Nano 220Mb/s I-Frame question
 

Hi Dan,

Is the 220Mb/s I-Frame recorded on the Nano the same codec as the ProRes HQ?

Ha!

I've been waiting for somebody asking this question at last. Since the very beginning of the nanoFlash existence, we've been touted about the virtues and advantages of the Sony Long-GOP codec - but I don't remember mentioning any details about the I-Frame "innards"...

Piotr I am sure Dan will have the answer.

Dear Paul,

No, Apple ProRes HQ, while it is also 220 Mbps, is different.

First of All, Apple ProRes is 10 bit.

The nanoFlash is 8-Bit as all MPEG-2 is 8-Bit and all XDCam HD422 is also 8-Bit as is EXCam Ex.

While 10-Bit is desirable, there is a price to pay for 10-Bit, it always takes up more space.

Note: in the following discussions, Apple ProRes is 10-Bit and the nanoFlash is 8-bit.
If one is using a good clean 10-bit source, then the 10-Bit recordings are desirable.
If not, then the 10-bit recordings cause the files to be larger with no apparent benefit.



Due to Apple ProRes being 10-bit, it would have to be 275 Mbps to equal the efficiency of 220 Mbps 8-Bit (with everything else being equal).

Or to put it differently, the nanoFlash, being 8-bit, at 176 Mbps would yield approximately the same efficiency as 10-Bit Apple ProRes at 220 Mbps (with everything else being equal).



Our files can be either Quicktime or MXF.

Thus, we write out Sony XDCam HD422 files (if 50 Mbps or higher) in a Quicktime wrapper.
Under 50 Mbps, we use Sony XDCam EX codec.

Our files can be dragged and dropped into a Sony XDCam HD422 timeline without any rendering.

Or, our files can be dragged and dropped into a Apple ProRes timeline.


So Paul, the answer is no, our files are not the same as Apple ProRes HQ.

And of course, we offer 280 Mbps, which would require the 10-Bit Apple ProRes to be 350 Mbps to be equivalent (with everything else being equal).

Dear Piotr,

Our Long-GOP is Sony's sixth or seventh generation of the MPEG-2 codec.

It is a very sophisticated, professional codec. And it is efficient.

This Long-GOP consists of I-Frames, B-Frames and P-Frames.
It has quite a few advantages.

Our "I-Frame Only" mode, has all I-Frames.

There are multiple advantages to this.

1. Some people prefer to edit in an IntraFrame Codec, and this is an IntraFrame codec.

2. It requires a lot of sophistication, and computing horsepower to implement a Long-GOP codec.

We limited Long-GOP to 180 Mbps, after than we use I-Frame Only, which requires much less computing horsepower.

This allows us to take the I-Frame Only to 280 Mbps.

We use Long-GOP, in HD, from 18 to 180 Mbps and I-Frame Only from 100 to 280 Mbps.

Dear Dan,

The CD Long-GOP codec is certainly very efficient - no doubts about it. At 100 Mbps, the I-Frame only is unwatchable - while for the Long-GoP, this is the "sweet spot" (with low-noise cameras; if the camera tends to generate noisy picture, I'd say the true sweet spot is at 50 Mbps: less noise, while already of Broadcast Quality).

But, as Rafael points out in another thread:

- I'd also like to very politely remind you that the L-GOP structure could be improved in terms of obtaining more consistency in the I,B and P frames quality.

This is why I usually only use L-GOP at 50 Mbps; when I need that extra quality to start with for heavy grading, I'll always choose I-Frame Only. Whether you support it or not, it now works at up to ad including 280 Mbps on my Transcend 400x cards (with the current Public Beta firmware)...

Thanks Dan I thought that was the case. Appreciate you letting me know your thoughts.

Dear Piotr,

There is one thing that I have not pointed out before.

With our Long-GOP, when there is an in-balance due to the amount of bandwidth allocated to the B & P frames, the codec module can detect this and make automatic adjustments.

But, if you evaluate the images on a frame by frame basis, you may see some frames before the codec senses the problem and makes these automatic adjustments.

