Audio Precision has updated its APx Series audio analyzers, allowing them to measure the digital error rate of a device handling lossy encoded digital audio in formats such as Dolby and DTS.
Every device that passes digital audio strives to be bit-accurate — that is, to pass the digital audio stream unchanged from its input to its output. However, devices may unintentionally truncate data, introduce dither, scale the signal or convert the sample rate. These errors may be hard to detect with a traditional THD+N measurement, but they can cause havoc for devices receiving corrupted data later in the signal path.
APx calculates the digital error rate by measuring a proprietary waveform with a deterministic relationship between samples. This allows the instrument to detect any errors in the output of a digital device on a sample-by-sample basis.
The algorithm used is generator-independent and allows the instrument to test both closed-loop digital devices, such as routers and switchers, and playback devices, including CD and DVD players.
The Digital Error measurement can also be used to test bit-for-bit accuracy over time (to more than 10,000 minutes), a useful feature for detecting intermittent errors that would otherwise be hard to reproduce.