Capture or play back audio with the specified sample
      format. Specify one of u8, s16le,
      s16be, s32le, s32be,
      float32le, float32be, ulaw,
      alaw, s32le, s32be,
      s24le, s24be, s24-32le,
      s24-32be. Depending on the endianess of the CPU the
      formats s16ne, s16re, s32ne,
      s32re, float32ne, float32re,
      s32ne, s32re, s24ne,
      s24re, s24-32ne, s24-32re (for
      native, resp. reverse endian) are available as aliases. Defaults
      to s16ne.