How much storage is required in DVD to digitised 2hour English movie?

Answer 1

As much or as little as desired. For the highest quality, you'll want as little compression as possible, which obviously requires more space. A single-layer, single-sided DVD is capable of storing up to 4.7GB, which is enough for 2 hours of DVD-quality video, including audio.

The exact space required will be determined by the original resolution of the video, and the adaptive bit rate required to compress it, which will vary from 3Mbit/s to 9.5Mbit/s. DVD-video also supports up to 8 simultaneous audio channels per video, allowing the user to choose between stereo and multi-channel options, or alternate audio tracks such as different languages or commentaries. The more audio channels there are, the more compressed the video needs to be, which sacrifices quality.

However, single-sided dual-layer DVDs can store up to 4 hours of DVD-video, leaving a lot more space for the audio tracks without sacrificing video quality. The downside is that there will be a perceptible pause during playback when the layer switch is encountered, unless the playback device incorporates a large enough buffer to compensate. That said, a well-authored DVD will typically place the layer switch during an appropriate scene change to minimise the disruption.