Complex sentence: At first, the intent was that the new film be around the same length as "Un Chien", only this time with sound; but by mid- 1930, the film had grown segmentally to an hour's duration.
Split into simpler sentences: At first, the intent was that the new film be around the same length as "Un Chien", only this time with sound. But by mid- 1930, the film had grown segmentally to an hour's duration.