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post #1 of 11 Old 12-02-2012, 04:10 PM - Thread Starter
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I've been searching the web for an answer to my question, but haven't been succesful. I'm hoping better informed folks here can provide some insight. In theory, if over the air broadcasters were to start using MPEG-4 compression, up to how many channels could they broadcast in 1080p/60fps? I know some folks aren't fans of multicasting, but I've been enjoyed it emmensely since my family made the switch to digital. I'd like to know more about possible advances.
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post #2 of 11 Old 12-02-2012, 04:32 PM
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Since there are no OTA broadcasters that use 1080p (ATSC does support it, though) and MPEG 4 isn't used, it's pretty much a moot question.
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post #3 of 11 Old 12-02-2012, 04:42 PM
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Quote:
Originally Posted by RikasAngel View Post

...up to how many channels could they broadcast in 1080p/60fps?
Same as now, about 100 subchannels per RF channel. Of course the compression artifacts would be so bad you probably woulnd't want to watch them. But it is moot because ATSC isn't going to MPEG-4 anytime in the near future.
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post #4 of 11 Old 12-02-2012, 10:16 PM
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Originally Posted by ProjectSHO89 View Post

Since there are no OTA broadcasters that use 1080p (ATSC does support it, though) and MPEG 4 isn't used, it's pretty much a moot question.

You're only half right. Several Ion stations broadcast a service called Airbox, which features 8 subchannels using H.264 MPEG-4 compression, in addition to the standard 3 MPEG-2 subchannels. AFAIK, it has only been rolled out to the public in Houston, but several stations broadcast the signal, including here in Phoenix. In Nov. 2011, while testing, three subchannels were broadcast unencrypted, which I could pick up using VLC. The video is 4x3 and uses anywhere from 0.8 to 1.5 Mbps bandwidth per subchannel. Quality was not bad. Currently, all subchannels are encrypted.
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post #5 of 11 Old 12-03-2012, 04:35 AM
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Yeah, didn't waste time considering the Airbox service since it's a subscription service. We'll see if it lasts any longer than Qualcom's ill-fated FLO service lasted.
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post #6 of 11 Old 12-05-2012, 10:31 AM
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This side of the pond we've switched one of our 6 multiplexes from our original OTA system (DVB-T 18-24Mbs - now 27Mbs max - using MPEG2 to carry SD 16:9 and 4:3) to a new improved system (DVB-T2 - 40Mbs - using H264 to carry HD 16:9 1080i content)

We're getting 4 or 5 H264 1080i streams (though the transmission encoders for some channels dynamically switch between 1080/25p and 1080/50i) in a 40Mbs DVB-T2 multiplex (using a standard UK 8MHz RF channel)

So we don't have 1080/50p broadcasts - we do have broadcasts dynamically flipping between 1080/25p and 1080/50i on a GOP-by-GOP basis (it's encoder driven not playout system driven)

Other European countries are using H264 for 1080i, 720p and 576i SD broadcasts - either using DVB-T or DVB-T2. Some are also still using MPEG2 for SD 576i - but no mainstream European broadcasters are using MPEG2 for HD.

For MPEG2 HD broadcasts I think only Australia is using HD MPEG2 with DVB-T (all other DVB-T/T2 broadcasting regions use H264 for HD), Japan is using it with ISDB-T (though South America is using H264 with ISDB-T), and the US/Canada/Mexico and Korea are using it with ATSC 8-VSB.
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post #7 of 11 Old 12-05-2012, 03:06 PM
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Don't forget that European and Australian channels are 33.3% wider than American channels. Having 8 MHz available instead of 6 definitely provides a boost for more bandwidth per allocated channels. Less total channels are available, though.
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post #8 of 11 Old 12-05-2012, 04:13 PM
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Originally Posted by dhett View Post

You're only half right.
No, 100% in the context of the OP's question. There is currently no way to do it with a normal TV set without some add-on hardware and likely a subscription fee, and there won't be anytime soon. Yes, there are all kinds of specialized services like Airbox that are possible with ATSC. But even those won't give OP the increase in the number of programs the OP is looking for.
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post #9 of 11 Old 12-06-2012, 12:49 PM
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Quote:
Originally Posted by ProjectSHO89 View Post

Don't forget that European and Australian channels are 33.3% wider than American channels. Having 8 MHz available instead of 6 definitely provides a boost for more bandwidth per allocated channels. Less total channels are available, though.

Yep - though DVB-T2 delivering 40Mbs in 8MHz and H264+AAC encoding are a pretty good combination. Since analogue switch off we've also been able to raise powers such that we can now get 24-27Mbs in an 8MHz DVB-T legacy mux (which carries SD 16:9 and 4:3 MPEG2 services)

Prior to analogue switch off most regions had 5 analogue channels and 6 or 7 digital muxes radiating (which meant 11 or 12 occupied 8MHz slots) so the digital powers were lower, and more robust but less efficient modes used (18Mbs per 8MHz slot) to increase coverage areas.
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post #10 of 11 Old 03-12-2013, 03:40 AM - Thread Starter
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Let's say for the sake of argument that an ATSC II standard was adopted and implemented. Could stations broadcast multiple high quality 1080p signals using MPEG 4? If so, up to how many could they broadcast? I've read at least one person mention that a statation could have three 1080i channels using MPEG 4. I'm curious about the possibilities MPEG 4 could present.
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post #11 of 11 Old 03-12-2013, 09:58 AM
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Quote:
Originally Posted by RikasAngel View Post

Let's say for the sake of argument that an ATSC II standard was adopted and implemented. Could stations broadcast multiple high quality 1080p signals using MPEG 4? If so, up to how many could they broadcast? I've read at least one person mention that a statation could have three 1080i channels using MPEG 4. I'm curious about the possibilities MPEG 4 could present.

In Norway, NRK run 3 x 720/50p channels and 2x576/50i channels using MPEG4 in a single 22Mbs DVB-T mux. Picture quality isn't too bad. They use 70kbs for HE-AAC 2.0 and 200kbs for HE-AAC 5.1 audio. (AC3 isn't used)

In the UK the BBC operate with 4-5 x 1080/50i channels using MPEG4 in a single 40Mbs DVB-T2 mux (they sub-let capacity to ITVHD and C4HD, and broadcast BBC One HD and BBC HD, and during the Olympics BBC Red Button HD). (Some of these channels switch dynamically between 1080/25p and 1080/50i based on programme content) Again, picture quality not too bad. Certainly a lot better than a lot of the US OTA MPEG2 stuff I've seen whilst on holiday in the States.

In both the Norwegian and British examples, statmuxing is used, where the pool of 22/40Mbs of data is shared dynamically between channels based on content.

When it comes to 1080p "proper" broadcasting, the only 1080/50p stuff I've seen has been on satellite. This was actually for 2160/50p broadcasts (aka 4k) which is being trialled by sending 4 quarter-screen 1920x1080/50p streams (Using H264 at Level 4.2 not the more usual Level 4.1 normally used OTA and for Blu-ray etc.) The broadcasts I've seen use 4 x 9.5Mbs H264 streams for reasonable, though not stellar, 1080/50p.
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