An advanced sampling rate conversion technique for video and graphics signals

We propose an advanced sampling rate conversion technique for TV applications, which enables high-quality conversions for both video and graphics signals. The converter has to satisfy two important constraints in order to obtain high-quality conversion. Firstly, the filter characteristics need to be adjusted to the statistics of the input signal (graphics vs. natural video scenes). Secondly, the system should operate well for both compression and expansion. It is known that high-quality compression is more difficult to realize, because the output signal may suffer from aliasing due to the required filtering of the baseband spectrum. The inequality between compression and expansion was solved by transposing the converter starting with the architecture for expansion based on a polyphase filter. This proposal is attractive because the transposed structure inherently prefilters the input signal according to the compression factor. Promising simulation results proved that high-quality conversion was indeed obtained in both cases