In cases of high noise images the I, B, and P Frames all become about the same size over time.
In normal video, I Frames are about 2X size of P Frames and 3-4X size of B Frames.

These types of problems should only occur on cases of excessive noise in the images or very high motion.

But then, the nanoFlash does a very good job with excessive detail in an image, or excessive motion.

Purposely sending excessive noise to the nanoFlash for testing purposes will only show abnormal conditions.

Purposely sending excessive detail or excessive motion in the images is a very valid test, in my opinion.
But sending excessive noise is not a valid test, in my opinion.

With excessive noise throughout the image, one is just overwhelming the codec.

A full uncompressed recorder would keep all of this noise, and then playback an image with excessive noise.

A low-bandwidth recorder will remove some of this noise, but low-bandwidth recorders also cannot distinguish between noise and detail, so the fine details and the noise are both reduced.



The CODEC inserts numerous I Frame type macroblocks whenever parts of the image are new to the stream (like in high noise environments).

To balance the bitrate, the I Frames must get smaller.

In effect, in very high noise environments, the video is recorded as if it were I frame only, thus negating the advantages of the Long-GOP efficiencies.

Luckily, normal video hardly ever generates this situation.

My comments have been approved by our Chief Engineer.

Dear Dan,

Thank you very much for this insightful explanation. I agree with most of its points but one:

- nobody (me neither) has been sending "excessive noise" to the nanoFlash in order to prove its "flaws" (or should I say "features"). All my observations, described in the "thread that refused to die", were based on real-life video from the EX1 camera, which - while not the quietest in the world - has a decent S/N ratio of 54dB.

The EX cameras are ENG-type machines, often used in less-than-perfect lighting conditions. Sadly, recording from them to the nanoFlash in the L-GOP format at bitrates higher than 100 Mbps, is denying the very purpose of the wonderful device that the nanoFlash truly is.

But as I said earlier - L-GOP at 50 Mbps for ENG style shooting, and I-Frame only at 220 Mbs+ for controlled environment recording, is the recipe that has worked fine for me for a long time now.

Dear Piotr,

I will word it differently.

To obtain the best results out of the nanoFlash, optimize your camera to produce the cleanest images before sending them to the nanoFlash.

Just to add that the only similarity are on the DTC compression side of both codecs.
Prores is a QT codec proprietary of Apple (10/12b/YUB/RGB/422/444-4) with presets data-rates/qualities, and always Intraframes. Is mostly a production codec, now with Alpha available.

MPEG-2 is quite different. Although we work with Intraframe MPEG-2, in fact still being GOPs.The trick is to use GOPs just one frame long.
MPEG-2 can be 420/422, but do not supports RGB color space, or 10b, neither 444 patterns (to fix those shortcomings has been developed the MP4 standard. Well, no RGB on MP4). MPEG-2 can not support Alpha.
rafael

Dear Dan,

Please don't think I'm beginning to split hair again - my background being engineering, I'm just curious. Also, your in-depth explanation has been backed up by CD's Chief Engineer - please let me try and take this opportunity to get some more understanding of the subject :)

When I re-read you explanation, the above statement caught my attention. I must say I either do not understand it properly, or - if my understanding is correct - I do not agree with it.

We all know that - both in theory and in practice - the higher the bitrate, the better the quality of the nanoFlash I-Frame only mode. The same cannot be said about Long-GOP, which tends to exaggerate noise at bitrates higher than 100 Mbps. But that means that if - in presence of noise from the camera, and recording in L-GOP format - the nanoFlash video "was recorded as if it were I frame only", its quality should increase with bitrate. This unfortunately is not the case...

Also the second part of the above statement of yours calls for some follow-up. The "L-GOP efficiency" can be simplistically defined as the PQ to file size ratio. The mechanism of increasing the proportion of I frames content against that of B and P frames that you attribute to excessive noise content does NOT force higher bitrate of the Long-GOP recoding, as all L-GOP modes from 50 Mbps up are CBR. Therefore, one cannot say the efficiency is suffering, as file sizes remain the same. Unless. one admits that the PQ is getting lower, which has always been my point!

