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| = Sample Rates in Rivendell =
| | Sample rates |
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| This page documents how audio sample rates are handled in the '''Rivendell Radio Automation System''', including supported rates, configuration considerations, and best practices for production and ingestion.
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| == Overview ==
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| Rivendell supports a '''fixed system‑wide sample rate'''. All audio stored in the Rivendell audio store must match the system's configured rate to ensure correct playback, timing accuracy, and log integrity.
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| Unlike some modern media systems, Rivendell does not transparently mix or resample audio files with differing sample rates at runtime.
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| == Supported Sample Rates ==
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| Rivendell supports the following PCM audio sample rates:
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| * '''44,100 Hz (44.1 kHz)'''
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| * '''48,000 Hz (48 kHz)'''
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| Only **one sample rate may be used per Rivendell system at a time**, and all audio files must match the configured rate.
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| ''Important:'' The chosen sample rate is a '''system‑level configuration decision'''. Mixing 44.1 kHz and 48 kHz audio in the same Rivendell system is not supported.
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| == Choosing a Sample Rate ==
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| === 44.1 kHz ===
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| 44.1 kHz has historically been the most common Rivendell configuration.
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| Advantages:
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| * Compatible with legacy CD‑based and broadcast workflows
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| * Widely used in existing Rivendell installations
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| * Proven stability
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| === 48 kHz ===
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| 48 kHz is commonly used in modern broadcast and video‑adjacent workflows.
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| Advantages:
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| * Industry standard for video and many modern broadcast chains
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| * Reduces the need for external sample‑rate conversion when interfacing with video systems
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| * Supported by Rivendell when configured consistently
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| ''Note:'' Switching an existing system from 44.1 kHz to 48 kHz requires re‑importing or converting all stored audio.
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| == Bit Depth ==
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| While this page focuses on sample rates, bit depth is also relevant.
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| * '''16‑bit''' linear PCM is the standard and recommended format.
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| * Some workflows may allow import of higher bit‑depth material, but audio is typically stored and processed as 16‑bit PCM.
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| == Channel Configuration ==
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| Rivendell supports both mono and stereo audio at either supported sample rate.
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| * Mono: Single channel PCM
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| * Stereo: Left / Right PCM
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| The configured system sample rate (44.1 kHz or 48 kHz) applies equally to mono and stereo files.
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| == Importing Audio ==
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| When importing audio into Rivendell using:
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| * '''rdimport'''
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| * Rivendell GUI import tools
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| * Automated ingest workflows
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| Ensure that all source files meet the system requirements:
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| * Sample Rate: '''Matches the system configuration (44.1 kHz or 48 kHz)'''
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| * Encoding: Linear PCM (WAV)
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| * Bit Depth: 16‑bit recommended
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| * Channels: Mono or Stereo
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| Files with mismatched sample rates must be converted before import.
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| == Sample Rate Conversion ==
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| Common source sample rates that may require conversion include:
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| * 44.1 kHz (if the system is configured for 48 kHz)
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| * 48 kHz (if the system is configured for 44.1 kHz)
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| * 96 kHz or higher (high‑resolution recording)
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| Best practices:
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| * Perform high‑quality offline resampling
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| * Avoid repeated conversion of the same audio
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| * Use dithering when reducing bit depth
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| == Clocking and Audio Hardware ==
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| System‑level sample rate configuration must align with audio hardware settings.
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| * Audio interfaces should run at the same sample rate as Rivendell
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| * External word clock sources should be stable and correctly distributed
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| * Hardware sample‑rate conversion should be avoided where possible
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| Improper clocking or mismatched rates may cause:
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| * Clicks or pops
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| * Timing drift
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| * Unstable playback
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| == Timing and Logs ==
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| Rivendell log timing and audio length calculations depend on a consistent sample rate.
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| * Segue calculations
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| * Event timing
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| * Length metadata
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