Sample Rates

Sample Rates in Rivendell

This page documents how audio sample rates are handled in the Rivendell Radio Automation System, including supported rates, system limitations, and best practices for production and ingestion.

Overview

Rivendell is designed primarily for broadcast radio environments and assumes a fixed digital audio sample rate throughout the system. Correct configuration and consistent audio formatting are critical to ensure reliable playback, accurate timing, and predictable audio quality.

Supported Sample Rates

Rivendell supports 44,100 Hz (44.1 kHz) PCM audio.

• 44.1 kHz is the **native and required sample rate** for all audio stored in the Rivendell audio store.
• Audio at other sample rates must be converted before being imported into Rivendell.

Bit Depth

While this page focuses on sample rates, bit depth is closely related and must also be considered.

• 16-bit linear PCM is the standard and most commonly used format.
• Some workflows may support 24-bit audio during import, but files are typically stored and processed as 16-bit audio internally.

Channel Configuration

Rivendell supports both mono and stereo audio at the supported sample rate.

• Mono: Single channel PCM
• Stereo: Two-channel PCM (Left / Right)

The sample rate requirement (44.1 kHz) applies equally to mono and stereo files.

Importing Audio

When importing audio into Rivendell using tools such as:

• rdimport
• Rivendell Import GUI
• External production workflows

ensure that all source files meet the following criteria:

• Sample Rate: 44,100 Hz
• Encoding: Linear PCM (WAV)
• Bit Depth: 16-bit (recommended)
• Channel Count: Mono or Stereo

If a file does not meet these requirements, it should be converted prior to import using an external audio editor or batch processing tool.

Sample Rate Conversion

Audio files created at common production or distribution sample rates such as:

• 48,000 Hz (video production)
• 96,000 Hz (high‑resolution recording)

must be resampled to 44.1 kHz before use in Rivendell.

Recommended practices:

• Use high‑quality offline resampling
• Avoid repeated resampling of the same audio
• Apply dithering when reducing bit depth

Clocking and Audio Hardware

Although Rivendell software assumes a 44.1 kHz internal rate, audio hardware configuration is also important.

• Audio interfaces should be locked to a stable clock source
• Hardware may run at 44.1 kHz or perform real‑time sample rate conversion internally
• Mixing differing hardware clock rates without proper synchronization can cause clicks, pops, or drift

Timing and Logs

Precise timing in Rivendell logs depends on all audio sharing the same sample rate.

• Segue calculations
• Event timing
• Length metadata

are all based on the assumption of 44.1 kHz source audio.

Using non‑conforming files may result in:

• Incorrect length reporting
• Timing drift
• Playback errors

Best Practices

• Standardize production workflows at 44.1 kHz
• Validate audio files before import
• Avoid on‑the‑fly sample rate conversion
• Document any exceptions clearly for engineering staff

See Also

• Audio Formats in Rivendell
• rdimport
• Audio Hardware Configuration
• Digital Audio Basics