English to Italian Art/Literary Cinema, Film, TV, Drama editing techniques

Here is the context - it is a question to a film director about the reasons behind shifting from 'traditional' editing (on film) to digital editing. I am struggling with the Italian translation for 'film rushes', 'sund rushes' and 'mag stock'. I found a definition for 'mag stock' but I cannot find a standard Italian translation for it:
http://www.creativeglossary.com/film/mag-stock--mag-track-ma...

Here is the sentence in question:
We needed to print the sound rushes on mag stock and also printing all the film rushes. Which was very espensive.

Thanks very much in advance for your help!