iGOP
 

I've been going over the various threads here and have to say my somewhat dim wit can't quite tie two things together.

I'm referring to long GOP (LG) versus I-frame (IF).

I understand the principle, which allows LG to reduce file size.

So at a given data rate, IF will be twice the file size of GOP, yes? Is it 2x?

But I am also to understand that one needs to go to perhaps 140Mbps IF to visually equal 100Mbps LG.

THIS aspect isn't so clear to me.

As has been expressed elsewhere, IF is an editing format, versus GOP which is a recording (delivery) format. Not unlike a work print versus camera negative (to use film as a reference).

As I tend to deal with finicky Hollywood studios, IF seems to make them happier, so card capacity is the main loser. With prices ever falling, this doesn't bother me.

I would like to know why IF is twice (if that's the number) as "good looking" (ignore the 'efficiency' claim) for a given data rate.

Dear Daniel,

For a given bit rate, I-Frame Only and Long-GOP file sizes will be the same. The bit-rate alone determines the file size.

Long-GOP is 2 to 2.5 times as efficient as I-Frame Only. Thus it takes fewer bits to give a given level of quality.

220 Mbps I-Frame Only looks good according to our customers.

100 Mbps Long-GOP also looks good according to our customers.

(Both of these statement are understated! The typical comment is "Stunning".)

One has to go much higher than 140 Mbps I-Frame Only to achieve the same quality as 100 Mbps Long-GOP. GOP can achieve much better image quality in lower bit rates due to its higher efficiency.


The concept that I-Frame Only is an editing format and Long-GOP is a delivery or recording format is wrong. We know that a lot of people hold this belief, but it is incorrect.



According to tests, performed by our customers, using Final Cut Pro, our 100 Mbps Long-GOP is just as easy to edit as our 220 Mbps I-Frame Only.



Many people equate Long-GOP with HDV. HDV was 1440 x 1080, and bit-staved at 25 Mbps.


Our Long-GOP is 1920 x 1080 and 100 Mbps which helps create a stunning image.


Your editing platform, such as Final Cut Pro, in HD, will most likely be wanting 1920 x 1080 (for 1080 modes) to edit your footages. As such, the codec expands the Long-GOP Sequence while decoding the frames.

But, since we recorded 1920 x 1080 and not 1440 x 1080, your editor does not have to perform the millions and millions of computer instructions per second, that were necessary in HDV to convert 1440 x 1080 to 1920 x 1080. This makes the process much faster, and your editor very responsive on modern computer platforms.

Since our 100 Mbps Long-GOP is much more compact in size than 220 Mbps I-Frame Only, your editor has less data to read from your disk drive. This also helps in making the editing experience enjoyable.

Ignoring all of the above technical reasons why, the following can be confirmed by our users.

For those editing in Final Cut Pro:

We have no complaints with the editing experience with our 100 Mbps Long-GOP.

We have no complaints with the editing experience with our 220 Mbps Long-GOP.

People like the image quality of both formats.

As always, we welcome comments.

Since I limited this discussion to Final Cut Pro, just to make the discussion easier, comments from real-world editors, using our files, Long-GOP or I-Frame Only are most welcome.

We are in a unique postion in that we support both formats, in one compact recorder. Thus, we can discuss this freely and openly as we do not have a marketing stake in which one you select, as this is just a menu selection in our device. But, we do have an opinion as to which one is more efficient.

I am at a distinct disadvantage, here, as I don't do FCP nor do the majority of my clients.

So unless a digital file simple drops into my editing system (usually Adobe products), the camera file can only work with software "enabling." And so far, this isn't working for me.

Enablers such as Calibrated only work to a point in, say Premiere. To really edit, one needs to see the footage on an external monitor, which is currently impossible (I'm AJA XENA 2K-based). So I ether edit strictly on my computer display or have to render the foreign format to the generic QuickTime I am used to working with.

Yet I am going to use your product.

Contradictory, but it's the price I will pay for the size/cost of your product.

Currently I'm setting up a complete heads to tail solution for a feature using your recording system, and look forward to working with it.

Dear Daniel,

We will do everything we can to assist.

I was using FCP as a good example, as I have actual knowledge of the comparisons I mentioned.

Adobe CS3/CS4 work fine with our 4:2:0 35 Mbps footage, but this is leaves out our great 4:2:2 footage.

Adobe CS3/CS4, with the MainConcept Adobe Plug-In should work well. We are waiting for the release of their latest upgrade which has been tested with our files. We expect this any week now.

So, if Adobe CS3/CS4 works for you, it should work for you with our files soon.

The MainConcept Adobe Plug-In is extra cost.

Dan -

Of course I've been following all this (I've read most of the threads over the past couple of weeks). I am quite familiar with the mac-centric design paradigm.

Adding a very expensive MC module is one way, though not pretty. And that won't help output through a pro card such as AJA or Blackmagic. And then there's Cineform, which itself is struggling to output via SDI (AJA, etc.) for pro editing.

4:2:0 is not an option. My clients don't have a sense of humor.

I've got so many cuts from the bleeding edge!

There is a HUGE customer base (10:1) that uses Premiere and are wandering around looking for solutions. Even Adobe recognizes this and often has a PC solution before MAC, these days. (no flaming, please, I am not bashing MAC)

All being said, stop reading this and get back to work. We all want you there 24/7!!!!!!!

(have a great weekend anyway)

Dear Daniel,

I liked your comments: "My customers do not have a sense of humor".

All kidding aside, we have been promised that Adobe will fully support our files in CS5.

In the meantime, MainConcept should work great as soon as they release it. We send them test files quite often, as we do Adobe.

(I corrrected a typo in my post. I said "our our" when I meant "out our", so my meaning may have gotten lost. My meaning was that 4:2:0 only is not a real solution, as it leaves out our 4:2:2 files.)