All in all, I'm afraid Dan that your own statement is - in fact - making my point that to keep the I-P-B frames proportion constant, the "Constant Quality" mode (called for in the other thread) should be adopted. This would increase the bitrate when necessary. Yes, file sizes would become greater - but the quality could benefit.

So, to summarize: I-Frame Only mode should always be used when PQ has priority over storage needs/costs (the higher PQ, the greater file sizes). On the other hand, CBR L-GOP quality is obviously better at lower bitrates/file sizes....With VBR, we could obtain higher L-GOP quality at the cost of somewhat greater file sizes (of course, with less detail/movement/noise, the file sizes could shrink again).

Please let us know what you and the Chief Engineer think.

Piotr

Piotr,

While what you are saying may be correct in terms of keeping the proportion of I, P and B frames constant, I think you really have to ask yourself if this a worthy endeavor for CD to undertake.

1) There may be realities of the Sony chip that can't be avoided, making such an undertaking not possible.

2) If possible, it still might wind up creating a Long-GOP structure that NLE's can't work with. I know Avid Media Composer only recently deals with Long-GOP 100, anything over 50 would cause a buffer overrun. Will a larger size Long-GOP work in Vegas, Avid, FCP, etc.? IDK. But this is a very important point. So even if CD gets things to work on their side, the NLE's have to adopt the codec on their side. Will you have to wait for that to happen? How long? (It took Avid years to adopt Long-GOP 100). In the meantime storage will be getting cheaper and faster. And each NLE maker has to decide if it's worth their time supporting yet another codec variation.

3) Let's for argument's sake even say that this new Long-GOP codec will work with NLE's right now. This new choice will be something like Long-GOP 180 and probably be visually equal to I-Frame only 220. This is a somewhat minor savings in storage size. Is this savings worth it as CF cards get cheaper and faster by the month?

So you may be correct about using a constant frame proportion. But even when stipulating that you are, I don't see how this really justifies CD's time. I don't mean to be contrary, and I find your posts very valuable. But I think this suggestion would be a lot of work to create an in-between storage size that NLE's might not even be able to deal with.

JMHO, and again I appreciate all your posts.

Hi Peter.

All I wrote/speculated about has been out of my technical curiosity, as stated at the beginning of the post.

Ever since Vegas Pro (starting with v.10) has been capable of playing all nanoFlash formats (including 280 Mbps I-Fo) full quality / full speed, I don't have any problem with the fact that with my particular camera, the L-GoP is only usable up to 100 Mbps (frankly, I'm only using 50/422 - just to stay at the Broadcast Quality side). When I need more headroom for pushing and pulling in CC/grading, I record I-Fo at 220 Mbps (and recently, sometimes even 280)...

So, my Friend, all is well - my questions and suggestions are purely academic.

:)

Piotr

PS. One thing in your otherwise perfectly sound reasoning I don't quite agree with, though: yes, with the method I proposed the L-GoP effective bitrate would go up considerably - but only in the case of lots of detail/noise/movement. With clean and static scenes, it could even drop down to 50 from the nominal of say 140 Mbps - thus, the average storage space required could as well remain unchanged :)

Dear Dan and Piotr,
I don't want to get on another technical discussion because I haven't done yet proper tests to compare quality issues, but I think that, if after proper test, I would reach the conclusion that the "NANO Sweet Spot" is 50Mbps, THIS WOULD BE A HUGE DECEPTION for my self.

I bought the NANO for:
- LGOP-shooting options (for general shooting) better than the SONY HD 422 50 Mbps (the NANO pictures at 100 Mbps MUST look better than at 50 Mbps and at 140 Mbps MUST look better than at 100 Mbps).
- High quality Intraframe options, for some specific situations (Intraframe pictures at high data-rate, should be virtually 8b Uncompressed).


