Practical DV FilmMaking

In terms of a ratio of information kept to that thrown away, mini-DV is 5:1, compared to 7:1 for analog Hi8 and 15:1 for VHS. How well a camera squashes down its information is crucial. The new generation of HD cameras have suffered from a poor compression method. It remains a problem for manufacturers to convince the market about HD because the recorded picture is so reduced from what it should be, given the huge size of each frame of HD video.

What happens when the image gets recorded onto tape

Digital tape is much more rugged than that used for analog S-VHS or VHS video. It is made of an advanced form of metal evaporated (ME) tape. It consists of a double-coated magnetic layer, which is in turn coated in tough carbon. This enables stored digital information to be played back with minimal loss of quality and less picture noise, or interference. 'Bleeding' from the audio track to the video tracks is also unlikely, further reducing interference.

Solid-state cameras record onto discs but have to use a sophisticated form of compression to enable it to do so. In consumer models images are recorded onto a fixed hard drive or onto DVDs, though the latter have failed to take off in the consumer sector in the way manufacturers would have liked. Cameras using hard drive recording have become more widely used, possibly a result of the iPod effect, where consumers understand and trust mini hard drives. A further development has been in removable hard drives. For filmmakers using cameras such as the Canon XZ2 or Sony PD170, the favourites of many low-budgeteers, hard drive recording was not possible until large removable 80 GB drives such as Holdan's Firestore made it to industry shows.

Compression

Format

MB/second

How many minutes of video for 1 GB on your PC

1:1

Broadcast

18.5

0.5

2:1

Direct transfer

9.3

1

3:1

Digi-Beta SP

6.2

2

4:1

Beta SP Pro

4.6

3

5:1

Beta Semi-Pro

3.7

4

5:1 in camera

Mini-DV

3.6

4

7:1

Hi-8, S-VHS Pro

2.6

6

10:1

Hi-8, S-VHS

1.85

9

15:1

VHS

1.2

14

Figure 2.2 Compression rates of camera formats.

Recording standards

There are several other factors that are worth mentioning in relation to recording. If you intend to make movies or programmes for selling in other countries, you need to know about the differences in broadcast standards around the world. Ultimately, this affects anyone who makes films because few people can afford to ignore the potentially lucrative returns in foreign markets. None of these problems are insurmountable, but being aware of them before you start a project can increase your chances of selling your work to a wide range of markets.

PAL, NTSC and SECAM

Each country has