Native Editing

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The Short Answer

Native editing means capturing a particular video format into the computer in the same basic format as it is on tape or a file-based medium like a P2 card. Its not transcoded (converted) into another format for use in the computer. The main benefit- no quality loss to capture the video, and in some cases (if no effects are applied), there is no quality loss when the video is output from the computer. Using DV as an example- on tape it’s a 25 Mbit/sec format, with a 5:1 compression ratio. Once in the computer, its still a 25 Mbit/sec format with 5:1 compression. One of the main benefits of capturing "natively" - the video is easy to work with as there is no other hardware involved in the capture process into the computer - just a simple connection from the camera or video deck to the computer via a single FireWire cable. Additionally, these various native formats have lower bit rates than if captured "uncompressed" through a dedicated I/O board (capture card). Therefore, when editing natively, you can generally get away with smaller, slower hard drives for video storage than when working at higher bit rates.

More Info

Native editing is a relatively new term in non linear editing. Once the video is captured, although its now a computer file instead of videotape- its basically the same video format.

We'll use Final Cut as an example, but the same principle applies to other video editing systems as well. The first "native" format available to Final Cut several years back was DV (Mini DV, DVCAM and DVCPRO). On tape, DV is just a series of 0's and 1's. Its digitally compressed on tape using a particular compression scheme, having a very specific color resolution, compression ratio (in this case 5:1 compression), bit depth and so on. When its captured "natively", there is a similar QuickTime mathematical format in the computer, a codec, which is using the same compression scheme as the DV on tape. After captured, the quality has not changed, its now wrapped in a QuickTime file instead of a videotape, but its still the same video format. There are several video formats that are supported natively in Final Cut, Avid and other video editing software. To date, one thing that all these video formats share in common is that their connection to the computer editing system is a single FireWire cable (also called iLink) connecting the camera or deck. Although not all of these formats are available on all editing systems natively, some formats that are capable of native editing in a variety of systems currently include DV, HDV, DVCPRO 50, DVCPRO HD, AVC-Intra, XDCAM HD and EX. Average consumers are becoming more aware of FireWire, as its now found on even the most inexpensive home camcorders, inexpensive hard drives and other peripherals.

Advantages Of Native Editing

Because the video is not captured "uncompressed" there is a substantial savings in bandwidth- in other words, you can get away with cheaper, slower hard drives for video storage. Yet there is no compromise in quality, no extra compression- nothing about the video is really changed on capture into or back out of the computer (in the case of DV, it still has a 5:1 compression, but no extra compression has occurred).

Here’s an example of the storage savings:

• DV has a bit rate of approximately 3.5 MBytes/sec.
• If the video is captured natively, the bit rate remains the same.
• If the video is captured using an uncompressed codec (through a dedicated capture card), the data rate can spike to 20-30 Mbytes/sec.

If captured natively, the video can be stored on many of today's relatively inexpensive FireWire hard drives. If captured uncompressed, the FireWire drive would not be fast enough. Some sort of more expensive video RAID is needed (multiple drives "striped" together to act as one really fast hard drive).

One of the big stories lately is how people are converting their aquisition format to the format called DVCPRO HD, one of Panasonic's HD video format. The David Fincher film Zodiac was shot using the Viper camera (a high end digital camera with resolution coming close to film resolution), then the high end digital files output from the camera were converted into DVCPRO HD for offline editing. The format has data rates almost as low as DV so storage is not an issue. The quality is fantastic, so the editors were able to work at a good resolution. The quality was even good enough that they used the results of their offline edit for some pre-screening purposes. Of course, for the final theatrical release, the filmmakers went back to their original high end source material to conform the final film prints. There are other codecs that are used for offline editing that are not native formats, but DV and DVCPRO HD have been popular now for several years for offline editing.

So native editing can be used for final finishing (online) or just for offline editing purposes.

Disadvantages Of Native Editing

Although its quick and easy to work with video natively, there are some things to consider. If the video will require heavy effects work- like chroma keying or will require multiple "passes" of effects, then this could cause a problem with natively captured video. Using DV again as an example, DV has a 5:1 compression ratio, a 4:1:1 color space and 8-bit depth. First off, trying to manipulate the video for intense effects work will be limited to this resolution. Second, when effects are applied to native video, the video must be re-compressed to incorporate the effect (this is referred to as rendering). If this is done over and over, it can lead to a build up of visual artifacts in the video, and the overall quality will start to decline. Although it should also be mentioned that since we are working with digital component video, the quality loss after one generation of recompression would probably never be noticed and you probably couldn't see a difference in the original video and the final recompressed video. If no effects are applied, then the video leaves the computer without any recompression- and stays at the same quality of the original.

For heavy effects work, titling and graphics it is preferable (if the budget allows) to capture the original compressed video into an uncompressed color space in the editing system, allowing the video to be more easily manipulated with effects, leading to potentially better final results. No recompression happens in this process. The only time compression comes back into the mix is when layed off to tape. If the tape format is high quality, like a Digital BETACAM, then the tape's mild compression won't cause any noticeable quality loss. If output back to a highly compressed format, like DV, then the advantages of working uncompressed are lost, as the video will take on the compression of that tape format.