Re: Sony X70 4K - Lowest bit rate in the industry!
 

Look, If Jody's position is that Sony's XAVC offers no quality advantages above 60Mbp/s than so be it. What can I say to that? It's his opinion. He has his own reasons.

Sony designed many XAVC modes that go WAY up the ladder in bit rate. (With 60mbp/s at the very bottom) Sony markets them as higher and higher in quality as they go up the list. They also charge more for each mode as it goes higher into the model lineup. It appears that 100Mbp/s is the new "basement" or "low standard" for 4k/UHD cameras as low as $499 and higher. I'll bet allot of money that Sony will never make another 4k camera at ANY price that has a maximum bit rate below 100Mbp/s.(Especially when their direct competition offers 100-150Mbp/s) Yeah,..I know...absolute crazy talk,..right?

I dont think that Sony actually realizes how good their 60Mbp/s is?? They certainly don't know that it's just as good as their 100Mbp/s. Stupid Sony, I guess.

Me? I agree with Sony engineers and XAVC designers. The science behind higher and higher bit rates in MY opinion is on Sony's side. Sony built it, they know XAVC best...in my opinion. (But maybe Jody and his people know things that Sony doesnt?..possibly)

I'm also certain the Motion Picture Experts Group will also agree that higher h.264 bit rates exhibit less and less artifacts and capture motion more accurately. This is why they increased the level restrictions over all the years for h.264. I do not believe they did this because it does nothing for quality. But hey,...again. More radical, crazy talk on my part I guess.

For me,..id rather shoot at the same bit rate that their "cheap and REALLY cheap" 4k models now shoot in today. (No I don't want the AX300's sensor,..I just want it's h.264 bit rate) Is that a terrible thing to want? Ridicules and horrible of me? What an absurd proposal on may part! How dare I ask this of an XDCAM camcorder?

I don't doubt Jody or his associates but If you polled colorists around the world, the general return would be: "The more information the better". (Matching codec for codec of course)

The guy doesn't agree with me or Sony. What do you want me to say to that?

I suppose we are now just beating a dead horse at this point. There is no way that anybody is going to convince me that much lower bit rates are just as good as higher ones within the same compression algorithm. Yes, if we compare H.264 vs H.265 HEVC, than yes, I will agree there. But this is all within the SAME MPEG H.264 LIBRARY.

One thing is certain: Neither one of us needs each other's "approval" of our opinions. I think we will both sleep perfectly well tonight.

Sony has stated they are working on this and I have a "feeling" (or hope) they they will succeed. Competition and market forces are pressuring Sony on this.

I just hope Jody doesn't persuade them that it's not necessary after all.

lol ;-)

Re: Sony X70 4K - Lowest bit rate in the industry!
 

I own an F55 and can shoot 4K Raw all day long.

My X70 is merely another tool I can use in many situations, and I know exactly what to expect from it because I've done the tests. I've posted videos of the results here and on the X70 Shooters FB page. Do your own or ignore mine or whatever. Makes no difference to me. Sony knows they have a terrific product and my tests have further validated that to them. (Yes, to SONY. I have done real-world testing and evaluating of a dozen camera systems for them over the past decade +, some of which can be found on their websites. I have met with the Japanese designers on many occasions and am proud to have had input as to some of their recent high-end camera systems.)

Just sharing my experiences. And in my 31 years in Hollywood, this adage has served me well:

"A man with an argument is no match for a man with an experience."

;-)

Re: Sony X70 4K - Lowest bit rate in the industry!
 

For the record, I love my X70. That's not the problem.

And all this experience you have collected in your career gives you the ability to declare that significantly higher h.264 bit rates do nothing for image quality or color grading?

Than why in the world would you ever want to shoot with your "F55 in 4K raw all day long"?

You "experience" goes against all the "experience" that Sony and MPEG have.

Here is some more crazy talk from me:

"Higher h.264 bit rates = more image data = more information to work with in post"

or...

"Lower h.264 compression ratios = more image data captured"

or...

"Higher h.264 bit rates allow for more bits to be allocated into the shadows of an image and less macro blocking as well as banding"

or

"Higher h.264 bit rates allows smaller block encoding of moving pixels and allows finer and more accurate motion detail and entropy estimation"



Yeah,...radical, weird crazy talk that is all completely FALSE!! Your "experience" says that I am completely dead wrong on this. In fact, I'm clearly displaying my lack of experience here. MPEG and Sony would CLEARLY not agree with these statements I have listed here!

Where do I get this stuff from? lol

;-)

Re: Sony X70 4K - Lowest bit rate in the industry!
 

Woah,..woah,...let me hit the breaks here.

If is the real "Jody Eldred" and not some "impostor"....

I just Googled you....I KNOW YOU! We have met before! I have talked to you several years in a row at the NAB Sony booth!! Many, MANY times actually!

Hey, for the record, I think you ARE are pretty cool guy. Sorry I did not recognize your name until I Googled you. Dang! Nah man, I dig you and respect what you have done with Sony. You are actually one of the cooler guys to talk to at the Sony booth. No B.S, I mean this sincerely, I really do.

I don't take back my stand on bit rates and maybe I have been a bit too sarcastic at times but I do certainly respect your work and experience.

