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Old May 20th, 2006, 08:50 AM   #1
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Realtime is real?

I have a dumb question, since I haven't used any special NLE hardware for editing. I understand that some hardware available will let you lay down a few tracks of videos, effects, transitions, etc. and it will playback realitime. But what I'm wondering is if it's really "realtime" (or at least extremely fast) when you render out your MPG files for DVD authoring. I can't think of any reason why someone would need to playback the timeline realtime when they have to render actual files for putting onto their DVDs. My impression of the hardware is to have it playable without rendering... but rendering is ultimately what's needed in the end. Could anyone help clear this up for me? Thanks.

-Michael
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Old May 20th, 2006, 10:13 AM   #2
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Michael: it's not a dumb question at all -- it's actually crucial if you're concerned about time-efficient video production. The term "real time" is used very loosely throughout the video industry, especially in marketing literature.

During the editing phase, "real time" should mean that you can view your editing changes instantly without having to render them, preferably at full resolution without dropping any frames. This is helpful for experimenting with different editing options and hence being more artistic, without having to wait for the computer to process your ideas. In practice there are limits to every editing program in terms of how much it can do in real time before it has to start compromising the playback quality and/or do some rendering. Different programs use different tricks to try to minimize these limitations, and it's hard to get accurate information on what that really means in terms of performance for any particular program.

As far as video output is concerned, "real time" can mean different things there too. During editing you may want to be able to view your project on a TV display in addition to your computer monitor, which requires some way to send a video signal to the TV directly from the editing timeline. This is fairly common for standard-definition video but currently rare for HD editing. (To display to an HDTV in real time you need a special video card or expansion board with suitable outputs.) You may also want to be able to record from your editing timeline back to a tape copy in your source format, which can be done in real time with DV but not with HDV.

When it comes to making a DVD, "real time" usually means it takes the same amount of time to create a DVD-ready file as the duration of your timeline. This has been possible using special hardware for some time now and more recently using software-based encoding on the latest fast computers. Without that it could take several hours to render an hour's worth of DVD material, which is a nuisance. And here comes the fun part: if you have editing software which can process your effects in real time and send those out to a standalone DVD recorder without rendering, you could in fact make a DVD directly from the timeline with no rendering and no authoring step. That would be the ultimate definition of real time DVD production, and is possible today within the editing limits discussed previously. Typically this creates a DVD with a limited menu structure which isn't very useful for most projects, but it is doable.

So the next time you hear the phrase "real time" used in regards to video production, remember that doesn't have a fixed meaning. You have to do some research or ask for clarification to find out what it means in terms of actual workflow.
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Old May 20th, 2006, 10:51 AM   #3
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Quote:
Originally Posted by Michael W. Niece
I can't think of any reason why someone would need to playback the timeline realtime when they have to render actual files for putting onto their DVDs.
I guess I'm not understanding your question. If you're just asking what the definition of realtime is then Kevin pretty much covered the gambit.

I'm just puzzled why you can't see the need to preview an edit in realtime before the final rendering phase to DVD.
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Old May 20th, 2006, 01:50 PM   #4
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I don't think I asked my question or hinted at it the way I thought I did. My question is this: can the hardware that allows realtime preview significantly cut back on the MPG render time? I understand that previewing the edit in realtime is great, but for me it all really comes down to how fast the MPG files are exported. I know computers, so I don't need the explanations for CPU speed, etc. I just want to know if the hardware also accelerates the render time so I can bring the edited video clips into my DVD authoring program.

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Old May 20th, 2006, 02:55 PM   #5
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Originally Posted by Michael W. Niece
I just want to know if the hardware also accelerates the render time so I can bring the edited video clips into my DVD authoring program.
-Michael
Yes, the right hardware will not only increase your realtime playback speed, it can also vastly speed up final rendering. That's not to say your NLE will always reuse the rendered files it generated for playback when making the final render - Indeed, depending on the encoding options it may have to start over.

But I'm curious as to why so much concern about the hardware affecting the final render. Accelerators are specifically made for realtime preview. I really don't care how long the final encoding process takes as long as the "write" speed to DVD is reliable.

