DTV Subchannels in Canada's Future? - Page 3 - Canadian TV, Computing and Home Theatre Forums

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post #31 of 81 (permalink) Old 2010-10-16, 09:55 AM
 
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The technology for higher resolutions @ lower Mb/s is on the horizon. Their goal is to acheive 720p quality # 6 Mb/s or less. That would allow for up to three 720p streams within 19.4Mb/s. So far the California and Georgia stations are all using SD 480i. To carry 10 streams in HD they would have to somehow achieve at least 720p/or720i resolution at less than 2 Mb/s without creating the need for upgraded consumer equipment.
It would be a shame if we settled for 720p streams. The difference between 1080 and 720 is just too great. Comparing ABC and NBC streams on a full HD display makes my point evident. Luckily most (all?) Canadian DTV stations will broadcast in 1080.

OTA is doomed for extinction if it cannot keep up with competing services in terms of picture quality. If 1080 streams have to be sacrificed for lower res just because people want more channels, OTA will quickly fall behind. I am confident that after investing billions into digital transmission gear, broadcasters will not allow this to happen.
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post #32 of 81 (permalink) Old 2010-10-16, 10:49 AM Thread Starter
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Broadcasting in 1080i is wasteful bandwidth use. Some will argue that 720p is better than 1080i. With newer technology on the horizon, it is possible to broadcast full 1080i quality at the same band usage as 720p using current consumer receiving equipment. If you have a 42+ screen size, then you can choose between cable's compromised compressed version of 1080i or you can go free with uncompressed OTA at 720p. I believe that the standard will end up at an enhanced 720p for all OTA anyway and it will be done using only 2 Mbits. Currently there are too many formats and resolutions for broadcasters to juggle with and that's why they are seeking the ultimate standard. Of course the benefit will be capacity for extra subchannels with extra bottom line advertising revenues. In the broadcast business, it's alway about how to make more advertising dollar$ show up on the bottom line.

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post #33 of 81 (permalink) Old 2010-10-16, 03:20 PM
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^^^^
There's not a lot of difference in bandwidth between 1080i and 720p. 1080i has 2.25x as many pixels as 720p, but 720p scans twice as often, so 1080i uses only 12.5% more bandwidth for the video. However, other things, such as audio, will be the same for both.
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post #34 of 81 (permalink) Old 2010-10-16, 06:33 PM
 
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For the foreseeable future the use of OTA bandwidth to achieve a given picture quality cannot be improved. There are hardly any TVs/PVRs with ATSC tuners that support MPEG4 part 10 (H.264) codecs, so we are stuck with MPEG2 and its greater use of bandwidth. The train has left the station. H.264 was added to the ATSC standard only in 2008. No broadcaster will begin to experiment with MPEG4, because nobody can watch it. Things look much better with DVB-T in Europe.

Let's not forget that a good deinterlacer can produce great motion flow before we make arguments like 720p is better than 1080i. High resolution is what blows us away!

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post #35 of 81 (permalink) Old 2010-10-17, 07:04 AM
 
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All sports and action is much better and more crisp in 720p than 1080i, also the higher res is not needed on hdtv's smaller than 42 inches. It should either be 720p or 1080p instead of interlacing HD picture which adds blur and lag. Watch OTA football on a 720p channel vs the 1080i channel and you will see.
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post #36 of 81 (permalink) Old 2010-10-19, 10:56 AM
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Some recent national adopters of ATSC in the Americas have opted to go immediately to ATSC Standard A/72, which includes ITU-T H.264 (MPEG-4), so clearly there is a pool of devices that will operate with it. The payoff is the capacity for several 1080p/DTS audio HD sub-channels within one channel's bandwidth, or of course all sorts of other slice-and-dice options for lower grade programming and data.

As I've said before, a Canadian move to MPEG-4 would require consumers to purchase STBs or other external devices while production of HDTVs with the newer system becomes more commonplace. New A/72 devices would be backward compatible with existing A/53 MPEG-2 channels or act simply as downconverters feeding an A/53 signal via HDMI, Component, S-Video, Composite, or RF signal to the consumer's existing gear.

Shelling out more $$$ is quite a lot to ask of many people who only just bought an HDTV, OTA STB, or tuner device that uses the original A/53 MPEG-2. We all know that many of the regular addicts here in the OTA Forum would gladly drop more $$$ into their systems if MPEG-4 was rolled out!

Last edited by stampeder; 2010-10-19 at 11:11 AM.
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post #37 of 81 (permalink) Old 2010-10-19, 02:54 PM
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I've watched MPEG-4 1080i — not over-the-air but through satellite (experimental PBS feed via Ku-band FTA). The picture quality is atrocious compared to the regular 1080i program encoded in MPEG-2. The MPEG-4 image isn't as crisp, there's more macroblocking, and the sound is different, too.
Would OTA MPEG-4 look/sound just as bad? Or would this depend totally on how individual broadcasters chose to set their MPEG-4 encoders?
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post #38 of 81 (permalink) Old 2010-10-19, 08:43 PM
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Even though they were using MPEG-4 the satellite company's use of the actual H.264 codec was probably not compliant with the ATSC's A/72 implementation. Also once they add their secret encryption sauce the satellite companies can really mess up programming.
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post #39 of 81 (permalink) Old 2010-10-20, 08:53 AM
 
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Some recent national adopters of ATSC in the Americas have opted to go immediately to ATSC Standard A/72
stampeder, do you more information on who these broadcasters are?
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post #40 of 81 (permalink) Old 2010-10-20, 10:27 AM
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a Canadian move to MPEG-4
Let's face it, a move by Canada would have little or no impact except increase costs dramatically for Canadian consumers. Canadian broadcasters have little interest in OTA while OTA operation lose money and fees from BDUs rake in windfall profits. The CRTC also has little interest in mandating new standards. The only thing that would force the adoption of new standards is a mandate from the FCC, which has happened historically. If the FCC steps in and says a new HD standard must be supported all new TVs by a certain date, it will happen.

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post #41 of 81 (permalink) Old 2010-10-20, 02:35 PM
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Originally Posted by schoenbe
more information on who these broadcasters are?
I'm frustrated because I should have bookmarked the info I had read about it but cannot locate it now. I'll try later to find it again. Almost all South America countries are transitioning to either ISDB-T or DVB-T, so the few ATSC adopters are the ones looking to go straight to A/72.
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post #42 of 81 (permalink) Old 2010-10-21, 03:10 PM
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I would love to see cp24, CBC Newsnetwork, CTV Newsnet, and on the more mindless side, although I assume it highly unlikely, TSN or Muchmusic.
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post #43 of 81 (permalink) Old 2010-10-27, 06:09 PM
 
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In the recent decision allowing Shaw to buy Canwest, the CRTC said - again, after the decision back in 2008 - that it is "pursuaded of the benefits of multiplexing", this time adding that mulitplexing could help with "diversity of voices and access, and [has the] potential to offset some of the negative impact resulting from media consolidation." Not sure exactly what they're talking about, but it certainly raises the possibility of adding community channels and the provincial broadcasters on private stations' subchannels. That would be a good service.
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post #44 of 81 (permalink) Old 2010-10-27, 10:46 PM
 
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How would, for example, french CBC stream english audio track? How many times have I seen something cool on french CBC I wish had an english track...
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post #45 of 81 (permalink) Old 2010-10-27, 10:59 PM
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I'm pretty sure the ATSC standard provides for alternate audio on the same channel. Much like SAP in the analog world....

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