I would like to get some feedback from both sides on seamless branching. Basically, more exact figures for the limitations of each format right before a branch could be taken or not. From what I've read the main track needs to be limited to an average of around 60% (or low 60s) of the peak mux rate for a short period right before the branch point. Hopefully somebody can correct that if it is wrong and provide exact numbers. My understanding is this is so that there will be enough data stored up to continue playing the video while the laser goes to the alternative track, if that track is to be played. Each alternative track would then have 2 branch points. I picture this like a train going down the tracks with a slower speed limit right before a point where the track splits and that speed limit needs to be observed whether taking the alternative track or not. And if the alternative track is taken, then the train needs to come back to the main track later.

An example of where branching can be useful are discs with regular cuts and alternative (like Director's or unrated) cuts where the user can choose which to watch. I believe that "AVP: Alien vs Predator" has been announced to have seamless branching for Blu-ray with 2 cuts. MI:3 for HD DVD has branching, but that shouldn't be confused for seamless branching from what I saw. One spot early had about a 1 second pause going to the alternative track and about a 5 second pause (although some of it might have been in the source) coming back to the main track. Another case where seamless branching can be useful is in changing things like a note or billboard that is shown so that it is in the language of the currently selected language track. With CGI getting better and better, this should be more possible in the future. I recall reading about "True Lies" needing modification to a name of a company on hats and things before it could be released because it was too close to a real company name, so I know they can modify things like that (although that wouldn't have been an example of seamless branching).

Some things we know are that HD DVD has a total mux rate of about 30Mbps for all audio and video (and 36Mbps off the discs) that comes from their choice to spin the discs at 1.0x, while Blu-ray is at 48Mbps total (and 54Mbps off the discs) that comes from their choice to spin the discs at 1.5x, while they have a max video rate of 40Mbps.

I am especially curious how the HD DVD side plans to handle seamless branch cases for average to hard scenes without degradation given their lower limits. Right now we have releases without seamless branching where things other than the main video take up about 11Mbps, leaving about 19Mbps peak for video. I'm pretty sure there are releases where the average (not the peak) for video is higher than 19Mbps. We have also been told that Microsoft has a plan to do dynamic muxing to deal with the 30Mbps ceiling, and that was before seamless branching was even discussed, from what I recall.

If we give them some benefit of the doubt and figure 8Mbps for things other than the main video, that would leave 22Mbps peak for video. Add seamless branching with those 8Mbps still being used and now with the total for everything right before a branch of somewhere around 19Mbps, that would leave 11Mbps for the main video. That would probably work if the video is easy there, but have more difficult video there and that is a whole lot more limiting than the 19Mbps peaks that we are seeing on some titles currently that still take weeks to get encode to the states we get them in. For the above I didn't even really include going to the 20/48 or 24/48 TrueHD that has been discussed, instead of the 16/48 TrueHD currently.

One more thing is that the average right before a branch point shouldn't be confused with averages we see for whole movies. Difficult frames tend to have a correlation to difficult frames around them. Just because a 2 hour movie can average 12Mbps and look good, that doesn't mean every 2 second segment of that movie could look good with 12Mbps.

So, I am curious. What is the plan for seamless branching support given the above issues and how will the more difficult cases be handled? Will the HD DVD team consider spinning the discs at 1.5x when/if they go to 45GB discs so that seamless branch points aren't nearly as limiting as they are with their 1.0x spin rate?

I already know that some won't want us talking about more difficult cases than we've seen or that I might get answers that include BD50s being science fiction, Blu-ray being MPEG-2 while HD DVD is VC-1, or that we shouldn't look at upcoming issues unless current discs compare in a certain way, but those are all to be expected at this point.

--Darin

Darin, with all respect, and not wanting to short-circuit any answers to your questions, I for one would not be dismayed if either format decided to put out two unbranching versions of a title out on one or two disks.
My holy grail would be to personally & non-sequentially flag to produce my own cut (there would be a lot more single story lines & dropped personal non-sequitors than editors/directors do). I could even see the studios doing this to provide "Clean" options if they thought it would sell. But I don't think they will support any of these.
So, when you mean seamless, do you mean an invisible track change and re-synch on a "random" basis? If HD can't do it, is BD going to do this on a meaningful level even if they can?
Having said that, I wait too for the answers to your query.

So, when you mean seamless, do you mean an invisible track change and re-synch on a "random" basis?Random would be really tough. I was talking about cases where the people encoding know where the alternative tracks are. An example might be a scene in one of the Lord of the Ring movies where the extended cut shows some more hits in a battle and if the user selects the extended cut the scene looks to them like it would if the other cut wasn't even on the disc (no pause) and vis versa if they watch the regular cut. I could also see them using something like this for "clean" or "family friendly" versions, although I don't know if we'll see that either. Definitely scenes where there is extra nudity over what was shown in the theaters would be an example of where they could include both versions with seamless branching.

I think they would want to be careful about including two discs of the same movie with different versions, because many people would just sell the version they don't want. Flippers with a version on each side would be one option, but I don't think that is as nice as single sided discs and I think many agree.

BD would be limited also, just as HD DVD would be even if they did up their disc spin rate to 1.5x. But not as limited as with 1.0x spin rate.

--Darin

Personally I think seamless branching is mostly irrelevant to most people, myself included.

think they would want to be careful about including two discs of the same movie with different versions, because many people would just sell the version they don't want.
They used to say the same thing about DVD, but just about nobody sells one of the two discs alone from a "deluxe" DVD. This is a non-issue.

They used to say the same thing about DVD, but just about nobody sells one of the two discs alone from a "deluxe" DVD. This is a non-issue.Are you talking about DVD releases where there are two discs and each disc contains a full version of the movie, or releases where there are extras on a second disc? They are very different things.

And it doesn't matter whether a person will watch the main version or the alternative version if seamless branching is used and the video is degraded at points to handle the branching.

--Darin

I think the truth is evident.

Both formats are hobbled by yet another generation of slow and crappy optical technology. Can't we just bypass the problems by storing the HD content on HDD storage and increasing the bandwidth the asics can handle?

Does someone have a link to a white paper on seamless branching? (Reg. DVD)

I don't think seamless branching will be used any more frequently in this generation than it was last time, there just isn't much call for it and it cuts off the additional double dip revenue stream.

