Popular wireless networking technology Wi-Fi seems to be everywhere from corporate offices to the corner coffee shop. If a group of Manhattan-based activists are correct, Wi-Fi may be appearing soon on a television screen near you.
“We had our first one hour live television cablecast Mar. 12,” says
Kenyatta Cheese, co-director of the Manhattan Neighborhood Network
(MNN).
MNN, the organization responsible for administering public access television in the Big Apple, began testing a portable television production platform composed of consumer-grade video cameras with off-the-shelf computer gear, using a Wi-Fi-based broadband Internet connection for distribution.
While refinement of the remote broadcasting set-up is needed, MNN, along with cable content producer LocationOne, successfully broadcast a short video segment using Wi-Fi.
The project is an “attempt to break away from classical TV production requiring hundreds of thousands of dollars,” but even more, the series of tests is a clear sign of the growing utility of 802.11 technology.
The video clip was produced using a consumer-grade camcorder, an Apple 802.11b Airport card, laptop and a Wi-Fi network in Manhattan’s Bryant Park.
While broadcast-quality video is often defined as 640-by-480 pixels at 30 frames per second (fps), MNN found viewers would accept 320-by-240 video doubled in size moving at 8fps. The group says 8fps is acceptable for watching short video clips of 30 seconds or less. A video rate of 15 fps is the minimum for the human eye to notice fluid motion, according to the organization.
Sending Wi-Fi Video
In the first test, conducted Jan. 14, the group used the Bryant Park Wi-Fi network to transfer an MPEG file over the Internet to a computer at MNN headquarters and then broadcast via cable.
The first test revealed consumer video gear coupled with a Wi-Fi Internet connection “offers a viable framework for distributed TV production via the Internet,” according to MNN Co-Director and Internet guru Kenyatta Cheese.
But there was room for improvement: mainly the weather. The cold January day dealt a blow to the battery life (under 90 minutes) for both the camcorder and the laptop’s CPU. A fast CPU is needed to encode the video at the 15 fps required for fluid motion. Also, the lack of many users on the frigid winter day did not reflect the demand on bandwidth a warmer day might create.
Wi-Fi Brooklyn Style
A second test took place February 7 using a Wi-Fi access point in the Clinton Hill section of Brooklyn. This time, the laptop’s battery was giving the computer’s CPU full power. Unlike the relatively quiet network in January, this access point — a node of the NYCWireless public Wi-Fi network — was located between two other nearby free hotspots, all operating on the same channel. The higher activity level provided a better glimpse into how video could be transmitted under real-world network loads with signal interference.
Despite the challenges, the group sent a 300 kbps video and audio stream over the Internet back to a studio for more than 12 hours. Although the public access group was able to achieve the desired 15 fps video rate, blocky “artifacts” remained in the broadcast version.
The third test, held the next day, exploring a Linux-based setup. This trial was able to achieve even better results, streaming video at 15 to 20 fps by replacing a USB video capture device with a PCI video capture card.
Now that the group has optimized images to fit the constraints of
mobile broadcasting, “our next step is to make it easy for anyone to
take their laptop and camera out to a Wi-Fi hotspot, connect to our
server and send a live video stream to the cable channel,” says
Cheese.
