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Picture aspect ratio and audio issues on the DTH and DTT platforms Zoltán Vigh Digital Transition Coordinator.

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Presentation on theme: "Picture aspect ratio and audio issues on the DTH and DTT platforms Zoltán Vigh Digital Transition Coordinator."— Presentation transcript:

1 Picture aspect ratio and audio issues on the DTH and DTT platforms Zoltán Vigh Digital Transition Coordinator

2 Introduction  MTVA is a state owned entity with approx employees, to service the public service TV and radio channels: Magyar Televízió and Duna Televízió, as well as Magyar Rádió  We purchase, produce, play out and distribute programs for these stations  We manage 4 HDTV channels and 8 radio channels.  M1 still has an analogue nationwide broadcast network and some programs are mainly for Hungary only  M2, Duna and Duna World (TV) are European coverage channels  Duna World (TV) and Duna World Radio are for the expat Hungarians living in North- and South-America, and Australia

3 I found these topics as a problem in the digital transition process  HD quality on IPTV after downscaling and upscaling at the home on a Full HD TV set  HD to SD scaling quality  SD enabling if there is no HD-SD simulcast  SD transrating (low quality) on DVB-C and DVB-S networks  AFD picture aspect handling (head ends, STBs, TVs)  Letterbox SD on a DVB network  WSS signal with anamorphic PAL on the analogue network  VBI Teletext transmission in the HD world  Subtitling on IPTV  AAC audio lip-sync issues with low cost STBs  Dolby Digital mixdown capability  I will show you some details in my presentation

4 Why HD?  After several years of MPEG-2 SD test transmission, the DVB-T MPEG-4 HD broadcasting started in 2008 at Budapest area, with the Beijing Olympic Games.  After this successful test, we continued the regular HD broadcasting of the public service channels M1, M2 and Duna  The reasons:  Today HD is the standard definition (see 4K, UHD)  All new studio equipment sold are HD only  All new TV sets sold are HD with internal upconversion to match the 1280x720 or 1920x1080 physical resolution of the display  The upconversion of the uncompressed SDI to HD-SDI with a broadcast unit is much better in quality than done from a highly compressed MPEG-2 SD signal with a consumer chipset used in the tv set  There is a 30%+ penetration of HDTVs in Hungary (approx. 1,4 million HDTV sold)  The TV picture size increased from cm to cm, we should serve the viewers

5 1080i vs 720p  We use the 1920x1080i/25 format, to maintain the highest resolution and match the resolution of the new HDTV sets  The reasons:  We have some HDCAM VTRs in use and these are 1080 only  The de-interlace math became very good, so it is easy to make a good quality 1080p or 720p video for the web streaming  All the European HD OB Vans are 25i, and we can get the full resolution signal from the international events  All the movies are 24P or 25P  Most of our programs are progressive style  A lot new production equipment are 25/25P only but full HD resolution (Sony CineAlta, DSLR video)  The people watch internet video and the progressive frame rate became wear off  Due to the restricted capacity of the DVB-T multiplex, we use 1440x1080  On satellite, we use 1920x1080 raster

6 Digital program distribution of our channels OURSELVES:  DVB-S2 (Eutelsat 9A, MHz)  Full raster HD, 10 Mbps average bitrate, with AFD picture aspect signaling  DVB-T  The public service is HD only (except the Duna World, due to limited network capacity), 7 Mbps average bitrate, with AFD picture aspect signaling  DVB-S (Eutelsat 9A, MHz)  Anamorphic SD (720x576 raster, full raster all time: 4:3 or anamorphic 16:9), with MPEG wide signallng. This will switch off on 31th December 2014 INDEPENDENT TELCO AND CABLE COMPANIES:  DVB-C (cable networks), IPTV (cable operators), DVB-S (DTH operators)  Anamorphic SD (720x576 raster, full raster all time: 4:3 or anamorphic 16:9), with MPEG wide signaling  DVB-C (cable operators), IPTV (cable operators), DVB-S2 (DTH operator)  HD (720p, 1440i or 1920i), no AFD picture aspect signaling

7 No HD and SD simulcast  We do not have a HD and SD simulcast on DVB-T for M1, M2 and Duna Reason:  No capacity  Cost  Quality  We will not have a HD and SD simulcast on satellite for M1, M2, Duna and Duna World after 2014 Reason:  Switch to DVB-S2 and forget DVB-S  Cost  Quality  More flexible capacity management (additional temporary or new channels)  To push the migration of the old SD home set top boxes to DVB-S2 and Conax capability for future temporary encryption

8 Problems with the simulcast-less broadcasting  Cable head ends would like to get the MPEG-2 SD transport stream to forward it as is onto their DVB-C networks (cheaper head end)  Picture aspect ratio issues (see later)  Country specific way, so very few equipment can handle all the requirements  Higher cost of the low end set top boxes (no issue anymore, the prices gone down really fast)  Education (EuroScart vs. HDMI cable connection)  HD logo usage (see later)  Slows down a bit the cable providers HD penetration development (they ask money for HD channels – so the free to air HD from us is against their business)