Are you talking about DVD releases where there are two discs and each disc contains a full version of the movie, or releases where there are extras on a second disc? They are very different things.
I am talking about DVD releases where there is more than 1 disc, with versions of the movie on separate discs. Brazil comes to mind.

Nobody breaks these box sets apart for sale. It is a complete non-issue.

The only time I've ever seen box sets broken apart for sale is when the different discs contain completely different movies or different episodes of TV shows.


I don't think seamless branching will be used any more frequently in this generation than it was last time, there just isn't much call for it and it cuts off the additional double dip revenue stream.
Yup. Seamless branching is mostly just a gimmick that consumers don't care about.

I am talking about DVD releases where there is more than 1 disc, with versions of the movie on separate discs. Brazil comes to mind.

Nobody breaks these box sets apart for sale. It is a complete non-issue.I wasn't talking about stores. I was talking about some individuals who will either sell or give away discs they won't use. I don't know about special things like Criterian collections, but studios are concerned about providing people separate discs of a movie where they can pass on the one they won't use. Do you understand why studios prefer combo discs with HD DVD to including an HD DVD and a DVD of the movie separately in the package?
Yup. Seamless branching is mostly just a gimmick that consumers don't care about.Most consumers won't even know when seamless branching is used. But studios like to put multiple copies of a movie on one disc for multiple reasons. One, so that they don't have to have separate releases for things like a rated cut and an unrated cut. It probably also helps sell it to some consumers as they see that they can choose the version they want to play at any time and aren't locked into one version at purchase. For instance, so they could play the rated version for certain people (like with younger people or their parents :)). But they don't have to know whether the versions were included completely separately or whether they were put on with seamless branching. From what I've seen, unrated and Director's cuts have become more common with time.

Why do you think "AVP: Alien vs Predator" will have two versions on one disc?

--Darin

Darin,
Have you heard that studios actually see a market for this feature ?

Art

I wasn't talking about stores. I was talking about some individuals who will either sell or give away discs they won't use. I don't know about special things like Criterian collections, but studios are concerned about providing people separate discs of a movie where they can pass on the one they won't use. Do you understand why studios prefer combo discs with HD DVD to including an HD DVD and a DVD of the movie separately in the package?
I have NEVER seen a broken up disc set on eBay. I suppose if I looked hard enough I could find rare instances of this, but again, this is a complete non-issue.

I, as a parent of young children, would love to see, and pay extra for seamless branching of certain movies so that they contain both an R-rated and PG-rated (or TV version if already available) on the same disc. I think this was possible even with DVD, but sadly people like myself must have been in the minority. There are many movies that I would love to watch with my wife and kids, but due to certain short scenes that they find objectionable, I cannot.

I, as a parent of young children, would love to see, and pay extra for seamless branching of certain movies so that they contain both an R-rated and PG-rated (or TV version if already available) on the same disc. I think this was possible even with DVD, but sadly people like myself must have been in the minority. There are many movies that I would love to watch with my wife and kids, but due to certain short scenes that they find objectionable, I cannot.
This is why I think seamless branching is unimportant. The studios are too lazy, proud or rich to do this now. By doing it they would expand the buyer base of every PG movie. Alternate cuts are of interest to a very few fans - 2 disk sets would work fine.

I think that most directors and perhaps some studios are opposed to sanitized versions of their movies. Several studios and the Directors Guild of America even won a lawsuit against a company named CleanFlicks that was producing edited versions of DVDs.

I also think that most "Directors Cut" DVD versions are versions that the director preferred but did not make it in the theatrical release due to either length or ratings (read NC-17) concerns. In almost all cases, I prefer the directors cut and would probably never watch or buy the original version.

Say that there were a PG-13 and an R rated version of the movie on the same disk, would there need to be some sort of parental control switch included? Would a minor be prohibited from buying such a disk? It seems easier to handle with 2 disks.

The studios may see some advantages to seamless branching, but I have yet to see any advantages that would interest me personally.

I see it as a niche item that will have very little practial impact. For most releases the deleted scenes or directors cut standalone version is sufficient.

Most movies don't have the interest to have this done, for a catalog title there no money to do it, and for most movies the directors have already walked away, its tough enough for them to record an audio track for the commentary.

I think seamless branching has its most potential to "G rating" neuter a movies naughty parts, but I think the cost of doing that from the studio side is noo much and artists would object so its a can of woems for the studios.

I think that most directors and perhaps some studios are opposed to sanitized versions of their movies. Several studios and the Directors Guild of America even won a lawsuit against a company named CleanFlicks that was producing edited versions of DVDs.
They made a big noise about artistic rights, but I think it boiled down that somebody else was making money doing the edits, when that right was exclusively theirs. IMO

I see it as a niche item that will have very little practial impact. For most releases the deleted scenes or directors cut standalone version is sufficient.

Most movies don't have the interest to have this done, for a catalog title there no money to do it, and for most movies the directors have already walked away, its tough enough for them to record an audio track for the commentary.

I think seamless branching has its most potential to "G rating" neuter a movies naughty parts, but I think the cost of doing that from the studio side is noo much and artists would object so its a can of woems for the studios.
For most movies that have been or will be shown on broadcast TV, sanitized versions are available or will soon be available. I really don't see why this can't be done for very little cost during mastering. I remember HK DVD version of Shaolin Soccer had seamless branching for both extended and normal version of the movie, and it worked relatively well.

Have you heard that studios actually see a market for this feature? I have heard of interest in it. But even besides that we can look at the fact that "AVP: Alien vs Predator" has been announced to use it on Blu-ray, Paramount used branching on MI:3 (although not seamless from what I could see), and there are DVDs with seamless branching.

Here is a DVD set for "The Lord of the Rings" on Amazon:

http://www.amazon.com/Rings-Trilogy-Theatrical-Extended-Limited/dp/B000GTLR2A/sr=8-1/qid=1163029298/ref=pd_bbs_sr_1/002-7169536-3162419?ie=UTF8&s=dvd

that says:
Disc 1 will present the Special Extended DVD Edition of the film split into two parts (on two sides of a DVD-18) at the break point of the initial DVD release. The Theatrical version will also be split into two parts (on two sides of a DVD-18) available through seamless branching.
...
Disc 1: For the first time, the Theatrical and Extended versions of each film are on one disc! This 2-sided DVD puts both versions of the epic film on one convenient, portable disc. You can choose which version you'd like to see from the main DVD menu.According to the specs, it looks like DTS 6.1 ES was on the original extended discs, but was dropped for the seamless version, which makes some sense given the limitations of branch points there.

