I am sure most of you have experienced the superb HD picture offered by Blu-ray discs, and wonder why over-the air (OTA) HD broadcast do not exhibit the same quality. The answer to this question is compound and has been discussed in similar blurbs on this subject. However, one of the broadcasters' limitations to optimizing HDTV is inherent in the ATSC standard itself, and that is the obsolete MPEG-2 compression system.
When the digital (HD or SD) signal is originally digitized...
[url=http://www.hdtvmagazine.com/columns/2009/03/eds_view_better_broadcast_hdtv.php]Read Column[/url]
Ed's View - Better Broadcast HDTV
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robmxb
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- Joined: Wed Apr 12, 2006 6:29 pm
8-VSB Proponents are Ingeneous Hypocrites
When a mobile version of 8-VSB was first proposed those proposing were adamant that all legacy receivers would at least be able to receive and view the signal if not take advantage of the added reception sensitivity. Later that changed to when some suggested that broadcasters would use an advanced codec with any mobile bandwidth that legacy receivers could not decode. Proponents then suggested that an additional "box" would be needed to decode the advanced codec. Now we will need an additional box because the M/H modulation is not itself receivable by legacy receivers. M/H is new in my book if a legacy receiver can't use it.
Whatever and however you twist it any bandwidth used for any purpose by broadcasters that cannot be received and viewed using a legacy receiver is NOT legal in my opinion.
Congress and the FCC would not allow broadcasters to use DVB-T as an ADDITIONAL modulation because it would require an additional "box" and confuse consumers. An additional "box" to receive DVB-T today could cost $15. How much will this additional 'box" cost consumers so that their legacy receiver can receive MOST of the bits being broadcast?
With new chipsets that receive ALL current world DTV modulation being sold and the possibility that Chinese manufactures to save warehouse cost will just install such omni DTV receivers in all DTV sets there may be no cost to consumers if a broadcaster in the US were to use say DVB-T2.
DVB-T2, in my opinion would allow THREE full HDTV programs to be multiplexed into ONE 6 MHz channel and they ALL would be receivable mobile.
We should just finally quit trying to justify 8-VSB which is the worst modulation in the world and just allow ONE other decent modulation in the US. If we did 8-VSB and M/H would quickly be dropped by broadcasters and free OTA DTV would survive and prosper as it is in ALL other countries where a decent modulation is in use.
The other option is to waste more time going down this 8-VSB dead-end while all the time trying to weasel around what is "legal" as per legacy receivers. We all know why we do this. If we ever let the truth out, that M/H is really not legal as per all previous BS spouted to fend off COFDM based modulations then we open the door to examine all current state of the art modulations.
That is, if legacy receives are being made obsolete and NEW receivers are needed, read another "BOX", then there is no reason not to re-open the whole matter and let ALL the spectrum be used with the latest and greatest modulation and codec.
If we need another "box" it might as well receive DVB-T2 or any and possibly all other modulations. Obviously it would be able to decode MPEG-4 (AVC) but it might be mandated, we seem to like mandating things in the US, to be upgradeable to more advanced codecs to come as I suggested back in 1999 when we also proposed that the US allow a co-modulation, DVB-T.
Whatever and however you twist it any bandwidth used for any purpose by broadcasters that cannot be received and viewed using a legacy receiver is NOT legal in my opinion.
Congress and the FCC would not allow broadcasters to use DVB-T as an ADDITIONAL modulation because it would require an additional "box" and confuse consumers. An additional "box" to receive DVB-T today could cost $15. How much will this additional 'box" cost consumers so that their legacy receiver can receive MOST of the bits being broadcast?
With new chipsets that receive ALL current world DTV modulation being sold and the possibility that Chinese manufactures to save warehouse cost will just install such omni DTV receivers in all DTV sets there may be no cost to consumers if a broadcaster in the US were to use say DVB-T2.
DVB-T2, in my opinion would allow THREE full HDTV programs to be multiplexed into ONE 6 MHz channel and they ALL would be receivable mobile.
We should just finally quit trying to justify 8-VSB which is the worst modulation in the world and just allow ONE other decent modulation in the US. If we did 8-VSB and M/H would quickly be dropped by broadcasters and free OTA DTV would survive and prosper as it is in ALL other countries where a decent modulation is in use.
The other option is to waste more time going down this 8-VSB dead-end while all the time trying to weasel around what is "legal" as per legacy receivers. We all know why we do this. If we ever let the truth out, that M/H is really not legal as per all previous BS spouted to fend off COFDM based modulations then we open the door to examine all current state of the art modulations.
That is, if legacy receives are being made obsolete and NEW receivers are needed, read another "BOX", then there is no reason not to re-open the whole matter and let ALL the spectrum be used with the latest and greatest modulation and codec.
