On Sat, May 04, 2013 at 03:01:11AM +0200, Nils Gey wrote:
  Hello list,
 libsndfile-info shows various useful information like the one at the end of this mail.
 I have Sonatina Symphonic Orchestra waves here (violins 1) and a one note wave includes
"Midi Note", "Loop Count" and "Cue Start : 92078  End :
223977", which is the actual loop start/end
 Is this custom data or does it follow a standard?
 And no matter what, how do I write that into my own wave files?
 I would prefer command line tools. But programming interfaces are fine as well. 
Nils and all,
Wikipedia says:
        Metadata
        As a derivative of RIFF, WAV files can be tagged with
        metadata in the INFO chunk. In addition, WAV files can embed
        Extensible Metadata Platform (XMP) data. Applications may
        not handle this extra information or may expect to see it in
        a particular place. Although the RIFF specification requires
        that applications ignore chunks they do not recognize, some
        applications are confused by additional chunks.[citation
        needed]
Is it possible these "standards" could be among those the
courts humbly bid that Microsoft open to the uncouth gaze of
slobbering masses? (Providing court-ordered data on file
formats used internally is an area that seems to attract
the most lackadaisical and error prone MS employees.)
Otherwise, there is plenty of code to study.
This parser reveals what data structures it expects...
if you speak C.
https://metacpan.org/source/AGRUNDMA/Audio-Scan-0.93/src/wav.c
Here is a metadata parser/writer for diverse file types.
https://metacpan.org/module/EXIFTOOL/Image-ExifTool-9.27/exiftool
HTH,
Joel
 Greetings,
 Nils
 $ sndfile-info test.wav
 Version : libsndfile-1.0.25
 ========================================
 File : test.wav
 Length : 896548
 RIFF : 896540
 WAVE
 fmt  : 16
   Format        : 0x1 => WAVE_FORMAT_PCM
   Channels      : 2
   Sample Rate   : 44100
   Block Align   : 4
   Bit Width     : 16
   Bytes/sec     : 176400
 data : 895916
 *** SAUR : 512 (unknown marker)
 smpl : 60
   Manufacturer : 0
   Product      : 0
   Period       : 22675 nsec
   Midi Note    : 76
   Pitch Fract. : 0
   SMPTE Format : 0
   SMPTE Offset : 00:00:00 00
   Loop Count   : 1
     Cue ID :  0  Type :  0  Start : 92078  End : 223977  Fraction :     0  Count :     0
   Sampler Data : 0
 End
 ----------------------------------------
 Sample Rate : 44100
 Frames      : 223979
 Channels    : 2
 Format      : 0x00010002
 Sections    : 1
 Seekable    : TRUE
 Duration    : 00:00:05.079
 Signal Max  : 31468 (-0.35 dB)
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--
Joel Roth