I don't see seamless branching as something were there will be less of it with time, but more if anything.

I have NEVER seen a broken up disc set on eBay. I suppose if I looked hard enough I could find rare instances of this, but again, this is a complete non-issue.So, do you believe that Amir's comments about studios wanting to use combo discs instead of including an HD DVD and a DVD because people could pass one on were false?

--Darin

...

So, do you believe that Amir's comments about studios wanting to use combo discs instead of including an HD DVD and a DVD because people could pass one on were false?

--Darin

you're not trying to rationalize studio paranoia, are you? :D

you're not trying to rationalize studio paranoia, are you? :DJust trying to live in the real world. :) The studios will do what the studios will do, whether I like it or not. We can argue about what they should do, but that is different than discussing what they will do.

--Darin

According to the specs, it looks like DTS 6.1 ES was on the original extended discs, but was dropped for the seamless version, which makes some sense given the limitations of branch points there.

I don't see seamless branching as something were there will be less of it with time, but more if anything.

Darin,

I agree that seamless branching is being used in DVD but we must realize that it isn't critical to consumer purchases. If LOTR was available in DTS 6.1 ES as only the EE, and DD 5.1 as both TE and EE, I bet you 90% of the AVSForum would buy the DTS 6.1ES with only EE simply because it isn't as big of a deal as the loss in sound.

Seamless branching eats up bandwith at the juncture points (as you noted). This really creates havoc for the compressionist and the sound mixer should be aware of this as well. If TrueHD tracks, or even DD+ could vary in bitrate rate around the branch points, this may free up bandwith (create 1 second of silence preceding and after branch point). The loss of sound would not be as annoying as the loss of video or a stutter.

I'm sure innovation will allow seamless branching in HD DVD. As you said, later in the format's life is when it will be utilized most. We can afford to enjoy what we have right now and work on that issue when consumers start hankering for a double dip. :)

what info from the bd side are you looking for exactly? ie, what info would be useful/helpful? keep in mind that the bd specs are 'confidential'...

what info from the bd side are you looking for exactly? ie, what info would be useful/helpful? keep in mind that the bd specs are 'confidential'...Basically, the bitrate limitations before the branch points. Like, is it ~60% of the normal rates as an average for the 2 seconds before the branch? And then whether there are any other relevant limitations related to these branch points.

--Darin

Here's a guess - you will never know

Here's a guess - you will never knowI think I'll be able to get the information. Might not be able to share it, but I think I'll get it at some point.

One thing that will be interesting is if somebody with a way to monitor the bitrate can do it for AVP, when that comes out. I just read that the G2 Toshiba player lists a bitrate monitor as a feature. I hope it is true as it could be very interesting if we can look at instantaneous bitrates.

--Darin

Seamless branching? Add that to the list of features I could not care less about. Move over IME and U-Control.

I guess I'm one of the few that see a lot of potential for seamless branching.

After watching Memento on dvd back in 2002, I immediately thought it'd be a great idea if there was an option to view the movie again, however, each scene in chronological order. I think people would have a better appreciation of how well-made the film was.

As someone mentioned Shaolin Soccer earlier (and with many foreign comedies), the Hong Kong and english releases were very different. Some of the humour that is hilarious to an asian audience just doesn't translate very well over to english and would only serve to leave an english audience scratching their head and bogging down the flow of the movie with uncomfortable dead spots. Hopefully with seamless branching, a viewer can choose the chinese language version and see the original cut; alternatively, if a viewer chose the english dubbed version, they'd get the edited version that keeps the humour relevent to the audience and the pace steady.

However, as a parent, I'd say the best use of seamless branching would be the ability to choose between various versions: an unrated cut, the original theater cut and a family-friendly (ie. tv broadcast) version. Doesn't most players already have parental control features built in? Why bother implementing this if they didn't intend to use it??

To say seamless branching is unimportant or calling it a non-issue appears lacking in imagination and short-selling the consumer.

To me seamless branching means, there are two versions of the same scene, not that one version has bits cut out of it. Is this what we are talking about?

As to whether it is worthwhile, I guess I'm one of those that don't really feel it is, but not strongly objecting it.

Many are asking for it as a means of parental control... I agree that many great movies could be made child friendly if only it had one or two scenes cut out of it, oftentimes these scenes are not totally necessary to move the story along. However I appreciate that it is the way the movie was intended, I feel if parents are looking out for their children (and that is a good thing) then it is a noble request, but at the same time I feel the directors etc. felt the movie was not intended for that audience anyway. It's not cut and dry like that rollercoaster ride at the amusement park where they designed the ride so that persons under a certain height (cue the clown) are prohibited from riding, but it is something along those lines in that the director intended it for a specific audience. Imagine if I write a thesis about some uber technology, I wouldn't be handing it over to someone who opposes technology to read it and then have them tell me what I wrote is offensive etc. It's the same here, if you read the classification and it says not recommended for under 15s etc. and you allow a 5 year old to watch it, then you can't really expect to have any legs to stand on when you try to trash the movie from that viewpoint.

At the end of the day, the movie wasn't designed for your kids, just like some magazines aren't designed for your kids. If you feel there is adequate value in the content bar a few naughty bits, then it's probably best if you ask your kids to close their eyes for the next few seconds and be done with that. Important is that you explain to them that they can't watch this bit because they aren't old enough to understand.

I recall watching Dead Poets Society when I was 14, it was a movie which I felt was fantastic then and now. There is a short section where they pull out a magazine and show the centrefold. That's about all there is in terms of naughty bits according to my memory. However if I were to dismiss the naughty bit, I'd still be concerned about the suicide bit, some 5 year olds won't take it very well.

