Please provide a VFP-optimised build for ffmpeg-debian

[Emmet Hikory]

Some ARM processors support vector floating point, which can cause significant improvements in the performance of floating point code. As this must be selected at compile-time, with the -mfpu=vfp CFLAG, this requires a special build.

For performance reasons on such hardware, please enable such a build for ffmpeg-debian for jaunty.

[Riku Voipio (riku-voipio)]

This is probably one of the few libs where many versions is granted (since the upstream provides excellent hand-optimised routines):

-armv5
-armv6+vfp
-armv7+neon

This leaves suboptimal cases for armv5+vfp users (kirkwood) and armv6 without vfp (nothing significant). Neither of these cases are on multimedia-oriented devices (at least for now), so it should be acceptable tradeoff.

[Reinhard Tartler (siretart)]

Does the dynamic linker provide hardware detection for loading shared libraries?

E.g. on powerpc, the ffmpeg package installs the optimised build in /usr/lib/altivec on altivec enabled machines. I'd need to know the directory name and the configure switch that needs to be enabled.

[Reinhard Tartler (siretart)]

The configure option needed should be --enable-vfp. If someone with arm could confirm that the switch works and provide me with the pathname the dynamic linker searches for on arm, it can be added trivially

[Reinhard Tartler (siretart)]

could someone with arm please provide the output of the following
command? The following is from i386, in order to fix this, the output on
armel is needed.

>> LD_LIBRARY_PATH=/lib:/usr/lib LD_DEBUG=libs /bin/true
      1023: find library=libc.so.6 [0]; searching
      1023: search path=/lib/tls/i686/sse2/cmov:/lib/tls/i686/sse2:/lib/tls/i686/cmov:/lib/tls/i686:/lib/tls/sse2/cmov:/lib/tls/sse2:/lib/tls/cmov:/lib/tls:/lib/i686/sse2/cmov:/lib/i686/sse2:/lib/i686/cmov:/lib/i686:/lib/sse2/cmov:/lib/sse2:/lib/cmov:/lib:/usr/lib/tls/i686/sse2/cmov:/usr/lib/tls/i686/sse2:/usr/lib/tls/i686/cmov:/usr/lib/tls/i686:/usr/lib/tls/sse2/cmov:/usr/lib/tls/sse2:/usr/lib/tls/cmov:/usr/lib/tls:/usr/lib/i686/sse2/cmov:/usr/lib/i686/sse2:/usr/lib/i686/cmov:/usr/lib/i686:/usr/lib/sse2/cmov:/usr/lib/sse2:/usr/lib/cmov:/usr/lib (system search path)
      1023: trying file=/lib/tls/i686/sse2/cmov/libc.so.6
      1023: trying file=/lib/tls/i686/sse2/libc.so.6
      1023: trying file=/lib/tls/i686/cmov/libc.so.6
      1023:
      1023:
      1023: calling init: /lib/tls/i686/cmov/libc.so.6
      1023:
      1023:
      1023: initialize program: /bin/true
      1023:
      1023:
      1023: transferring control: /bin/true
      1023:

--
Gruesse/greetings,
Reinhard Tartler, KeyID 945348A4

[Steve Langasek (vorlon)]

The version of ffmpeg-debian which appears to fix this has been accepted into jaunty. Changelog:

ffmpeg-debian (3:0.svn20090303-1ubuntu6) jaunty; urgency=low

  * vfp CFLAGS: add "-mfpu=vfp -mfloat-abi=softfp".

 -- Loic Minier <email address hidden> Fri, 10 Apr 2009 21:34:29 +0200

ffmpeg-debian (3:0.svn20090303-1ubuntu5) jaunty; urgency=low

  * Disable more autodetected ARM arch features.
  * Add neon and vfp flavors to armel disabled for now.
  * Enable vfp pass on armel; leave the neon disabled.

 -- Loïc Minier <email address hidden> Fri, 10 Apr 2009 17:58:52 +0200