[FFmpeg-devel] [PATCH] fix --enable-runtime-cpudetect --disable-amd3dnow compilation

Alex Converse alex.converse
Tue Sep 7 12:48:24 CEST 2010

On Sat, Sep 4, 2010 at 7:08 PM, Michael Niedermayer <michaelni at gmx.at> wrote:
> On Fri, Sep 03, 2010 at 06:06:11PM -0400, Alexander Strange wrote:
>> CC ? ? ?libswscale/swscale.o
>> ...
>> libswscale/swscale.c: In function ?ff_getSwsFunc?:
>> libswscale/swscale.c:1268: warning: implicit declaration of function ?sws_init_swScale_3DNow?
>> libswscale/swscale.c:1269: error: ?swScale_3DNow? undeclared (first use in this function)
>> libswscale/swscale.c:1269: error: (Each undeclared identifier is reported only once
>> libswscale/swscale.c:1269: error: for each function it appears in.)
>> Alternatively, it could declare prototypes for sws_init_swScale_3DNow / swScale_3DNow even if they aren't being compiled.
>> That would let us use "if (COMPILE_TEMPLATE_AMD3DNOW && flags & SWS_CPU_CAPS_3DNOW)" instead of #ifdefs. But it might make some of the other templating more complex.
> the code was designed for 2 cases
> 1. runtime cpu detection (for distros) to support whatever cpu the user has
> 2. compiletime detection (for an individual user) to support his cpu

Is there substantial overhead in using runtime cpudetect (1) for an
individual users CPU (2)? dsputil and av_fft don't support compiletime
CPU detect on x86 and everyone seems ok with that.


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