No 720p support in BluRay

[Richard Leadbetter]

You guys seem to know much more about Blu-Ray than I do, so I'm wondering if you can answer some questions for me...

Let's say I have a 1280x720 movie running at 59.94fps with a 5.1 audio mix. Can I encode to MPEG2 in this format and produce a Blu-Ray compliant stream? Will a new wave of MPEG2 encoders be required or will good old Procoder 2 do the job?

Would I need any kind of special audio encoding to do the job? I take it that old fashioned DD5.1 is not supported. What is the maximum bitrate I can use to encode these movies?

Right now, I understand that Ulead DVD Factory 5 can author rudimentary Blu-Ray disks. Are there any other authoring tools aside from Scenarist BD that can do the job?

[Joe Carney]

As far as using mpeg4 instead of 2...
I can think of one thing, cost savings....
When they want to sell box sets, or 2 or 3 movies as a packaging special...then mpeg4 could be an option just to fit everything on a single disk.
I've actually bought a few of those cheesy z grade horror movie packs with 10 DVDs in them, be nice to cut it down to 1 or 2.

Then with the advancment of IP/TV vc-1 and h.264 seem to be the leading candidates.

But who really knows how the market will shake out. Not me

[Jake Strickbine]

Originally Posted by Richard Leadbetter

Let's say I have a 1280x720 movie running at 59.94fps with a 5.1 audio mix. Can I encode to MPEG2 in this format and produce a Blu-Ray compliant stream?

Absolutely- as a matter of fact, the initial theatrical releases in BR format will all be MPEG-2 with 5.1 audio.

Originally Posted by Richard Leadbetter

Would I need any kind of special audio encoding to do the job? I take it that old fashioned DD5.1 is not supported. What is the maximum bitrate I can use to encode these movies?

DD 5.1 is, indeed supported- that's no problem. The maximum total bitrate for BR is 36 mbps, which should allow for 2 hours of high quality MPEG-2 on a single layer BR disc, or 4 hours worth if you use VC-1 or AVC.

Originally Posted by Richard Leadbetter

Right now, I understand that Ulead DVD Factory 5 can author rudimentary Blu-Ray disks. Are there any other authoring tools aside from Scenarist BD that can do the job?

None that I know of at this very moment, but there should be a wealth of options by year's end- everything from Nero to DVD Studio should be offering BR/HD-DVD authoring support.

[Richard Leadbetter]

Thanks for the response. I'd certainly be interested in seeing what the old Spruce/current DVD Studio guys come up with in terms of Blu-Ray support. I think it has HD-DVD support right now.

If they supported Blu-Ray I might even buy a Mac *gasp*

I have heard a dirty rumour that the consumer-level tools will be limited to MPEG2 though. Even at 32mbps, I'm seeing some artefacting at 720p/60 (!)

[Guy Barwood]

I heard similar info from the Pioneer guy (consumer authoring only being MPG2). He also said he has heard that those HD-DVD people trying to author with VC1 & mpg4 (currently trying to make Hollywood releases etc) are experiencing a significant number of problems using these codecs vs MPG2. This could be caused by Senarist though.

36Mbps = 16.2GB per hour
25GB per layer = about 1.5 hours per BR using its max data rate, rather than 2hours.

Fortunately we shouldn't need 36Mbps. Even just re-coding 720p HDV to the correct GOP structure for BR and maintaining its approximate 20Mbps gives 9GB per hour or around 2.7 hours.

PS: This Pioneer guy also said they have no plans to support MACs with with next gen drive, but he was talking from a Pioneer Australia perspective. I wouldn't doubt Apple will licence a model as an Apple SuperDupa Drive...

[Richard Leadbetter]

Hmmmm... I'm in regular contact with Microsoft and their work with VC-1 is extraordinary - and has been for many months. Their 15mbps encodes of notoriously difficult Xbox 360 720p/60 footage are practically flawless. Game footage has an infinite depth of field and hard, defined edges - extremely hard to compress compared to 'normal' HD material. Certainly, I'm finding it extremely tough for MPEG2 to get close right now, even with double the bandwidth.

