# 14.10 `sndhdr` -- Determine type of sound file

The `sndhdr` provides utility functions which attempt to determine the type of sound data which is in a file. When these functions are able to determine what type of sound data is stored in a file, they return a tuple `(type, sampling_rate, channels, frames, bits_per_sample)`. The value for type indicates the data type and will be one of the strings `'aifc'`, `'aiff'`, `'au'`, `'hcom'`, `'sndr'`, `'sndt'`, `'voc'`, `'wav'`, `'8svx'`, `'sb'`, `'ub'`, or `'ul'`. The sampling_rate will be either the actual value or `0` if unknown or difficult to decode. Similarly, channels will be either the number of channels or `0` if it cannot be determined or if the value is difficult to decode. The value for frames will be either the number of frames or `-1`. The last item in the tuple, bits_per_sample, will either be the sample size in bits or `'A'` for A-LAW or `'U'` for u-LAW .

`what`(filename)
  Determines the type of sound data stored in the file filename using `whathdr()`. If it succeeds, returns a tuple as described above, otherwise `None` is returned.

`whathdr`(filename)
  Determines the type of sound data stored in a file based on the file header. The name of the file is given by filename. This function returns a tuple as described above on success, or `None`.