What is aptX™ Low Latency—and why does it matter to you?
aptX™ Low Latency reduces delay and gives you high quality, synchronised, lip synced sound when you are watching TV, or gaming with a wireless headset.
Qualcomm® has developed various types of aptX™. The fastest one is aptX™ Low Latency, which has a delay of only 40 ms end to end. This is the one Telme2 is has applied in both our TosBlue transmitters and BHX headsets.
When we have two parallel transmission channels, it is important that they are synchronized, i. e. that the sound output from both channels arrives at the receiving end the same time. Most of us can accept a difference of up to 50 ms (milliseconds) delay between the two channels without noticing any problem. So when the sound arrives within a “window” of 50 ms, we may say that the two channels are in sync. If it is more – like 100 ms - we start noticing the delay.
Example:
Let’s say two persons are watching TV. Person 1 uses a headset and person 2 is listening to the internal TV speakers.:
If person 1 is using a Telme2 BHX headset, then there will be practically no “latency time” – i.e. the the two sound outputs will be in sync. Everything is fine.
Now, you may wonder why person 1 is using a headset. If she is hard of hearing she may adjust the sound louder in her headset. Person 2 may listen to the TV sound from the internal speakers at a low pleasent level for her. If a headset without aptX Low Latency is used, a noticeable delay will occur. How annoing this is, may depend on the following:
– If the headset has good passive noise reduction, then the sound from the speakers may hardly be heard inside the headset – then it is almost OK. The lesser problem is that the sound and picture is not quite in sync.
More about aptX here: www.aptX.com
So what is "latency time":
“Latency time” is the time it takes from signal input to signal output of an electronic device. It is also referred to as “throughput time” of a device. As an example, our TosBlue units receives optical digital signals—also referred to as SPDIF or Toslink signals—from the TV. The unit converts these signals into electrical signals and further into wireless Bluetooth transmission signals.
This process takes some time, referred to as “conversion time” or “latency”.
Then, what is aptX™:
aptX™ is an advanced audio compression algorithm. The technology is used in the signal conversion process and is done in hardware, as opposed to software, which is slower. Telme2 is using the fastest available latency aptX technology. (35 ms)
So why is aptx with low latency so important?
In most cases latency is NOT important. If you are transmitting sound from your smartphone, tablet or PC to our BHX headset – low latency is not important at all. The reason being that the sound path will not be synchronized with another sound path or visual path. So any delay will not be noticed.
When you use the TosBlue units connected to your TV, then synchronization of sound and picture are important.
Let me explain:
The TosBlue unit is transmitting sound from your TV to a bluetooth headset. If the TosBlue unit and/or headset did not use aptX technology – the sound would be delayed in the software conversion process in both units. The result would have been sound delay. If the delay is considerable, you may also notice that the sound in the headset is not in sync with the moving Picture in Your TV.
NOTE also: On many new TV’s you may adjust the output timing on the Toslink output port. Then you may adjust until the timing.. In best case you may be able to compensate for most of the delay and a headsdet without aptX may be used without any timing problems.
However, we recommend to use Telme2’s BHX Hi-Fi stereo headset with best aptX included. Then no adjustment is required. With the headset upgarded to BlueTooth 4.2, you will be able to enjoy fantastic sound with no delay.
We Call the combination of a TosBlue unit and the BHX headset for tvSoundCast. The tvSoundCast is offered in 3 versiens. Find out which Version is most suitable for you.