The speech file should be recorded at 16 bits/sample, 8000 samples/second, and named "pre_g726.wav".
The files, containing test vectors, which are supplied with the G.726 specification, should be copied to itutests/g726 so the files are arranged in the same directory heirarchy in which they are supplied. That is, you should have file names like
itutests/g726/DISK1/INPUT/NRM.M itutests/g726/DISK1/INPUT/OVR.M itutests/g726/DISK2/INPUT/NRM.A itutests/g726/DISK2/INPUT/OVR.A
in your spandsp source tree. The ITU tests can then be run by executing g726_tests without any parameters.
To perform a general audio quality test, g726_tests should be run with a parameter specifying the required bit rate for compression. The valid parameters are "-16", "-24", "-32", and "-40". The file pre_g726.wav will be compressed to the specified bit rate, decompressed, and the resulting audio stored in post_g726.wav. pre_g726.wav must be a valid wave file containing a single channel of 16 bit linear PCM data, at 8000 samples/second.