But you may have a need to get things to DVD quickly. I don't.
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Old May 20th, 2006, 07:40 PM   #6
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i did afew massive write ups of this issue quite a while ago. From Prem with Matrox and Storm cards, through to Vegas and "what is realtime" editing....keyword being editing

if u cant find the posts , ill ramble on some time later..
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Old May 21st, 2006, 09:37 AM   #7
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Kevins basically hit the nail on the head.. but thers a couple of things which are fundamental to what people percieve as "realtime"

there is realtime editing, and there is realtime output.

realtime editing is what is precicely waht Kevin has written, Some NLEs are better at it than others. In this instance, Vegas (as an example) is a predominantly STRONG editor when it comes to realtime tweaking and manipulation, all the while the timeline is being played back or looped.
Many NLEs can do this, but not all do it the same way.
This si where the differnces take hold.
Take Premiere6.5 with a Storm 2 card, on a beasty win2k system and u can get about 13 DV tracks, and a title overlay running realtime, ZERO dropped frames.. i know this to be true as we built one for a client and went nuts with it.. usual tests on our systems show at least 8 DV tracks without dropped frames or buffer stops.

BUT ad a filter on any of these, and this is where things get iffy..
Prerendering.. what it is.. basically u take a chunk of video (in Premieres case, usually the "red marker area" on the timeline..) or in Edius, u render and replace...
Now to play this back, in realtime u must prerender it.. Not so much the Storm as in moreso the RTx100, but still u must render.. this render could take anything depending on whats going on.. but it IS accelerated rendering... but your still rendering..
SO what have u got... ??
WEll basiclaly from teh trend of the way NLEs have evolved, is that HW based systems, from Edius SP through to the RTx2, through to Vegas 6 and final cut, all have their major strengths in ONE or the OTHER... Im yet to see both, unless of course your talking avid or axio, but theyre another story..
So waht are u left with.. Most SW based NLEs are strong in the editing and realtime manipulation within the edit. Such as realtime tweaking of keyframes during playback and filter adding removing etc etc HW based NLEs are restricted to the HW, being that for the HW to provide realtime output, certain conditions must be met, such as video codecs, projec tproperties, video properties, video formats and sources etc etc
In many cases, some might disagree with me here, but i believe SW bnased NLEs with the power of todays PC's are running rings around Hardware accelerated devices.
When u consider that an MPG render of an AVI file can be cut down to 1/3rd realtime if using Procoder or Main COncept standalone encoder, it beats the "realtime" output of one of these cards. As these cards are in fact realtime.. 2 hours will take 2 hours to transcode to MPG2. Go SW, and 2hrs will take about 40 mins on a good system..
On the flipside.. to get the AVI OUT of the NLE to be one big movie file, the HW will win hands down.. But ONLY IF you use the effects and filters supported by the HW acceleration device. As an example, in Premiere, if u use the Matrox effects, u wont have to prerender.. but use a Premiere native effect, u do... even if u have the RTx it wont mean jack...
On the flipside use a SW based NLE and ur render may take considerably longer, however if the NLE u use supports and performs well on a Hyperthreading computer, or on a multi cpu unit then the output may match this realtime output with the acceleration card.. maybe even beat it... Ive seen Vegas systems runnign CC and compositing run rings around an RTx system, but on the flipside, with intense effects, the Matrox poos on Vegas.. ive done renders in Premiere which take 7 minutes, while vegas, to do the same thing, took 14hours..
One other thing to note.. is that with hardware, u are restricted to that hardware. I cannot change the project settings, u cant change your mind if ur client wants 16:9 instead of 4:3, u cant switch over to progressive scan why??
Coz you are restricted to teh HW limitiations of teh HW itself.
In most cases, its project settings. Take matrox, een with the RTx2, u cannot edit 720p HDV, but u can do 1080i.. why?? reslolution. The highest res the card can do is 576p, it cannot do 720p. this kills off all the JVC HDVers out there.. as well as the Canon H1ers who use 24f... on top of that, the HW itself has its own limitations.. well not limitations, but quirks.. such as aliasing. As its hardware, aliasing can create jagies. Predominiantly on titles and transitions liek page peels.. do a Page peel in Vegas, looks schmick, do it matrox and it looks like poo. But it STILL edits in native m2t (not that id recommend it), and it still produces a final render much faster than a SW based NLE.. to some people this realtime playback is more important that realtime editing.
Some people prefer to start and stop, but users of SW editors prefer to edit in realtime with afew dropped frames, then render overnight

SO from here its a toss up.. do u go HW and prerender everythign u want to view in realtime? Or do u EDIT in realtime and take a hit when rendering? How fast do u work? How fast must u get the job out? Do u prefer to edit without interuption with a continual flow, or are u ok with prerenderng as u go along and check filters and transitions? Are ur projects all teh same source? or will u be working on a variety of differnt formats? How will u export? DO these HW acceleration cards export in teh web based formats u require? or do u need to get a transcoding tool to do that for you?

