libsndfile is a C library for reading and writing sound files such as AIFF, AU, WAV, and others through one standard interface. It can currently read/write 8, 16, 24 and 32-bit PCM files as well as 32 and 64-bit floating point WAV files and a number of compressed formats. It compiles and runs on *nix, MacOS, and Win32.
Secret Rabbit Code is a sample rate converter for audio. It is capable of arbitrary and time varying conversions. It can downsample by a factor of 256 and upsample by the same factor. The ratio of input and output sample rates can be a real number. The conversion ratio can also vary with time for speeding up and slowing down effects.
Where is the source code? The license is NOT GPL.
The license on this is supposed to be GPL but the source is
nowhere to be found. In addition the LICENSE file in the
binary distribution contains restrictions in addition to the
GPL. One of these is as follows:
'You may freely use the program provided that you fall into one
of the categories "Private use", "In Non-profit
organizations", "For system administration" and
"For evaluation purposes".
This rules out the use of the program for commercial purposes
and therefore contravenes the GPL.