[Vorbis] Crash in mdct_forward

[matthew.tennant at symbian.com]

Hello all,
        I am playing around, trying to get an OggVorbis encoder 
implementation working on the Symbian OS. 
Unfortunately I am getting a crash - here is the stack

vorbis_analysis_blockout
_ve_envelope_search
_ve_amp
mdct_forward
free
User::Free(void *)
RHeap::Free(void *)
RHeap::GetAddress(const void *)const 
RHeap::CheckCell(const RHeap::SCell *)const 
Panic(TCdtPanic)
User::Panic(const TDesC16 &, int)

In the case here the free call is doing something very bad 
(like for example freeing some memory already freed). Hence the crash.
Perhaps my entire vorbis configuration is broken before 
the vorbis_analysis_blockout call - this would explain the crash
Here is some logging of the vorbis APIs that are being called before the 
crash happens:-

       88.675   Called vorbis_analysis_buffer with int vals = 1024
       88.675   Called vorbis_analysis_wrote with vals = 1024
       88.675   about to call vorbis_analysis_blockout (returned 0)
       88.700   Called vorbis_analysis_buffer with int vals = 1024
       88.700   Called vorbis_analysis_wrote with vals = 1024
       88.700   about to call vorbis_analysis_blockout (returned 0)
       88.725   Called vorbis_analysis_buffer with int vals = 1024
       88.725   Called vorbis_analysis_wrote with vals = 1024
       88.725   about to call vorbis_analysis_blockout
       88.730   Thread MMFAudioServer.exe::Local-0134f468 Panic USER 42

A quick search of Google shows that my particular callstack has occured 
before - in 2002.
 At that time it was fixed by 
monty at xiph.org. That may or may not have been a related problem.
(http://trac.xiph.org/cgi-bin/trac.cgi/ticket/216)

Does anyone have any ideas on how to fix this?



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