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

[Jean-Marc Valin]

Hi Frank,

Sorry, I *do* care about the problem and just happen to be overworked at 
the moment. What I suspect is that the pitch gain gets close enough to 
unity that the loss makes it bust. Did you test with the floating-point 
code?

	Jean-Marc

On 2010-01-13 03:45, Frank Lorenz wrote:
> Hi,
>
> is no one willing to spent some effort on this topic? At least it would
> be good
> to know if anybody can reproduce this problem.
>
> I did further investigation on the topic and found out that the encoder
> in fixed
> point mode produces absolutely different pitch and pitch gain parameters
> than in
> floating point mode (for a 2000 Hz input signal). The codec breaks on
> frame loss
> if the encoder is in fixed point mode, decoder doesn't matter, so I
> assume the
> pitch parameters are "bad".
> Maybe its caused by accuracy/rounding problems for this periodic signal?
>
> Because I do not know much about the internals of Speex, it's hard for me to
> analyse the pitch / pitch gain computation. Some help would be really
> nice...
>
> best regards,
> Frank
>
>
>
> ---------- Ursprüngliche Nachricht ----------
> Von: Frank Lorenz <Frank_wtal at web.de>
> An: speex-dev at xiph.org
> Datum: 4. Januar 2010 um 09:57
> Betreff: Re: [Speex-dev] Fixed Point on wideband-mode: Single Frame loss
> on 2000
> Hz sine causes "freak off"
>
>
> Hi Jean-Marc, all,
>
> I didn't get any response to my issue up to now and would like to now if
> anyone
> can reproduce this behaviour and if there is some idea what happens. I am
> willing to fix this issue, but because I do not know the internals of
> speex, I
> need some advice on how to proceed...
>
> best regards,
> Frank
>
>
>
> Frank Lorenz <Frank_wtal at web.de> hat am 21. Dezember 2009 um 10:49
> geschrieben:
>
>  > 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
>  >
>  >
>  > ---------- Ursprüngliche 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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