I understand the effects of noise on the GOPs efficiency (In effect, in very high noise environments, the video is recorded as if it were I frame only, thus negating the advantages of the Long-GOP efficiencies).
BUT I understand that this effect MUST be palliated by increasing the data-rate.

In fact this is the only reason of having scalable data-rate: To counteract that "efficiency reduction" on picture with high noise, high detail and fast motion.

So, if there is not an obvious improvement at 100Mbps over 50 Mbps: There is something wrong.
This whatever the signal comes from (noisy EX-1 included).

Addressing high details and fast moving pictures have no much science: Add MORE data-rate.
But If Noise is our real life issue, is the one that needs to be addressed.
I understand that noise is the most stressing issue for a codec, therefore when managing NOISE, is when a good codec should shine.


Dan wrote:
"Our Long-GOP is Sony's sixth or seventh generation of the MPEG-2 code"

Right, but SONY seems to be very conservative and haven't pushed further than the 50Mbps.
The NANO is the first real opportunity to try to get the most of the codec.

I understand that CD may have some legal limits about what he can try to do or implement on the Processor/Codec.
I understand, that in CD you have been really busy fixing other issues.
What I would like to know in short, is if there is any room for improvement.
if the LGOPs structure can be optimized (if there is any thing to be optimized), or if CD considers that is closed and there is nothing else to do.

Piotr,
I propose you a proper test.
First we have to compose a test signal including video with some motion graphics generated by AE or so.
The point would be to feed the NANO from an AJA, BlackMagic or so, instead of from a camera.
Then will be easy compare and see how data rate-affect the NANO files.
Cheers,
rafael

Long GOP Image Quality Considerations
 

Hi Rafael:
I have done extensive image quality testing with my Flash XDR recording @ all Long GOP data rates. As far as I can tell, this Sony XDCAM HD 4:2:2 hardware encoder used in both the Nano Flash and Flash XDR is optimized to produce high quality results @ only 50 Mbps to go inside XDCAM camcorders to record to disk. Therefore, in Long GOP the sweet spot cannot be anything other than @ Long GOP 50 Mbps. In I-Frame (Intra) recording, the sweet spot is 220 to 280 Mbps. Only the high end I-Frame data rates are actually superior to the Long GOP 50 Mbps data rate. IMHO, there's no such thing as a "sweet spot" at 100 Mbps, or higher. I think you may have been labouring under the false impression that your camera's output is preventing you from obtaining better results at higher data rates because of "so called" noisy video signal output. With all due respect to you, I find this explanation to be nothing short of an insult to my intelligence.

Dear Rafael and Dan,

It is a good feeling I'm not alone :)

On the other hand - while I share Rafael's opinions in 100% - I'm afraid the two of us (well, plus Gints perhaps) is not enough to make CD look into the problem seriously. If most customers seems to be satisfied, why should they care - am I right here, Dan?

This is not criticizing CD's attitude at all - just stating the obvious fact that when - in order to make just a couple of customers even happier - considerable resources would have to be involved, it wouldn't be a very pragmatic way of operating in the business environment. I'm sure Dan would confirm my thinking :)

Like you, Rafael, I also used to be very disappointed that the L-GoP picture quality is not at all scalable with the bit rates. But I guess I've already settled with my work-arounds...

Rafael, I'm just trying to be realistic here; with the large sensor cameras' advent, S/N of 60b and above is going to become standard. I haven't tried it personally, but I suspect that with such a low noise sources, even the 180 Mbps L-GoP picture from the nanoFlash looks gorgeous. Also, I agree that, as you suggest, a camera could be eliminated as the picture source for the sake of proper tests - but...and I'm going to be very frank with you now... not being able to afford a better camera than my EX1 in the foreseeable future, I'd rather not know how much better my video COULD look.

I guess this attitude has a lot to do with my age and health problems - I never used to compromise like that in the past. Nevertheless, I'll always back up your efforts and help you in testing things.

