The 200ms latency 'wasn't possible' because of how TCP congestion control works. Spotify used to use 2 channels for downloading - the first chunks would come from their servers, then you would try and download the rest of the song and do read-ahead on the p2p network. Consequently, the TCP connection to their servers would be idle for a bit causing the congestion window size to drop back to 1 segment (1500 bytes) in size. Over higher latency networks (wireless), TCP slow-start could take up to a couple of seconds to get up to speed, as you need a RTT to increment the segment size. Spotify's trick was to build (compile, more likely :)) a version of TCP on their servers that prevented the congestion window from connected clients from dropping back.
The 200ms latency 'wasn't possible' because of how TCP congestion control works. Spotify used to use 2 channels for downloading - the first chunks would come from their servers, then you would try and download the rest of the song and do read-ahead on the p2p network. Consequently, the TCP connection to their servers would be idle for a bit causing the congestion window size to drop back to 1 segment (1500 bytes) in size. Over higher latency networks (wireless), TCP slow-start could take up to a couple of seconds to get up to speed, as you need a RTT to increment the segment size. Spotify's trick was to build (compile, more likely :)) a version of TCP on their servers that prevented the congestion window from connected clients from dropping back.