Pat Murphy's fascinating documentary on the silk weavers of Uttar Pradesh in northern India begins at sunrise and ends in the steamy evening. Tana Bana is just 78 minutes long, yet it manages to pack an enormous amount of information within its beautifully appointed frame.

We meet the men at the loom, the designers of the saris and the chaps who sell the garments. “Madam, whatever sari you wear looks really good on you,” a universal salesman says to an older lady (as they all do).

It hardly needs to be said that the trade is threatened by computerisation and globalisation. Along the way, Murphy ties the new technologies in with the old. One of the designers now originates patterns on a computer. Later he colours in a grid whose individual cells look eerily like pixels. The cards that drive the looms were, of course, among the earliest types of computer programme.

Such connections are left to the viewer in a film that, while rich with luscious shots of fabrics, dye and crumbling architecture, remains rigorous in its focus on the aesthetics and economics of this ancient industry. A closing myth concerning the Buddha connects the film to the ages.