Microsoft announces external HD-DVD drive for Xbox 360

[Titanio]

Can we be sure of that? We've seen multiple HD streams on Cell, but the moment demands are beyond a SPE's individual capabilities, can a single HD stream be decompressed across multiple SPE's? Given the seriel nature of the data I'd have thought not

I'll admit, I assume it's possible to split across multiple SPEs. If it can't - I guess it comes down to whether a single SPE could handle 1080p at 60 rather than 120 (which I don't think it could!). Given the demo at CES, 60 is at least possible.

The question makes me wonder, though, about the figure given at E3 - 12 "HD" streams simultaneously. If that was the whole chip (PPE + 7 SPUs, which you'd think it would be in order to claim the highest number possible), it suggests some streams maybe be getting split across multiple SPEs somewhere (the only other explanation would be that some SPEs are doing more than one stream, but why not all then?).

edit - a quick google suggests parallel decoding within a single stream is possible, but that may depend on the codec you use..the example I'm looking at is just MPEG decoding, I don't know how it would apply to MPEG-2, VC1 etc.

edit 2 - MPEG2 looks possible also. There are a number of papers out there on it, at least. I'm no expert when it comes to decoding, though, perhaps someone more familiar with the issues could comment on this.

 

[cthellis42]

Geez, there's just no end to the rationalization. So now HD-DVD is using a better codec because it has to?

Who was this in response to?

 

[ihamoitc2005]

Compression

FIRST... BR DOES NOT support 1080P at 60fps. It only supports 1080P at 24fps. It does support 1080i at 60fps.

And less compression != good. They landscape is littered with codecs that provided less compression and less quality.

Aaron Spink
speaking for myself inc.

Current Blu-ray "DISC" is for 1080P @ 24fps, but 1080P @ 60fps for player is no problem and already such player is shown. It is announced that some early player will not have "full feature" and Samsung 1080i player is good example. Samsung designed everything "in-house" and did not have 1080p to have fast development.

Maybe I misunderstand but it sounds like you say you like more compression and less space.

 

[Bigus Dickus]

Who was this in response to?

ihamoitc2005

 

[ihamoitc2005]

Bells and whistles

I'm not up on these things but might it be for BR that it's 1080i at 60 fps but upscaled DVD at 1080p at 60fps?

Also I wouldn't expect a PS3 to have all the bells and whistles as a dedicated BR player.

Sony Blu-ray decoder is software running on CELL chip so bells & whistles is software feature. PS3 has probably much more powerful CELL chip than any Blu-ray player (also bllutooth, 512mb ram, etc) and has 1080P 60fps output unlike rushed Samsung product which to save development time (not production cost) has no 1080P support. Also, because of extra space of blu-ray even uncompressed audio is possible. This is very nice for hifi type buyer with nice audio system.

 

[ihamoitc2005]

Rationalization?

Geez, there's just no end to the rationalization. So now HD-DVD is using a better codec because it has to?

What rationalization do you speak of my friend? Both can support vc1 and mpeg2 no problem.

As for HD-DVD, it is using vc-1 because vc-1 is optimzed for low-bit-rate application. It is possible to get same quality from mpeg2 with newest encoder and careful settings but vc-1 is easy and no problem. HD-DVD has not so much space only 30GB so low-bit-rate is needed. Between low-bit-rate vc1 and high bit-rate mpeg2, maybe on small window on computer screen maybe difference is not so large but mpeg2 has much better quality on large HDTV display where artifacts are easy to see for all.

 

[Hardknock]

Between low-bit-rate vc1 and high bit-rate mpeg2, maybe on small window on computer screen maybe difference is not so large but mpeg2 has much better quality on large HDTV display where artifacts are easy to see for all.

This is not true at all, but I'll let you think what you like.

 

[ihamoitc2005]

Disagree

This is not true at all, but I'll let you think what you like.

Maybe I misunderstand your statement but are you saying low bit-rate vc-1 has same or higher image quality as high bit-rate (almost 2x) mpeg2? If this is what you are saying I am sorry I have to disagree. For small space of HD-DVD codec optimized for very low bit-rate like vc-1 is perhaps best and most efficient choice but for large capacity Blu-ray this compromise is not required and standard DVD level compression is no problem.

 

[Hardknock]

Just because one codec has better compression doesn't mean it automatically has worse image quality. I think both will have the same image quality from what I've heard no?

 

[AlphaWolf]

Maybe I misunderstand your statement but are you saying low bit-rate vc-1 has same or higher image quality as high bit-rate (almost 2x) mpeg2? If this is what you are saying I am sorry I have to disagree. For small space of HD-DVD codec optimized for very low bit-rate like vc-1 is perhaps best and most efficient choice but for large capacity Blu-ray this compromise is not required and standard DVD level compression is no problem.

There's a study linked in that other thread (warner supports blu-ray) that shows that 17mbps VC1 was perceived to be roughly the same as uncompressed. While 24mbps mpeg2 was shown to be inferior. Not sure how much more bit-rate the mpeg2 stream would take to get to equal, but you're not really going to surpass the quality (of 17mbps vc1) if people already couldn't tell the difference.

 

[Carl B]

There's a study linked in that other thread (warner supports blu-ray) that shows that 17mbps VC1 was perceived to be roughly the same as uncompressed. While 24mbps mpeg2 was shown to be inferior. Not sure how much more bit-rate the mpeg2 stream would take to get to equal, but you're not really going to surpass the quality (of 17mbps vc1) if people already couldn't tell the difference.