I hope you understand,

Piotr

Dear Rafael and Piotr,

I do not agree at all that 50 Mbps Long-GOP is the new sweet spot.
The compression ratio for 35 Mbps 4:2:0 and 50 Mbps 4:2:2 is approximately the same.

We have over 2,800 nanoFlashes in the field. Many are using 100 Mbps.
We have the results of the Video Clarity System.

We have had numerous comments from professional people that they can see a visual improvement when switching from 50 Mbps to 100 Mbps.

Piotr, in the past you have, at times, been reluctant to share the source files, camera settings, etc., that you used to make your judgments.

With the images that you have shared, they have tended to be in less than ideal lighting conditions, and you have not provided your camera settings.

Thus, we cannot independently confirm your findings or conclusions.

A video recorder cannot distinguish noise from video detail.
Lower bit-rate recordings will hide some of the noise.
Higher bit-rate recordings will show more detail and noise.

We have thousands of people who are happy with the image quality they are getting from their nanoFlashes and quite a few use 100 Mbps Long-GOP. I do not know how many, but I talk with many of our customers.

There are, of course, fewer people that use 140 Mbps, and 180 Mbps Long-GOP.

My own personal recommendations are to shoot 100 Mbps Long-GOP (unless you are using certain versions of Avid) and then use 140 Mbps Long-GOP if one expects an extreme amount of detail or motion.

The high bit-rate I-Frame Only modes are recommended also in special cases.
And I never recommend shooting 100 Mbps I-Frame Only.


Rafael, I highly appreciate your suggestion for a carefully controlled test.

I feel that, if such a test is performed, the details of the test should be public.

If a camera is used as the source, we should be able to see/access the source files as recorded in camera. We should have the camera details, such as Picture Profile, gain settings, aperture, lens used, lighting levels, etc. It should be an open test so that others can comment.

Ideally, we would have the HD-SDI recorded as uncompressed, then compared to the in-camera and nanoFlash files.

If we use carefully generated and clean (as noise free as possible) source, then the test can be more meaningful.

Sony spent untold millions of dollars developing the Codec module that we use in the nanoFlash.

We have control of various internal aspects of how it works.

But, please understand that we need to maintain compatibility with many different Non-Linear Editors.
We would be doing a grave disservice to our customers if we introduced something that did not work with a wide variety of NLE's.

We also like to be very responsive to our customer's wishes.

We fully support any testing that anyone wants to perform, but for the tests to be meaningful to us, we need lots of details.

And yes, technically there are settings that could be changed.

But, I suggest that proper, controlled tests be run first.

And I welcome others to comment on their own "Sweet Sport" with the nanoFlash.

Please understand that when we tell others about the "Sweet Spot", we are taking into consideration image quality and file size.

The nanoFlash does not care, and neither do we if someone wants to record at a different bit-rate or in a different mode. Many shooting situations and quality needs are different.

….Hi Dan:
In my testing and shooting use, I have found 50 Mbps Long GOP to be the real "sweet spot." I cannot see any appreciable difference on my Sony Broadcast HD-SDI HD monitor, which would justify the large file size of recording 100 Mbps files. However, I have found I-Frame 220 Mbps and 280 Mbps recording to be far superior to any Long GOP recording data rate. I can see a demonstrable difference between Long GOP 50 Mbps and I-Frame 280 Mbps.

Given the current quality fluctuation from I to P/B frames, I don't trust material at 140 MBps LongGOP. Step through some frames of detailed Long-GOP material and see if you notice this quality fluctuation. I saw a mushier frame roughly every six frames in Sony Vegas for 1080p30 video, though I don't have an explanation for the length of that interval. In the past, I described this as a sharp frame, but really, it's just a mushy frame in which details across the frame are softened. Is this is an artifact of SonyVegas? I just repeated this with 720p60 video at 140 MBps LongGOP. In that footage, the artifact was a mushy frame nearly every six frames. When I couldn't detect a mushy frame every 6 frames, the mushy frame showed up 12 frames later, but not every time.

