Speex dev - Dec 2009 - Fwd: Fixed Point on wideband-mode: Single Frame loss on 2000 Hz sine causes "freak off"

An update:

I found that the "ADD32: output is not int:" messages are caused by
the enhancer. When I turn the enhancer off, the messages vanish, but the
"freak out" of the codec is still there - so the problem seems not to
be related to the overflow messages.

best regards,
Frank


---------- Urspr?ngliche Nachricht ----------
Von: Frank Lorenz <Frank_wtal at web.de>
An: speex-dev at xiph.org
Datum: 18. Dezember 2009 um 13:36
Betreff: [Speex-dev] Fixed Point on wideband-mode: Single Frame loss on 2000 Hz
sine causes "freak off"

Hi,

I'm quite sure we found a bug inside the codec (1.2rc1, wideband mode). It
only
occurs when speex is compiled with the FIXED_POINT flag.

I feed in a 2000 Hz sine wave (-15 dBFS). When I simulate a single frame loss
(i.e. pass a null pointer to speex_decode_int as second parameter for just one
frame), the decoder
starts to freak out a second later: It produces horrible noise with 0 dBFS. This
horrible noise will not vanish until you turn off the input signal.

I did some investigation on this with FIXED_DEBUG. The error messages are (lots
of this):
ADD32: output is not int: 1702286034 in ltp.c: line 68
ADD32: output is not int: 1455757562 in ltp.c: line 69

Call stack for this (only set the break point once, may be there are other call
stacks on error, too):

sb_decode ( ) at sb_celp.c:898
nb_decode ( ) at nb_celp.c:1471
multicomb ( ) at filter.c:709
interp_pitch ( ) at filter.c:603
inner_prod ( ) at ltp.c:68

Can you help please?

best regards,
Frank
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