Methods of using phases to reduce bandwidths or to transport data with multimedia codecs using only magnitudes or amplitudes. Multimedia codecs (compression methods), based only on FFT (Fast Fourier Transform) have recently been proposed. These codecs use the largest dots (foreground) and the most energetic bands (background). Mid-quality versions are based only on the largest local peaks. Phases can be ignored with larger local peaks or in the background. One can also use the amplitudes of the sines and cosines, the phases being recalculated from these amplitudes. This invention describes methods for giving utility to the reintroduced phases, in particular: - The local peaks are grouped so as to have a very narrow bandwidth, the phases containing the displacements of these peaks. - Data is transported in phases, between two multimedia frames or in the background. - We leave the points in their place and we store data in the phases. - We transport the points of the foreground in the phases of the background. Transmissions are made in the time domain after inverse FFT. High speed communications are supported using techniques similar to OFDM (Orthogonal Frequency-Division Multiplexing). These methods are intended to be used in particular with connected objects, in the physical layers of computer networks and in blockchain technologies.
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