My fingers make weird words (or at least WRONG) as well.

Any rumors on CS5? I only recently went CS4 since many vendors STILL haven't written drivers, etc.

Dear Daniel,

Sorry, I do not know when.

This is not like that.
MPEG-2 LG exist before NLEs, before digital distribution and before 99% of the stuff we have now in our digital scene.
Probably GOPs is the first revolucionary implementation of the digital technology applied to video.
Intraframe is much primitive concept.

You can not think about quality in those terms.
The 160Mbps of my NANO doesn't look "5 times better" than my EX-1 35Mbps footage.
You can not look for more quality but for "less degradation" of the original picture.
Many times you won't see the difference at bare eyes. Just zoom in a little bit.
rafael

We shall disagree on compression.

Much of my work requires effects work, thus my clients have heavy demands. An image blown up on the theater screen is a tad more critical than for a TV.

I've had clients insist on shooting 65mm when 16mm would have been fine.

Personally, I simply chose the tool that fits.

Choices are good.

Some Comments
 

...No it's not wrong Dan. Long GOP was invented for the Hollywood Studios to be just that - an ultra high quality delivery medium, and that's exactly what it is. This is the major reason why Avid Media Composer did not support Long GOP as an editable format until very recently. I frame has always been, from the ground up, an MPEG format designed to be first editable by *consumer* editing applications, such as Avid Liguid (Now EOL'd) and Ulead. The first *professional* NLE to allow I-Frame editing was the Matrox Digi-Suite. After Matrox enabled I-Frame, then Avid followed.

....Sony adopted Long - GOP encoding schemes for their cameras because of the superior encoding efficiency afforded by Long GOP

...Yes, you are quite correct. FCP works well with Long-GOP. This is a good work around for us who are having serious dificulty editing Long-GOP in Avid. Unfortunately, I, and many other shooters are forced to deliver footage, or work post using NLE's which are dictated to us by the producers and TV Networks which higher us. I'm very sorry to say they don't use FCP - They almost exclusively cut everything on Avid Media Composer. Wether folks agree that Avid is the best or not, this is what they are using. Long GOP is iffy at best in Avid Media Composer at data rates abouve 50 Mbps. I have heard conflicting reports that Long-GOP 100 Mbps works in AMC 4.0.2 or not. I will test it as soon as I receive my upgrade from Avid next week.

...Yup. I get this reaction each time I mention shooting in Long GOP. The response from network people is, "Why do you want to shoot in HDV for ?"


...You are absolutely right. The 100 Mbps Long -GOP is stunning, and the 140 and 160 Long -GOP is darn near equal to uncompressed video IMHO. Unfortunately, I can't edit the stuff properly in the industry's number 1 editor, so it doesn't really matter for us. I think the best solution is to playout the beautiful Long-GOP via the HD-SDI into an editor like AMC and edit this way, but for clip based import editing, I would recommend not using the Long-GOP because it's presently too iffy for pro post at Networks for now. I expect this to change as Convergent Design is working closely with Avid to have 100 % stability for their Long-GOP 100 Mbps. I hope it will not stop there, but the 140 and the 160 Long-GOP flavors will also be supported.

....BTW, their is this sense I get from reading several posts on this forum that I-Frame MPEG 2 video is somehow inferior to Long-GOP. I-Frame looks just as good my friends as Long-GOP - the only caveate here is it takes higher data rates to get there. Now we have big memmory cards so who cares ? I would like to see a 330 and 440 I Frame data rate in the XDR.

...What ? So what ? We are only talking about Mbps here Dan. Anyone with 2 Gigs or more of RAM in the MAC or PC is OK for this. If they are using the recommended Sandisk CF cards, then there shouldn't be any hickups.

....Yes, and in those days no NLE ever offered to edit Long GOP *or any MPEG format" for that matter. NLE's originally only captured and edited MJEPEG codec based video *Only.* There were two factors which became the real game changer for the addition of editable Long GOP MPEG 2:

1. Editors started to get handed DVD discs as source material and were asked to re-edit the disc and spit it back out again as a new DVD title (Re-Authoring jobs). EDIT: Avid Liquid was amazing for this job because it could take the DVD material straight in and edit it !

* I purchased a wonderful little program called Cinematize 2 Pro, which extracts the MPEG Long GOP material off of the DVD and converts it to a meriad of editing codecs like Quicktime, or uncompressed. Most editors never even considered trying to bring in Long GOP DVD material into a project. EDIT: Until Avid Liquid.

2. Sony: Sony is the real and ultimate game changer here. Sony's line of XDCAM HD and EXCAM Long GOP codec based cameras are now he driving force pushing the editable Long-GOP movement. Now this makes sense that a camera manufacturor would want to use a codec which had the maximum efficency in encoding possible with the smallest file size obtainable to save precious memmory card storage space. Only Long-GOP based codecs can achieve this result, Certainly I-Frame MPEG is too inefficient for these purposes.

The Bottom Line:
Avid will finally qualify 100 Mbps and higher Long-GOP codecs sooner or later (Oh Lord may it be sooner). Final Cut Pro will qualify MXF based media be it in whatever codec and all will be well for us XDR and Nano shooters.

** Tonight I watched a Blu-ray DVD, which was projected on a huge screen in native HD 720p of the movie Crank 2: High Voltage. This movie was shot in bit starved HDV 25 Mbps Long-GOP with Canon Camcorders and it looked increadibly good ! No jaggies, or scan lines. High detail resolution in facial complexion and eyes. Significant film gamma and color depth for something shot in 4:2:0 color space. If you guys get the chance, go rent a Blu-ray disc of this movie from your local blockbuster. You will be surprised.