Cheers...
Duy-Khang Hoang

After watching Memento on dvd back in 2002, I immediately thought it'd be a great idea if there was an option to view the movie again, however, each scene in chronological order. I think people would have a better appreciation of how well-made the film was.
You know this was an option on this movie. As I recall, you had to go into the special features and then rearrange the tire changing test in chronological order to find a hidden option to replay the movie in chronological order through seamless branching. Although it made the movie easier to follow, I preferred the original version.

what good is ANY seamless branching if the soundtrack cannot branch seamlessly? (Soundtracks often are changed to accomodate extended scenes).

Seamless branching? Add that to the list of features I could not care less about. Move over IME and U-Control.

With seamless branching I am given the option of whether I want to see the tacked-on song on Lion King and Beauty and the Beast or not.

With seamless branching I can select which cut of the Alien movies I want to see.

With seamless branching you can watch the movie with an alternate ending on 16 Blocks (but only on the DVD, not the hidef discs).

Seamless branching is a nice feature. Not often necessary, but why give up on it, especially now that alternate/extended/director's cut are all over the place?

Basically, the bitrate limitations before the branch points. Like, is it ~60% of the normal rates as an average for the 2 seconds before the branch? And then whether there are any other relevant limitations related to these branch points.

--Darin

there are two types of "seamless branching" in general, one is which there are different angles the other is where there is alternate content. from what i gather, the alternate content type of seamless connections refers to content stored at different locations on the disc so i don't believe these items are muxed together. there are requirements to be able to jump to the spot on the disc where the alternate content resides before the buffer memory(ies) run out.

i would expect this is the same for both formats?

I have NEVER seen a broken up disc set on eBay. I suppose if I looked hard enough I could find rare instances of this, but again, this is a complete non-issue.

Maybe not ebay. But if I had a combo set with, say, an HD DVD and a regular DVD I think it would be very likely I'd give the DVD away to any of my friends that wanted it. And by the doctrine of first sale I believe it would be legal for me to do that.

- Tom

I actually think there would be (or at least should be) a huge market for seamless branching combined with v-chip-like technology. The idea would be to leave your player locked to play G/PG (Airplane version) content unless a password was given to unlock it.

We already know there are multiple versions of most all movies shown on TV or airplanes so we might as well automate the process and streamline the distribution. Heck, once they do that you might even get the option dial up and purchase the upgrade to get the x-rated version of Alien some such. ;)

Which, for some odd reason, brings me to the idea that if a player had a hard drive and some clever logic it could cache branching points to the hard drive first with a little buffering and avoid possible delays at branches.

- Tom

there are two types of "seamless branching" in general, one is which there are different angles the other is where there is alternate content. from what i gather, the alternate content type of seamless connections refers to content stored at different locations on the disc so i don't believe these items are muxed together. there are requirements to be able to jump to the spot on the disc where the alternate content resides before the buffer memory(ies) run out.

i would expect this is the same for both formats?I expect the types to be the same, but from what I've read Blu-ray mandates more buffer memory to go along with their faster spin rate and higher normal bandwidth limitations.

--Darin

there are requirements to be able to jump to the spot on the disc where the alternate content resides before the buffer memory(ies) run out.

BenDover :not only that but catch up as well. The point is relatively near the connection points the BW needs to be lower in order to fill up the buffer and jump and have time to restart filling the buffer.

i.e. these are not real numbers, and they would depend on the jump.

let's say you need to reduce by 10mbps 30-10=20mbps so for a few seconds before and after the jump the limit is 20 but not 30. For BD it becomes 38 vs 48.

Yet another thing that BD can do better in theory, but still doesn't currently in reality. HD-DVD has already provent it can do branching...is it seemless? No, but so what? BD currently doesn't even have non-seemless branching as of yet.

Even if BD does eventually get branching, and it is seemelss, it's pretty much at the bottom of my list of priorities, and I'm willing to guess it's at the bottom of most consumer's wishes as well. There would have been more branching titles in SD-DVD (which can branch, X-Men, anyone?) if it were such a desired feature.

When BD can take a title that exists on HD-DVD and show that the higher bandwidth has provided better AQ/PQ, then there's something to talk about.

HD-DVD has already provent it can do branching...is it seemless? No, but so what?

so now seamless branching is a bad thing as well, you want to watch a movie and have it freeze and jump.

so now seamless branching is a bad thing as well, you want to watch a movie and have it freeze and jump.

Ah yes, the champion of putting words in other peoples' mouths has returned. Point out where I said it's a bad thing.

:rolleyes:

if a studio uses branching, do you care if it is seamless or not?

I'm bumping this because I've just read that the Blade Runner Collector's Edition will be released on August. It will feature as many as four cuts:
- The 1982 US theatrical cut
- The 1982 International theatrical cut
- The 1992 director's cut
- The Definitive Cut

As any Blade Runner fan worth his salt will know, the differences between the three cuts in existence are slight, and having seen what was done with the Alien films, it should be possible to use seamless branching for those.

Last June I asked whether Blu-ray and HD DVD supported seamless branching, and Cjplay replied:

Simple answer, yes HD-DVD does. Unsure about BD, but it'd be bad if it didn't. The big requirements for branching are a low enough mux rate at the point of the branch. With Polar Express, for example, there were several points in the film where scenes showing text (i.e. the tickets, "devoid of life", etc.) were replaced depending on the audio language chosen. These were branches. The laser must be able to jump from the end of one buffer state to the beginning of a whole new buffer state with room in the buffer to accommodate both and seamlessly play 2 different GOPs. Without advanced tools to ensure the functionality and spec compliance, this would be EXTREMELY difficult to pull off. However, those tools are coming to fruition and as soon as they do, you'll see some branching.

So are those tools ready?

According to highdefdigest, the Alien vs Predator BD has seamless branching.