9 Aspect ratio handling  No picture aspect defined in HD standards  There are 16:9 AND 4:3 contents time multiplexed in the program (archive 4:3, new 16:9), there is no way to convert the 4:3 content to 16:9, due to quality, composition and copyright issues  There is no simulcast (on DVB-T and on DVB-S2 from 2015) – must switch  There is a need for picture aspect signaling in HD too, for automatic downscaling to letterbox (for analogue cable networks) or to anamorphic 16:9/4:3 full frame (for digital cable and sat networks)  Very few consumer set top box has AFD capability  Very few professional cable head end equipment has AFD capability  Some tv sets handle the AFD in a wrong method: if they get the 4:3 code then they widen the 4:3 picture to fill the entire screen to save the display against burn in. This is not good and the user can not set the correct 4:3 aspect ration manually in some cases.

10 What we give to the service providers?  For cable and sat operators who get our signal on fiber:  We embed WSS onto line 23 of SDI video  We embed AFD into HD-SDI video  We embed VBI teletext into SDI video  We attach stereo and AC3 encoded audio in the SDI signals  We maintain time-sync of the video and audio signals  For other cable operators, who get our signal from air:  We require time-sync from our distributors (Antenna Hungaria, Eutelsat)  We specify all the details of our multiplexes.  One public service multiplex with 3 HD, 1 SD and 3 radio on DVB-T  One LEGACY public service multiplex with 4 MPEG-2 SD (+ picture aspect info) with stereo MPEG-1 audio and TXT and several radio on DVB-S, switch off on the end of 2014  One public service multiplex with 4 MPEG-4 HD (+ AFD) with AC3 and TXT and several AAC high quality radio on DVB-S2

11 What we require from the cable and DTH operators?  Our channels are must carry and we do not have any contract for distribution. Not easy situation.  Transmit all part of our signal, including TXT (it’s the law) and all audio channels  Do not rescale the signal (720x576 to 544x576, or 1920x1080 to 1280x720)  Do not re-encode or transrate our MPEG signal  Handle the picture aspect ratio information according to the network  Do not crop our 16:9 signal to 4:3, no center-cut enabled. We DO NOT shoot 4:3 safe, the station ID and the PG information are on the 16:9 area, and we place the captions and graphics on the full 16:9 area  We ask them to use our HD signals as their source for SD too (better quality)  We ask them not to use our SD signals, because it will switch off in 2014  Transmit all of our HD signals if they have a HD package  We ask to place our HD signals in the BASIC tier

12 HD logo on screen if there is no simulcast of SD and HD  How to handle the HD logo on screen?  NatGeo, Eurosport, History and others has a simulcast and use HD logo on the HD stream. They use HD logo on SD original content too, and this is bad.  M1, M2 and Duna does not have an SD simulcast, so the source signal is HD all the time for the analogue and digital cable networks too  We mark the original HD content only with the HD logo, not the entire program, but on all platforms (HD and SD).  Both are not the perfect solution: some of our viewers believe they watch real HD content on their CRT screen. This is bad.  We could not find a good solution yet. If we would not use the HD logo, but our competitors do, then our viewers will say there is no HD on our channels.  This is more a marketing issue then technical.

13 Audio formats we use ON DVB-T  We use MPEG-1 Layer II for DVB-T as a primary and legacy stereo format  We use Dolby Digital AC3 and a surround format for Hungarian language content (dubbed and original)  We will use AAC (standardized for the Hungarian DVB-T network) for original language, but in stereo only (the home theater amplifiers does not handle AAC audio in most cases as a surround format) ON OUR SATELLITE SERVICE  We use MPEG-1 Layer II for legacy on DVB-S, both for Hungarian and original language  We use Dolby Digital AC3 only with the HD streams on DVB-S2, there is no legacy stereo. We use AAC for radio. The mixdown should be handled by the cable head end IRD or by the home sat receiver. SPECIFICATION!

14 Lip-sync issue with AAC audio  We received some lip-sync issues for other tv channels (RTL, TV2) on the DVB-T network.  These tv channels use AAC audio only  Some low cost set top boxes used by small analogue cable operators may loose the audio-video sync after hours continues operation. So, there is a need for a reset every 24 hours!  This is not a problem with MPEG-1 Layer II, we did not get any feedback on our channels.

15 Subtitling  The subtitling is a must by the Media Law in Hungary, to help the hearing impaired people to watch tv  The time-sync is a critical requirement for subtitles  On analogue cable the only widely used method is the TELETEXT  We have one common teletext signal for our four channels, and we use four pages (111, 222, 333, 444) for the channel specific subtitles  The TELETEXT is not impemented in HD-SDI signal format, so we should provide a time-synced SD downconverted version of the video in SDI format  This SDI video with embedded teletext data then became encoded to MPEG- 2 and the teletext stream will be used by the multiplexer. The timing is critical (MPEG-2 SD and MPEG-4 HD encoding time is different).  The digital cable and SAT operators can transcode the teletext subtitles to DVB-SUB format to use in their own networks  There is not teletext on IPTV, the operators without their own subtitle method have legal problems

16 Thank you for your attention! Zoltán VIGH


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