VC-1 WMV Playback on Xbox 360

[veffremov]

Does it have to be plugged in or is it just first use then your right? Thanks

Yes it needs to be plugged ina and you need to insert the disk in the HD-DVD addon. It will not play HD-DVD data format media from the internal DVD drive.

[easy2Bcheesy]

I notice that the Xbox Live Marketplace will have full downloads of HD movies and TV shows. You'll be able to download the Matrix and Superman Returns for example.

I'm assuming that these will be 720p/24 VC-1 files which should be interesting from an encoding point of view.

[veffremov]

Just only one question you said the faster decoding will "come with the drive and go with the drive" does that mean it's a hardware codec inside the drive that does the HD-DVD VC-1/H.264 decoding ? i don't understand from a technical standpoint why the dashboard shouldn't be able to use that, @ the moment this sound's like plain consumer restrictions to me nothing more.

I would like to appologize for the confusion this has caused to the community of WMV enthusiasts.

While this is certainly a restriction today, it was not done deliberately, but for pure technical reasons. As I said before I hope we could address this in future updates of the flash, but I can not give you a guarantee that will happen.

We know what the problem is, we have an idea how to solve it, there was just not enough time to do it for this update.

For sure being vocal on these issues matter to the people in charge, so keep the requests comming.

Thanks,
Venelin

PS: there is no HW decoder in the HD-DVD addon. The software to support HD-DVD playback comes with the drive and is somewhat tied with the device. That is the extend of the techncical details I'm willing to share on that issue.

[easy2Bcheesy]

Those behemot like companies think they're the "king of the hill" and have their own way of doing things. They will never change their mind.
It's like hoping MS will remove the absurd license restrictions on Vista... or remove DRM from WMP...

In fairness, competition definitely helps. We have a native 1080p output on Xbox 360 because of competition and this must surely be the reason we can run WMV content of our own in the first place. If (and it's a big if) Sony do allow unrestricted AVC playback it will be because of the same reason.

I am disappointed that the full VC1 implementation is not included on Xbox 360 (especially as the work is done for HD DVD playback) but I imagine that I'm in a tiny percentage of people who would even dream of trying 720p/60 in the first place.

[veffremov]

I am disappointed that the full VC1 implementation is not included on Xbox 360 (especially as the work is done for HD DVD playback)..

I would like to clear a confusion here which starts some speculations in the wrong direction.

HD-DVD playback requires a restricted VC-1 decoder and this is what has been implemented and optimized for the HD-DVD addon.

A fully compliant VC-1 decoder is delivered in the dash player, however the perf is not as good.

I think the reasons are obvious: in the HD-DVD scenario you have restricted/compliant content, in the dash the content is user created so we must support all VC-1 features.

[veffremov]

I realized I may have misled some of you to believe that purchasing the HD-DVD addon will somehow enable the dash player to play VC-1 files with higher bitrates. That is not the case.

The HD-DVD addon is for playback of DVD and HD-DVD disks only. If you can create a HD-DVD formated disk on either DVD9 or HD-DVD media the addon and the associated software will play it. That is about all it does.

[easy2Bcheesy]

Many thanks for all your info and clarification, it's been very useful.

[Bathrone]

Yes many thanks Veffremov. With your information we can start doing good WMV encodes and enjoy that on the 360.

I might be stretching my luck with this question, but hypotehtically if an ICT enfroced HD-DVD was inserted into the HD-DVD add on, does the player respect the ICT and reduce the resolution given it is over vga/component?

[zambelli]

First of all, I'd like to thank Venelin for taking the time to clarify all the confusion surrounding WMV9/VC-1 playback on the 360. :)

I wanted to throw in one more detail about HD-DVD support in both Xbox 360 and Vista Premium/Ultimate. A lot of people assume that just because decoders for MPEG-2, H.264 and VC-1 exist, they they will be able to leverage those decoders for playback of their MPEG, MP4 and WMV files. Well, not so fast. A lot of the HD-DVD decoders (and not just the ones made by Microsoft, but by other companies) are targetted at HD-DVD playback and nothing else. They could be restricted to specific profiles as mandated by the HD-DVD spec. Furtermore, a decoder alone isn't enough to read an MP4 file or a MPEG-2 PS file - you still need parsers and splitters and all that good stuff. So bottom line: as HD-DVD software solutions become more prominent in the months to come, don't always assume that an advertisement of HD-DVD support extends to anything beyond HD-DVD playback. We take it for granted today that Nvidia's PureVideo decoder handles ATSC decoding as well as DVD decoding, but remember that with HD-DVD/BluRay we're still in the infancy stages - so that kind of extensive support might still be a long way away.