EDIT : I barely see this quality fluctuation at 100 MBps LongGOP. An given that none of the footage (Piotr's or mine), is staged well, a good test at 35 Mbps, 100 MBps and 140 MBps LongGOP and a high I-Frame rate is necessary.
Long-GOP should provide a coding efficiency of 2-3x over I-Frame only. So, we should be seeing 100 MBps LongGOP with quality equivalent to I-Frame only 220. A ConstantQ implementation would fluctuate in bitrate and provide higher bitrates when needed. The value here is the preservation of the quality of the material, not so much the file size. A Constant Q implementation may also provide a method to estimate the bitrate needed for particular material. A real-time bitrate monitor in the case of VBR or even a bitrate recommendation function would be useful to help select the bitrate or quality needed for a scene - a lofty request indeed.

Dear Piotr,
I'm sure that if we show evidences that the NANO efficiency is not as expected, CD will have a look on that.
I have also an EX-1 as my main camera, so I have the same concerns than you, but if we want to know bout the NANO, we have to eliminate variants as cameras.
We don't need any special kind os test, but a workflow where the only possible added noise comes from the NANO.
Where we can compare a clean picture, with flats areas, gradients, fast moving areas, high detail areas and noisy areas. Easy to compare and easy to identify individual frames.
Basically we have been comparing SxS files with the NANO files. Those are very poor conditions to extract any valid conclusion.

Dear Dan,
I don't say that "50mbps" is the sweet spot. I'm very happy working at 100Mbps. That's the average data-rate I had in mind before buying the NANO.
I haven't had time to make any kind of half-serious test as I all ready said.
I'm very happy with the noise of my EX-1 and I have no reasons to think that the NANO introduces any noise.
Dan, the "Efficiency Curves " tests that you brought here, for my self, are most clarifying, but as camera/editors they result very "theoretical" for us.
We need to see and compare on the picture.
I don't think we need too complicated tests. Most of the times zooming just a bit is enough to find what you are looking for.
I have no power-horses to work on HD Uncompress, but I don't thin k that necessary.
I think that something like Prores HQ or AVID DNx would be more good.
The test will work if is:
- Easy to compare and spot differences.
- Identify single frames.
- Easy to share and compare on every body computer.
I'll post you a possible test picture.
rafael

Except for the fact that codec efficiency and advantages may decrease w/ data rate. That's why AVCHD looks so much better at low bit rates, but at high bit rates, MPEG-2 and other "old" codecs can look very good.

Long-GOP works great when frames are mostly the same. But as you give more data rate for the codec to use, you have more detail and more slight variation from frame to frame, so the efficiency advantage of Long-GOP diminishes. Adding data rate to the codec also improves the quality of the I frames, so the potential lower quality of P and B frames may become more objectionable. Which is why I know the proposal for changing the size ratio for I, P and B frames. But the easiest solution is to throw some more bandwidth at the problem and make everything I-frames. I don't see the big issue with that.

So I agree with Piotr (who's posts have been a great contribution to the nano's acceptance and real benefit to CD, even if it doesn't always feel like it for them) that this is an academic discussion. If possible, it would be a lot of work to save space that is getting cheaper all the time.

And when you throw in that NLE's will have to work with this modified Long-GOP format for it to be useful, I think it really becomes a non-starter. JMHO, but I think the rationale makes sense.

Thank you, Peter, for your correct interpretation of my posts' true intention :)

After a year of 100-140 Mbps LongGOP, going I-Frame is my conclusion as well, and the Nano 220-280 Mbps I-frame looks great. My major regret is that I thought moving from 100 Mbps to 140 Mbps LongGOP would yield better video, and due to the interframe quality fluctuation, it did not. Since I shot in parallel with an EX1 with 16 GB SDHC and Nano with 64 GB CF (2 x 32GB), I just figured I may as well use the CF space for 4x the EX1 35 Mbps data rate.

The bottom line then Gents, either use 50Mb L-GOP or 280 i - frame. I'm happy with that.

To get even better quality from my EX3, i'm going to have to upgrade the lens.

