Re: [Mxflib-developers] Overriding file IO in mxflib

[Matt B. <ma...@be...>]

At 15:51 02/02/2004, Mathew Spencer wrote:
>Hi all,
>
>I am currently working on wrapping mxflib so that it can be used as a 
>plugin to a gstreamer pipeline (for those that don't know gstreamer, its 
>an open source direct-show style streaming media framework.  See 
>http://freedesktop.org/~gstreamer ).

Ack.


>For me to be able to do this, I need to be able to abstract the file IO 
>functions.  There seems to be some support to do this already through use 
>of the MXFLIB_NO_FILE_IO,

Yes, this was added to allow the library to be used with DirectShow.

>but under linux, using this flag causes problems with klvlib's file io 
>functions as KLVFile is hard coded to FILE*.

Hmm, not sure why, but I am currently re-working the code to remove klvlib 
dependency so it should go away soon...

>Is anyone aware of this problem?  Is there a recommended solution to this 
>problem?
>
>Could I suggest a list of callback functions to be used (much as in a 
>linux device driver) with a set of defaults defined for the currently 
>supported platforms.  This should also allow the removal of duplicate 
>function declarations in mxflib's system.h.

I would be interested in a few more details of this proposal - at the 
moment if you specify MXFLIB_NO_FILE_IO then the client code provides file 
I/O functions with the same name as the normal library ones.  This should 
be about as efficient as possible without adding stream code to the library.

>I am willing to supply a patch to achieve this (although I am only able to 
>test under Linux here).

Is this really necessary? - if you believe so then I would be happy to look 
at the code.


>Regards,
>
>Mat


Matt