The wireless headsets give a certain degree of freedom of movement when using them both for watching the movies, playing games, or just listening to music; that wired headphones just can’t match. But all of them have a certain lag, a delay between what is happening on your screen and you hear it. When watching movies or playing games it can be a problem.
Because Bluetooth has very limited bandwidth for sending and receiving data, the audio signal needs to be compressed before being transmitted to your headphones. When they receive it, a signal needs to be decompressed so it could be played. This takes time and can make the sound late.
The high-end wireless headphones usually have this delay between 30 and 35 milliseconds, which is practically imperceptible. But this lag can be as high as 500 milliseconds, and very often you can do things that will decrease it. But first, you should understand why and how this delay is created.
WHAT CAUSES AUDIO LAG
To understand how the latency is introduced in your audio, it is important to understand how it reaches your headphones. This is the easiest to understand from the way it happens when playing video games. When something happens in the game, it is usually accompanied by a sound effect, walking, shooting, casting spells, objects colliding, and such.
At that time, the game sends an instruction to the sound processor to play a certain audio file. Because the file is in a digital format, if using wired headphones, the sound processor translates it into an analog signal, a fluctuating electric current. When it reaches your headphones it causes the magnetic field in the speaker to fluctuate, which then makes a special membrane vibrate and produce the sound.
This whole process takes between 5 and 10 milliseconds, which is impossible to notice. When it comes to wireless headphones, there are some additional steps. Today, the most common are wireless headphones that connect to your devices with a Bluetooth connection. BT has a very narrow bandwidth, a very small amount of data can be transmitted through it, so the data must be compressed.
When the sound processor gets the instruction to send audio to your headphones, it knows whether they are wired or wireless. It is the information it gets through audio drivers and settings of your device. If they are wireless, it will compress or encode the audio data and send it as a radio signal to your headphones.
When they receive the signal, headphones then need to decompress it and convert it from digital to an analog signal. Encoding and decoding audio data takes some time to be completed, and it creates a delay that can range from 30 to 300 milliseconds.
The exact delay depends on several factors, the codec used, the distance between your device and headphones, radio-signal interferences, and the quality of your headphones; are the four most common factors.
HOW VARIOUS FACTORS CREATE LATENCY
When using wireless headphones, certain latency is just unavoidable. The audio signal needs to be compressed to be sent over Bluetooth and then decompressed in your headset, plus must be converted from digital into an analog signal so that speakers can play it. Certain factors can make this delay longer.
Bluetooth has a limit on how much data it can transmit per second, to overcome this limit sound data must be compressed or encoded. In other words, shrank. Different codecs use different methods for this, I will not go into details that are beyond the scope of this article. Important thing is that the speed at which this encoding is done varies greatly between codecs.
Consequently, the speed at which your headphones decode this signal also varies. Better codecs do it quicker. For example, the aptX Low Latency (aptX LL) codec takes around 35 milliseconds to encode and decode audio signals. Some older codecs can take even above 200 milliseconds.
Further away from your device your headphones are the slower data transmission is, but also more likely to have errors in the data. Bluetooth uses error correction methods for this, but because it uses radio with distance its strength decreases. This decrease in signal strength also decreases the available bandwidth which simply makes audio data reach your headphones slower, and increases the latency.
Bluetooth uses radio signals for communication between devices and transmission of data. An inherent problem with radio communication is that it’s sensitive to interference from other sources of radio signals. That can be other active Bluetooth devices, but also the WiFi network, wireless mouse or keyboard, and many other sources.
Probably the source of the highest level of delay is your headphones themselves. The quality of the Bluetooth chip in them, the supported version of BT protocol, and the quality of the DAC can severely impact the delay of the sound signal. Higher-quality wireless headphones will have higher quality components and support the most advanced BT protocol because of this they will also have the lowest latency.
HOW TO DECREASE AUDIO DELAY WHEN WATCHING MOVIES
Most of the audio and video codecs you could use while watching movies or listening to music on YouTube or in many popular video programs have the ability to detect the latency of your headphones and appropriately sync the video with the audio.
You can notice that this is going on when you are pausing the video. If it takes for the playback a noticeable fraction of a second to stop but there is no delay between audio and video, the syncing is happening.
Sometimes you may notice that the audio is not synchronized with the video and that it is a bit delayed. In case that you have several Bluetooth devices paired with your PC or mobile phone, it can be a bit overwhelming for the BT controller. So, the easiest way to fix it is turning off and then on the BT connection.
Another reason for the lack of sync can be improperly selected codecs. You should make sure that in your video player and Bluetooth settings you have selected codecs that your headphones can use. In the case of a mismatch, your device will fall back to using the default SBC codec, which is supported by almost all devices but is rarely the fastest available on your device.
When using Bluetooth headphones on a PC, outdated drivers can also introduce excessive latency. When you first pair your headphones with your PC, Windows will install the Bluetooth drivers’ version it was shipped with, which certainly will be an outdated one. So, you should manually update the drivers.
HOW TO DECREASE AUDIO DELAY WHEN PLAYING GAMES
When it comes to playing games with wireless headphones, you should be aware that there is a limit to how much you can decrease the delay. But also, there is a limit in how you can decrease it. When it comes to mobile phones, you should first make sure that your headphones support the highest Bluetooth version your device supports.
Using BT 4.0 headphones on a phone that supports BT 5.0 is not a smart choice, because you will be missing out on all of the latency-decreasing advantages of BT 5.0. You should also make sure that your headphones support and that your phone has selected the fastest codec both are supporting.
For the iOS devices, the best codec is AAC, while for the Android it is aptX LL. Some phone manufacturers of Android devices, unfortunately, don’t support aptX codecs but use proprietary ones. If you are a Samsung user, their Scalable Codec is of comparable quality with aptX.
Decreasing the delay on PC is a different story altogether. Because Windows doesn’t support aptX LL, but only vanilla aptX codec, when using Bluetooth headphones delay of around 120 milliseconds is the minimum you can reach. You can decrease the delay to this lower level by making certain that your BT and audio drivers are updated, but also that you are using high-quality headphones.
The impact of the quality of your headphones is something you have no influence over, so fixing the latency issues may require buying new, better ones. If you decide that this is an appropriate solution for you, then ditching Bluetooth is a good option. Many high-quality wireless gaming headsets don’t use BT, but instead the same 2.4 GHz connection as your WiFi.
The 2.4 GHz wireless headphones still have latency, but it is often in 15 to 20 milliseconds range. This delay is for all intents and purposes unnoticeable, and these wireless headphones will provide you the best gaming experience while allowing you to freely move around.
Using wireless headphones comes with the advantages of having one less cable that creates an unsightly mess out of your gaming PC or limiting how far away from your device you can move. Unfortunately, they also come with the drawback of introducing a delay into the audio playback, whether you are watching movies, listening to music, or playing games.
This delay cannot be eliminated completely but can be decreased by using proper low-latency codecs on your phones, or using 2.4 GHz wireless headphones on your PC. Both of these solutions have latencies that are practically imperceptible.