The decision to pay the extra fees and move from
dial-up to broadband usually involves meeting three wants: faster
downloads, faster uploads and live streaming video.
The transmission of live streaming video is
dependent on bandwidth, video codecs and the ability to transmit as
many frames per second as possible. Let’s review how these variables
effect video on dial-up and broadband.
First a little background on bandwidths and
speeds. A lot of people use the terms bandwidth and speeds
interchangeably, so it’s important to clarify the difference. Think
of a water pipe. You can get more water through the pipe by
increasing the pressure to send it through faster. This increases
the “speed.” You can also get more water out the end by increasing
the size of the pipe. This increases the “bandwidth”
When you go from a dial-up ISP to a broadband ISP,
you increase the size of the pipe by getting more bandwidth. This
way you can get more data through the pipe in the same amount of
time, thus allowing faster uploads and downloads. Video is data,
too, but good video requires enormous amounts of data. Because of
this, video is often referred to as a bandwidth hog. When you
increase the bandwidth, you allow more video through in the same
amount of time.
Programmers can use creative and complicated
mathematical formulas called algorithms to put the data into packets
that allow more packets to go through the pipe. This is comparable
to increasing the speed of the water in the pipeline. In the world
of video, the algorithm is called a codec. Well known codecs include
MPEG-4, MPEG-2 and JPEG.
In order to evaluate codecs, a definition of
quality is necessary. The number of frames per second (fps) is
usually the objective measurement of video quality. “Broadcast
quality video” is an overused term that typically means 25 to 35
fps. Independent of theoretical rates, most live video streamed on
the internet through broadband is in the range of 10 to 15 fps. It’s
not like HDTV or like movies in the theater, but it is sufficient
for the purpose.
JPEG transmits video like a movie. Each full
picture frame from the “film strip” is transmitted and viewed. When
the individual pictures, called frames, are accumulated together
rapidly, they appear to display motion, just like a film strip.
MPEG-2, MPEG-4 and others don’t send a full frame
each time. They send what’s called an I-Frame, which is a full
frame, only once in a while. In between the I-Frames, they only send
the video data that change. So, if the image is from a fixed camera
in a room where someone is walking, the wall doesn’t change, so the
image of the wall is not sent with each frame. Only the spots where
the person is moving are transmitted between the I-frames. This
eliminates a lot of data without changing the quality of the video.
So, with the same amount of data, the end result can be more frames
per second. This is why MPEG-2 and MPEG-4 are said to offer higher
quality video.
What is bandwidth? Bandwidth is the amount of data
that can be sent in a second, typically measured in kilobits per
second (kbps). Did you ever notice how TV reporters on satellite
phones sometimes look weird? They are usually transmitting at very
low bandwidths of less than 5 fps. Have you asked yourself why cell
phone voice plans typically can only transmit still video images, or
video clips that are so slow that motion is not apparent? That’s
because their maximum bandwidth is 9.6 kbps, also considered very
low.
Cell phone data plans and dial-up telephone
service fall in the less than 56 kbps range. Broadband is above 56
kbps. Cable companies typically offer it in 128 kbps or 256 kbps
increments. However, these are maximum rates. For example, dial-up
telephone usually fluctuates between 30 and 45 kbps in the real
world, even though it is theoretically 56 kbps.
MPEG-4 and its many variants are pretty much the
standard for sending video over broadband. Many different companies
have developed their own unique twist to try to take into account
variations in bandwidth that result in interruptions, pixilation and
video tears. But, with a 256 kbps bandwidth, video can stream on
average at 10 to 15 fps, and may even peak at 20 or 25 fps depending
on the fluctuation. Unfortunately, on dial-up, the number of frames
per second that these standard codecs can deliver is less than 5
frames per second, and often only 1 frame per second.
Some new video codecs are allowing frame rates of
12 fps over dial-up services, in many ways comparable to the video
offered over broadband. This has expanded the ability to transmit
quality video through dial-up.
To summarize the water pipe analogy, different
video codecs can increase the water flow by increasing the number of
frames per second at the end of the pipe without increasing the size
of the pipe. Switching from dial-up to broadband is a way to
increase the size of the pipe so that more frames per second can
come out the end of the pipe.
Cost is always a consideration, with dial-up being
less expensive. Also, many people worldwide do not have the
availability of broadband, so dial-up is their only option.
Comet Video Technologies develops products and
services for the low bandwidth transmission of video through
satellites, cell voice plans, cell data plans, telephone dial-up and
broadband. http://www.cometvt.com
Readers have permission to duplicate and
distribute the above article in its entirety. We request that the
final paragraph be included in each reproduction.
Howard Becker is CEO of Comet Video Technologies.
For the past 20 years, Becker has been CEO of consumer product and
video technology companies as large as $25 million in sales, as well
as a consultant for start-up technology companies. He has an MBA is
from the University of Chicago and a BS from Rensselaer Polytechnic
Institute and is a former CPA with Big Four Experience. He developed
the first published integration of the Fama-Miller efficient market
model and the Black-Scholes Option pricing model, thus creating a
theoretical justification for the trading of derivitives on index
funds. He is author of a number of published papers on semiconductor
based heating elements, as well as a paper on the objective
measurement of job placement for individuals with disabilities.