I'm bumping this because I've just read that the Blade Runner Collector's Edition will be released on August. It will feature as many as four cuts:
- The 1982 US theatrical cut
- The 1982 International theatrical cut
- The 1992 director's cut
- The Definitive Cut


Oh drool! That's a must have. :)

Grubert not exactly seamless branching as we are discussing . But if you get Resident evil:Apocalypse, you can pick the extras you want to see during the movie. They are integrated into the movie at specific locations. I checked the featurettes without realizing what it did and during the movie at the appropriate time they played, when the company name first comes up the "corporate malfeasance" starts, when the two main female characters meet the "game babes" starts ..... and when they are done the movie continues. (the only negatives is that you don’t realize it branched when it starts and at the end they have credits)

assuming both formats have data rate drop buffer requirements:

all hddvd players require 128mbytes storage. current bluray require 64kb, but after june 2007 will require 256mbytes. so i don't see why seamless branching would be a problem for either format when they can use that (pre-fill the storage space before the movie starts when you select special version)

because 128mbytes (or 64 or 256) is not a lot and 30mbps is really limiting when you don't need to worry about going lower to add seek .... time

because 128mbytes (or 64 or 256) is not a lot and 30mbps is really limiting when you don't need to worry about going lower to add seek .... time

At an avg bitrate of 12Mbps, 128MB gives you 85 seconds of buffer. At 20MBps, that's 51 seconds. Both of those would seem to be WELL in excess of head seek time requirements, which I would expect to take 5 seconds or less, based on how long a chapter jump takes my HD DVD player.

So it should not seem too difficult to find a point on the disc leading up to the branch point where the avg data rate drops long enough to fill the buffer for 5 seconds or so to make the jump, and then again to come back.

assuming both formats have data rate drop buffer requirements:

all hddvd players require 128mbytes storage. current bluray require 64kb, but after june 2007 will require 256mbytes. so i don't see why seamless branching would be a problem for either format when they can use that (pre-fill the storage space before the movie starts when you select special version)Just because players require a certain amount of storage that doesn't necessarily mean that it could be used for this kind of thing. It is possible and would seem like one way to go (with some delay at the beginning of the movie), but do you know that this memory is available for this kind of thing, or are you guessing? Players are required to have buffers that allow them to go over their normal peak rate (about 30Mbps for HD DVD and about 48Mbps for Blu-ray) for short periods of time and I think that these buffers are relevant to the seamless branch points. My understanding of the HD DVD spec is that the average for the 2 seconds before a branch points needs to be 18Mbps or less to keep the branch seamless. I would think that they would call out ways to allow higher with the use of the memory you are talking about if their spec architecture was done that way and it would be nice to hear if that is the case.

This might turn out to be like the audio where it is possible to architect a system where secondary audio doesn't replicate things from the main track (like Spanish and English) to save on bandwidth usage, but neither format did it that way.

--Darin

assuming both formats have data rate drop buffer requirements:

all hddvd players require 128mbytes storage. current bluray require 64kb, but after june 2007 will require 256mbytes. so i don't see why seamless branching would be a problem for either format when they can use that (pre-fill the storage space before the movie starts when you select special version)

I believe that those are the minimum non-volatile memory requirements, usually flash memory for a stand-alone.

The HD DVD spec requires 33Mbps read speed. The write speed isn't defined, I don't believe, but clearly it would be much lower, so the NV can't be used for the high bandwidth buffering.

Keith Jack has said the Sigma Design's reference BD player design defines 512MB of DRAM and 1G of flash.

So it should not seem too difficult to find a point on the disc leading up to the branch point where the avg data rate drops long enough to fill the buffer for 5 seconds or so to make the jump, and then again to come back.



so you think the movie should be bastardized by either putting the brake where it does not belong or reducing the BW required to do the scene justice. The whole point is that the BW is not enough and that with branching it becomes even more restrictive.

so you think the movie should be bastardized by either putting the brake where it does not belong or reducing the BW required to do the scene justice. The whole point is that the BW is not enough and that with branching it becomes even more restrictive.

No, I'm challenging the "not enough" bandwidth claim.

If I need to break by 1:23:45, and there's a point 30 seconds earlier at 1:24:15 where the scene avg bitrate is below the break threshold, I'll do it there, and include an extras 30 second "lead in" on the alternate scene.

The average and peak bitrates, along with the buffer sizes, clearly indicate that a 5-second buffer-fill time isn't going to be hard.

No, I'm challenging the "not enough" bandwidth claim.

If I need to break by 1:23:45, and there's a point 30 seconds earlier at 1:24:15 where the scene avg bitrate is below the break threshold, I'll do it there, and include an extras 30 second "lead in" on the alternate scene.

The average and peak bitrates, along with the buffer sizes, clearly indicate that a 5-second buffer-fill time isn't going to be hard.What buffer are you referring to here? From what I've read, HD DVD requires the overall average to be 18Mbps or less mux rate (video, audio, etc.) for the 2 seconds before a break specifically for buffer filling already. Are you talking about the 128MB (I think that is it) of storage elsewhere? If so, do you have any information that it can be used for this kind of thing? If that memory could be used, why would the specs for HD DVD require the 18Mbps limit before branches for them to be seamless? Basically, are you saying that they don't have to meet that 18Mbps limit for the branch points that get encoded in?

--Darin

If I need to break by 1:23:45, and there's a point 30 seconds earlier at 1:24:15 where the scene avg bitrate is below the break threshold, I'll do it there, and include an extras 30 second "lead in" on the alternate scene.


That's a clever, albeit "The Descent PiP wasteful" way around the problem. :)

It would cause issues on any title that had lots of these. For example, Disney animations frequently have written text in the scene replaced with localized versions.

If there was a lot of that, a 5-30 second lead-in per branch would add up in a hurry.

Gary

Personally I think seamless branching is mostly irrelevant to most people, myself included.
Guys - am I misunderstanding something here?

Seamless branching is *widely* used by DVDs. I have lots of DVDs where you can choose the "Theatrical" version or the "Directors cut" - and seamless branching is generally used to accomplish this. ie Ray

Are we dealing (in advance) with some new "feature" (read failing) of BR players? Is this why the Sony player couldn't handle the "pseudo PiP" (ie seamless branching) used on the Descent BR disc?

What I DO know is that the specs for the buffer memory on HD DVD are very high to accomodate seamless branching - I think offhand it is a second at full bitrate.

What's the Bluray player requirement on this BTW?

What buffer are you referring to here? From what I've read, HD DVD requires the overall average to be 18Mbps or less mux rate (video, audio, etc.) for the 2 seconds before a break specifically for buffer filling already. Are you talking about the 128MB (I think that is it) of storage elsewhere? If so, do you have any information that it can be used for this kind of thing? If that memory could be used, why would the specs for HD DVD require the 18Mbps limit before branches for them to be seamless? Basically, are you saying that they don't have to meet that 18Mbps limit for the branch points that get encoded in?