I am sure I will benefit from the bandwidth advantages that moving to AP will give on 30fps content but it is cold comfort, somewhat.
Keep in mind that switching from Main Profile to Advanced Profile is not enough to increase quality. Quality is subject to encoder efficiency, not profile level. The differences between profiles - in any codec - are in the feature set and decoder complexity. It is implied that AP content is more difficult to decode than MP content - that's the whole point of having profiles defined to start with.

What exactly does AP bring as an advantage over MP? Take a look the feature tables at http://en.wikipedia.org/wiki/VC-1 and http://forum.doom9.org/showthread.php?t=112634. AP's most important features are:
Interlaced encoding support
Chroma and luma range reduction
Coded resolution != Display resolution
Bitstream level metadata
So as you can see, none of that really affects quality. Microsoft's latest version of the WMV9 (WMV3/WVC1) encoder is v11, now available for download with the v11 Player and WMF SDK. If you use this encoder to encode to either Main Profile or Advanced Profile, you ought to be able to get the same quality for both because most of the quality-related optimizations (i.e. B-frames, inloop filtering, perceptual optimization, etc.) apply to both MP and AP.

So don't feel like you have to encode to AP just because it's there. If MP is more appropriate for your scenario, then go with that instead.

[easy2Bcheesy]

This is all really valuable info - many thanks for taking the time to look into this issue for us :)

[Gunhed]

ehm, wrong post. my fault. sorry

[Valeron]

a 3 core PowerPC machine(with great vector unit built-in, tons of vector register files....according to hardware details you provide) running at 3.2GHz can't decode 720p content smoothly?

do any of you guys write the decoder with Java?

[Sagittaire]

a 3 core PowerPC machine(with great vector unit built-in, tons of vector register files....according to hardware details you provide) running at 3.2GHz can't decode 720p content smoothly?

do any of you guys write the decoder with Java?

well in fact 720p60 use certainely same CPU charge than 1080p30 (1280*720*60 ~ 1920*1080*30)

[Valeron]

well in fact 720p60 use certainely same CPU charge than 1080p30 (1280*720*60 ~ 1920*1080*30)

it's not that kind of case such a great horse power built-in system can't handle, imo.
well, someone had ever told me the performance of the chip in xbox 360 is just identical to the P3 733, now i believe......

[popper]

VC-1 Simple, Main and Advanced profile for 720p up to 60 fps for bitrates 6-8MBps. 1080p 24fps same bitrates (loop filter off).

Do not use display size != encoded size.

Anything above may or may not work - there are no hard limits and it is certainly content dependent. The only limit is the CPU performance.

Media center extender uses more or less the same decoder, so it supports the same profiles. However there are some system level differences and some features like non square pixels work in MCX and do not in the dash.

PhotoStory 1,2 and 3 is supported in the MCX - I don't have hard limits on the video size, but 800x600 should work fine.

Audio WMA Standard up to 320 kbps, WMA Pro up to 7.1@768kbps, WMA Lossless. (This is only when the audio is bundled with a video track).

As you get agressive in audio it eats from the video decode cycles, so you may want to lower the video settings if you want Lossless 5.1.

Hope this answers your questions.

looking at your No.'s it would appear that the codec has not yet been made to take advantage of the AltiVec vector Unit ?,or infact even use it at all,is that correct, if that is the case, is there any timeline when this AltiVec optimiseing might happen and become available?.

also, am i to assume that the UK version with its pal 50/25 can be pushed to the better bitrate, if so what.

also it seems rather odd that zambelli etc tells us that to compare VC-1 to AVC at lower bitrates isnt the right thing to do ,we should always compare at the higher bitrate.

so the question seems to be, is your 'for bitrates 6-8MBps' the ball park figure we should be using for our general testing or the MAX settings for both when testing?.... :cool:

more of a question for the readers but now that we have the likes of the bbc/sky HD streams is anyone really going to use 720p/i today for anything other than perhaps some special projects, and if so is it better to assume everyone will be trying to use/using 1080p/i for most 360 streaming ? and so that is our benchmark?.

