[Ffmpeg-devel] sse sigsegv and libavcodec/wmadec.c

[Benjamin Larsson]

Michael Niedermayer skrev:
> Hi
>
> On Thu, Dec 07, 2006 at 10:43:17AM +0100, Benjamin Larsson wrote:
>   
>> Rich Felker skrev:
>>     
>>> On Thu, Dec 07, 2006 at 10:16:22AM +0100, Benjamin Larsson wrote:
>>>  
>>>       
>>>> How about to malloc all "sse" buffers. We are talking about 2-3 buffers 
>>>> in 1or 2 codecs.
>>>>    
>>>>         
>>> Is there any permenant place to keep them in the codec context? Global
>>> vars and per-run malloc/free are both out of the question I would think...
>>>
>>> Rich
>>>  
>>>       
>> No but it should be as easy as adding it to the wmacontext.
>>     
>
> yes but these arent the only stack arrays which are affected, theres
> alot more in the mmx code all ovr ffmpeg, its just that the mmx code doesnt
> crash but rather runs slower (which then makes ffmpeg look slow compared to
> other applications on windows ...)
>
> [...]
>   
Ok, and should we care about this ? I don't see how the mmx case can be 
fixed cleanly in source. To me that's the job of the compiler. There was 
a patch that allocated arrays with some extra elements and then aligned 
the array pointer. That is the only way I think it could be done 
reliable in source. But then we would need to pollute all the code that 
uses stack arrays.

MvH
Benjamin Larsson