fons adriaensen wrote: libsndfile already supports the addition of a number of specific chunk types like PEAK, strings in the INFO chunk etc. There is no existing chunk type which does what you require. In addition, it would be a bad idea to define your own custom chunk type to do this. However, it would be possible to add a comment string containing the data you require as a text string. See: http://www.mega-nerd.com/libsndfile/api.html#string HTH, Erik -- +-----------------------------------------------------------+ Erik de Castro Lopo +-----------------------------------------------------------+ "The object-oriented model makes it easy to build up programs by accretion. What this often means, in practice, is that it provides a structured way to write spaghetti code." -- Paul Graham