[Valeron]

well, the xenon(chip in xbox 360) embrace 2 register files every core, there's 128x128bit stuff in one files. totally 6 group of this files for 6 parellely VMX128(enhanced AltiVec imo) units. in contrast, A64 and Core has only total 16 vector register
the VMX128 units can issue SIMD instructions in 4~14 clock cycle latency

all the info above is from IBM's xenon intro on it's official site.

do any of you think such a chip can't decode 720p VC-1 content?

perhaps...... this chip is good on paper but very bad for real application like Cyrix.....(i still remember GOW is image wise by far the best game i've seen)

[popper]

VC-1 AP has a feature, where the codec pictures are smaller size then the display size. Similar to non suqre pixels, but works to resize in both directions: vertical and horizontal.

For example you may encode 1920x1080 content as 1280x720, but set the display size to 1920x1080 - the decoder will resize internally to the display size.

The feature is designed for TV Broadcast scenarios, not terribly usefull for offline encoding.

Anyway we have a big perf hit if that feature is used. I hope we can adress this in feature updates.

interesting, thanks.

it sounds like the current 360 codec is CPU bound and not using the offload capabilitys of the GFX chip at the moment, or as above, the Altivec.

is this intentional or a 'feature' to be looked at later after yesturdays PS3 launch tests hit doom9 threads ;)

[popper]

I would like to clear a confusion here which starts some speculations in the wrong direction.

{DRM Restricted commercial}HD-DVD playback requires a restricted VC-1 decoder and this is what has been implemented and optimized for the HD-DVD addon.

A fully compliant VC-1 decoder is delivered in the dash player, however the perf is not as good.

I think the reasons are obvious: in the HD-DVD scenario you {want/}have {UN}restricted/compliant {[HD]}content, in the dash the content is user created so we must support all VC-1 features.

of course you do realise that the people on this very board are more likely to encode their user created content to a far higher standard than your average HD-DVD just because they can.

anyone done some super HD encodes yet LOL, just because the displays arnt around just yet doesnt mean doom9'ers havent tryed... stereo HD video being a very good example and we know thats being worked on right now.

they are looking to use their next kit to its full potential, if as your trying to tell us that the standard XB360 cant play these users files, or cant play them unless you buy the add-on as a requirement (is it even available yet?) then theres a problem right there.

what of all the old user content everyone here has, such as the Mpeg-4 part 2 and part 10 content,lots of these files are unrestricted and intentionally so , your telling them they cant play their files because their locked out of that ability and PERHAPS it might be fixed or it MIGHT NOT.

we know full well how powerful the chips are, super-HD not a problem, so its a software problem/fix/feature that might get fixed sometime.

it just doesnt seem like a very good way to get people this cristmas to buy and advocating the machine as [U]the must have living room content player, and so that means its games all the way with the ODD video now and then, arr well, time to look at the next machine on the list that can play what the user wants to play, unrestricted HD user created content..... with a few commercial HD-DVD's/BR now and then..., welcome to the wonderful world of [HD]IPTV my friends, it might not be using the MS OS of choice though, try YellowDog5 instead perhaps.

red:is me

[popper]

First of all, I'd like to thank Venelin for taking the time to clarify all the confusion surrounding WMV9/VC-1 playback on the 360. :)

I wanted to throw in one more detail about HD-DVD support in both Xbox 360 and Vista Premium/Ultimate. A lot of people assume that just because decoders for MPEG-2, H.264 and VC-1 exist, they they will be able to leverage those decoders for playback of their MPEG, MP4 and WMV files. Well, not so fast. A lot of the HD-DVD decoders (and not just the ones made by Microsoft, but by other companies) are targetted at HD-DVD playback and nothing else. They could be restricted to specific profiles as mandated by the HD-DVD spec. Furtermore, a decoder alone isn't enough to read an MP4 file or a MPEG-2 PS file - you still need parsers and splitters and all that good stuff. So bottom line: as HD-DVD software solutions become more prominent in the months to come, don't always assume that an advertisement of HD-DVD support extends to anything beyond HD-DVD playback. We take it for granted today that Nvidia's PureVideo decoder handles ATSC decoding as well as DVD decoding, but remember that with HD-DVD/BluRay we're still in the infancy stages - so that kind of extensive support might still be a long way away.


Keep in mind that switching from Main Profile to Advanced Profile is not enough to increase quality. Quality is subject to encoder efficiency, not profile level. The differences between profiles - in any codec - are in the feature set and decoder complexity. It is implied that AP content is more difficult to decode than MP content - that's the whole point of having profiles defined to start with.

