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  • Anti-aliasing distortion in VSL SE orchestral strings

    S
    S

     How can one reduce or eliminate the pronounced anti-aliasing distortion that is audible in playback of Orchestral Strings in VSL SE and SE+ -- especially in the violins. 

    On the VSL website, the webpage on Numerical Sound's FORTI for Vienna Suite states: "Numerical Sound TILT Filters create the ability to reduce the dreaded “sample transient clarity” that keeps most digital pieces from sounding acoustic."  I assume the dreaded distortion in sample clarity is anti-aliasing distortion.

    Does that mean that I have to purchase Vienna Suite and FORTI in order to attenuate the high-frequency distortion I hear in the Special Edition Orchestral Strings, particularly the violins?  Is there any way to attenuate this distortion in Vienna Ensemble?

    MS
  • D
    D
    What exactly is the anti-aliasing distortion?
    How would you define it? What does it sound like?
  • S
    S

     It sounds like high-frequency distortion mixed into each note.  It is pronounced in VSL SE/SE+ Orchestral Strings -- especially in the violins.  It is so audible, everyone who listens to my pieces for string orchestra (played back with Sibelius 6.2 &SE+) notices it.  This distortion is also audible on SE+ Solo Strings.  This is not a minor problem.  It is always present.  It is even more noticible on notes with accent marks.  Orchestral strings and solo strings in SE/SE+ sound dreadful.

    I am able to reduce this distortion slightly in Vienna Ensemble by going into the Sustain articulations with Control Edit, and reducing the volume to 55.  Below 55, sustained notes become too weak.  Nevertheless, this distortion is still audible in the strings.

    All of my volume levels in Sibelius mixer and VE mixer are fine.  None of them are set even close to overload.  The distortion is audible even when the strings play p.

    MS

    VSL SE & SE+

    VE  (Latest download)

    Windows 7 64-bit; very fast AMD CPU

    4 gigs ram

    M-Audio Delta card (latest 64 bit driver)

    I am trying a demo of Vienna Suite, Convolution Reverb.  The distortion is audible with and without reverb.
  • DietzD
    VSL Team
    DietzD

    Sorry to hear about your problems, MS, but it seems as you're having a unique issue here.

    Let's get the nomenclature straight first: Are you talking about Aliasing? That would be a low-pitched (not high-pitched) sound, inverse dependent  on the pitch of the actual sample. The reason of would be a infringement of Shannon's sampling theorem (please  see here -> [URL]http://en.wikipedia.org/wiki/Nyquist–Shannon_sampling_theorem[/URL] for details).

    An Anti-Aliasing Filter is used to avoid Aliasing. It has to take care that no harmonic content is left in a sample above the half of the sample rate (i.e. nothing above 22.050 Hz in case of 44.1 kHz). It's highly unlikely that our A/D-or sampling rate converters have an error here, as then especially instruments with _real_ HF content (like a triangle that easily goes beyond 50 kHz) would sound _really_ awful. :-)

    Or are you talking about distortion? This would be a nonlinearity in volume and has per se nothing to do with Aliasing. Of course this would be possible due to excessive volume in the analogue domain, but given the fact that each and every of our samples is listened to by at least ten pairs of highly trained ears before its released, that is very unlikely. - BTW - we can't overload a sample digitally (by human measures) because the whole editing process is kept in 32 bit floating point, as well as all of our software products. This gives us an internal headroom of around 1600 dB, if I remember correctly. 8-)

    In a nutshell - I can't really understand the term "anti aliasing distortion". I would suggest that you get in contact with our support team. They will talk you through the process of trouble shooting step-by-step. I could imagine that you have a problem with wordclock synchronization, a bad audio connection, or maybe even interspersion from a shaky hard disk connector.

    All the best,

    /Dietz - Vienna Symphonic Library