Specifications
13
A Digital Video Primer
What makes DV better than analog video?
ere are many benets of the standard DV format, particularly when compared to analog
devices like VHS decks and Hi-8 cameras:
• Superior images and sound: A DV camcorder can capture much higher quality video than
other consumer video devices. DV video provides 500 lines of horizontal resolution, compared
to about 250 for VHS, resulting in a much sharper and higher quality image. Not only is the
video resolution better, so is the color accuracy. DV sound, too, is of much higher quality. DV
can provide better-than-CD quality stereo sound recorded at a sampling rate of 48 kHz, and bit
depth of 16 bits.
• No generation loss: Since the connection to your computer is digital, there is no generation loss
when transferring DV. You can make a copy of a copy of a copy of a DV tape, and it will still be
as good as the original.
• No need for a video capture card: Because digitization occurs in the camera, you don’t need an
analog-to-digital video capture card in your computer.
• Better engineering: e quality of DV videotape is better than what analog devices provide.
Plus, the smaller size and smoother transport mechanism of the tape means DV cameras can
be smaller and have more battery life than their analog counterparts.
Is DV perfect?
e image quality of the DV format has been tested by both human and mechanical means.
is testing ranks DV quality with Beta-SP, which has been the mainstay for professional video
production for decades. But DV is not perfect.
Because the video is compressed, it may include visible quality degradations, known as com-
pression artifacts. ese artifacts, which result from the color compression, are most noticeable
around sharp color boundaries like white text on a black background. e lower color sampling
(4:1:1) in DV compression can also cause problems when performing professional compositing.
Also, compression adds noise to the picture. If DV is repeatedly decompressed and then recom-
pressed, the quality of the image degrades noticeably. is process is dierent from copying DV
from generation to generation without processing, which is lossless.
While DV isn’t perfect, it is certainly the highest-quality, most cost-eective standard deni-
tion video format ever made for the average consumer and many professionals. e entire video
industry has been transformed by the low cost and high quality of the DV solution.
DV variations
ere are a many variations to the DV format, including but not limited to:
• Sony Digital8: A prosumer-targeted variation that oers the same data rate and color sampling
as DV25, but at a slightly lower resolution. e Digital8 camcorder is designed to accommodate
customers who want to move up to digital video, but who might have a signicant investment
in analog Hi-8 movies. e Digital8 camcorder records digitally on Hi8 videotape cassettes,
but it can also play back analog Hi-8.
• Sony DVCAM and Panasonic DVPRO or DVCPRO: ese formats use the same DV25 compression
as DV, but record less video on each tape. Putting less data on the tape makes the record-
ing more durable and facilitates better interchange between devices. Both the DVCAM and
DVCPRO systems are designed with the professional in mind for applications such as elec-
tronic news gathering. e DVCAM and DVCPRO tape and tape shells are more durable than
standard DV or miniDV, and the gear is typically more rugged and higher quality overall.
• Sony DV50, Panasonic DVPRO50 or DVCPRO50, and JVC D-9 (Digital-S): As the name suggests,
DV50 video streams at 50 Mbps. e format oers 4:2:2 color sampling and lower compression
than DV25, making the video quality of this standard extremely high, suitable for the most
demanding professional broadcast purposes. Variations allow for progressive scanning.
• DV100, DVPROHD and D-9 HD: Used for HD (high denition) recording, DV100 oers a data
rate of 100 Mbps and 4:2:2 color sampling.
HDVTHE NEXT GENERATION
In October, 2003, four leading video equipment
manufacturers (Canon, Sharp, Sony, and JVC) nalized
the specication for a new consumer/prosumer digi-
tal video format that records and plays back HD video
on standard DV or miniDV cassettes. Since then, HDV
camcorders have been released by all of the above
manufacturers, at steadily decreasing prices: from
$1,500 for consumer models to $10,000 for models
aimed at professionals.
HDV uses MPEG-2 compression to record 720p (pro-
gressive) or 1080i (interlaced) HD formats, supporting
frame rates of 25p, 30p, 50p, and 60p for 720p at a
data rate of 19 Mbps, and 50i and 60i for 1080i at a
data rate of 25 Mbps. Audio is recorded using 16-bit,
48 kHz, MPEG-1 Audio Layer-2 encoding at 384 Kbps.
Although the size of the picture is larger (1280 x
720 for 720p and 1440 x 1080 for 1080i), the actual
resolution is about the same as standard DV, using
4:2:0 color sampling. Newer models have added 24P
support for digital cinema use.