[vorbis-dev] Problems trying to run the examples in windows v orbis sdk

[Chris Parsons]

> On 9/4/2001 at 6:00 PM Pablos-Sanchez, Rolando wrote:
> 
> >I have compiled the example 'encoder_example.c' just to start, and it
> >compiles, but I got a error in the following line just at the beginning: 
> >vorbis_encode_init(&vi,2,44100, -1, 128000, -1);
> >The error is more or less: The instruction at '0xaddresss' referenced
> >memory at '0xaddress'. The memory could not be "read".
> 
> The work around for this problem is to include vorbisenc.c in the vorbis
DLL and not have a
> separate, stand alone vorbisenc.dll.  If you do this, then this problem
disappears.  Obviously,
> since the vorbisenc code is quite large, and a lot of applications will
only be decoding, this
> is not a permenent solution.
> 
> This may have to do with how global data is treated in DLLs, which is that
each client gets a 
> fresh instance of the global data.  The problem seems to be accessing
_time_P accross DLLs
> (vorbisenc.dll accessing _time_P in vorbis.dll)  I'm thinking of trying a
named data segment.

That is exactly what the case is.  There is only a couple of ways to savely
access global data across DLL's in Windows, probably the safest is to use
CreateFileMapping() with a named memory space.  This way if the space was
already created by a previous instance of the DLL it will open that space
and not create a new one.  It used to be possible to pass global pointers
across DLL's in Windows 3.x and to some extent with Win 9x, but it's more or
less down right illegal in Win NT x.  It is legal however for a memory space
allocated with GlobalAlloc to be passed to the calling application (or DLL)
by handle.

Chris

--- >8 ----
List archives:  http://www.xiph.org/archives/
Ogg project homepage: http://www.xiph.org/ogg/
To unsubscribe from this list, send a message to 'vorbis-dev-request at xiph.org'
containing only the word 'unsubscribe' in the body.  No subject is needed.
Unsubscribe messages sent to the list will be ignored/filtered.