Now You've Got it ! :-)
 

…Hi Kris & Gints, & Piotr: Now you have the three maximum quality settings of the Nano Flash & Flash XDR.

As one of the seemingly few XLH1/nano users, at least compared with EX1/3s, and one who videos wildlife, mainly birds , what would be a recommended best setting? I'm guessing 220 Mbs I-frame.
(I use PhotoFast 533x 64gb cards)

Ron

Dear Ron,

Our 280 Mbps is our best quality.

Our 220 Mbps is our second best quality and it is very close to 280 Mbps in quality.

Thanks, Dan. One of my CF Cards has some footage taken at 100Mbps Long GOP. Can I continue using this card with a 220Mbps I-Frame setting?


Ron

Dear Ron,

Yes, you can, no problems. The nanoFlash can handle this fine.

You can actually mix and match any footage on the nanoFlash.

However, If you are playing back the footage on the nanoFlash, when one clip ends, and the next one is in a different format, such as changing from HD to SD or 1080 to 720, the picture will break up as the nanoFlash has to adjust to the next format on the fly.

When you import the clips into your editing system, all will be fine.

If you playback any clip, starting with one format, any clip on the card, it will play back properly.
The only problem is when the format of the clips changes on the fly.

Ron,

I use 220mb I-frame with my XLH1S/Nano combo. Footage always comes out great!

…Hi Ron:
I use Long GOP 50 Mbps and HDV for my paying jobs, and I-Frame 220 & 280 Mbps for my personal work with my XL H1.

Great.
For me if the NANO pictures at 220/280 Mbps I-frame looks great, MEANS NOTHING.
That's what is expected

What I want is that the 100Mbps and 140 Mbps LGOP look AS GOOD as the 220/280 I-Frame.
This is what the NANO MPEG-2 supposed to do; isn't it?.

So:
- If people are not using 100/140Mbps because there is not a clear advantage over 50Mbps: There is something WRONG.
- If we are not getting similar quality on 100/140Mbps LGOP and 220/280Mbps I-frame: There is something WRONG.

I haven't bought the nano to record at 35/50Mbps (SONY does that).
I haven't bought the NANO to record at 220/280 Mbps. That data-rate is CRAZY.

The NANO should shine at 100/140 Mbps L-GOPs. There is where should show the advantages relating Quality/File Size. There you should get the same quality than I-Frame 220/280 Mbps, but half file size.
Again, if this doesn't happens: There is something very WRONG because all that we heard about L-GOPs efficiency is FALSE.

rafael

PS:We are saying many no senses about efficency/data-rate.
FACT: 140/180Mbps L-GOPs and 220/280Mbps I-Frame, should look VIRTUALLY UNCOMPRESED.

To compare the efficiency, we have to start from those data-rates down.
We can not take like reference the EX 4.2.0/35Mbps files, and see how rising the data-rate the picture improves (or not).
We have to start by the top setting and see how the picture degrades when reducing data-rate.

Thanks Michael,

I went out this morning to try the new settings on some Bewick's Swans (Whistling is the Yank sub-species) which I found yesterday, but as is invariably the case the birds had flown. I'll have another go tomorrow,

Ron

Hi Michael,

I have the same setup and also do some wildlife shooting. I normally use 100mbps Long GOP setting with a prebuffer. I really appreciate the pre-buffer because often an action starts more quickly than I can predict it.

This morning I went to try the suggestions in this thread, setting my nano to I frame and 280mbps. The nanoflash reduced my speed to 140mbps. I tried again at 220mbps and again the nanoflash reduced the bitrate to 140mbps. I then removed the prebuffer setting and the nanoflash allowed the two faster bitrates (220 and 280) with no difficulties.

Something to be aware of.

Alan

Thanks for the info Alan. I use my XL/Nano mostly for tv broadcast or narrative work, where prebuffer is not a requirement for me, so I never use it. Its good to know this.

RE: 100 and 140mb L-GOP

I would think that since Sony has never had a product that utilized this codec at those bitrates, that they didn't optimize it at those bitrates. They do with 50mb, and thats why it looks the way it does.

