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What country has the Best HDTV Picture Quality?

3K views 28 replies 7 participants last post by  dr1394 
#1 ·
#1.) What country has the Best HDTV Picture Quality?

#2.) Does the U.S. have the BEST H.D. Picture or No?

#3.) Is the U.S. Behind the times in Television Picture Quality
#3a.) (or) are we in the Front of the pack???
 
#3 ·
We use MPEG2 which is a quite old compression technique, many other countries including Europe use MPEG4 which is more efficient making better use of it's bandwidth.
That being said in N. America a clear channel(no subs) 1080i or even 720p channel can look quite good even on a large screen, once you start adding sub channels or things like MDTV things can go down hill very quickly.
 
#4 ·
Yep - USA, Canada, Mexico, South Korea, Japan and Aus use MPEG2 for HD OTA - almost everywhere else on the planet uses MPEG4/H264 for HD.

In the UK we get 5x1080/50i services into one OTA channel using second-generation DVB-T2 modulation which delivers 40Mbs of data in a UK 8MHz channel, and with the services statmuxed and H264 compression we get watchable HD (certainly better than the MPEG2 NBC I saw in New York a few years ago) These are full 1920x1080 services (at one point 1440x1080 was used when HD Cam and DVC Pro HD, which only record 1440x1080 at 50Hz, were in widespread use)
 
#7 · (Edited)
PSB 3 carries :

BBC One HD (24 hours)
BBC Two HD (24 hours)
ITV HD (24 Hours)
C4 HD (24 Hours)
BBC Three HD (1900-0400ish) / CBBC HD (0600ish-1900)

So 6 services/channels, but two of them share the same video and audio streams (though are mapped to different LCNs and SIDs so appear as different channels) and don't broadcast at the same time, so only 5 1080/50i streams at any given time. There are quite a few time-exclusive (aka timex) services in the UK - BBC Four and CBeebies are the same.

PSB3 and COM7 are both DVB-T2 40.25Mbs (32k carriers 256QAM)
 
#6 · (Edited)
AT&T Uverse Fibre-Optic/Twin-Copper-Pair system is ALL MPEG4:
https://forums.att.com/t5/Device-Setup/U-Verse-Technical-documentation/td-p/3901711

Dishnet SAT system is MPEG4 on East Coast but reportedly has not yet killed MPEG2 on West Coast:
https://support.dish.com/viewtopic.php?f=11&t=20

DirecTV SAT system is MPEG4 in many markets...fol. is from TWO YEARS AGO, so I wouldn't be surprised if they have completed the conversion (ALL customers need newer Receivers):
http://www.dbstalk.com/topic/194087-list-of-mpeg-4-markets

ALL SAT & CABLE Systems have made efforts to adopt MPEG4 for as much of the
production & distribution stream as is possible, including MPEG4 (or better) files on
the Video Servers & MPEG4 via SAT to Receivers.

If you use www.lyngsat.com to look at HD Channels on AMC and GALAXY Satellites, which feed Cable Headends in North America, you'll see that there are only a few MPEG2 channels not yet converted to MPEG4....which means EACH Cable Headend is using and maintaining HUNDREDS of expensive MPEG4-To-MPEG2 Transcoders that are hopefully going AWAY sometime in the (near?) future:
http://www.lyngsat.com/hd/america.html

BTW: Since Cable STB/DVR's are paid off by subscribers in about 2-years, it would be EASY to upgrade a few PREMIUM UHD Digital Tier Customers with new "4K" compatible equipments

And by killing off 70+ Analog Channels, they are in the process of freeing up 70*38.8 = 2716 Mbps of data rate capacity...which is enhanced by upcoming use of more efficient MPEG4 (or HEVC for "4K") and Switched Digital Video (SDV) so that most ACTIVE programs only consume bandwidth when requested by a customer on the local HFC "loop" (about 400 customers).

It also means the "Standard" Internet Data Rate is in the process of jumping from 10-15 Mbps to 50 Mbps with 4 and 8 Channel Bonded Cable Modems....and much higher for extra cost.
 