--Darin

No. I'm referring to the 128MB storage providing enough of a buffer to make it seamless.

And, that from what I can tell, 5 seconds of time for a re-seek would be plenty. If the spec says only 2 seconds are needed, that's even easier.

Given the ABR's of titles, I don't think finding a 2-second spot under 18 is going to be a huge problem.

That's a clever, albeit "The Descent PiP wasteful" way around the problem. :)

It would cause issues on any title that had lots of these. For example, Disney animations frequently have written text in the scene replaced with localized versions.

If there was a lot of that, a 5-30 second lead-in per branch would add up in a hurry.

Gary

I was quoting a kind of worst case there at 30 seconds. Geven the ABR's, published for several movies, I don't think it's going to be too difficult to get under 18 for two seconds.

Even if you have to do it on average 10 seconds ahead... you could have 50 branches and be "wasting" less than 9 minutes of video. And I suspect that's a pretty worst-case scenario.

What's the Bluray player requirement on this BTW?I haven't gotten any exact figures for Blu-ray, but I would expect it to be in about the same range as HD DVD as far as percentage of max mux rate. 60% of 30 is 18 and 60% of 48 is 28.8. If they break out video separately, then 60% of 40 is 24 for the video part.
No. I'm referring to the 128MB storage providing enough of a buffer to make it seamless.

And, that from what I can tell, 5 seconds of time for a re-seek would be plenty. If the spec says only 2 seconds are needed, that's even easier.

Given the ABR's of titles, I don't think finding a 2-second spot under 18 is going to be a huge problem.Again, why do you think the 128MB of storage can be used for seamless branching? As I mentioned before, this seems to be along the same kinds of lines of hope as saying that 3 different audio tracks for languages could be used for compressed together to save bandwidth, but DVD, HD DVD, and Blu-ray didn't design their systems for that. Do you have anything that indicates that the 128MB of storage is relevant to seamless branching and if so, why do you think they even have the 18Mbps limit for branches?
I was quoting a kind of worst case there at 30 seconds. Geven the ABR's, published for several movies, I don't think it's going to be too difficult to get under 18 for two seconds.Do you mean those ABRs where they pick some of the lower ones and then publish those or are you talking about ABRs where all movies are considered? Remember that audio and things comes out of this and it isn't that the video just gets 18Mbps.

--Darin

No. I'm referring to the 128MB storage providing enough of a buffer to make it seamless.


That is non-volatile and usually flash. It doesn't have sufficient write speed bandwidth to be used that way.

The spec only requires 33Mbps read speed (slower than the optical drive!).

Gary

Again, why do you think the 128MB of storage can be used for seamless branching? As I mentioned before, this seems to be along the same kinds of lines of hope as saying that 3 different audio tracks for languages could be used for compressed together to save bandwidth, but DVD, HD DVD, and Blu-ray didn't design their systems for that. Do you have anything that indicates that the 128MB of storage is relevant to seamless branching and if so, why do you think they even have the 18Mbps limit for branches?
Do you mean those ABRs where they pick some of the lower ones and then publish those or are you talking about ABRs where all movies are considered? Remember that audio and things comes out of this and it isn't that the video just gets 18Mbps.

--Darin

(Answering the question to me, where you inadvertently attributed the quote to rdjam)

I was going off info in post #'s 45 & 46. But the point is well taken that the persistent storage flash RAM is indeed probably separate from the "branch buffers". Although honestly, the point I'm attempting to make is that I doubt finding a branch point leading up to the new scene with a <= 18Mbps data rate is all that difficult. And even if you had to branch a few seconds early to do it, I doubt it's gonna kill you unless you have LOTS of branches.

So, I'm simply going to assume that if they have a spec for seamless branching, there's probably adequate buffer to accommodate it. (I wasn't attempting to make a "buffer allows for greater data rate during branches" argument, if I came across that way it was unintentional).

I suppose a little back of the envelope scribbling might tell us that the buffers = (MaxMux - PreBranchRate) * LeadInTime. That's (30Mbs - 18Mbps) * 2 seconds. That's 24 Megabits, or 3 Megabytes. That seem right?

Anyway, if you have some further insight as to how this all works, I'm all ears.

I haven't gotten any exact figures for Blu-ray, but I would expect it to be in about the same range as HD DVD as far as percentage of max mux rate. 60% of 30 is 18 and 60% of 48 is 28.8. If they break out video separately, then 60% of 40 is 24 for the video part.
Again, why do you think the 128MB of storage can be used for seamless branching? As I mentioned before, this seems to be along the same kinds of lines of hope as saying that 3 different audio tracks for languages could be used for compressed together to save bandwidth, but DVD, HD DVD, and Blu-ray didn't design their systems for that. Do you have anything that indicates that the 128MB of storage is relevant to seamless branching and if so, why do you think they even have the 18Mbps limit for branches?--Darin
Hi Darin, as Steve points out, I think you've misquoted in your post. If you get a chance to edit it that would be cool.

Re: your question here about the 128 megs, my immediate guess is that this memory was not spec'd or designed for that use and would probably be much slower than would be required. The fact that it is non-volatile memory would strengthen said assumption.

I believe that the memory for the playback buffering is entirely separate and not included in this number, as it is more integral with the core electronics.

@Steve - I'm guessing closer to 4.5 MB for the buffer.

(Answering the question to me, where you inadvertently attributed the quote to rdjam)Hi Darin, as Steve points out, I think you've misquoted in your post. If you get a chance to edit it that would be cool.Sorry guys. I fixed it.
So, I'm simply going to assume that if they have a spec for seamless branching, there's probably adequate buffer to accommodate it.DVD had seamless branching, but the seamlessly branched version of LOTR didn't have DTS and reportedly looked pretty poor. I don't know that it is the reason it looked poor (and haven't seen it to verify that it did), but it does sound suspicous. I think that backing up to try to find a good spot for a branch is a good idea. Given that lossless audio alone can take up 4Mbps or more, I'm not confident that they will be able to find reasonable ways to keep an 18Mbps total from affecting the video though. Maybe they'll stay away from the 24/48 7.1 kind of thing that can have peaks like 6.6Mbps and average of close to 4.5Mbps if they do a title with seamless branching, but it would be nice if LOTR could be seamless branched without leaving the best audio off. A 4Mbps main audio track with two 640k secondary language tracks would leave a little under 13Mbps for the video there. I know that "Batman Begins" was probably under 13Mbps average, but some other titles are much higher. A newer version of the encoder would probably do better, but "Full Metal Jacket" averaged something like 25Mbps just for the video with VC-1. I believe it was 1.78:1 though.

