2002 - cesnet
2002 - cesnet 2002 - cesnet
22 Special VideoconferencesThis project was focused on high-quality videoconferences. Our goals can bedivided into two categories. The first one is to design a suitable testing methodologybased on findings achieved in 2001 and prepare appropriate testingmaterials for it. The second objective is to utilize these materials for the actualevaluation of selected devices. As a final consequence, our activities lead tobuilding of the infrastructure needed, which will allow expanding the spectrumof services provided by CESNET.As their name indicates, the special videoconferences are intended for a certain(special) category of users, which is delimited clearly enough in thesedays. This is given by the specific needs of this category of users and especiallythe technical requirements resulting from these needs. The devices involvedare not easily available or routinely used, but utilize state-of-the-art technologies.This brings both the corresponding technical demands for the operatorsand significant expenses for the equipment and for ensuring the actual videobroadcasts.Special videoconferences are currently applied mainly in the area of humanand veterinary medicine, biology, chemistry, pharmacology, etc. Their greatdemands are determined by several key parameters.The first parameter is the high resolution. The TV PAL standard is consideredto be the minimum, i.e., digital processing of 720 × 576 pixels at the frequency of50 frames per second according to CCIR 601. However, the required resolutionthat we have to take into account for the future corresponds more to the HDTVstandard.Another important parameter is the colour accuracy. A video recording orbroadcast with distorted colours is useless for medical diagnostics. The mostimportant is the dynamic behaviour of the entire video chain. In this type ofvideoconference, image degradation that would cause image disintegrationmust not occur. A video that becomes “pixelated” is, of course, unsuitable anduseless.The digitalized TV signal has high bandwidth demands. The transfer of raw datawould be very demanding for the network throughput. That is why the datahave to be compressed substantially. Lossy compression methods are used,which have a strong negative effect on the resulting quality of the video transferred.It is the most crucial modification of data throughout their path.The migration to new IP-based technology represented the essential problemfor operation of high-quality videoconferences and video broadcasts. The IPbehaviour, wide range of technologies in the market and definition of minimalparameters for specific ways of use influenced the selection of a suitable device.210 High-speed National Research Network and its New Applications 2002
First of all, we had to define an appropriate testing methodology. Initially, atthe end of 2001 and the beginning of this year, we were attempting to transmitstatic or computer generated images in laboratory conditions. This simplifiedapproach turned out to be useless. Results were degraded by significant errors.In this period, we tested several borrowed devices. However, because thesubsequent evaluation indicated that we did not use suitable tests, we have torepeat this testing.After a new problem analysis, we defined the testing methodology and preparedseveral testing video sequences in compliance with the experience of leadingEuropean and world workplaces (such as GDM). The video sequences areoriented on the most common errors that occur in practice. We also recordedseveral testing videos where no problems should arise. These videos are usedas reference/comparative materials.By the time this report was written, we had created video sequences for testingdynamic states, colour representation and shape accuracy, and other potentialflaws. All testing videos are now available at the workplace of VFU Brno.The following tests were created:1. tests of dynamic states• snail with vertigo• straw movement• sewer rat blood collection2. colour representation tests• cow surgery (white, red, green)• crocodile surgery (red shades, skin colour component)• snake surgery (white, red)3. shape distortion tests, colour distortion tests• endoscopy of reptile airways with a halogen bulb• endoscopy of reptile airways with a xenon bulb4. tests of improperly illuminated videos• lecture with a strong side illumination• lecture with a low-level illumination, recorded from a greater distance(degraded by noise)5. comparative tests• lecture with normal illumination• chemical laboratory recording (clear liquid, blue shades)In the following period, we plan to further increase the number of testingrecords according to our needs. We practically evaluated the new tests usingborrowed equipment and a testing workplace of a cooperating company. Forthe tests, we used several cards by Optibase with different performance levels.High-speed National Research Network and its New Applications 2002211
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First of all, we had to define an appropriate testing methodology. Initially, atthe end of 2001 and the beginning of this year, we were attempting to transmitstatic or computer generated images in laboratory conditions. This simplifiedapproach turned out to be useless. Results were degraded by significant errors.In this period, we tested several borrowed devices. However, because thesubsequent evaluation indicated that we did not use suitable tests, we have torepeat this testing.After a new problem analysis, we defined the testing methodology and preparedseveral testing video sequences in compliance with the experience of leadingEuropean and world workplaces (such as GDM). The video sequences areoriented on the most common errors that occur in practice. We also recordedseveral testing videos where no problems should arise. These videos are usedas reference/comparative materials.By the time this report was written, we had created video sequences for testingdynamic states, colour representation and shape accuracy, and other potentialflaws. All testing videos are now available at the workplace of VFU Brno.The following tests were created:1. tests of dynamic states• snail with vertigo• straw movement• sewer rat blood collection2. colour representation tests• cow surgery (white, red, green)• crocodile surgery (red shades, skin colour component)• snake surgery (white, red)3. shape distortion tests, colour distortion tests• endoscopy of reptile airways with a halogen bulb• endoscopy of reptile airways with a xenon bulb4. tests of improperly illuminated videos• lecture with a strong side illumination• lecture with a low-level illumination, recorded from a greater distance(degraded by noise)5. comparative tests• lecture with normal illumination• chemical laboratory recording (clear liquid, blue shades)In the following period, we plan to further increase the number of testingrecords according to our needs. We practically evaluated the new tests usingborrowed equipment and a testing workplace of a cooperating company. Forthe tests, we used several cards by Optibase with different performance levels.High-speed National Research Network and its New Applications <strong>2002</strong>211
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