D2.3 Interim Report on Pilot Services - the School of Engineering ...

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Being able to use archived material subtitled with conventional teletext subtitlesContinue to use our existing teletext authoring systemBeing able to author and playout both types of subtitles when simulcasting onanalogue and digital channelsThere was a long list of requirements for deciding on a transcoder system, the mostimportant were these: Clean graphic presentation of the subtitlesKeeping the original teletext formattingMaximum compatibility to existing end devices (set top boxes)Maximum variety of design features (e.g. graded transparency)In the end RBB tested three transcoder systems with 13 set-top-boxes. These includedpopular older boxes and the most popular new boxes on the market in Germany. Theobjectives of this test was to find not only the best production system but also the “bestend device”, a user friendly device which showed the DVB-subtitles broadcast by RBBin a problem free manner. This was to be the device to be given to the 50 RBB testers asa test device. For the tests, the different transcoder modules received a pre-produced testtransport stream encompassing the teletext data. A DVB-T modulator then broadcast aDVB-T signal including DVB-subtitles to the different end devices. The result shownby each of the receivers with each of the transcoder modules was examined according anumber of criteria like functionality, usability or readability. Both conventional screensand LCD screens were tested. All major different layout options were tested likestripe/banner, box, and outline/shadow with different fonts. Given the fact that we aretalking about “mature technology” the test results were quite disheartening. In the end,only four set-top-boxes were found to bring satisfying results with the best transcodermodule that was finally chosen by RBB. One of these four boxes turned out to bringslightly better results than the others and was chosen to be handed out to the testers as itwas felt to be important for the testers to have a problem free depiction of the DVBsubtitles.The most obvious problem was depicting a transparent background. Most boxes hadproblems with depicting that and showed corrupted letters without any background atall. Another problem was displaying a box or a banner/stripe, in some instances the TVscreen went completely black and only the subtitles were shown. The “outline” modewas the best option for most boxes, meaning that the subtitles were readable but in someinstances not shown as envisaged in the “outline” mode but in boxes or banners.Although, this mode was not displayed in the correct way in the case of many boxes atleast the subtitles could be read when shown not in “outline” but in a box or otherdifferent ways. RBB will get back to the manufacturers of the set top boxes andrecommend that all but one of the 13 boxes should be improved.In the end, one transcoding system, the FAB Subtitler, and one testing device, thePhilips DTR 220, were chosen.Page 26
Problems with subtitle trans-coding1. Three line subtitle problemDuring the process of transcoding teletext subtitles to DVB subtitles RBB experienced afew difficulties. One immediate problem was the faulty presentation of triple-spacesubtitles. Triple space subtitles are only used in one regular programme originating fromone of RBB’s partner broadcasters. However, as this is the main nationwide newsprogramme at 8pm people were considerably irritated. In teletext the triple-space text isrealised by showing the first two lines as one teletext page and by instantly adding athird line as another page, but without removing the former one. The DVB subtitletranscoder did not accept the “do-not-remove” tag and deleted the first two lines oncethe third one was to be presented. Thus, only the third line was shown and most of thesubtitle information was lost for the viewer. Additionally, there was a text positioningproblem. The first two lines where presented in the middle for a few milliseconds, butthe third line removed the first ones and appeared left-aligned, so that the viewerexperienced not only fragmented but also jumping text.The transcoder manufacturer was able to avoid this faulty presentation behaviour bychanging the software into accepting the “do-not-remove” tag. Currently the triplespaceDVB subtitle presentation is much better, both the alignment and the entireness.2. “Jumping subtitles”Another faulty pattern that should not have occurred at all was what we call “subtitlejumping”. The picture below shows one example of this: the teletext subtitles are leftaligned both as a text block and concerning the single lines, the DVB subtitles arecentred and the lines are also centred. Something like this happened in different textpositions. However, there was not a regular pattern at first sight, it all happened in avery arbitrary way sometimes the positioning was right, sometimes not, so theimpression is of “jumping text“ which is very irritating. Nearly all the different textpositions of the teletext are presented in the wrong way in such an “irregular manner”.Of course the basic requirement was to have DVB-subtitles that looked exactly the samein terms of position as the original teletext subtitles. What was done to solve thisproblem was to analyse the teletext input going into the transcoder system. Seven suchfaulty positioning patterns were identified. The teletext authoring / editing system usesspace characters to position the subtitles on the screen. Transformation of this alignmentdata is not really working inside the subtitle editing software. The DVB ST Transcodercannot interpret several sequenced space characters. The solution is that the softwarereads and considers spaces and can calculate the subtitle position within the screenwidth. The manufacturer is now working on that problem. A possible forced centrealignment as a work around was not a satisfying option.Page 27
Page 1 and 2: COMPETITIVENESS AND INNOVATION FRAM
Page 3 and 4: 1 Executive SummaryThis report cove
Page 5 and 6: Gaps in knowledge of the efficacy o
Page 7 and 8: 3 What was originally planned3.1 Br
Page 9 and 10: 3.1.2 RBBRBB planned to test both D
Page 11 and 12: · Position· Subtitles may appear
Page 13 and 14: · Context information through icon
Page 15 and 16: 4 What has been done to date4.1 Bro
Page 17 and 18: DVB-Subtitles Test-MethodThe techno
Page 19 and 20: Explanations:Each of the five selec
Page 21 and 22: 6) Questionnaires will be sent to u
Page 23 and 24: 4.2 Universities and the mature acc
Page 25: 5 Preliminary Findings5.1 Broadcast
Page 29 and 30: The negative comments mainly covere
Page 31 and 32: 6 Preliminary ConclusionsAt the tim
Page 33 and 34: 8 Appendix 1 Design document for DR
Page 35 and 36: expectancy increases and the elderl
Page 37 and 38: . Self-assessment of capability usi
Page 39 and 40: 9 Appendix 2 Questionnaires1- Sampl
Page 41 and 42: □ Assistive device (wireless / in
Page 43 and 44: □ To have information on what typ
Page 45 and 46: ☐ TV ☐ TV digital ☐ Ordenador
Page 47 and 48: h. Cuando hay sonidos, ¿cómo pref
Page 49 and 50: Catalan sitcoms Plats Bruts —late
Page 51 and 52: WP 2.4 Implementation of Pilot Eval
Page 53 and 54: Dissemination: Results to be presen
Page 55 and 56: Audio description / audio subtitlin

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