As all HD-DVD titles on the shelves now are VC-1, I'd imagine the problems have been solved by and large and I'm fairly certain that it will be the future of encoding. Compression algorhythms have come a long way since MPEG2.

With regards the MPEG2 GOP structure, if they are using shorter GOPs on Blu-Ray, presumably this introduces more reference I-Frames. This will obviously result in a better picture quality but surely it will drink up the bandwidth?

It would also mean that our current HD encoding tools are useless for Blu-Ray which is a bit of a pisser considering that people already have 'homebrew' 1080i MPEG2 program streams working a treat on HD-DVD.

Is there any other source for this shorter GOP story?

[Richard Hunter]

Originally Posted by Jake Strickbine

No deinterlacing is required to display 1080i on a 720p set. 720p displays are fixed pixel by nature, and they run at 60hz, which is the key- the 1080i source is simply rescaled, and the fields are displayed as if they were frames at 720p/60 (59.94 fps). There's no field interpolation and no introduction of new motion artifacting caused by this process..

Hi Jake. Can you please explain how this works, because something doesn't seem quite right to me. I thought that, even when there is no rescaling involved, if you show interlaced video on a progressive panel without deinterlacing it, you would get interlacing artifacts. For example, if I show an interlaced DV AVI file on a PC's LCD monitor, I can easily see edge tearing on moving objects because each pair of fields is simply combined into frames. How do the 720p panels manage to avoid this without deinterlacing the 1080i video?

Richard

[John Mitchell]

Originally Posted by Guy Barwood

36Mbps = 16.2GB per hour
25GB per layer = about 1.5 hours per BR using its max data rate, rather than 2hours.

Hmm - if your original calculations are right 16.2 goes into 50 3x by my calculations. I'm sure I read somewhere that Sony have already demo'd a 100G BluRay disk with a promise of bigger capacities to come.

I also only made it 15.82 actual gigabytes an hour, but I'm guessing that 25GB per layer are maybe metric GB hence your figure?

[John Mitchell]

Originally Posted by Richard Hunter

Hi Jake. Can you please explain how this works, because something doesn't seem quite right to me. I thought that, even when there is no rescaling involved, if you show interlaced video on a progressive panel without deinterlacing it, you would get interlacing artifacts. For example, if I show an interlaced DV AVI file on a PC's LCD monitor, I can easily see edge tearing on moving objects because each pair of fields is simply combined into frames. How do the 720p panels manage to avoid this without deinterlacing the 1080i video?

Richard

Richard, Jake is sort of correct. The point I took from his previous post was that given a 1080i60 source you can make a 540P60 source (because you have enough lines vertically ie 540 lines every field) then you can upscale it to 720P quite effectively. I'm not sure if this still holds up when we're talking about 48i OR 50i embedded inthe 60 stream - I don't think most sets can display true 48Hz or 50hz (although some can display 100Hz) so his argument seems sound.

My point always was that *any* kind of scaling introduces artifacts, but certainly scaling from 1080i to 720P is nowhere near as bad as scaling from 540i or 576i. But consider this - if a scaler in an HD set does a poor job of scaling SD pictures, why would it be any better when scaling HD pictures (it's actually more data to manipulate)?

I always assumed that what was happening at the cheaper end of the scaling market in panels was that the set was re-compressing the image (re-encoding the MPEG stream to a data rate it could handle before scaling and re-encoding it to the panels native size). This was because on a lot of images I could see seemed to show excessive MPEG artifacting. However Jake seems to be much more knowlegeable in this area than me, so I guess I am seeing the results of excessive post processing.

Bottom line - nothing looks as good to me as my projector run from a DVDO iScan. (although I'm sure there are even better scalers than that if you want to spend the money) I watch HD off air and bypass (passthru) the scaler for that (it doesn't handle 1080i) and the projector seems to do an OK job with 1080i - but no better than standard def DVD scaled.

