rtDVT using MPEG2 [4 : 2 : 2] compression and a bandwidth of 40 Mb/s did not effectively differ from the original video images in routine tele-endoscopy. The qualitative requirements in diagnostic video endoscopy, however, are obviously much higher than previously assumed, since experienced endoscopists detected a loss of image quality and a reduction in diagnostic usability with any reduction in the technical specification. Modern methods of data compression, broadband networks and a network protocol with good quality-of-service guarantees are therefore prerequisites for diagnostic rtDVT.

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With the continuous increase of network capacities, video transmissions in medicine are becoming an effective tool for second opinion diagnosis, archiving and teaching environments. This study investigates video compression delay times and transmission impairments for different compression formats and describes the resulting picture qualities. For the evaluation endoscopic video sequences were produced with different compression formats and bandwidth requirements. In a second step an impairment tool was used to introduce error rates to the video material to simulate network behavior. A group of medical experts evaluated the video sequences rating visibility of errors, artifacts, sharpness, overall picture quality and suitability for a medical diagnosis. The results clearly establish lower boundaries for picture quality deteriorated by compression and network impairments, and introduce limits for medical assessments.

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This investigation provides performance measurements over layer 2 and layer 3 connections across the European testbed MUPBED, the German testbed VIOLA and the German Research Network X-WiN. The analysis first evaluates Quality of Service (QoS) parameters delay and jitter of layer 2 tunnels across both testbeds and includes an assessment of the jitter behavior of high-bandwidth video transmissions using several hundred Megabit/s. The layer 2 measurements are then compared to layer 3 traffic behavior of the German Research Network. In an additional case study, the results of the measurements are applied to the transmission of uncompressed video and consequential quality perception in connection with Forward Error Correction (FEC) mechanisms and QoS requirements for interactive high-quality applications.