Dear Friends,

We perform quite a lot of testing with our Flash XDR's and nanoFlashes.

And, of course, we welcome the opinions of others.

Is anyone really saying that 100 Mbps is worse than 50 Mbps?

If so, then that conculusion is not borne out by objective testing using very sophisticated systems designed to test video quality objectively.

50 Mbps 4:2:2 and 35 Mbps 4:2:0 have approximately the same compression ratio, when one considers the extra data present in the 4:2:2 video stream.

We fully support the conclusion that 50 Mbps 4:2:2 is Broadcast Quality.

I also state that 100 Mbps 4:2:2 gives one more assuance that there will not be problems in the video stream when there is an excessive amount of detail and an excessive amount of motion.

Sony spent untold millions of dollars developing the codec module. Far more than what would be justified to use it in only two cameras.

Also there are untold numbers of our customers using 100 Mbps Long-GOP with great success.

Since the nanoFlash and Flash XDR's are very versatile devices, you may run your own tests, put it through you own post process, and make your own decision.

Dear Rafael,

You don't even have an idea how much better your above post has made me feel. So far, I've felt very lonely in my opinions, and frankly have given up pursuing the matter further as people (not just CD) started treated me like a paranoiac :)

Unfortunately, I don't have the hardware required to run the testing you proposed in your email to Dan and myself. Therefore, I'd be very grateful if you run the tests yourself, and publish the result in the original thread of mine (the one that "refuses to die"") :)).

Piotr

Dear Dan,
I stated that I shoot a 99% of my work at 100Mbps.
That's the standard quality I want from my NANO, and I'm very happy with it.
I don't gonna waist my time testing 50Mbps, because I don't need any test to know what a 50% cut in data-rate can do to my picture.
I may spend time in making tests with 140/180Mbps to see if those extra 40/80Mbps improves my "standard 100Mbps" shooting.
I just wanted people to be a bit more critic or experimental.
I wouldn't be happy If I would be limiting my NANO to shoot 50MbpsLGOPs and 220Mbps IF.

We all agree that most of the tests brought here so far, do not stand a close examination.
They have been done with a variety of cameras, presets, subjects,.. Most can not be reproduced.
A proper test needs to be repeatable as many times as needed.

As I posted you I'm preparing a simple test that we can share and try, whatever our system or NLE.
The process will be very simple:
- Generate a high quality clip (with signals able to test the behave on detail, fast moving picture and noise)
- Play that clip through a reliable video-card with SDI Out.
- Record the SDI to the NANO at different data-rates/structures.
Then, comparing the signal before/after NANO would be easy done in anyone computer.
I'm far from my place, so I won't be able to prepare this till the end of January.
Best,
rafael

Long GOP 50 Mbps is a setting which has been optimized
 

…Hi Rafael: Wrong ! Sony has most likely *Optimized* the Long GOP 50 Mbps setting, because this is what gets recorded to disk in the XDCAM HD cameras, so I think this makes Long GOP 50 Mbps the real sweet spot in the Long GOP family of settings. Just because you double a codec's data rate does not automatically imply it will be superior. I think my XL H1's 25 Mbps HDV tapes look *Equal* to Long GOP 50 Mbps (Only in daylight shooting), but the low data rate codec suddenly reveals itself in lower light and indoor shooting. The Long GOP family of settings in my XDR are far superior in low light interior shooting conditions, plus the fuller HD raster and extra color space reveal themselves in lower light interior shooting as far superior versus HDV. You have four major factors working for you with the Nano/XDR which make things look better.

1. Superior Color Space: 4:2:2 vs 4:2:0
2. Superior HD Raster Size: 1920 x 1080 vs 1440 x 1080 in some cameras.
3. Superior Processing Sony Codec Hardware Chip: Settable to higher data rates then in camera recorders.
4. Ultra High I-Frame data rate recording: 280 Mbps which is the *Only* setting where the claim can truly be made that it looks close to uncompressed recording.