These are some questions to ask yourself and when u do, you will discover which direction you will go.

Personally i prefer sw, as for me, editing is key.. for me, to edit faster and more efficently is what my ultimate goal is. I can render overnight if need be.. but if my editing flow gets broke.. then i get broke..
SW also allows for variable fle inputs on the one timeline wihtout the need to conform to certain specs. Edius is Brilliant with this in mind, as Vegas. Liquid 6 is also a brilliant tool, marred only by the abysaml databasing system and not so realtime editing and tweaking. I can ramp a clip, but i cant tweak that ramp is its playing back.. But with its abysmall databasing system it gives L6 the power to do background rendering.. so u dont get the best of both worlds)

What people need to understand when looking for an NLE, is what it can do for them when it comes to the work they do. Every single NLE has its quirks, its strengths and its weaknesses. Pinning down those nuances for each NLE is paramount in the decision making. To be honest, its like buying a car. There will be things u like about the BMW which the Merc doesnt have. Other times, ud jump in the Mustang, floor it, go WOW at how fast u got there, but then realise that the Beamer and the Merc are slower, but even with that, they might feel better for you. the handling might be easier for you. The layout might be more intuitive to you. the feel of the wheel as u drive it flows niceley without too much of a fight.
Its all relative to what YOU need as a driver.. coz at thw end of the day, youre the one driving the car, and if the car doesnt perform the way u want it to, youll be sorely dissapointed when u get to your destination...
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Old May 21st, 2006, 10:58 AM   #8
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Peter's post is a good example of how hard it is to get accurate information about "real time" editing. Vegas does a good job of maintaining an effective editing workflow through clever programming tricks, but it's ultimately not a real-time editing tool. What Vegas does is compromise the preview quality to keep editing moving, but that means you aren't seeing the full effect of your work and can't record it in real time back to tape or a DVD burner or whatever. And contrary to what Peter said, hardware-based editing solutions can do a lot in real-time without rendering anything, up to the limits of available processing power. Peter also implied that hardware-based editing solutions may have limitations which software based editors don't have, which is true in some situations but not necessarily the ones he mentioned. And as Peter noted Vegas is notoriously slow for generating finished output files, compared (for example) to hardware cards which can render DVD files in 1:1 time. Peter's right that how an editing program works relative to your personal style may be more important than other considerations, but that's an interface issue and not a matter of real-time performance.

As I said before, "real time" should ideally mean you see your editing changes instantly at full resolution and full frame rate, with the ability to output same to a TV or recording device without rendering. No editing solution can do that in all situations for complex timelines, but some come closer than others.
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Old May 21st, 2006, 11:08 AM   #9
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Quote:
Originally Posted by Michael W. Niece
My question is this: can the hardware that allows realtime preview significantly cut back on the MPG render time?
That varies from product to product. For example, the original Canopus DVStorm card didn't include real-time MPEG2 encoding as a standard feature but did offer it as a separate add-on solution; the DVStorm2 card has a real-time MPEG2 encoder built in. I'm not sure exactly which Matrox cards have the same feature, but I'm pretty sure the latest ones all have real-time MPEG2 encoding. So yes, a hardware editing accelerator may also accelerate DVD production, and that's a very useful thing. I still use my DVStorm2 card to generate SD MPEG2 files from HDV source material in real time, which as far as I know no other editing solution can do. (Except maybe on a really fast computer with a good software-based encoder.)