I wonder if they will use seamless branching for a "Bladerunner" release. I'm not sure how that one would be for compressing. The DVD looked horrible IMO and an HD version I saw had quite a few compression artifacts.

--Darin

Just posted this on the insider thread.

Dances with Wolves would see to be the perfect test case for seamless branching.

They are using AVC and SL25 Blu-ray disc. Why not use 50GB and AVC and show what Clu--ray can d do with that case with seamless branching by having both versions on the same disc.

This is one case, where there is a very long version of a movie and a much shorter version avalaible and its an epic. Why didn't they try it here???

Gents:

Dances with Wolves is being released by Fox on BD SL 25GB with AVC and the length is being reduced from 236 minutes to 181 minutes,

Why wouldn't this be a perfect candidate for a DL 50GB disc? With branching ? Isn't this the perfect case to justify why DL50s are needed? AVS should have enough space with a 50GB disc to store the full length of it.

I would love to have this in its full version and have the ability to play the shorter cut as well. Seriously this is one of those epic films that I would love to see in true HD.

Any thoughts?

Seamless branching? Add that to the list of features I could not care less about. Move over IME and U-Control. Yeah, I didn't until I started using it. Now I watch some movies twice once pure and once we me f**king with it.

Plus with HDi I always watch the extra now on HD DVD, when I rarely did on DVD. that menu at the start and me not getting off my butt to change the disc just breaks down that last barrier to encourage me to watch them.

Just posted this on the insider thread.

Dances with Wolves would see to be the perfect test case for seamless branching.

They are using AVC and SL25 Blu-ray disc. Why not use 50GB and AVC and show what Clu--ray can d do with that case with seamless branching by having both versions on the same disc.

This is one case, where there is a very long version of a movie and a much shorter version avalaible and its an epic. Why didn't they try it here???

Darn good question. And most discussions of DWW are disappointed that the 181 minute version is all that is being offered. But, start with the question: Why isn't the full version being offered?

You seem to be implying a technology limitation, where to me it seems to be a deliberate marketing decision: Planned double dipping.

I won't buy T2 until I can get the special edition. Or LOTRx3 until the EE.

Alien, Aliens and The Abyss better be the director's cuts!

Gary

^^^ Actually I wsan't thinking about it that term, I would think AVC and BD50 would more than fit and BD50s can certainly be made in enough quantaties now to cover a single release.

I will rent LOTR until I get the EE. I might buy T2 from Europe.

Agree on the Alien series and The Abyss.

But now that you mention it , this whole thread (after having read through it) does seem like another try to find a way to justify the extra bandwidth or capacity of Blu-ray over HD DVD.

You seem to be implying a technology limitation, where to me it seems to be a deliberate marketing decision: Planned double dipping. i hate freaken Double dipping, I was hoping the studios would move away from that in these new optical formats.

Why King Kong HD DVD was not offered as extended version, while it was available in DVD?

DVD had seamless branching, but the seamlessly branched version of LOTR didn't have DTS and reportedly looked pretty poor. I don't know that it is the reason it looked poor (and haven't seen it to verify that it did), but it does sound suspicous.

On the other hand the 4 films from the Alien Quadrilogy featured dual cuts with seamless branching and DTS sound and PQ was great. See this extensive review on thedigitalbits (http://www.thedigitalbits.com/reviews3/alienquad00.html).

Sorry guys. I fixed it.
DVD had seamless branching, but the seamlessly branched version of LOTR didn't have DTS and reportedly looked pretty poor. I don't know that it is the reason it looked poor (and haven't seen it to verify that it did), but it does sound suspicous. I think that backing up to try to find a good spot for a branch is a good idea. Given that lossless audio alone can take up 4Mbps or more, I'm not confident that they will be able to find reasonable ways to keep an 18Mbps total from affecting the video though. Maybe they'll stay away from the 24/48 7.1 kind of thing that can have peaks like 6.6Mbps and average of close to 4.5Mbps if they do a title with seamless branching, but it would be nice if LOTR could be seamless branched without leaving the best audio off. A 4Mbps main audio track with two 640k secondary language tracks would leave a little under 13Mbps for the video there. I know that "Batman Begins" was probably under 13Mbps average, but some other titles are much higher. A newer version of the encoder would probably do better, but "Full Metal Jacket" averaged something like 25Mbps just for the video with VC-1. I believe it was 1.78:1 though.

I wonder if they will use seamless branching for a "Bladerunner" release. I'm not sure how that one would be for compressing. The DVD looked horrible IMO and an HD version I saw had quite a few compression artifacts.

--Darin

Any ideas how "many" branches such titles would be likely to have? I'm wondering what the real-world impact of having to branch 30-45 seconds early would be (in order to find the right bitrate spot). Are we talking a dozen or two? Or 50?

Thinking this thru: would dynamux help us here? Being able to select a point where that 4+Mbs track is at an ebb would make it easier to select a branch point.

But now that you mention it , this whole thread (after having read through it) does seem like another try to find a way to justify the extra bandwidth or capacity of Blu-ray over HD DVD.

I think a 1.85 AR + IME + lossless audio + seamless branching title needs to be demonstrated from HD DVD before we can declare bandwidth a non-issue.

What usually happens is people start justifying not having certain things to get the bandwidth down to the point that HD DVD can manage. Witness the current DD+ is better than lossless push.

Gary

But now that you mention it , this whole thread (after having read through it) does seem like another try to find a way to justify the extra bandwidth or capacity of Blu-ray over HD DVD.

That doesn't make it less of a legitimate concern to be valued on its own terms.

Just imagine if E.T. is released... and it's only the 20th Anniversary edition with CGI E.T.!! :eek:

^^^ Actually I wsan't thinking about it that term, I would think AVC and BD50 would more than fit and BD50s can certainly be made in enough quantaties now to cover a single release.

