[FFmpeg-trac] #1241(avcodec:new): ffmpeg

FFmpeg trac at avcodec.org
Sun Apr 22 12:02:33 CEST 2012


#1241: ffmpeg
---------------------------------+---------------------------------------
             Reporter:  nadav    |                     Type:  defect
               Status:  new      |                 Priority:  normal
            Component:  avcodec  |                  Version:  unspecified
             Keywords:           |               Blocked By:
             Blocking:           |  Reproduced by developer:  0
Analyzed by developer:  0        |
---------------------------------+---------------------------------------
 == Environment ==
 || OS || Ubuntu 11.10 ||
 || RELEASE || 0.10.2.git ||
 || Platform || Android ||
 || neon || --disable-neon ||
 || optimizations || --disable-optimizations ||

  == Problem ==
 || Problem || ffmpeg build is trying to compile 'neon' although this
 instruction set is disabled @ ./configure ( '--disable-neon' ) ||
 || Symptom || libavcodec/libavcodec.so: undefined reference to
 `ff_pred16x16_vert_neon' ... ||
 || Analysis || The problem is in affect ONLY when compiling with
 '--disable-optimizations', going though the code, at multiple places the
 line 'if (HAVE_NEON)' is used, my assumption is that when the optimizer is
 on, the 'if (HAVE_NEON)' phrases are omitted from compilation, and, when
 the optimization is disabled, they ( neon phrases ) are not, and thus, the
 import table for neon instructions @ 'if (false)' phrases is added the
 neon instructions ( although they are not used by the code ), and this,
 leads to the undefined reference linker error. ||

-- 
Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/1241>
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