During the lock down and this pandemic one of the barriers that for music educators have become a dificulty has been the problems of latency in videochats, difficukting, even making unviable to make music in group in real time.
Anyone knows some app, or device or strategy that minimize this effect?
Latency of audio transfer over the internet is related to the amount of data that can be reliably transported and received during a specific time and the amount of CPU that is available for digital signal processing (DSP) of analog-digital and digital-analog conversion.
For a low latency you, firstly, need enough processing power to handle whatever conversion is happening, the larger the bit-depth and amount of data in the audio stream per second (usually kb/s) the more CPU power you need. This is for encoding and decoding. (DSP of Tx & Rx) There are external devices that are dedicated to this which can offload processing from your computer, like the sound card mentioned above.
So an external audio interface or dedicated sound card is desirable for lower latency.
Secondly, you need to have a stable and consistent internet connection that can handle constant streams of audio data at the desired rate. This is limited by factors such as radio problems (due to the physics of a medium and data transmitted by radio waves, as used in cases to WiFi, mobile data etc) and congestion problems (using shared networks, priority and network overload by too much data).
Radio problems can be fixed by using an ethernet cable instead of WiFi and congestion can be limited by transferring lower amounts of data, by being the only one on the network and making sure that the modem or router can handle those data speeds. Buffer size on the receiving codec (or video/audio software) is also important, but this is usually adjusted automatically. If there are problems with data transfer, the codec compensates by lowering the quality (kb/s).
However, the internet gives no guarantees for a stable reliable connection, this can be helped though, by buying a dedicated symmetrical (the same upload and download speeds) internet service, but these are expensive and only guarantee a certain quality on the way to the internet, but not while on the internet.
Data redundancy, such as duplication and sending extra data like FEC etc, is another way of mitigating data loss but these are advanced and not a feature on most commercial products.
To summarise, it's quite difficult to have low latency streaming for audio or video between peers over the internet.
So some tips:
1. Get a dedicated sound card or external audio interface
2. Use a cable, do not use WiFi. Although even 4G is better than WiFi in most cases.
3. Check the upload speed provided by your internet supplier. This is what is most important when streaming.
4. These fixes need to be done on both sides, but at least your side so the other person gets the shortest latency.
Hope this was helpful,
Ben
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