On Fri, Dec 24, 2010 at 06:51:18PM +0100, Jörn Nettingsmeier wrote: > On 12/24/2010 06:07 PM, Q wrote: > > Out of interest, how high can intersample peaks get above the highest > > peaks in a file? > > imagine the positive half of a sine wave, so that two consecutive > samples representing the very top of the wave are at 0dBFS. it is clear > that between those samples, the real peak value of the sound must be > higher than 0dBFS, and the reconstruction filter will see this higher > value. that means unless your analog stage has headroom for this, it > will clip. the higher the frequency, the higher above full scale those > inter-sample peaks can be. In theory it could be any value. In practice it's limited by the lenght of the antialiasing filter. You get the maximum output for a series of samples at max amplitude (+ or - 1) and matching the sign of the IR of the filter at half a sample delay. For example, if '+' means a sample of +1, and '-' a -1, then the sequence of 20 samples: -+-+-+-+-++-+-+-+-+- will produce of peak of more than 8 dB above FS. It's very unlikely to get such a sequence with natural sounds, but quite possible with synthetic signals or when using agressive mastering techniques. Ciao, -- FA There are three of them, and Alleline. _______________________________________________ Linux-audio-user mailing list Linux-audio-user@xxxxxxxxxxxxxxxxxxxx http://lists.linuxaudio.org/listinfo/linux-audio-user