What exactly does AP bring as an advantage over MP? Take a look the feature tables at http://en.wikipedia.org/wiki/VC-1 and http://forum.doom9.org/showthread.php?t=112634. AP's most important features are:
Interlaced encoding support
Chroma and luma range reduction
Coded resolution != Display resolution
Bitstream level metadata
So as you can see, none of that really affects quality. Microsoft's latest version of the WMV9 (WMV3/WVC1) encoder is v11, now available for download with the v11 Player and WMF SDK. If you use this encoder to encode to either Main Profile or Advanced Profile, you ought to be able to get the same quality for both because most of the quality-related optimizations (i.e. B-frames, inloop filtering, perceptual optimization, etc.) apply to both MP and AP.

So don't feel like you have to encode to AP just because it's there. If MP is more appropriate for your scenario, then go with that instead.

zambelli, thank you , very useful info as always.

perhaps im just being slow this morning but when you say 'HD-DVD support' your refering to the actual media as apposed to a HD-DVD compatible encoded file, it seems if we cant place our HD-DVD compatible files on to this media we cant play it on 360, even from the internal Hard drive or the network?.

one interesting point (although unless theres a way to got it on there and running its unusable i suppose),is that ffmpeg since version 0.4.7: had AltiVec optimizations (by Magnus Damn and others).
http://ffmpeg.mplayerhq.hu/changelog.html
VC-1/WMV3/WMV9 video decoder is in there too, wmv3 is also altivec optimized according to lu_zero,
dont know about the rest.
"lu_zero: Wed Sep 13, 2006
Quite old news, btw now we have also vp6 for those flash video addicted.

(wmv3 is also altivec optimized, so isn't running that bad)"

i thought everyone is now useing DVB for the likes of [HD]IPTV and the rest, so is that US ATSC still used/important, i thought it now also had DVB extentions or something (not that it matter here in the UK and EU)?.

[zambelli]

perhaps im just being slow this morning but when you say 'HD-DVD support' your refering to the actual media as apposed to a HD-DVD compatible encoded file, it seems if we cant place our HD-DVD compatible files on to this media we cant play it on 360, even from the internal Hard drive or the network?.
Right, that's exactly my point. Too many people read too much into "HD-DVD support". Such wording suggests only support of the HD-DVD optical disc standard. It doesn't imply offline file playback, MP4 parsing, and who knows what else.


VC-1/WMV3/WMV9 video decoder is in there too, wmv3 is also altivec optimized according to lu_zero,
dont know about the rest.
I haven't had a chance to check out the WMV9 decoder in latest ffdshow builds yet. Do you know it they reverse engineered it or if they followed VC-1 specs?

[foxyshadis]

The first WMV3/9 decoder was reverse engineered, never really worked, and stalled a year or two ago. It was ripped and replaced after VC-1 specs came out as one of the summer of code projects. I don't think it's 100% HP or MP compatible, but it does most streams (with occasional non-fatal bugs).

[popper]

Right, that's exactly my point. Too many people read too much into "HD-DVD support". Such wording suggests only support of the HD-DVD optical disc standard. It doesn't imply offline file playback, MP4 parsing, and who knows what else.


I haven't had a chance to check out the WMV9 decoder in latest ffdshow builds yet. Do you know it they reverse engineered it or if they followed VC-1 specs?

im afaid i dont know, it gets very confusing when you refer to WMV9/VC-1 as there appears to be a reference to it here from 2004

http://www.multimedia.cx/pre/re-wmv9.html
"Practical Reverse Engineering
by Mike Melanson (mike at multimedia.cx)
Updated June 29, 2004

Example: Windows Media Video 9
For this experiment, I decided to target Microsoft's Windows Media Video 9 (WMV9) binary codec module. This is a big target. One reason I chose this is because popular Unix media players can already use the Win32 binary decoding module in order to decode the data via some clever hacking. Thus, it is (relatively) simple to add hooks into these open source programs to gather execution profiling data. "

but then theres also links about useing the reference decoder too
http://multimedia.cx/eggs/2005/09/
"September 15th, 2005 by Multimedia Mike
Pursuant to DVD Jon’s post about compiling and using the SMPTE reference VC-1/VC-9/WMV3/WMV9 decoder with VLC, I wrote an FFmpeg module to use the same reference code. Next, I will try to adapt it to xine. Though I hope we do not grow too collectively complacent with this decoder.

