This invention solves problems due to employing error degraded data in digital processing. It particularly solves multi-generation problems wherein transform data degrade during each inverse transform and forward transform cycle even without any processing due to the rounding and clipping errors. It provides methods, systems and devices for reduced-error processing of transform-coded data. After inverse transformation of transform data, high-precision numbers are converted to integers and clipped to an allowed range forming converted data. High-precision differences are obtained by subtracting the high-precision output of the inverse transform from the converted data. The converted data can be manipulated and sent to output devices which expect integer data. Processed high-precision numbers are formed by adding the high-precision differences to the processed converted data. Thus, the rounding and clipping errors are greatly reduced in the processed high-precision numbers. The processed high-precision numbers are used for further processing including forward transforming back to the transform domain. In another embodiment of the present invention processed high-precision numbers are generated by selecting the high-precision numbers instead of the manipulated converted data whenever the manipulated converted data still equals the converted data. Although advantageous to many applications employing digital transformed data, the invention is particularly advantageous for use in digital studios during editing of MPEG-coded, JPEG-coded and wavelet-coded video and audio data.