Ask questions to Compression Engineer insider "drmpeg"

[phloyd]

Originally Posted by drmpeg

At high bitrates, H.264 may have an advantage since the loop filter can be entirely disabled (which seems to be the case for many current movies) and more high frequency detail can be coded by the use of flatter scaling matrices.

This is interesting since Ben W from *cough*soft has stated a number of times that at the bitrates used for HD Media the loop filter is needed. It appears that his statement is incorrect based on these real examples - something I am happy to see (not that he was wrong, but that the loop filter is not always neeed).

[dialog_gvf]

Originally Posted by drmpeg

Anything that uses a real-time encoder. Right now, satellite is the major user of H.264 real-time encoders. IPTV will probably be next, followed by cable. ATSC will be the last.

Cable will have to go to H.264 eventually because of 1080p@60. I know there's a lot of naysayers about 1080p@60, but it's going to happen, and soon. This whitepaper claims that 1080p@60 only takes 20% more bandwidth.

http://www.ambarella.com/docs/1080p60.pdf

Ron

Interesting. Wow 1080p/60 sports will be amazing!

So, ATSC are really going to obsolete all those FCC mandated tuners in HDTV?

Gary

[drmpeg]

Originally Posted by phloyd

This is interesting since Ben W from *cough*soft has stated a number of times that at the bitrates used for HD Media the loop filter is needed. It appears that his statement is incorrect based on these real examples - something I am happy to see (not that he was wrong, but that the loop filter is not always needed).

I've created a version of the reference decoder that reports the number of filtered luma pixels, so that folks can check movies (to see if the loop filter is disabled) for themselves. Here's the post on AVSForum:

http://www.avsforum.com/avs-vb/showt...1#post12558851

Ron

[drmpeg]

Originally Posted by dialog_gvf

Interesting. Wow 1080p/60 sports will be amazing!

So, ATSC are really going to obsolete all those FCC mandated tuners in HDTV?

Gary

It's very unclear what ATSC will be doing about H.264 and/or 1080p@60. There was some talk about a layered approach to 1080p@60. An MPEG-2 base layer that current receivers can decode, and an enhancement layer (possibly H.264) to get to 1080p@60. The problem is that the best base layer would be 720p@60, not 1080i@30 (I like to use the 1080i@30 frames/sec nomenclature rather than 1080i@60 fields/sec), so many networks would have infrastructure problems if they wanted to use the layered 1080p@60 approach.

Ron

[drmpeg]

Originally Posted by gand41f

Are you talking about NBC11/KNTV? That's funny...I always used to think they are the worst. Now that I have a 1080p TV, ABC and Fox look bad, the latter even though it doesn't have any sub-channels. This might have something to do with my particular TV not having a dot by dot mode for 720p ATSC signals.

On the other hand, CBS looks fabulous both on my old and new TV. On my old TV it was CBS > Fox > ABC > NBC (the latter two have subchannels), on my new TV it is CBS > NBC > Fox > ABC although NBC looks pretty bad when there is lots of movement. One particular moment I remember is the opening ceremony of the Winter Olympics in Turin, the flame was looking absolutely terrible with pixellation artifacts. Did they get a new encoder since then?

enjoy
gandalf

Yes, KNTV-DT. They switched to a Harmonic encoder right after the Olympics. I think it looks pretty good, but certainly not perfect.

KPIX-DT (CBS) is still using their old (circa 1998) Harris encoder, but they have the bitrate maxed out at 18 Mbps for the video stream. Like I said, more bitrate is alway better.

Ron

[drmpeg]

Originally Posted by fronn

Hi Ron,

Is there any sort of push for them to upgrade or are they not likely to upgrade until they decide to switch to an H.264 encoder? (and then proceed to use that same encoder for 10 years)

Is upgrading encoders a large endeavor or are these stations just lazy and unwilling want to drop the cash for a smaller segment of the market? Additionally (I'm not sure if any of this is really in your realm), are they likely to be more caring about their broadcast quality when HD becomes more mainstream... or is this just how it goes for some of the stations?

Sorry for the large amount of questions, but they all kind of relate.

Ultimately, I'm curious if the situation with HD broadcast/cable/sat quality likely to actually get better over time, or are we destined to a land of mediocrity where it is at it's best right now (as more channels are stuffed into a fixed amount of bandwidth, quality may even go down?)... Is there a push to make the quality better over the next several years and we just so happen to be in a time where adding channels is more important than channel quality, or are they quite content with the quality we have now?

I would expect stations will consider MPEG-2 encoder upgrades after the end of the transition in February 2009. Until then, many stations are not motivated since they believe that their revenue stream is coming from analog, not digital.

The H.264 situation for OTA is painful since there are legacy MPEG-2 only receivers out there. H.264 would be the only way to increase quality for single stream stations and to arrive at acceptable quality for multicast stations. We'll just have to see what happens. Hopefully, things will change after the transition.

Ron

[Mr_Bester]

I just noticed your signature, thanks for the test patterns.

[gand41f]

Originally Posted by drmpeg

Yes, KNTV-DT. They switched to a Harmonic encoder right after the Olympics. I think it looks pretty good, but certainly not perfect.

