Technische Beschreibung
On November 26, 1995, SWF (a German broadcaster), in cooperation with GMD, Deutsche Telekom and SGI, recorded the award ceremonies for Video Only (an international video art competition) in a virtual studio that was delivered in real time over ATM. Live camera tracking data from the recording site - a blue room studio in Baden-Baden - was sent to GMD in Bonn over 300 km away. Using an SGI Onyx/RealityEngine2, GMD rendered the virtual studio in sync with the remote camera motion and sent back a broadcast quality signal for both the background and the accompanying mask to SWF over a SDH/STM1 ATM connection. The virtual studio was then chroma-keyed with the live camera signal and recorded. In addition, to compare performance and quality, a second camera was connected to a local virtual studio system. This was, to the authors' knowledge, the first use of a distributed virtual studio for a broadcast video production. The configuration of the involved video components used for the Baden-Baden test is shown in figure 5 below. The video equipment in the Baden-Baden test generally accepted serial digital video (CCIR 601 4:2:2) connections with a data rate of 270 Mbps. Each ETSI encoder compressed the 270 Mbps 4:2:2 data stream to a 34 Mbps E3 signal. A E3/ATM terminal adapter was used to transmit these 34 Mbps streams over 2 ATM virtual channel connections (VCCs) of 40 Mbps each, using AAL-1 constant bitrate circuit emulation yielding a total load of 80 Mbps on the ATM link. Tracking data was sent via a separate 32 kbps VCC within the same 155 Mbps ATM connection. The Baden-Baden test successfully demonstrated the viability of remote rendering of a virtual studio via ATM. During the nearly two hours used for the production (which was broadcast after editing) there were no network problems, the remote signal was stable and of the same apparent quality as the local signal, and the additional delay introduced by the network was negligible (ATM delay from Bonn to Baden-Baden was 4 ms).
Cf.: BREITENEDER, Christian; GIBBS, Simon; HEIDEN, Wolfgang; KAUL, Manfred; STEINBERG, Dirk; WASSERSCHAFF, Markus: DISTRIBUTED VIDEO PRODUCTION OVER ATM, http://viswiz.gmd.de/DVP/Public/publ/ecmast96/final.htm