Two ABC O&O's send 6mbps dvd-rate HD - What is going on?

Local issue. Still getting 13.5Mbit/s from WFAA Dallas, though for some ridiculous reason they crossconvert to 1080i.

KABC in LA runs around 11-12 Mbs on the 720P HD channel. WFAA is 1080i because all the Belo owned stations are with the possible exception of their FOX affiliates. Is WFAA running Oprah and ET in HD?

That's a lousy reason to do it. HD quality on WFAA is pretty bad on sports. I believe they pass all syndicated shows in HD when available. Belo upgraded all their stations to be fully HD a year ago, and with WFAA being their flagship, I'd expect nothing less.

Topic title changed.

FWIW, Stargate Atlantis moved off most Fox O&O stations 2 weeks ago. In this market it moved to a station that is 1920x1080i instead of Fox 720p.

Obviously, SG-Atlantis is 16:9 Letterbox, though SD on these stations.

I am very shocked at how much better it looks on the 1080i than the 720p, even though it is upconverted from 480 on both. I did not expect to see hardly any difference and I am very shocked at what I do see.

After that, I'm not really sure that its entirely bad taking some of these up to 1080i instead of 720p. Sure, its not like 1920x1080i native, but still, there is clearly a difference in 480 upconverted to 1080 v 720.

I would think that most of the different could be attributed to the quality of the upconverter at the two stations. There is an incredibly wide difference in the quality of these things, ranging from pretty darned good, to unbelievably bad. Also, on syndicated material, how the station handles the material internally makes a big difference. Some places still route or switch SD video in composite form, which does not upconvert well. Lots of variables.

I suspect it is because no deinterlacing is needed when going from 480i->1080i, while it is needed when going from 480i->720p. 480i->1080i consists of resizing 240 line fields to 540 line fields, while 720p requires going to 720 line frames. If the upscaler were to correctly remove the 2:3 pulldown, and duplicate/resize frames to get to 720p, I suspect the 720p broadcasts would look as good as if not better than 1080i. Unfortunately, very few upscalers seem to be capable of this; most appear to simply perform a bob deinterlace to get to 480p then resize to 720p.

Getting back on-topic, ABC stations have always been some of the biggest abusers of PQ: the ABC stations in DMAs 1, 2, 3, 4, 5, 6, 7, 10, and 11 all run 2 SD subs in addition to their HD; 9, 12, and 14 run 1 SD sub in addition to HD; 6 and 8 are converted to 1080i. Of the top 15 DMAs, only the ABC stations in 13 and 15 provide a single, 720p program to their viewers.

Three could be other issues besides which HD standard the SD is being upconverted to. I've not noticed much difference between the two for upconversions when I've switched standards on the same upconverter. Maybe the station playing it in 1080i could play it in 720p one day for a comparison

WTVD-11 ABC O&O Raleigh, NC

Looks like crap.

But, how did it look? You state that this is lower than DVD, but most DVDs I have checked are variable bit rate and run at around 3-4 Mbps with occasional peaks at 8-9 Mbps. One example would be the first LOTR DVD which still looked pretty darn good.

Off-Topic: How can I check my local bitrates? I want to test it to add some input

Not a valid comparison. DVDs have roughly half the resolution. With the extra information being sent through the pipe, you need a higher bit rate to avoid macroblocking.

That's why D* was also downrezzing when they were sending the previously pitiful bit rates with MPEG2. If they hadn't, the picture would have looked even worse.

Actually, most anamorphic DVD's average at around 5 Mbps. 480p has 2.67 times less pixels than 720p, so it looks good at a much lower bitrate. Of course NTSC DVD's are actually 480i and movies are telecined to 24p, but thats getting technical.

I would love to see screens, I bet they're really bad.

My point was that his statement that it is a lower bitrate than DVD was not necessarily true, especially if both were VBR. I have monitored bitrates and observed PQ many times where programs that had a lower average bitrate looked much better than programs at considerably higher average bitrates. The reason being that a noisy input to an encoder will produce a higher average bitrate than a clean one and produce a less satisfying result.