If we need another "box" it might as well receive DVB-T2 or any and possibly all other modulations. Obviously it would be able to decode MPEG-4 (AVC) but it might be mandated, we seem to like mandating things in the US, to be upgradeable to more advanced codecs to come as I suggested back in 1999 when we also proposed that the US allow a co-modulation, DVB-T.
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brewster
- Member
- Posts: 6
- Joined: Thu Aug 02, 2007 9:33 pm
Question on Blu-Ray and general comments
Hi Ed,
As a general comment, I have seen that a good high quality multipass encoder can get good results. However my understanding (and please someone jump in and correct me) is that a lot of content is encoded on the fly, and there is no real way to get "best" results in that scenario?
I also notice cable system tend to have really bad quality, and since they're paying for satellite bandwidth for the feeds, I can only assume that in doing an economic tradeoff (as a monopoly) they crank up the compression (MPEG4) to keep the cost down and then transcode locally back to MPEG2. I know you were focused on broadcast, but IMHO the only real opportunity is with cable systems as new/better boxes could be given to customers; people are not going to run out and buy new sets for a government mandated ATSC II.
However, and there's a snowball's chance in hell of this happening, IMHO any new *public* broadcast standard should use license (patent) free audio and video standards. The headaches associated with licensing create a lot of wasted effort, and the open source community has shown that good things can be done. The government (i.e. our taxes) has sponsored plenty of university research, it's time to cash that in for the "good of the people". Of course there's no lobbyist for an open source/patent free solution so it will never happen...but it's still nice to dream about the innovation that could have been...
You didn't mention it, but IMHO not only is 4:2:2 needed, but 12 bit samples. I would actually pick that as more important than 4:2:0 as the loss of color detail is only apparent on very large screens, but the artifacts from the current use of 8 bits is obvious even on a tiny screen.
Thanks
As a general comment, I have seen that a good high quality multipass encoder can get good results. However my understanding (and please someone jump in and correct me) is that a lot of content is encoded on the fly, and there is no real way to get "best" results in that scenario?
I also notice cable system tend to have really bad quality, and since they're paying for satellite bandwidth for the feeds, I can only assume that in doing an economic tradeoff (as a monopoly) they crank up the compression (MPEG4) to keep the cost down and then transcode locally back to MPEG2. I know you were focused on broadcast, but IMHO the only real opportunity is with cable systems as new/better boxes could be given to customers; people are not going to run out and buy new sets for a government mandated ATSC II.
However, and there's a snowball's chance in hell of this happening, IMHO any new *public* broadcast standard should use license (patent) free audio and video standards. The headaches associated with licensing create a lot of wasted effort, and the open source community has shown that good things can be done. The government (i.e. our taxes) has sponsored plenty of university research, it's time to cash that in for the "good of the people". Of course there's no lobbyist for an open source/patent free solution so it will never happen...but it's still nice to dream about the innovation that could have been...
You didn't mention it, but IMHO not only is 4:2:2 needed, but 12 bit samples. I would actually pick that as more important than 4:2:0 as the loss of color detail is only apparent on very large screens, but the artifacts from the current use of 8 bits is obvious even on a tiny screen.
Do you have more information on this? All of my available information is that all of the format/profiles on BluRay for VC-1/h264/mp2 are all 4:2:0 8 bit.The ability of Blu-ray to offer 4:2:2 color quality levels
Thanks
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kpaulsen
- New Member
- Posts: 1
- Joined: Thu Mar 26, 2009 12:12 pm
ATSC A/153 vs. Bluray
I think there may be a misinterpretation. The M/H Candidate Standard A/153 Part 7 (available from the ATSC.org web site for free) states pixel resolutions in the H and V dimensions. The M/H system uses MPEG-4 Part 10 AVC and SVC video coding as described in ITU Rec. H.264 | ISO/IEC 14496-10, with certain constraints. The pixel counts for the AVC being 240 x 416 (wide screen) and for SVC as 360 x624 and 480 x 832. Both are progressive scan systems, and these are 'before compression' ratios. I seriously doubt that even scaling up to 15 Mbps (consuming nearly all of the available video payload) for an OTA 8VSB DTT system would look good without a considerable amount of 'post processing'.
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jmyers
- New Member
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- Joined: Wed Feb 16, 2005 5:15 pm
Huh?
You seem to imply that MPEG-4 gives a better quality of picture then MPEG-2. However most the places I go online to read about MPEG-4 diputes this idea. Instead the web says that MPEG-4 is good for more channels to be pushed out due to it's enhanced compression processing ability. So who is right, you or all the other websites out there that state that a better quality image is NOT what you really get with MPEG-4. Help me understand please. Till then call me confused. 