I tried decoding 3 different WMV3 videos from 3 unique sources. The reference decoder seemed to work fine on 2 videos but not on the third."

thanks foxy ;) , i suppose if its based on the reference design thats the better option and your thinking of helping that progess perhaps?,

[sjchmura]

So in summary:

1. We need to restrict the bitrate to 8000 average / 15000 peak 720p to get good playback from the 360 native DVD drive, streaming, etc..

2. If you purchase the HDDVD addon (now $159 at circuit city btw) we can encode AVC, higher bitrate VC-1 etc and it will use the "new codecs" that enable multithreading support.

Correct?

[zambelli]

2. If you purchase the HDDVD addon (now $159 at circuit city btw) we can encode AVC, higher bitrate VC-1 etc and it will use the "new codecs" that enable multithreading support.
See http://forum.doom9.org/showthread.php?p=899669#post899669 and http://forum.doom9.org/showthread.php?p=897611#post897611. These decoders will only be used for HD-DVD playback - not ASF playback, not AVI playback, not MP4 playback.

[woah!]

i read somewhere that the xbox360 can only do 24/30fps at 720p not 60fps. i read that on passing and cant remember where :(

[sjchmura]

Zambelli,

Thanks for the help and to the rest of the MS MVP's and employees.

So again...

If you play the a WMV VC1 DVD-ROM through the HD-DVD "box" will that permit higher bit rates?

Second, I would NOT recommend 8000/15000 max. I tried encoding some PBS stuff and it was stuttering badly when turned to 720p. I am trying now at 8000/12000.

Third:

ULEAD is now advertising "burn HD-DVD to a DVD9 or 5" in a compliant format with MovieFactory 5 Plus. So based on your posts above, this will work in the HD-DVD drive - correct?

[jm9843]

If you play the a WMV VC1 DVD-ROM through the HD-DVD "box" will that permit higher bit rates?

ULEAD is now advertising "burn HD-DVD to a DVD9 or 5" in a compliant format with MovieFactory 5 Plus. So based on your posts above, this will work in the HD-DVD drive - correct?

I'm not Zambelli but your first assumption is correct. HD DVD authored content on red laser media (DVD9 or 5) is part of the spec which the Xbox 360 addon implements.

A word of warning: ULEAD will want to reencode your VC1 content to MPEG2. I'm not aware of a consumer level software package that will author an HD DVD w/ VC1 yet.

[sjchmura]

jm - good catch....

I am trying to figure out if the new Pinnacle Beta does this. This would be a $100 solution adn would be great.

[sjchmura]

So the new pinaccle will transocde to their own MPEG4 but will NOT accept VC-1 :(

[veffremov]

looking at your No.'s it would appear that the codec has not yet been made to take advantage of the AltiVec vector Unit ?

The CPU in Xbox does not support AltiVec. It supports a different kind of vector commands.

[CruNcher]

I would like to clear a confusion here which starts some speculations in the wrong direction.

HD-DVD playback requires a restricted VC-1 decoder and this is what has been implemented and optimized for the HD-DVD addon.

A fully compliant VC-1 decoder is delivered in the dash player, however the perf is not as good.

I think the reasons are obvious: in the HD-DVD scenario you have restricted/compliant content, in the dash the content is user created so we must support all VC-1 features.


Sorry vffremov, but what the hell has another Profile todo with the overall Decoder Engine speed ? that makes no sense you don't need 2 decoders just 1 optimized one see CoreAVCs perfect optimization work on their AVC Software Decoder or Sony's work on the PS3 Decoder. And Microsoft Guys are not able to get a fast all in one Decoder working on a Platform and Video Standard they Designed (and claimed to be less Complex), that sounds strange to me so you really "meesed it up" can't belive that somehow and another thing is why don't you take advantage of ATI's GPU for the Decoding ? somehow i doub't that it's more energy efficient todo everything on the CPU.

[easy2Bcheesy]

I think it's been pointed out that they have one dedicated decoder optimised exclusively for HD DVD VC-1 compliant streams, and then a general purpose 'catch all' decoder which handles any WMV stream... but only runs on one thread.

I'm sure there are any number of reasons for this. For example, it may well have been the case that the addition to playback 'homebrew' WMV streams was added to the 360 spec later on in the development of the new dashboard.

