[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
Thu Jan 14 08:11:43 PST 2010

Hi again,

I tested lower cumul_gain limit values. In fact, I reduced the value to 240000, 230000, 220000, ..., 20000, 10000, 5000, 2000, 1000, 500.  (quality 7, complexity 2)

For input signal 2000 Hz, the values 190000, 130000, 60000, and 1000 look o.k., all others don't. For 500, the (zoomed out) waveform shows some kind of amplitude ripple -- i think, this value is definetely too low.
I tested the good values for 2200 Hz input, too. Only the value 1000 looks more or less o.k. (no huge instability, but some kind of visible "artifact" inside the fade in after the frame loss), for the other values the codec is not stable.

So, this does not seem to be a solution. Any further ideas what to test?

best regards,

Jean-Marc Valin <jean-marc.valin at usherbrooke.ca> hat am 14. Januar 2010 um 13:15 geschrieben:

> What happens if you change that line:
> if (cumul_gain > 262144)
> to use a smaller value? What value works OK (if any)?
> One more thing, when things go wrong, do they eventually go back to
> normal or does the codec never recover? It's unavoidable that the audio
> goes bad for a short period of time because of the long-term predictor.
>         Jean-Marc
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