Unfortunately, below a certain point, the best hardware in the world isn't going to produce a satisfactory result, much less a good one.

6Mb/s is simply not good enough for MPEG2 HD with any on screen movement. Even static shots will show too much crawl to really be considered acceptable. I'll give you 8-10 for certain content, but never 6.

But, I still haven't received an answer to my original question, "What does it look like?". That is the only criteria that matters.

I would also like to know if it was CBR or VBR, and if it was VBR what were the peak bitrates?

Here's a screencap of KTRK-DT Houston (ABC O&O). It's upconverted to near 1080i resolution for whatever reason, but you can still see the artifacts.

http://img442.imageshack.us/my.php?i...taculartd6.jpg (original post)

This is a relatively static image in all probablity, and the PQ's still bad.

I've read that these stations recently got new Harris "NetVX" encoders, which are supposed to be more efficient than the old equipment at the station. Either the NetVX order didn't include statistical multiplexers, or the statmuxers aren't programmed to apply bitrate in a liberal enough fashion. With two SD subchannels, when non-upconverted 720p HD programming is on, HD bitrate should average much more than 6.5 Mbps (more like 10-12 Mbps at least), and should peak around 14 Mbps during complex motion transfers.

Another thing to worry about is how ABC stations will handle ATSC M/H. It's currently in draft form, and once it's finalized, it'll allow for easy portable reception of ATSC signals, something people with portable analog TVs are clamoring for. Of course with analog shutoff, new portable TVs will have to be purchased, but ones capable of picking up ATSC M/H will have more robust reception. This standard will probably be rushed to operation by TV stations as they'll want a competitive advantage over the others. The M/H stream uses the bandwidth equivalent of one SD subchannel.

I personally think Harris encoders don't have the firepower to properly handle 720p and three subchannels (which is what two subchannels + and an M/H stream effectively is), even when "properly" muxed. I'm sure that most AVSers here would agree that one of the subchannels at each ABC O&O station should go away when the M/H stream goes online. But even if one of the subchannels is dropped, the muxes will still have to be recalibrated so that SD subchannel bandwidth drops significantly as HD bandwidth increases. Null packet transfer should never exceed half a megabit per second, and using statmuxers removes the last excuses for using more.

Harris flexicoders (and JVC) use VBR. AFAIK, you cannot set them to a static bit rate the way you can with Harmonic and Tandberg encoders. At least that is my experience with the various brand of encoders we have here.

I know the Flexicoders have the option to do statmuxing, but none of my old local stations (in Phoenix) who used Flexicoders were ever able to get it to work properly. IIRC, it didn't work right when using an external DD audio encoder, which was required to provide 5.1 audio because the Flexicoder's built-in encoder only supports 2 channels. There was always a very slight variation between high motion and low motion, but it was on the order of +/- 250kb/s, certainly nothing that would have a noticeable impact on quality.

I believe ABC O&Os are using the NetVX now. There's only so much a statmuxer can do, especially when the station insists on running subs at full 704x480i resolution and dedicates enough bitrate for them to remain watchable all the time. NBC O&O KXAS here in Dallas is making the best of the situation NBC corporate is putting them in: they are required to carry both Weather+ and Universal Sports in addition to their main HD program. So, they're running Weather- at 480x480i at around 1.15Mb/s, and Universal Sports at 528x480i at about 2.5Mb/s. They run the HD video VBR between 13 and 15Mbit/s. It's certainly watchable for 24p content, though SNF gets ugly at times.

Yea, They come standard with VBR for HD, statmuxing between multiple channels is an expensive option. The statmux pool also has to be configured properly to work properly.

Oh boy - wait til they discover the problem with NetVX encoders and Cisco/SA8300HD DVRs which both parties have been pointing the finger at the other saying they are doing nothing wrong for 11 months now.