One thing about the new update which I find really irritating is that I would very much like to burn a DVD titleset onto a disc, but include WMVs in the DVD-ROM portion. But as soon as the 360 sees a DVD titleset, it auto-starts, and even when using the guide button, the option to view video files on the disk is blanked out. Is there anything wrong with the concept of burning, say, a home movie onto DVD to play on standalone players while having a WMV version burnt for HD viewing on the 360?

The PS3 media player, by contrast, has had far more thought put into it and is full of nice, pleasant surprises.

[popper]

The CPU in Xbox does not support AltiVec. It supports a different kind of vector commands.
really?, would you happen to have links to the information
as regards that, and also a full rundown of the spec of this 'different kind of vector commands' with code examples would be very interesting to see perhaps, urls please?.

[veffremov]

really?, would you happen to have links to the information

Unfortunately the detailed specs/instruction set of the CPU are not public.

[popper]

veffremov:
The CPU in Xbox does not support AltiVec. It supports a different kind of vector commands.
Unfortunately the detailed specs/instruction set of the CPU are not public.

thanks veffremov.


it seems rather odd though given that the official IBM link

http://www-128.ibm.com/developerworks/power/library/pa-fpfxbox/
states
"The Xbox 360 CPU architecture

The Xbox 360 system has a single chip (with 165 million transistors) for its CPU. This chip is in fact a three-way symmetric multiprocessor design. The three PowerPC cores are identical, except that they are physically reflected through the X and Y axis. Each of the CPU cores is a specialized PowerPC chip with a VMX128 extension related to (and partially compatible with) the VMX instructions in the G4 and G5 CPUs. The three CPU cores share a 1MB Level2 cache. Each processor has 32KB each of data and instruction Level1 cache. The chip's front-side bus/physical interface has a 21.6GB/second bandwidth, and runs at 5.4GHz. The high frequency clocks are generated on-chip by four phase-locked loops: two for the core clocks, two for the PHY clock."

and
" While the term VMX is familiar to PowerPC users, the implementation on the Xbox 360 processor is a new design called VMX128 which was specially enhanced to accelerate 3D graphics and game physics.

The number of vector registers was increased from 32 to 128. All 128 registers are directly addressable, and the original 32 registers are mapped to the first 32 entries of 128-entry vector register file, and so are compatible with the original PowerPC ISA. We also added a number of new instructions.

Instructions were added to calculate the dot-product of two vectors made from three or four floating point values. Data formatting instructions were added to help improve the processing of data that has been packed into memory to reduce the program size. These include: instructions for rotate and insert operations, pack/unpack instructions for handling Direct3D® data types, and loads and stores for misaligned data. The VMX128 ISA is binary-compatible with a subset of VMX. A few vector floating point and vector integer instructions are no longer supported, and attempting to execute them will result in the system illegal instruction handler being invoked.

The Level2 cache provides 1MB of cache shared by the three processing units. It uses a MESI protocol for memory coherency, and is eight-way set associative. The cache itself provides single-bit correct, double-bit detect ECC validation. "


given that right now, [linux dev]people are installing and able to run/running the standard PPC compiled Altivec enabled linux apps
(devs might like to look at http://www.freevec.org/ for the replacement AltiVec routines for GLIBC) on their PS3's with its ppc derived CPU, are the readers to assume that the Xbox 360 CPU with its secret AltVec extended unit is still going to be unavailable to the end users even after a full years head start?.

again if the answer is yes (unless your a payed up dev OC)then again, it seems like a disadvantage to the [potential]Xbox 360(homebrew,3rd party dev etc) users/developers.....

i get the impression that there is no current plans to open up the power of the 360 PPC Altivec/VMX128 unit generally and so artificially restrict its full market potential for several years yet, thats a shame........

[halim]

Hi guys,

Sorry about the delay.
The numbers below indicate the numbers with which you should be able to encode and get pretty good results.

I did categorize them by frame-rate, and all the analysis below uses 720p.


24fps: B-rate of 15Mbps is safe, 20 might play properly.
30fps: B-rate of 15Mbps is good. Above that is questionable
60fps: 5Mbps is safe, and around 6 Mbps would be the peak.


Intuitively, going abit above those numbers might work, but doubling them would be a stretch.

Note: The rough f-rate/b-rate values above did utilize the various VBR/CBR modes. However, Constraint Peak VBR seamed to have the slight edge over other modes.

[sjchmura]

SO what peak value do you recommend??? I ASSume you are referring to Peak being about 2000kbits/sec????