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Digital Video Editing
- — 28 October, 2005 14:44
- Potential to reality - Software, the missing link
- What you will need for hassle free video editing
- Why does video take up so much hard drive space?
- What is Firewire?
- Firewire Vs USB
- Video editing software
Why does video take up so much hard drive space?
Video is a continuous stream of still images that our brains interpret as motion. In Australia we use the PAL TV system, which has 25 image frames every second, each made up of 720 by 576 pixels.
Non-compressed video data creates huge files. For example, a 10-second uncompressed video file can take up to 340MB. That's 34MB of data per second. In order to just capture a 20-minute video file, over 40GB of storage space would be required. To get around this problem, compression formats were devised to dramatically reduce file size, yet retain acceptable quality. These compressors work by throwing out data unimportant to the overall quality of the image.
Compression formats include:
- Motion-JPEG (M-JPEG): This is capable of producing up to S-VHS quality video files. It was the most popular high quality video editing compression format until the arrival of DVD.
- MPEG (Motion Professional Experts Group): These formats provide a variety of different compression and video resolution options to suit different ways of watching video. MPEG-1 was developed for the VideoCD format, which allows over an hour of VHS quality video to fit onto a 650MB CD. MPEG-2 delivers a high quality low compression video file able to produce DVD quality video and audio. MPEG-4 offers a variable compression rate, making it perfect for delivery of video over the web at different connection speeds. DivX, an extremely popular and un-ratified format, is a derivative of MPEG-4.
- DV: This is the format used by DV camcorders and is similar in quality to MPEG-2, although it is usually at a lower compression rate. Many video camera enthusiasts are surprised to hear that the DV footage that comes straight out of a camcorder is compressed (usually at 5:1). The main reason for this is to save space (one hour of uncompressed video would take up around 120GB) and also, no commercially available PC system is able to deal with the transfer rates needed of around 34MBps.
- Other web compression formats popular for web videos include Indeo, Cinepak and the popular Apple Quicktime, which in is very similar to MPEG-4.
Assuming you already have your DV camcorder and software application, the only addition to a standard PC needed for editing DV is a Firewire card. Many PCs now come with Firewire (also known as iLink or IEEE1394) although USB 2.0 is more common. Many camcorders offer USB 2.0 functionality as well as Firewire, which is useful for creating streaming video and the occasional DVD movie. However, Firewire is still the best way to deal with DV, as it offers greater control over the camcorder during the video transfer process and the transfer technology is more reliable.