July 2, 2009

Multimedia Codecs, Compression, and Streaming in 3G-324m

Thanks to Christoph K. for this clear and expert post about 3G videocalling 3G video telephony generally operates over a single 64 kbit/s connection where both parties need to share the available bandwidth. Effectively, the application then is left with 60 kbit/s, or less that are dedicated for both media types, since H.245 call control messages reduce the gross bandwidth. In 3G-324M systems, the bandwidth is allocated dynamically; however, generally said, every party has 50% of the bandwidth available for sending audio and video signals. In a typical unidirectional scenario, 12.2 kbit/s are allocated for the speech codec, and a bitrate of 43-48 kbit/s is allowed for the video data (Sang-Bong, Tae-Jung and Jae-Won). By employing rate control methods in the media encoders, the network can dynamically change these bitrates depending on network conditions and application demand. When two parties […]