[mythtv] [PATCH] cropping filter, + filterchains bugs

Andrew Mahone andrewmahone at eml.cc
Sun Nov 16 06:39:07 EST 2003

On Sunday 16 November 2003 02:11, D Banerjee wrote:
> Also some stuff is broken in the new filter chains. It seems that the
> filter chain init is hooked in the wrong place, as it continuously reloads
> the filters from disk. In fact while debugging I didn't need to restart
> anything in order to test, but exiting mythtv after chaning the file on
> disk would segfault both mythtv and mythbackend, and at other random times.
> I'm not sure how this is happening. Many times when loading/unloading
> filters (i.e. denoise3d as playback filter) it will also segfault the
> backend on unload, sometimes I get an error from free() complaining of an
> invalid pointer.
> -Debabrata

Filter libraries are opened once for each instance of the filter (this is 
actually pretty much how they were done before, too).  Dlopen should ensure 
that there is actually only one instance of a library loaded at a time.  
There are a number of places that might need a reload sometimes that 
generally will not.  Perhaps LoadFiters could optionally be given a filter 
chain, in which case it would test to make sure that the filter chain matches 
the requested one before it actually rebuilds it?

I have also noticed some segfaults on unload for denoise3d, which seem to go 
away if I use less agressive optimization when compiling.  Denoise3d as a 
playback filter shouldn't be able to crash the backend, however, because the 
backend should not be loading any filters in this case.

  Andrew Mahone
  andrewmahone AT eml DOT cc

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