ASIO

ASIO (Audio Stream Input/Output) is a low-latency audio interface standard developed by Steinberg and supported by virtually every professional audio interface. ASIO bypasses Windows' audio stack entirely and talks to the hardware through a driver the manufacturer ships with the device. The result is the lowest reliable latency available on Windows, with deterministic buffer behavior — the right interface when WATCHOUT shares a venue with live performers, in-ear monitor mixes, or any setup where audio timing must be tight.

ASIO is supported by manufacturers including RME, MOTU, Focusrite (Pro range), Universal Audio, Antelope Audio, PreSonus, Steinberg, Behringer (X-series and above), and most professional audio device vendors. Consumer USB audio devices typically do not ship with ASIO — use WASAPI or WASAPI Exclusive for those.

Configuring an ASIO Device

  1. Install the manufacturer's ASIO driver on the node, and confirm the device appears in the vendor's control panel.
  2. In the Devices window, click Add → Audio Device.
  3. Set Node to the machine that hosts the interface.
  4. Set Device Type to ASIO.
  5. Pick the interface from the Device dropdown. The list reflects what the vendor's ASIO driver advertises on the node.
  6. Pick the Channels count. Most professional interfaces report all their outputs (often 8, 16, 32, or more) — choose enough channels for the show's routing.
  7. Pick the Format (for example 48000Hz, 24 bit). ASIO drivers typically expose a single sample-rate + bit-depth combination that matches the device's current configuration in the vendor control panel.
  8. Enable the device with the heart icon.

Buffer Size and Driver Latency

Each ASIO driver has its own control panel where you set the buffer size — the chunk of samples the driver delivers per cycle. The buffer size, more than anything else, determines the latency: smaller buffers mean lower latency but more CPU per cycle and a higher risk of dropouts under load.

The buffer size is configured in the vendor's ASIO control panel, not in WATCHOUT. Typical values:

  • 256 samples @ 48 kHz — about 5 ms; tight but requires a competent CPU and a clean system (no background tasks competing for CPU time).
  • 512 samples @ 48 kHz — about 10 ms; a common safe default for show playback.
  • 1024 samples @ 48 kHz — about 21 ms; the safest choice if the node is also rendering heavy video.

WATCHOUT's Latency slider is the ±100 ms manual offset described in Audio Devices → Latency, added on top of the driver's intrinsic latency — use it to compensate for downstream gear, not to fix dropouts.

When to Use ASIO

  • The interface is from a professional audio vendor that ships an ASIO driver.
  • You need predictable, low latency (in-ear systems, live music sync, theatrical sound effects).
  • The node is dedicated enough to give ASIO consistent CPU access.

When Not to Use ASIO

  • The device has no ASIO driver — use WASAPI or WASAPI Exclusive.
  • The audio is destined for receivers on a Dante network — use Dante Audio instead. WATCHOUT's built-in Dante publishes to the network directly, without the extra hop of routing ASIO through a software sound card.
  • Another process on the same node also needs to open the same ASIO driver. ASIO is typically single-client per driver instance — the driver opens both directions (input and output) and only the first process to claim it succeeds. This matters when WATCHOUT's audio renderer wants ASIO for playback and the LTC Bridge wants to capture timecode from the same card. In that scenario, put one of the two sides on WASAPI or WASAPI Exclusive — see Sharing a Card with Audio Input.

Troubleshooting

For ASIO symptoms and fixes (empty device list, glitches, single format option, high CPU), see Audio Issues → ASIO.

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