#8 ·
#9 ·
Suggest writing the ITU directly or through the United Nations and suggest an international test, as the ITU did with film theaters back in ~2001. This post has links to tech papers describing the international testing. Filmed multiburst patterns were used--hard to duplicate probably without cheating, but perhaps something could be used, without announcements, like well-known sports programs. Test equipment, like spectrum analyzers, could indicate the maximum effective resolutions available in homes. Also, it's possible to measure (effective resolutions) in specific captured images for comparisons, as shown in this post . -- John
 
#18 · (Edited)
The DVB-T2 SDR transmitter is now up and running.

https://github.com/drmpeg/gr-dvbt2

I'm still waiting for my PCTV 292e USB receiver (ships from Europe), so I haven't done a lot of testing. However, an SDR enthusiast in the UK has tested it with his consumer TV and verified that it does work (at least with a 4K/64QAM mode).

Performance is good, and the 40.2 Mbps BBC 32K/256QAM mode is possible. In fact, the 44.8 Mbps Ofcom mode 6 (also 32K/256QAM, but 3/4 code rate) is possible. The Ofcom modes are listed in this document.

http://stakeholders.ofcom.org.uk/bi...projects/dtv/BBC_submission_on_UK_transm1.pdf

Next up will be to add the version 1.3.1 features, including T2-Lite. Here's the bladeRF transmitted spectrum in 7 MHz channel mode. The little "ears" on both sides are aliasing artefacts and can be removed with a little tighter filtering or with oversampling. The not quite flat channel response is also a hardware artefact.



Ron
 
#13 ·
The rotated constellation technique is pretty cool. It's not the rotation itself, but the combination of rotation and cyclic delay that adds robustness. Here's a plot of the rotated 16QAM constellation followed by a plot after cyclic delay. The cyclic delay creates a "virtual" constellation with 64 points. The cyclic delay trick is that each IQ symbol is split and the Q portion is delayed one symbol. This causes the I portion of the symbol to be sent on a different OFDM carrier and at a different time than the Q portion. If there's an error burst on the channel and either the I or Q portion gets wiped out (but probably not both since they're being sent on different frequencies and time), the receiver can still decode the symbol by making a "soft" decision from just the I or Q component alone.

The BBC uses rotated constellations on the 256QAM multiplexes. It's not as effective at 256QAM as it is at lower order constellations, but it doesn't hurt.





Ron
 
#14 ·
Are you using SDR for the DVB-S2/S2X demodulation? If so what's the performance like, and what SDR receiver are you using?

The rotated constellation technique is very clever. Remember seeing it at a broadcast expo in the early days of the BBC pushing DVB-T2 as the 'next big thing' - which it became. Finally DVB-T2 tuners are appearing at a decent price point (for a long time there was only a single USB PC T2 tuner at around GBP£60, but you can now get a couple of models for nearer GBP£25). Microsoft have just launched a USB DVB-T/T2/C USB tuner for the Xbox One for £25. Hopefully it will get Linux/Windows support soon if it doesn't have it already.
 
#15 ·
Are you using SDR for the DVB-S2/S2X demodulation? If so what's the performance like, and what SDR receiver are you using?
I'm just focusing on digital television transmitters (modulators) for now. In GnuRadio, transmitters make for a nice clean implementation and the performance is usually pretty good. The DVB-S2 transmitter I linked previously can generate a 24 MHz wide signal at 89 Mbps on a run of the mill 4 core Intel processor. In fact, the USB3.0 interface to the SDR is more of a problem, with not all controllers providing high throughput.

SDR receivers are quite a bit more complex. There's the problem of acquiring symbol synchronization (which usually requires some feedback loop) and the FEC decoding can really take a lot of CPU cycles. Even Viterbi decoding is pretty intensive, and the new LDPC stuff makes matters worse. Here's a nice blog entry about Viterbi decoding for DVB-T.

http://yo3iiu.ro/blog/?p=1393

For testing the DVB-S2 transmitter, I bought a commercial receiver from a small company in Canada.

http://novra.com/product-line/s300-dvb-s2-ip-satellite-data-receiver/

It was a little expensive, but it was one of the only receivers that could do the DVB-S2 16APSK and 32APSK modulation modes. It's also a stand alone box, so no USB or PCI issues to deal with. It just sends the decoded Transport Stream over Ethernet in a VLC compatible UDP format.

The DVB-S2X implementation is still untested. There just aren't any consumer grade receivers available yet (the specification was just released in March 2014).

