OS X Messages
Messages is a video, screen sharing, file transfer, and text-chat platform that ships with OS X 10.8. It supports multiple chat protocols such as AIM, Yahoo, Google Talk, and Jabber, as well as Apple's iMessages protocol. Despite this support, Messages appears to segregate each protocol, meaning that a user with an AIM account cannot communicate with a Yahoo user.
Messages offers only a single option for adjusting the signal: a bandwidth limit (down to 100kbps/12.5kB).
Communications
Weimar and San Diego tested video chat and file transfer using the AIM protocol. Performance was hit and miss. The best aspect was latency, with both sides agreeing that the timing of communications felt natural. Video quality was significantly different on each side: Weimar witnessed crisp imagery from San Diego, while San Diego consistently received blocky video featuring varying degrees of artifacts. Audio dropouts correlated with video performance.
A view of San Diego
A view of Weimar
It's worth noting that at one point, Messages lost connection, throwing an error message and crashing San Diego's cable modem. This is considered worth mentioning, since San Diego had memory of this happening before, in a different city with a different ISP.
File transfers worked well, with recordings for this project exchanged via drag-and-drop into Messages' text chat window. Transfer rates of 135K were reached, and were probably limited only by our ISP services.
Sending Signals
Audio signals were generated by each side, transmitted via Soundflower through Messages, and recorded via Soundflower on the other side. Dropouts were naturally the most significant problem, but in a sine wave test, a strong amplitude modulation would appear and disappear at 50Hz. This is evident in the accompanying screen shot.
A spectrum plot of white noise shows the removal of all frequencies above 6000 Hz, and a roll off of frequencies below 300 Hz.
Pure 1kHz sine from Weimar
White noise from Weimar
White noise from Weimar (spectrum)