KPIX-DT (CBS) is still using their old (circa 1998) Harris encoder, but they have the bitrate maxed out at 18 Mbps for the video stream. Like I said, more bitrate is alway better.

I see. I guess my impression of the horrible picture quality of Olympics was so strong that it kinda clouded my judgment. I didn't watch KNTV too much after that initial impression, and having to rotate my antenna by hand to watch it (unless they are having a very good signal day ) didn't help either.

By the way, what do you think about KTVU (Fox) and KGO (ABC)? They look pretty terrible on my 1080p LCD, although I used to think especially KTVU looks pretty good. I'm wondering if it has anything to do with the extra scaling because of overscan (as I mentioned previously, my TV can't cancel overscan on 720p ATSC signals). KTVU doesn't have any sub-channels so the bitrate should be maxed out, right?

enjoy
gandalf

[jorg]

hello, i am very curious about how much bandwidth satalight providers such has dish network or bell or direct tv

some thing i have noticed in the industry

providers have what seems lke very low bandwidth "inventory" to work with

providers has resorted(dish network is the only one i can confirm) but they have been broadcasting 720i then recombining it in the receiver and with direct tv and dish network for the hd mpeg-4 they require people to have an adapter(im unsure what exactly this dose)

but im wondering how restricted are they as in terms of bit rate and how mite u think they could fix this

also how do u think they will fix this program upgrade there satilites? perhaps?

and im am also curious on how avc h.246 will develop in the future will it be more efficient if so how much more improvement % wise do u speculate

and looking more into the future do u have any ideas onto which compression method is next vc-2 perhaps or avd/h.492? (made up names) what do u think will be the"next big thing"?

[dialog_gvf]

Originally Posted by drmpeg

It's very unclear what ATSC will be doing about H.264 and/or 1080p@60. There was some talk about a layered approach to 1080p@60. An MPEG-2 base layer that current receivers can decode, and an enhancement layer (possibly H.264) to get to 1080p@60. The problem is that the best base layer would be 720p@60, not 1080i@30 (I like to use the 1080i@30 frames/sec nomenclature rather than 1080i@60 fields/sec), so many networks would have infrastructure problems if they wanted to use the layered 1080p@60 approach.

A layered approach is interesting.

What is the true horizontal resolution for broadcast HD @1080i30? Using a layered approach would probably mean 1280x1080p, wouldn't it? Or could more horizontal resolution for the core 720p also be available?

I've posted an idea of going beyond 1080p for Blu-ray using a layered approach. You'd download a secondary video file which would provide the extra detail. This would allow pretty much indefinite use of a core format.

Since OTA transmission is but one way of delivering broadcast, would you expect broadcasters to go to 1080p/60 and merely downconvert to 1080i/30 for OTA? Do cablecos and satcos get their DTV feeds by yanking them off the air, or by a distribution network?

Gary

[shueardm]

Back onto Blu-ray for a moment if you dont mind Ron,

I'm authoring H.264 from Grass Valley ProCoder 3 at 1920x1080 50i for use in Adobe Encore CS3. It sometimes works and sometimes doesn't, throwing out a "code 6 error" at me. If this is Encore's way of telling me that it is not a legal BD stream then I would like to know what parameters to change. Problem is, it is virtually impossible to find a list of specs that say how an AVCHD file should be encoded to be legal. Any help appreciated.

also, is 1440x1080 50/60i really legal for HDMV content? Some suggest it is, others say it's not.
Regards
Mark

[drmpeg]

Originally Posted by shueardm

Back onto Blu-ray for a moment if you dont mind Ron,

I'm authoring H.264 from Grass Valley ProCoder 3 at 1920x1080 50i for use in Adobe Encore CS3. It sometimes works and sometimes doesn't, throwing out a "code 6 error" at me. If this is Encore's way of telling me that it is not a legal BD stream then I would like to know what parameters to change. Problem is, it is virtually impossible to find a list of specs that say how an AVCHD file should be encoded to be legal. Any help appreciated.

also, is 1440x1080 50/60i really legal for HDMV content? Some suggest it is, others say it's not.
Regards
Mark

The various BDMV and ACVHD authoring programs each have their own concept of what is compliant and what is not. Scenarist seems to be the pickiest and the Ulead tools seem to be the most lenient. Your the first I've heard using the Grass Valley stuff, so you may be breaking new ground.

1920x1080@25i should be okay. In the Blu-ray spec, 25i is included as a bitstream format, but the player support is optional. Also, 1440 wide is part of the spec, so your bitstreams should be okay.

The problem is that "code 6 error" is pretty cryptic. At least in Scenarist, the error messages are fairly specific (although not all). It's difficult to say what "code 6 error" really means. Maybe you should provide some feedback to Grass Valley and/or Adobe saying that the error codes are less than helpful.

BTW, what codec are you using? H.264, VC-1 or MPEG-2? Each one has it's own funny little Blu-ray constraints, with MPEG-2 being the least affected.

