[Speex-dev] Fwd: Re: Fixed Point on wideband-mode: Single Frame loss on 2000 Hz sine causes "freak off"

Frank Lorenz Frank_wtal at web.de
Mon Feb 1 08:27:26 PST 2010


Hi Jean-Marc,

dBFS means dB relative to digital full scale. In other words: a sine value of -42 dBFS will, on a 16 bit PCM signal, swing between 131 and -131 only (16384 * 10^(-42/20))
So we are far below +/-8000.

At the moment, I'm out of ideas how to debug systematically. That even very small rounding errors alter pitch values fundamentally makes the situation worse for me, because it means that the huge differences in pitch between fixed and floating point are not neccessary part of the problem.
Do you have some tips for me how to proceed?

cheers,
Frank
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