:
- Low quality audio: 64 – 96 kbps
- Medium quality audio: 128 – 192 kbps
- High quality audio: 256 – 320 kbps
So, there you have it. Audio delay doesn’t have to be the thing that derails your videos and live streams on OBS. Using some of the tips and tricks we’ve outlined above you can bring your audio and video back into sync, and keep your projects looking and sounding professional. For more OBS guides and video production tips, subscribe to our YouTube channel or check out our blog.