[jazzbo]

Originally Posted by roann

The track stays at the same encoding level, no re-encoding, only shifting bytes.

Shntool (and therefore Trader's Little Helper) will not reencode to compression level 5 when fixing SBEs.

I don't see how it's possible, as it is bytes in the uncompressed audio stream, not the compressed side that need to be moved so the data needs to be piped back through flac by shntool in order to make the correction.

I also tested it, and shntool clearly recompresses at level 5 when doing a SBE fix.

First the original files:

kevin@dizzy:/data2/test$ shntool len *.wav
    length     expanded size   cdr  WAVE problems filename
     6:12.52       65744012    -b-   --   -----   track1.wav
     1:33.32       16479368    -b-   --   -----   track2.wav
     7:46.09       82223380 B                     (totals for 2 files, 1.0000 overall compression ratio)

Compress to flac level 8:

kevin@dizzy:/data2/test$ flac -8 *.wav

flac 1.1.2, Copyright (C) 2000,2001,2002,2003,2004,2005  Josh Coalson
flac comes with ABSOLUTELY NO WARRANTY.  This is free software, and you are
welcome to redistribute it under certain conditions.  Type `flac' for details.

options: -P 4096 -b 4608 -m -l 12 -e -q 0 -r 0,6
track1.wav: wrote 32738704 bytes, ratio=0.498
track2.wav: wrote 7648176 bytes, ratio=0.464

Check the level 8 flac files:

kevin@dizzy:/data2/test$ shntool len *.flac
    length     expanded size   cdr  WAVE problems filename
     6:12.52       65744012    -b-   --   ---xx   track1.flac
     1:33.32       16479368    -b-   --   ---xx   track2.flac
     7:46.09       82223380 B                     (totals for 2 files, 0.4912 overall compression ratio)

Now do a quick fix of the files using shntool's fix mode taking a flac file as input and pushing it back out as a flac.

kevin@dizzy:/data2/test$ shntool fix -o flac *.flac
shntool [fix]: warning: no shift direction specified - assuming backward shift
track1.flac --> track1-fixed.flac ... done.
track2.flac --> track2-fixed.flac ... done.
Padded 'track2-fixed.flac' with 276 zero-bytes.

Let's check the file sizes and confirm the corrections. As you can see the uncompressed stream for track 1 was reduced in size, but the compressed file is now ~90k larger. That is because of shntool recompressing at level 5 rather than retaining level 8.

kevin@dizzy:/data2/test$ ls -l *.flac
-rw-r--r--  1 kevin kevin 32829902 2005-04-16 19:09 track1-fixed.flac
-rw-r--r--  1 kevin kevin 32738704 2005-04-16 19:05 track1.flac
-rw-r--r--  1 kevin kevin  7664871 2005-04-16 19:09 track2-fixed.flac
-rw-r--r--  1 kevin kevin  7648176 2005-04-16 19:05 track2.flac
kevin@dizzy:/data2/test$ shntool len *.flac
    length     expanded size   cdr  WAVE problems filename
     6:12.52       65743148    ---   --   ---xx   track1-fixed.flac
     6:12.52       65744012    -b-   --   ---xx   track1.flac
     1:33.32       16480508    ---   --   ---xx   track2-fixed.flac
     1:33.32       16479368    -b-   --   ---xx   track2.flac
    15:32.18      164447036 B                     (totals for 4 files, 0.4918 overall compression ratio)