The HD Bottleneck

Fun little reminder from Ars Technica on just how hard it is going to be to get the vaunted "triple play"—voice, data, and video all on the same wire—into American homes. This is important as the entire regulatory framework of telecom at both the state and federal level assumes the triple play is right around the corner, that the cable and phone duopoly will actually compete for customers, Wire vs. Wire.

Not so fast. Eric Bangeman explains:

Voice and data are no problem. Plug your VoIP-capable router into a phone jack and you've got phone service throughout the house. And 802.11g can transmit data faster than it can be downloaded over the vast majority of Internet connections. High-definition video is the sticking point.

MPEG2 HD video streams need an average of 10 to 18Mbps of bandwidth, with a peak somewhere between 13 and 19Mbps. When you add DVR-like functions such as fast-forward, rewind, and other modes to the equation, the bandwidth can spike to nearly 60Mbps. A typical scenario of a single HDTV stream, 2 SDTV double hops (e.g., going from , and a single ATSC digital TV stream requires anywhere from 50 to 84Mbps, with the upper ceiling hitting 148Mbps if all four streams were performing DVR-like functions simultaneously.

Plus content providers will insist that all HD content that enters the home is wrapped in some protective DRM sheath. Not impossible to overcome hurdles—Bangeman provides some likely solutions—but not exactly like flipping a switch, either.