As someone else said it's not necessarily that big a deal to have to wait a few hours to render a DVD file, but it's nice not to have to do that.
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Old May 21st, 2006, 12:21 PM   #10
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My reason for asking is because I'm torn between Edius and Premiere Pro 2.0. Realize that I have no special video hardware ... just a basic FireWire card. I love using Edius because the effects are pulled off so much faster, but the real plug-ins I use (like Twixtor and Sapphire's neat library of filters) can't be used with Edius. I'll take the time to use Premiere to render out certain chunks of my video so I can import them into Edius, but it's like stealing from Peter to give to Paul who gives it right back to Peter. Premiere's *end results* (with the help of the plug-ins, of course) are phenominal (sp?) compared to Edius, but just the *preview* renderings take so damn long it's not funny ... plus I have to turn around and render everything *again* to export the movies (Premiere won't use the rendered timeline for anything in exports, I"m convinced of that).

I don't want to start a conversation about what kind of hardware I'd need, really. I just wanted to know if getting an accelerator would also help the final render time.

Rick: it's not really so much as that I need to get the movies out quickly, but rather a means to getting the 36,000 frames (20 minutes) rendered faster than 5 or 6 hours. Not to mention that while it renders at night sometimes Premiere explodes (another topic altogether) and I'm too busy sleeping to notice -- a perfectly good 7 hours of reserved render time gone to waste. I know perfectly well that the filters are the cause for slowing down the render time, true enough, but hopefully there's hardware out there that'll help get them running faster.

-Michael
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Old May 21st, 2006, 03:18 PM   #11
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Quote:
Originally Posted by Michael W. Niece
My reason for asking is because I'm torn between Edius and Premiere Pro 2.0. Realize that I have no special video hardware ... just a basic FireWire card. I love using Edius because the effects are pulled off so much faster, but the real plug-ins I use (like Twixtor and Sapphire's neat library of filters) can't be used with Edius. faster.
Maybe you can do away with Premiere and use After Effects since those plugins work in that environment as well. Plus AE can do so much more when you need it. Lots of Edius users out there as well.

True, PPro's render files are useless for other tasks but I don't know too many NLE's that keep them for the final render. (Perhaps Avid's Liquid does but not sure). I tried Vegas for a while but went back to Premiere primarily because *it does* prerender playback footage and keeps it (and for basic tasks it does that relatively quickly enough).

But again for me to use playback footage for the final render would be pointless anyway because depending on the length of the final DVD I'll always need to reencode it anyway.

Sorry about the stability errors with Premiere. I had problems with PPro 1.5 on that front but with 2.0... so far so good.
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Old May 21st, 2006, 05:56 PM   #12
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Michael: you might consider getting a Matrox RT.X100 accelerator card while they're still available; I'm pretty sure this includes a real-time MPEG2 encoder. Getting your final DVD files quickly is a handy thing to be able to do.

http://www.videoguys.com/rtx100.html
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Old May 21st, 2006, 07:57 PM   #13
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I have the Matrox card and if you stick to the Matrox transitions and functions, such as cropping, color correcting, etc... it is realtime with no rendering. You can't throw 20 layers and transitions and expect to get real time. If you keep it relatively simple it is real time as well as the export. If I have 90 minutes of video, it will take 90 minutes to export DVD quality MPEG2.

***the key is to use the transitions and filters that come with the card. If you don't there will be the normal rendering times..
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Old May 22nd, 2006, 01:38 AM   #14
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and as mike said, and as i mentioned in my initial post, by sticking with the HW filters and transitions, youre using teh HW codecs in turn speeding things u as these are acelerated (either in preview and in output)

"I still use my DVStorm2 card to generate SD MPEG2 files from HDV source material in real time, which as far as I know no other editing solution can do. (Except maybe on a really fast computer with a good software-based encoder.) "
Ricks on teh money here. Canopus have done an AWESOME job of the transition from Sd into HDV. The fact that the storm2, to this day, can downscale HDV down to SD, in realtime, and look friggin incredible is something to be said about the Canopus technology. No other card that i know of apart from teh Axio can do this. I dont even think Avid can do this but ihavent really looked into it.

Matrox RTx100, as well as the Storm2 (with the mpg2 daughterboard) can all render out to MPG2 in realtime without the need to render to AVI first.. now for those wanting to just do basic cuts and deliver to MPG2 without the need of transfering the edit to tape, these are the BEST solutions. Again however, your restricted to the HW confinements when it comes to the actual editing...
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Old May 22nd, 2006, 02:07 AM   #15
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the fastest way to get DVD from video, is to buy a cheap standalone DVD recorder.
No encoding or burning time, you just press the rec key and play the video from your PC. this will not allow you to tweak many parameters but usually gives decent result.
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