Alpha just because I'm curious, were they compressed to the same level (seems that for a study like that they should be), or were the levels different? I mean either way I could believe it, obviously the 'cheapness' of going MPEG-2 is a big factor for Sony's own studios. But I'd be interested to know how the viewers would feel at the same bit-ratea, but were MPEG-2 to use lower levels of compression.

 

[ihamoitc2005]

Just because one codec has better compression doesn't mean it automatically has worse image quality.

This is true because many variables like type of scenes, codec, type of codec, and care of encoding process by content owner. Even same codec at same bit-rate can have different quality.

I think both will have the same image quality from what I've heard no?

For low-bit-rate vc1 usually has noticable advantage but if vc1 is low bit rate and mpeg2 is almost 2x higher then probably mpeg2 has much better look. If vc-1 is low bit rate and mpeg2 bit-rate is only little more then maybe quality is same or maybe even vc-1 is better. Best application of vc-1 is for high compression requirement.

 

[Sis]

Alpha just because I'm curious, were they compressed to the same level (seems that for a study like that they should be), or were the levels different? I mean either way I could believe it, obviously the 'cheapness' of going MPEG-2 is a big factor for Sony's own studios. But I'd be interested to know how the viewers would feel at the same bit-ratea, but were MPEG-2 to use lower levels of compression.

I posted this in the CES thread, but it seems relevant here:

Some good in-person impressions of the Blu-Ray and HD-DVD demos:

http://www.avsforum.com/avs-vb/showthread.php?p=6866449&&#post6866449

Some selected interesting bits from that link:

I visited BD/HD DVD related booths. This is purely my opinion, but Panasonic seems the king of picture quality of next gen disc demonstration at CES.

All BDA companies except Panasonic seem to demonstrate MPEG2, Panasonic demoed H.264 video playback for trailers (VBR 16Mbps) and BD-J interactive demo (also VBR 16Mbps). I simply couldn't find any compression artifact even on the 65" Full HD plasma, from the distance of 30cm to the panel. On the other hand, other companies demo clip shows artifacts and blocky, especially Sharp's one is terribly bad. Sony's MPEG2 (VBR 20Mbps) looks better than others, but is still behind to Panasonic.

<rest snipped>

.Sis

 

[scooby_dooby]

If vc-1 is low bit rate and mpeg2 bit-rate is only little more then maybe quality is same or maybe even vc-1 is better. Best application of vc-1 is for high compression requirement.

Except in the real world we seem to see companies using ~20mbps for their MPG2 compression. That's far worse than VC1 at 16mbps.

The real question is, will we actually see 32mbps MP2 movies? Otherwise MP4 is the way to go without discussion. And if so, is there enough difference between a 16mbps MP4 and 32mbps MP2 to warrant throwing away half your disc space?

 

[ihamoitc2005]

Except in the real world we seem to see companies using ~20mbps for their MPG2 compression. That's far worse than VC1 at 16mbps.

The real question is, will we actually see 32mbps MP2 movies? Otherwise MP4 is the way to go without discussion. And if so, is there enough difference between a 16mbps MP4 and 32mbps MP2 to warrant throwing away half your disc space?

I do not think "much better" because sometimes mpeg2 can have very good quality at low bit rate but for future format probably publisher will choose codec depending on space requirement. So very long feature (like 3-4 hr movie) with large extra content that is low-bit-rate vc-1 on Blu-ray must be very low bit-rate vc-1 on HD-DVD with many artifacts. So this is benefit of extra space.

 

[scooby_dooby]

Why do you always talk in theoretical terms like "high" or "low"?

We're at the point where we can can make good estimates of the bitrates they will be using when they launch their respective libraries in a just few months.

Sony's format seems to be a 20mbps MPG2, and 16mbps MPG4 seems like it will be the bit-rate of choice for HD-DVD. In this scenario, it seems MPG2 has a clear disadvantage in both picture quality and disc space.

 

[Carl B]

I posted this in the CES thread, but it seems relevant here:


Some selected interesting bits from that link:

.Sis

Thanks .Sis - yeah I'm not doubting though that VC-1 would look better than MPEG-2 if both were on Blu-ray, I guess my question more revolves around VC-1 on HD-DVD with 15 GB of space to work with vs MPEG-2 with 25 GB of space to work with, how is the video quality going to compare?

 

[ban25]

edit - a quick google suggests parallel decoding within a single stream is possible, but that may depend on the codec you use..the example I'm looking at is just MPEG decoding, I don't know how it would apply to MPEG-2, VC1 etc.

edit 2 - MPEG2 looks possible also. There are a number of papers out there on it, at least. I'm no expert when it comes to decoding, though, perhaps someone more familiar with the issues could comment on this.

Might want to look here:

http://mplayerxp.sourceforge.net/

Though I'm not sure how it distributes the workload across threads (could decode video on one and sound on the other or something).

 

[ihamoitc2005]

Space

In this scenario, it seems MPG2 has a clear disadvantage in both picture quality and disc space.

So in situations where low-bit-rate is needed, then codec with better low-bit-rate performance will be used, no? I think this is quite logical.

What is important is how much space is available because unlike codec which can be of any type available space is fixed and cannot change. With more space, higher bit-rate can be used so no matter what codec any publisher chooses for one movie, that codec can have much better image quality on disc with much more space because higher bit-rate for that codec can be used. Also extra content, uncompressed audio, many other benefits for extra space and each choice is by individual movie publisher since hardware can support any codec.

 

[Bigus Dickus]

can can can can can.

That's all I hear you say.

The important question is will.

will will will will will. Will some BR content use 32mbps for shorter films? Or will everything default to 20mbps, as seems likely?

Truth be told, I think both formats will likely produce the same quality with roughly the same effective storage (length). I just want one to win quickly so we don't have another DVD-A/SACD mess.