Saturday, September 21, 2013

ASIO, BUFFER SIZE and LATENCY! A guide for dummies.

Hello and welcome to this week's article!
Today we're going to talk about a topic that comes before the beginning of a recording session: how to set up the drivers in our computer in order to be able to work without problems.

First off the Drivers: each Audio Interface has its own driver software, that "explains" to our computer how to communicate with it.
When it comes to using a Daw, the part of the interface driver that is important is the ASIO section (audio streaming input output): this is the protocol for audio transmission, created by Steinberg, that lets us record and play one or more channels at the same time, with a very low latency.
Once we have set the Asio driver of our interface in our Daw, the workstation will stream all the input and output audio data from our interface.
If we have no Audio Interface but we need to record something on a Daw, we can use a driver called Asio 4 All, keeping in mind that the integrated preamp of our motherboard is really cheap, and it's a good idea to buy a dedicated interface as soon as possible, if we want to produce music.

Now that we have all setup we can try to create or to open a project, and see if we can hear everything well or there are problems: we could experience some mistimed sound, or some random pop or crackle (notice that this errors are not present on the tracks, they are just playback artifacts generated randomly when the Cpu is under an excessive stress).
This happens because our computer, in order to let us hear properly all the tracks (with all the eventual real time processing) needs to buffer the audio prior to let us hear it: the smaller the buffer size is, the lower the latency will be;
making the buffer smaller comes at a price, however.
With a smaller buffer, there is less overhead for delays in processing, therefore the CPU will need to work harder to ensure that any delay is kept within the time allowed by the buffer, and the more the Cpu works and the smaller the buffer is, the more is likely to experience dropouts, pops and crackles.

What we need is a very good Cpu and a lot of Ram, in order to be able to keep the latency low without too many problems; we can start by choosing from the Interface driver a small buffer and as soon as we experience problems we can increase it of one step, until we find the buffer size that lets us work perfectly at the minimum latency possible.

Coming to the latency, we're obviously talking about the delay between when we play a note and when it is received from the computer, processed and sent back to us through the monitors (or the headphones).
When mixing, latency is not a major problem if all the tracks are playing in perfect synchronization among them, the problem is particularly tedious when recording: if we are recording a singer or a guitarist, the maximum monitoring latency tolerable is 10ms or less: with a higher latency it becomes almost impossible to play.
If the latency is unbearable the only solution is to reduce the buffer size, and if this brings pops and crackles, the only thing to do is to try to lighten the Cpu load by disabling all the unnecessary real time effects, or muting tracks, leaving on just the most essential ones.
The ideal is to use a smaller buffer when recording, and a larger one when mixing.

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