[FFmpeg-user] Disable decoder for shared library

[Carl Eugen Hoyos]

tyler wear <tylerbwear <at> gmail.com> writes:

> libavcodec/libavcodec.so: undefined reference to `ff_fft_calc_neon'
> libavcodec/libavcodec.so: undefined reference to `ff_fft_fixed_calc_neon'
> libavcodec/libavcodec.so: undefined reference to `ff_fft_permute_neon'

I know this isn't your fault, but all ia32 and 
intel64 compilers / linkers I ever tested reported 
in which object files they found unresolved symbols...

> collect2: ld returned 1 exit status
> make: *** [ffprobe_g] Error 1
> 
> full configure command:
> 
> ./configure --enable-cross-compile
> --cross-prefix=.../codesourcery/arm-2010q1/bin/arm-none-linux-gnueabi-
> --cc=.../codesourcery/arm-2010q1/bin/arm-none-linux-gnueabi-gcc

(100% unrelated: Is it really necessary to specify 
both a cross-prefix and an identical complete path 
to gcc? I never used cross-compilation.)

> --arch=arm --target-os=linux --enable-armv5te --disable-armv6 
> --disable-mmx --enable-shared --disable-doc --disable-htmlpages 
> --disable-manpages --disable-podpages --disable-txtpages 
> --disable-avdevice --disable-swresample --disable-swscale
> --disable-postproc --enable-small --disable-avfilter --disable-debug
> --disable-ffserver --disable-ffplay --extra-cflags=-fPIC 
> --enable-gpl  --disable-network  --disable-zlib
> --disable-ffmpeg  --disable-encoders --disable-decoders

It is absolutely possible (and even likely) that there 
is a bug, but since I honestly don't see how this 
configure line makes any sense and I cannot reproduce 
the problem on intel64, I suggest you simply add 
--enable-fft.

If you want to fix this yourself, search for the file in 
libavcodec/arm that is missing an "#if CONFIG_FFT" and 
add it there, don't forget to send a patch.

Carl Eugen