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Subject: Silent Play definitely relates to bit-swapping
From: Michael O'Quinn (michael_at_oquinn.info)
Date: 2003-04-12


Since I can now reproduce this error at will on virtually any song, I've
noticed that the silence really isn't silent. It's filled with a series
of distinctive pops, clicks, and sometimes chirps. This "non-silence" is
the same each time a passage is played silently, but it's different for
each song.

I just took the latest source ("rockbox-daily-20030411.tar.gz") and
compiled it to confirm it works. I then disabled bit-swapping altogether
by...

*** mpeg.c.old Fri Apr 11 15:44:11 2003
--- mpeg.c Fri Apr 11 15:44:58 2003
***************
*** 38,42 ****
  #endif

! extern void bitswap(unsigned char *data, int length);

  #ifdef HAVE_MAS3587F
--- 38,42 ----
  #endif

! /* extern void bitswap(unsigned char *data, int length); */

  #ifdef HAVE_MAS3587F
***************
*** 1241,1245 ****
                               amount_to_swap);

! bitswap(mp3buf + mp3buf_swapwrite, amount_to_swap);

      mp3buf_swapwrite += amount_to_swap;
--- 1241,1245 ----
                               amount_to_swap);

! /* bitswap(mp3buf + mp3buf_swapwrite, amount_to_swap); */

      mp3buf_swapwrite += amount_to_swap;

...and recompiling.

With this build, when I play songs they have the exact same blurps at the
exact same places as when the Silent Play Feature activates on a normal
build.

Hence, Silent Play is NOT a problem reading from the disk, but IS a
problem with bit-swapping.

Michael



Page was last modified "Jan 10 2012" The Rockbox Crew
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