Zoltan_Vigh_ITU_20121106

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					 Picture aspect ratio and
 audio issues on the DTH
    and DTT platforms




                    Zoltán Vigh
Digital Transition Coordinator
Introduction



§   MTVA is a state owned entity with approx. 2000 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
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
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 55-72 cm to 84-104 cm, we should serve the
       viewers
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 1920x1080 @ 25i, and we can get the full
       resolution signal from the international events
     § All the movies are 1920x1080 @ 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
Digital program distribution of our channels

                                OURSELVES:
§   DVB-S2 (Eutelsat 9A, 11958 MHz)
     § Full raster HD, 1920x1080 @ 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), 1440x1080 @ 7 Mbps average bitrate, with AFD picture aspect signaling
§   DVB-S (Eutelsat 9A, 11766 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
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
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)
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.
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
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
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.
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!
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 24-48 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.
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
Thank you for your attention!


         Zoltán VIGH

     vigh.zoltan@mtva.hu
        +36 30 370-7340

				
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