[Bug 1690] libvorbis 1.1.1 compiled by GCC4 fails to produce correct files

blfs-bugs at linuxfromscratch.org blfs-bugs at linuxfromscratch.org
Thu Nov 17 08:27:52 PST 2005


http://blfs-bugs.linuxfromscratch.org/show_bug.cgi?id=1690





------- Additional Comments From sknolli at astro.physik.uni-goettingen.de  2005-11-17 09:27 -------
Compiling libvorbis 1.1.1 with
  $ ./configure --prefix=/usr
  $ make
  $ make install
using
  $ gcc --version
  gcc (GCC) 4.0.2
Note that the CFLAGS set by the package are:
  -O20 -ffast-math -mno-ieee-fp -D_REENTRANT -fsigned-char  -DUSE_MEMORY_H

Now convert a wav --> ogg by
  $ oggenc -q 4 -o test1.ogg track01.cdda.wav
  Opening with wav module: WAV file reader
  Encoding "track01.cdda.wav" to 
           "test1.ogg" 
  at quality 4,00
          [100,0%] [ 0m00s remaining] | 

  Done encoding file "test1.ogg"

          File length:  3m 34,0s
          Elapsed time: 0m 32,8s
          Rate:         6,5504
          Average bitrate: 156,4 kb/s

Listen to it, it will sound bad. Hissing etc.

Now again to libvorbis:
  $  patch -Np1 -i ../libvorbis-1.1.1-gcc4-fix_optimization-1.patch
  $ ./configure --prefix=/usr
  $ make
  $ make install
CFLAGS used here are the same as above:
  -O20 -ffast-math -mno-ieee-fp -D_REENTRANT -fsigned-char  -DUSE_MEMORY_H

Trying the encoding again:
  $ oggenc -q 4 -o test1.ogg track01.cdda.wav
  Opening with wav module: WAV file reader
  Encoding "track01.cdda.wav" to 
           "test2.ogg" 
  at quality 4,00
          [ 99,7%] [ 0m00s remaining] / 

  Done encoding file "test2.ogg"

          File length:  3m 34,0s
          Elapsed time: 0m 31,8s
          Rate:         6,7622
          Average bitrate: 126,3 kb/s

Note the different bitrate as compared to the first run.  Playing the second
file now reveals the quality difference.

The setting -q 4 is supposed to be a traget bitrate of ~128kB/s, the difference
might be less audible when using a higher setting like -q 8 or so.

As to libvorbis-1.1.0 vs. 1.1.1: The bug was discovered in 1.1.0 but wasn't
fixed until recently, so also affects 1.1.1.

HTH,
Cheers,
Steffen



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