Ron

[ADIDAS]

shueardm, have you updated to Encore 3.0.2 that came out this month? That might help.

drmpeg,

I see that there are advanced H.264 profiles that support 4k resolution, 14 bit and YUV 4:4:4 color. (ie Red One resolution). What are the chances of cable or Blu-ray supporting higher resolution or expanded color in the future?

[shueardm]

Originally Posted by drmpeg

The various BDMV and ACVHD authoring programs each have their own concept of what is compliant and what is not. Scenarist seems to be the pickiest and the Ulead tools seem to be the most lenient. Your the first I've heard using the Grass Valley stuff, so you may be breaking new ground.

Yeah ProCoder 3 had H.264 output from the start but no-one could get it to work for Blu-ray. I just fiddled until i came up with something that worked. I saved the preset files and posted on the Grass Valley forum if anyone wants to try. http://ediusforum.grassvalley.com/fo...ead.php?t=4146.

I'm obviously using H.264 and i have told Adobe about the constant errors. They are "getting back to me" after they investigate "apparently". I don't dare tell them that I am encoding outside Encore because they will just dump the ticket and tell me to encode using the Encore encoder. It would be great if the error told us what was wrong. The worst thing about the error is that it only appears when you are half way through building a volume or image. ie, the video imports fine (without the need for transcoding). You dont know you have a problem until you build.

I've done maybe 10 projects each of 1 hour or more with about a 50% success rate.

[shueardm]

Originally Posted by ADIDAS

shueardm, have you updated to Encore 3.0.2 that came out this month? That might help.

Where? It's not on the updates page and nor when i check for updates from Encore. The latest reads 3.01 (which i have)
Thanks

[drmpeg]

Originally Posted by ADIDAS

drmpeg,

I see that there are advanced H.264 profiles that support 4k resolution, 14 bit and YUV 4:4:4 color. (ie Red One resolution). What are the chances of cable or Blu-ray supporting higher resolution or expanded color in the future?

The Mitsubishi folks think that consumer applications are ready for 4:4:4 encoding.

http://ftp3.itu.ch/av-arch/jvt-site/...a/JVT-X043.zip

http://ftp3.itu.ch/av-arch/jvt-site/...a/JVT-X044.zip

http://ftp3.itu.ch/av-arch/jvt-site/...n/JVT-Y034.zip

http://ftp3.itu.ch/av-arch/jvt-site/...n/JVT-Y088.zip

http://ftp3.itu.ch/av-arch/jvt-site/...a/JVT-Z022.zip

Ron

[drmpeg]

Originally Posted by shueardm

I'm obviously using H.264....

Sorry, I was under the influence of a few cocktails when I made that post late last night (left coast time).

Originally Posted by shueardm

The worst thing about the error is that it only appears when you are half way through building a volume or image. ie, the video imports fine (without the need for transcoding). You dont know you have a problem until you build.

Just guessing, but it sounds like a VBV (now called CPB in H.264) buffer violation that's occurring at some point in your video clip. You may want to try the Elecard buffer analyzer.

http://www.elecard.com/products/prod...ffer-analyzer/

Ron

[shueardm]

There's a setting called "video PID" in ProCoder AVC encoder, perhaps that is it. What should it be though?

Thansk for the link, I'll try it out.

[shueardm]

You are right Ron. Apparently the buffer should be 30000000 bits or less. I got SONIC to use their verifyer and it showed these errors.

Stream Verifier, version 1.71
Copyright (C) 2005-2007, Sonic Solutions. All rights reserved.

AVC Analyzing file: D:\Assets\example_h264.264



Log generate
With BD checking.





**** New GOVU: 0 Number of frame: 1 Stream Position: 0
****BD_HDMV_ERROR: Invalid cpb_size, it should be less or equal than 30000000 bits: 93749248
****BD_HDMV_ERROR: If level_idc in SPS indicates level 4.1, each picture shall be encoded as multi-slice picture with 4 or more slices per picture, the current number of slice is: 1

**** New GOVU: 1 Number of frame: 2 Stream Position: 145720
****BD_HDMV_ERROR: Invalid cpb_size, it should be less or equal than 30000000 bits: 93749248
****BD_HDMV_ERROR: If level_idc in SPS indicates level 4.1, each picture shall be encoded as multi-slice picture with 4 or more slices per picture, the current number of slice is: 1
****BD_HDMV_ERROR: No delimiter found
****BD_HDMV_ERROR: Expecting Sequence parameters
****BD_HDMV_ERROR: Expecting VUI parameters
****BD_HDMV_Warning: Expecting HRD parameters
****BD_HDMV_ERROR: Expecting picture parameters set
etc etc

So the buffer is way over for a start, it's a surprise i could get it to author at all, I've done a few AVC discs and they look great. So sometimes it picks it up and spits it out and other times it doesn't.

Now i need to know how to change the buffer as it isn't an option unless it;s the PID?

[drmpeg]

Originally Posted by shueardm

There's a setting called "video PID" in ProCoder AVC encoder, perhaps that is it. What should it be though?

Thanks for the link, I'll try it out.

The video PID is a Transport Stream value. For HDMV and AVCHD, it should be 4113 or 0x1011.

Ron