Solid State Logic has released X-ISM, a freeware plug-in which can interpret inter-sample peaks, allowing engineers to make informed judgements about the resultant sound quality of the mix.
When a digitally-recorded sound is played-back it must be converted into an analogue representation at some point. This is performed by the DAC (digital to analogue converter). Commonly used over-sampling DACs apply a ‘reconstruction’ filter to convert the periodic sample levels back into a discrete signal. In simple terms they ‘fill in the gaps’ using interpolation so that digital artefacts are reduced to a minimum.
Regardless of the reconstruction filter’s design, in certain circumstances it is possible for a reconstruction filter to produce signals greater than 0dBfs even if the samples used to create these signals are all within the 0dBfs limit.
X-ISM uses significant processing to provide a combination of up-sampling and filtering that mimics the operation of an oversampling DAC’s reconstruction process. The result is a meter that shows inter-sample errors and provides a useful tool that most DAW metering misses.
X-ISM is available for Windows PC and Mac OS X (VST/AU/RTAS via VST-RTAS wrapper from FXpansion).
You will need an account with SSL to download this plug-in, but if you don’t have one yet you can register for free.
More information: Solid State Logic