[Guy Barwood]

Originally Posted by John Mitchell

Hmm - if your original calculations are right 16.2 goes into 50 3x by my calculations. I'm sure I read somewhere that Sony have already demo'd a 100G BluRay disk with a promise of bigger capacities to come.

I also only made it 15.82 actual gigabytes an hour, but I'm guessing that 25GB per layer are maybe metric GB hence your figure?

Given I worked out 16.2 = 1.5Hr per layer it makes sense a two layer 50GB disk would support 3 hours does it not?

36Mbps /8 = 4.5MBps = 270MB/minute = 16,200 MB per hour.
=16.2GB per hour using 1000MB per GB or
= 15.82GB oer hour using 1024MB per GB

The relevant question is if the 25GB is 25 x 1000MB or 25x 1024MB (probably neither if we consider below)?

DVDs are stated as 4.7GB but I believe that is using 1000MB=1GB resulting in a little under 4.5GB usable using 1024MB=1GB etc

PS: Most HDD manufactures quantify their drives using 1GB = 1 Billion bytes, not 1024 MB and I think DVD, BR and HD-DVD will do the same.

[Graeme Nattress]

What looks like excessive artifacting on a Plasma is in fact the pulse width modulation that it uses to generate all it's greyscale levels (really the plasma pixel is binary - on or off, so it needs to be modulated to produce different visible levels) interfering with movement in the image and the human visual system.

And you're right, 1080i60 should convert to 720p60 by splitting each field into a 540p60 frame, then upscaling to 720p. Given all modern displays are inherently progressive, 720p is displayed on a 1080p screen by simple upscaling.

Graeme

[John Mitchell]

Originally Posted by Guy Barwood

Given I worked out 16.2 = 1.5Hr per layer it makes sense a two layer 50GB disk would support 3 hours does it not?

36Mbps /8 = 4.5MBps = 270MB/minute = 16,200 MB per hour.
=16.2GB per hour using 1000MB per GB or
= 15.82GB oer hour using 1024MB per GB

The relevant question is if the 25GB is 25 x 1000MB or 25x 1024MB (probably neither if we consider below)?

DVDs are stated as 4.7GB but I believe that is using 1000MB=1GB resulting in a little under 4.5GB usable using 1024MB=1GB etc

PS: Most HDD manufactures quantify their drives using 1GB = 1 Billion bytes, not 1024 MB and I think DVD, BR and HD-DVD will do the same.

Sorry Guy - I misread your intent - I thought you were saying you couldn't fit a 2 hour movie on a BluRay disc at it's maximum data rate. I have since discovered that all the current BD movies are single layer? very strange decision.

[Kevin Shaw]

Originally Posted by Guy Barwood

The relevant question is if the 25GB is 25 x 1000MB or 25x 1024MB (probably neither if we consider below)?

Most computer media capacities are now expressed in decimal rather than binary amounts, and that's officially recognized as the modern standard. (Binary calculations are supposed to be expressed using a new set of terms approved in 1998: see http://en.wikipedia.org/wiki/Mebibyte.) A better question is what's the formatted capacity, and how full can you fill it before playback at the outer edge gets iffy? So let's say a single-layer Blu-ray disc holds ~24,000,000,000 bytes comfortably * 8 bits per byte = ~92 minutes at 36 Mbps or 128 minutes at 25 Mbps or 185 minutes at 18 Mbps. That sounds like plenty to me, and I'd rather not have to fuss with multi-layer discs.

[Guy Barwood]

Originally Posted by Kevin Shaw

...I'd rather not have to fuss with multi-layer discs.

Same here. While I have burnt a few DL DVD-Rs and they have worked, for a while anyway*, I have never used them to provide a finished video to a client.

*As feared even with Verbatim DL disks it doesn't take long for the same disk in the same player to start having playback problems. Its like after burning, the reflectivity steadily degrades for a while reducing compatibility with time. DL BR will need so time to convince me its a safe delivery format.

[John Mitchell]

I was of course referring to multi-layer replicated commercial disks (movies) and not burnt disks. I thought Sony had already been using dual layer BD-R on XDCam? Maybe not.