Technical question: Is BEV 1080i or 720p?

  • Thread starter Thread starter travisbell
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The straight answer is that BTV converts all channels to 720P, if that's your question. This has also been discussed in the BTV PQ thread:

http://www.digitalhome.ca/forum/showthread.php?t=76129 Formats
 
With the introduction of the nextgen hidef formats, compression pretty much (at least for the moment) moved from hardware to software. Microsoft involvement had probably something to do with this as well. It paid off in spades - the VC-1 encoding codec has improved immensly over the last year. This would not be possible with hardware encoders where every change to the codec would need over a year to be implemented in silicon.
Anyhow, compressionists claim that the software encoders work similar to the hardware ones - they are just offering many more ways to optimize the compression/encoding. This is paid for with the amount of time needed to do it - about 3-4 times slower than real time.

I think the satellite industry can benefit greatly from going to MPEG-4/AVC or maybe even VC-1 encoding - at least for the pre-recorded footage where real-time'ness is not important (e.g. movies). They just have to do it right - and around 10Mbps pipe would be good enough for any but the most demanding real-time footage.

It would be interesting to hear from BEV/SC insiders how this process works inside the company.
Regrettably, they are mostly interested in bashing the competition, making unsubstantiated claims, branding pirates and resorting to pure lies. Too bad.

Diogen.
 
Maybe I'll need to check again these days, but 2 months ago all US network channels that originated in 1080i WERE 1080i on BEV (plus CityTV and CBC). When is your information from? If it's not something very recent, you've been lied to.
 
Compared to 2 months ago, only 2 stations - CBS-W and Citytv have gone from 1920x1080i to 1280x720p. There are still 7 or so that are still 1080i - all US network feeds plus CBC.
It goes to show that even the highest ranking people at BEV are not quite aware of technical details. Or they were talking more along the lines that the transition from 1080i to 720p is ongoing, and assuming it has already been finished. I can see the trend, but it's not a fact yet. People with 1080i or p capable TVs may still want to set their STB output to 1080i for now.
 
I don't think the bitrate allowance is to blame. At least not only that.
Even using MPEG-2 you can get very good quality compression: if you use a high quality source, good codec, VBR and have a good compressionist.
Broadcasters don't have control over some of those and don't care about others. And as long as the majority doesn't have a HDTV
(doesn't know how to get hidef in many cases) and have no idea what artifacts are - broadacsters will get away with it.

It will change over time.

Diogen.
 
Good enough, 57. Though it seems some are still going on about it in this thread. Thanks for the link though.
 
A coworker's friend scanned the HD channels for me. Here's what he reported as of last night:

ABCHE 1280x720, 16000Kbps, AC3 2Ch, 48.0KHz, 384Kbps
ABCHW
CTVHE
CTVHW
RAPHD
VUFHD
VUHD
and many more

CBCHE 1920x1080, 17100kbps
CBSHE
CBSHW
NBCHE
PBSHE
PBSHW
SN_HD
VUFH1
and many more

The bitrate fluctuates based on the content.
 
To elaborate on the bitrate issue:
Encoding of movies and real time events (sports, news, etc.) can be different.
Movies can have a multi-pass hand-tuned copy available for the networks to broadcast. News have to be encoded real time and hence no multi-pass.

When encoding movies using VBR, it is common to use the peak bitrate PBR 50% higher than the average ABR. Since all the movies I've seen on BEV movie channels use a tad under 12Mbps average bitrate, it could be they are encoded 12/18Mbps (ABR/PBR).

On the other hand, if each transponder on BEV/82 can handle only about 30Mbps, and some have two hidef channels on them, it would suggest the peak bitrate can't exceed 15Mbps.

Anybody knows any details about it?

HDNet curently uses 15.5 Mbps and shares the transponder with BTV-HD that is not active yet. It probably means that BTV-HD will be on a bitrate diet when activated or both will have around 14Mbps.

Diogen.
 
There is a few posts above that have some really good dumps, but I can confirm now that BEV definitely has the capability to change on the fly. On MCHD1 they were 1080i, then dropped to 720p once the movie ended.

I've done a few other spot checks and this appears to be common, handing out bandwidth as required.
 
editor / Falcon,

I posed the question directly to the Bell ExpressVu product manager responsible for the 9200 during a Bell press event last October (see my post above) and another member posted an email came from a Bell CSR today stating that it was native.

So that leaves two options:

  • Either product managers and CSR's at ExpressVu don't know what their saying or
  • you're mistaken.

Thoughts?
 
So here's a question I haven't seen discussed yet. When an HD channel is showing
upconverted SD, why does it take just as many bits on my 9200's hard drive as true HD?

Rob
 
Hugh, this issue has always been clear as mud. See the following two links, which are also referenced in the Digital Home FAQ on "HDTV Formats".

Global stating they send 720P to BEV.

http://www.digitalhomecanada.com/forum/showpost.php?p=330618&postcount=76

PowerPoint Presentation by BEV Exec.

http://digitalhomecanada.com/forum/showpost.php?p=322876&postcount=31

Both links are from this year, although the PP presentation is October 2005.
 
57, I totally agree that it is clear as mud hence why I didn't say editor and Falcon are wrong, merely that they are at odds with Bell product managers and Bell Customer service representatives.

Frankly, I tend to believe the 720P all-the-time theory but the good folks at Bell can't decide so how can we say definitively?
 
Well, the thread is pretty old and the last post before post 71 was almost three years ago. Information from 2008/9 indicates nothing but 720P.
 
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