I will rent LOTR until I get the EE. I might buy T2 from Europe.

Agree on the Alien series and The Abyss.

But now that you mention it , this whole thread (after having read through it) does seem like another try to find a way to justify the extra bandwidth or capacity of Blu-ray over HD DVD.

did it honestly take you reading the whole thread through to figure that out ? ;) :p :D :eek: (i think that is all the applicable smiles ;))

here's the thing, a max anything will always be a limitation at some point; e.g., you have a bd title, encoded using mpeg2 and at least one pcm track...of course you have the bitrate meter maxed out to accomodate mpeg2 and pcm, now don't you think you could run into a similar situation with branching? you may just have to do as scaesere so aptly points out and make your branch at some more accomodating point...this is all TOTALLY hidden from the user...would we ever know where the branch was made?

btw, there are all sorts of numbers floating around the hd dvd spec that deal with seamless branching...one says 18 but yet there is another point where the max is 24...there are also cosiderations of contiguous vs. interleaved...i don't fully understand it all at this point and don't have the time right now but will look at it more closesly at some point.

Geven the ABR's, published for several movies, I don't think it's going to be too difficult to get under 18 for two seconds.Somebody looked at the file size for a movie we were discussing before ("Miami Vice") and did a calculation of the ABR. They got between 17Mbps and 18Mbps for the video ABR for that one. I haven't checked it, but it looks like the video PBR for that one would be about 25Mbps. Higher than it would have been if Universal had actually put TrueHD on that like it was originally announced with.

I don't know how many branches would be needed for some of these regular movies. If a common word (like the name of a boat) is going to be changed and it is shown a lot, then it could be quite a few, but I don't know the numbers in general. Looking for a good branch point is part of what I would expect the tools to do, at least once the tools are mature enough for that.
But now that you mention it , this whole thread (after having read through it) does seem like another try to find a way to justify the extra bandwidth or capacity of Blu-ray over HD DVD.Some people in the design phase are the types to sit around and claim that they aren't overdesigning their system like the other guys, all while being ignorant of some of the more difficult things they will be expected to do. Not comprehending how secondary audio tracks actually work with respect to the subject or not understanding seamless branching aren't really things that are conducive to coming up with the best design for things like disc spin rate and mux rates. Then after the fact if the system wasn't designed to handle some of the cases well that weren't considered by some of those who should have considered them, it is likely that they will start spinning things as avoiding overdesign and that the other side is just looking for cases to justify their design. Well, maybe the other side understood a while ago why the spin rate and max mux rates mattered and hopefully Toshiba understands it better now and the information that they may go to the same spin rate as Blu-ray is a reasonable indicator that somebody believes that a 1.5x spin rate is a good idea.

In the long run maybe aiming for a lower design while telling everybody that more than that wouldn't be smart, in order to get out of the starting gate quickly, and then later on borrowing or copying from the other side's design will work out.

I doubt that those who brag about how they didn't overdesign their system realized at design time how much trouble they were going to have just including 24/48 lossless audio for movies instead of limiting just about all audio down to 16/48 before using lossless compression from that point. And that is even before using seamless branching.

I wish that some of those who could have influenced the design for the HD DVD system had put more thought into how secondary audio takes away from the available bandwidth for other things and how seamless branching plays into this. Maybe they would have used a 1.5x spin rate in the past instead of just being at the point of hinting to us now that they might add it. But if they go to 1.5x now, I will consider it better late than never.
btw, there are all sorts of numbers floating around the hd dvd spec that deal with seamless branching...one says 18 but yet there is another point where the max is 24...I believe that the 24Mbps is for layer changes. The average needs to be low enough before a layer change to make it seamless. A layer change and moving to a different spot on the disc are not the same thing, which I understand is why the seamless branch limitation is lower.

--Darin

I believe that the 24Mbps is for layer changes. The average needs to be low enough before a layer change to make it seamless. A layer change and moving to a different spot on the disc are not the same thing, which I understand is why the seamless branch limitation is lower.


Right. A layer change is a focus depth change at the current tracking point. A seamless branch is a movement of the OPU to a different part of the disc, and a reacquisition of the focus on the current layer.

Clearly the former can occur faster than the latter. And it is the time the event takes that determines the bandwidth due to needing to keep the decoding buffer primed for seamless (layer change/branch) decoding.

Gary

An interesting case cropped up: 16 Blocks.

The DVD had an alternate ending, which could be viewed on its own or as part of the film via seamless branching.

The HD DVD released in North America was a combo, so obviously it was impossible to watch the film in hidef with the alternate ending.

The BD released in NA included the alternate ending, but I haven't read any reports of integrated playback.

Now here where it gets interesting:

16 Blocks have been announced on HD DVD and BD in Germany (http://www.areadvd.de/hd-dvd/2007/16_Blocks_BD_HD_DVD.shtml). As you will probably know, there are no HD DVD combos in Europe, so bonus are always on the same side as the feature. However, seamless branching is mentioned only on the BD release.

...


I believe that the 24Mbps is for layer changes. The average needs to be low enough before a layer change to make it seamless. A layer change and moving to a different spot on the disc are not the same thing, which I understand is why the seamless branch limitation is lower.

--Darin


the 24 figure is specifically in a table specifying seamless branching parameters so i'm not sure about this explanation...

the 24 figure is specifically in a table specifying seamless branching parameters so i'm not sure about this explanation...What other values are in the table? Is this a public table or something that can't be shared?

Thanks,
Darin

An interesting case cropped up: 16 Blocks.
...
As you will probably know, there are no HD DVD combos in Europe, so bonus are always on the same side as the feature. However, seamless branching is mentioned only on the BD release.Interesting. I'm pretty sure I watched this on HD DVD and watched the alternative ending from the extras menu after the movie was done. I don't remember anything about being able to choose which version of the movie to watch, but it has been a while.

--Darin

Watch the Featurette! Cool feature, damn I love interactivity. Enjoy!

Branching coming to HD-DVD & Blu-ray Return To House On Haunted Hill Oct 2007 (http://media.dvd.ign.com/media/952/952951/vids_1.html)

Spidey 2 is also going to have seamless branching for v2.1