Ron
 
#20 ·
Impressive stuff ! So in theory would this allow me to use a bladeRF and GnuRadio with suitable encoding (if needed) and muxing (like Open Broadcast Encoder?) to run a DVB-T2 channel at home on my internal RF distribution system? Love the idea of downlinking some DVB-S2 stuff and re-encoding it so that TVs around the house could watch it.
 
#21 ·
Yes, that would be entirely possible. It's exactly the same thing that Trip in VA is doing in this thread.

http://www.avsforum.com/forum/25-hd...dvhs-vcr-built-atsc-tuner-6.html#post29264817

The big difference is that you'll need enough CPU cycles to do both the GnuRadio processing (which is significant) and the re-multiplexing processing. The good news is that this could easily be split between machines, with one doing the DVB-S2 capture and re-multiplexing and another doing the DVB-T2 modulator (and using a UDP or TCP/IP source on the modulator instead of a file source).

It might all fit on one machine by using a lower bitrate DVB-T2 profile. The 4K/64QAM profile that my UK friend tested with is a lot lighter on the CPU and still provides 27.6 Mbps in an 8 MHz channel.

Also, you may be able to use a cheaper SDR. The hackRF at $300 should work (it's known to work for 2K DVB-T in a 6 MHz channel).

https://greatscottgadgets.com/hackrf/

The peak output power of the bladeRF is +6 dBm (4 milliwatts), so that's more than enough to drive many splitters. I use at least a 20 dB attenuator when I hook up receivers or test equipment directly. In the previous spectrum analyzer plot I posted, the average output power was about -16 dBm (around -60 dBm on the trace, 20 dB attenuator and 23.5 dB RBW correction factor).

Ron
 
#22 · (Edited)
What kind of CPU level are we talking for the GnuRadio stuff? Quad i5? Quad i7? I'd kind of naively assumed that remuxing was relatively straightforward in CPU terms and wouldn't add much overhead? There may be good reasons to do it on a separate box though. (I have a spare Chromebox 2955U which I hack around with Linux on - wondered if that might be a good fit)

What I'd love to be able to do is add a couple of satellite channels to a DVB-T/T2 distribution system. Suspect they would both be around 13Mbs peak but they are statmuxed so I'd need to ensure some headroom. I know I could do this easier with DLNA or an external IPTV box, but there is something so nice about just having channel numbers to tune to (though I guess EPG stuff would be tricky as you would only get EIT stuff - if I could work out in any way how to do it - when I was tuned to the channel in question)
 
#28 ·
Love the idea of downlinking a couple of satellite channels and adding them to my domestic RF. Could get 2 or 3 HD services into 40Mbs without transcoding.

Though it may be that some of the USB/PCI-e DVB-T modulator solutions are more cost effective? Lower data bandwidth (as they are T not T2) - but still a possibly neat solution : http://www.hides.com.tw/product_opencaster_Expand_dvb-t_modulator_eng.html Seem to be in use with Radio Amateurs?

(But way less cool than SDR DVB-T2!)
 
#29 ·
Love the idea of downlinking a couple of satellite channels and adding them to my domestic RF. Could get 2 or 3 HD services into 40Mbs without transcoding.

Though it may be that some of the USB/PCI-e DVB-T modulator solutions are more cost effective? Lower data bandwidth (as they are T not T2) - but still a possibly neat solution : http://www.hides.com.tw/product_opencaster_Expand_dvb-t_modulator_eng.html Seem to be in use with Radio Amateurs?

(But way less cool than SDR DVB-T2!)
Yes, the Hides stuff is becoming popular with the few of us doing digital television on the amateur radio bands. Here's a presentation at a digital conference. Skip to 7:23 for the actual talk.



The DVB-T2 effort is targeted at using T2-Lite with the 1.7 MHz channel mode. With QPSK and 1/3 code rate, the required signal to noise ratio is just a couple of dB. Perfect for amateur radio.

Also, the PAPR algorithm is very useful. Power amplifiers have to be "backed off" by about 10 dB to remain linear. So a 25 watt CW amplifier is only good for 2.5 watts of average DVB-T/T2 power. The PAPR algorithm gets you a few more dB out of an amplifier.

You can also do MISO (multiple-input and single-output) with DVB-T2. There's some higher end SDR's that are MISO (and MIMO) capable.

https://www.ettus.com/product/details/UB210-KIT

Ron
 
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