[FFmpeg-devel] Question about -fPIC usage for some files

Loren Merritt lorenm
Sat Feb 9 07:14:09 CET 2008

On Sat, 9 Feb 2008, Michael Niedermayer wrote:
>> apply_welch_window_sse2 has six constraints:
>>         :"+&r"(i), "+&r"(j)\
>>         :"r"(w_data+n2), "r"(w_data+len-2-n2),\
>>          "r"(data+n2), "r"(data+len-2-n2)\
>> It only fails if that's inlined; I think the VLA use is breaking it:
>>     double tmp[len + lag + 2];
> btw, it seems that whoever wrote this missed a quite obvious optimization
> opertunity, that is:
> len-n2 = n2

I missed that because it's not true for odd len. Still ok; sse2 needs a 
separate case for even and odd anyway.
Odd len isn't used in any of the flac presets, and might not be useful, 
but is currently allowed by ffmpeg -frame_size

--Loren Merritt

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