Low-latency sound

What it is

LatencyThe delay between sound being made and you hearing it. Low latency matters when you record or play music. is the delay between a sound happening and you hearing it through the computer. While you watch a film it does not matter. While you sing into a microphone and listen to yourself in headphones, or play a keyboard into a music app, a delay of a few hundredths of a second already sounds like an echo. The delay comes from the bufferSound prepared ahead of time. A smaller buffer means less delay but can crackle.: the small batch of sound the computer prepares before it plays it. A small buffer means less delay, but the computer must keep up; if it does not, you hear a click (a dropoutA click or a gap in the sound when the computer could not keep up with the buffer.). Settings > Sound > Pro Audio sets that buffer for the whole computer.

Why

There is no buffer that is right for everything. Monitoring through a music app wants the smallest; a stream wants a middle size; video and Bluetooth want a large one, and a laptop on battery saves power with a large one. So WolOS leaves the buffer on Automatic for everyday use, lets music apps and games ask for small buffers on their own, and gives you one place to fix the size for a session. A web browser cannot drag the whole computer down to a tiny buffer: ordinary apps have a floor, while music apps and games may go to the smallest.

How

1. Check the sound first. Open TerminalA window where you type commands instead of clicking. Super+Return opens one. (Super+Space, type te, Return) and run:

   wol audio doctor

   You see each check (the sound services, inputs above their normal level, forced buffers, dropouts, the streaming pieces), each with the exact fix.

2. Open Settings > Sound. Press Super+, and choose Sound, or type "buffer" in the Settings search field. You see the outputs and inputs at the top. Pro Audio is further down the page.

   

3. Choose a Buffer size in Pro Audio for the job:

   Job	Buffer size
   Live monitoring through a music app (Ardour, for example)	64 samples (1.3 ms)
   Streaming and recording a voice	256 samples
   Everything else, and Bluetooth	Automatic

   The change applies at once, survives a restart, and stays until you change it back.

4. Leave Sample rateHow many sound measurements are taken every second, for example 44,100 or 96,000. Automatic follows the file you play. on Automatic unless a session needs one rate throughout. Automatic follows 44.1, 88.2 and 96 kHz material instead of converting it.
5. Watch Dropouts. The Pro Audio card counts them: "None", or how many since sound started. If the number grows while you record, choose the next larger buffer.

Music apps and audio interfaces

Music apps such as Ardour see WolOS's sound server as their own audio engine, with the buffer you chose, so there is nothing else to start. The Creative module adds Ardour and the piece they need; see Creative apps in one step. A USB audio interface keeps its own knobs for microphone gain. To give a music app every channel of an interface raw, switch the card's profile to Pro Audio in a terminal: pactl list short cards names the card, then pactl set-card-profile <card> pro-audio.

A worked example

Alice plays a keyboard into Ardour and hears her notes a hair too late. She opens Settings > Sound, finds Pro Audio and chooses 64 samples. The delay is gone, but after a minute she hears small clicks and the Dropouts count starts to grow, so she chooses 128 samples instead. Clicks stop, and the notes still feel instant. When the session is over she sets the buffer back to Automatic.

If something goes wrong

Related

Sound for creators · Sound · Creative apps in one step · Settings