The variations of the compression degree and of pulse contrast are dependent on shape, parameters of the medium, type of applied compressor, inhomogeneity of the pulse phase along the beam profile, and limitations by competing nonlinear processes. Numerical simulations showed the possibility of effective compression of self-modulated pulses of Joule energy level without much deterioration of their contrast. The supercompression regime of self-modulated and modulated pulses with supergaussian-shaped envelopes lead to a compression degree tens of times greater than those obtained through chirped pulse amplification technique. Using pulses with supergaussian shapes also decreased chip distortions.