  Wavelet frames for $L^2({\mathbb R})$ can be characterized by means of
spectral techniques. This work uses spectral formulas to determine all the
tight wavelet frames for $L^2({\mathbb R})$ with a fixed finite number of
generators of minimal support. The method associates wavelet frames of this
type with certain inner operator-valued functions in Hardy spaces. The cases
with one and two generators are completely solved.