Care to elaborate on that? I know the NetVX's film detection mode on 720p results in a stream that breaks non-compliant decoders since they won't follow the repeat frame flags, but I haven't seen mention of any issues specifically affecting the 8300. D*/E*'s equipment was affected by the missing repeat frames on the HD LILs for WLS Chicago and WSB Atlanta (not an O&O, but still using the NetVX), but both were resolved after the stations' engineers disabled film detection on the encoders.

This is audio - and it does not matter if 720p or 1080i. Happens on still graphics (newscasts) with no motion in video.

2 different problems in this thread, one of them caused by NetVX (heck the other might be as well - and no one has put it together yet).

http://www.avsforum.com/avs-vb/showthread.php?t=909615

Post 45 sums up the 2 different problems.

Only current solution is to (1) drop the 5.1 audio for 2.0 audio and/or (2) reduce the audio bitrate significantly - as both Cisco and Harris say their units are operating nominally and compliant.

I read through that post, and I wouldn't blame Harris for it (for full disclosure, I prefer Harmonic for encoders).

The first issue isn't the NetVX's fault; FOX (the network which airs Kitchen Nightmares) uses Tandberg video encoders. The second issue as noted in that thread has been noted in both FOX shows and NetVX-encoded shows, which leads me to believe that the problem, if not on Scientific Atlanta's end, isn't in the NetVX, but in the 5.1 audio encoder used. If the audio from affected broadcasts can be traced back to a single external surround audio encoder, then that manufacturer should be the one being blamed by SA if they don't want to blame themselves. If multiple audio encoders are being used in affected programming, then Scientific Atlanta is almost certainly the one at fault here.

The problem was, in a future post in the linked thread, theoretically linked to poorly-built HDD drives, which seems reasonable, considering programming decodes properly when viewed live. If programming decodes properly live, it should decode properly when being viewed at a later time (given it was recorded properly). Harris and Scientific Atlanta should be working more closely together to find the problem (since pointing fingers won't help anything). However, it's probably simply related to a poorly-built hard disk drive that the 8300HD is using, or poor electronics in the 8300HD's motherboard, or something like that. I wouldn't be surprised if the 8300HD's HDD was made by some off-brand Chinese company that SA picked for its lowest cost.

I checked KABC tonight on DWTS.The video bitrate was around 12.2 to 12.6 Mbs.

What were your thoughts on picture quality? (Actually, the best way to judge KABC PQ and bitrate allocation, is with NASCAR and college football, but still...)

As noted, 1 of the 2 problems is clearly with the Harris Encoder. The other, I have no first hand experience with, only seeing it (or hearing it) once two weeks ago while in DC on a TV that was NOT connected to a SA8300 -and in real time live - not from DVR. As you are in the DC area, you might be more familar with it than I am.

The Harris NetVX Encoder/SA8300HD problem occurs whether live or delayed. Harris has looked at the streams and claims they are in compliance to ATSC standards. If the problem was the dolby encoder, one would expect the problem to be evident in virtually every market where SA equipment is used.

The Hard Drive does not care what type of encoder a station uses - nor can it tell (and fwiw, SA's used Maxtor Drives up until the time they were purchased by Seagate).

I read the entire thread, and I don't quite get how you've determined that. This post, this post, this post, this post, and this post all claim that viewing all live HD programming is fine. Also, most of the problems occur on FOX HD programming only, and as I said before, they use Tandberg HD encoders. How can you claim that a) the audio dropouts occur on both live broadcast and recordings, b) Harris's NetVX has anything to do with this?


I have had no such issues with local FOX OTA (I use a Samsung DTB-H260F OTA non-DVR HD tuner). That said, remember that FOX uses Tandberg, not Harris.


Maybe it is, and people aren't reporting it publicly. Alternately, some might have units that work just fine 24/7, like this guy.


The use of IDE hard drives vs. SATA drives might have something to do with the problem, but I'm not sure, especially since some users, like this one, connected an external SATA hard drive, and it eliminated most, but not all, of the issue. As far as I can tell, the problem probably is poor quality control on Scientific Atlanta's end, but it may also be a poorly calibrated 5.1 audio encoder model. I still can't see how the dropouts are a NetVX issue.