When I see you next year at NAB, you might want to kill me but I'll still want to shake your hand. I'm totally cool with you. Sorry, I didn't know this was you all this time. If I had Googled you earlier, I would not have changed my position but I would have changed my tone.

I hope we can just laugh at this next year. ;-)

Re: Sony X70 4K - Lowest bit rate in the industry!
 

This compression vs bit rate argument has been around for a long time and was discussed to death many times in the early days of XDCam 35-mbit vs 50-mbit yet their corresponding compression ratios were very much the same. As Jody says "How does it look." If it holds up in post and especially if transferred to a higher level codec and works in the real world and everybody is happy with the result that should be the final arbiter.

I've shot countless hours of broadcast on both the 50-mbit and 35-mbit XDCam flavors and never had an issue with networks here and overseas and subjectively it's it very hard to tell the difference in the picture quality given that both come of correctly set up cameras. I've lost count of the number of hours we have shot in 35-mbit that has been rendered to 50-mbit for delivery to TV and never once had a query on quality.

As Alistair quoted way back in 2009:

"4:2:2 = (1920×1080 + 960×1080 + 960×1080) x30(fps) x8 (bits) = 995Mb/s. Divide by 19.9 and we get 50Mb/s

4:2:0 = (1920×1080 + 960×1080) x30(fps) x8(bit) = 746Mb/s. Divide by 21.3 and we get 35Mb/s

So from this we see that the compression ratio for EX is 21:1 and for XDCAM HD 422 20:1. This is extremely close and in terms of compression artifacts means there will be little, if any, difference between the two."

HD Warrior » Blog Archiv » XDCAM 422 v XDCAM EX by Alister Chapman

In the real world I have found this to be pretty true so we can't judge everything on bit rate and compression ratios alone.

It is also well know that Sony have their own proprietary compression algorithms that comply with the H.624 standards. Therefore we are only surmising when we say there must be a difference between the 60 and 100-mbit bit rates re artifacts when we don't know whether Sony is using a different proprietary algorithm for the the bit rate compression between the AX100 vs the X70. On that basis alone it makes it almost impossible to come up with an objective assessment of the differences between the two bit rates.

I've long ago given up nit-picking with the numbers. If it was all based on numbers then the Go-Pro would never have had a look in in the broadcast world yet they are everywhere like a plague. As Jody says if it looks good, feels good and works okay for the project you are working on run with it.

Chris Young
CYV Productions
Sydney

Re: Sony X70 4K - Lowest bit rate in the industry!
 

I want to be really clear on something here...and maybe this has gotten lost in my CODEC complaints.

I strongly believe the Sony PXW-X70 is EASILY the best "palm-corder" on the market today. Canon's offering is not even close. JVC's model is nice but I'll take Sony's larger 1 inch-type sensor and front end over that JVC model ANY day. (even though the JVC sports 150Mbps h.264)

I am VERY happy I bought it and I'm very happy I bought the 4k upgrade too.

My writing is NOT a "bitch session" about a camera I hate...far from it. It will be a great tool of mine for many years to come. (or until Sony replaces the model, and I buy that one. hehe)

I am a die-hard Sony freak and over all, they have gotten more money form me that I want to think about. Sony is ONLY company I buy camcorders or photo cameras from. I work for a global media company and I buy TONS of Sony products too at work.

With all this said clearly. I do get bothered at times when I see cheaper Handycam's and Alphas receive features that more expensive models don't get. The new RX10-II has 100Mbp/s AND SLOG-2...this bothers me. A while back ago the NEX5 got peaking and the far more expensive VG-10 was not allowed to have it. I called Sony and protested and complained...do you know what happened? At the very end of the VG10's sales life, as it was being discontinued and the new VG20 was being released, Sony released a tiny VG10 firmware update. Guess what the firmware did?....Added peaking! (no, I cant take credit for that. Allot of customers demanded it on the internet and blogs and forums)

That's the only reason why I do this. If Chevy allows the Tahoe to have leather seats but then limits it's Escalade sister to be locked down to cloth seats only,...there is something wrong with that.

I just hate seeing features in cheap cameras that are locked out of much more expensive ones. (I know consumer Alpha, Handycam and Pro departments debate this stuff internally within Sony too)

I'm sure that you know the FS7 vs. F5 scandal...That wasn't fair and Sony fixed that with an upgrade option for F5 customers. Good job on that.

That's all I'm trying to say here. Sony, please try to be "feature consistent" as cameras go up the ladder.

I can already see this coming. Sometime down the road, Sony will have two 4k brother and sister models. An XDCAM "pro" version and a Handycam "consumer" version. What is going to happen? Sony consumer division will somehow give the Handycam version 4K 60P and the more expensive XDCAM will be stuck with only 30p for a long while. It sounds funny,...but it's certainly quite possible! haha

Re: Sony X70 4K - Lowest bit rate in the industry!
 

I agree with everything you say here Chris. I'm not going to name names here but...the media company that I work for setup an HD deliverables standard for "Gold", "Silver" and "Bronz". Sony was very unhappy with where we placed 35Mbp/s XDCAM EX and really wanted us to change our standard. We didn't. At a SMPTE meeting in our office, Sony sent their CTO (I wont type his name but he was EXCELLENT btw) and even he tried to pitch XDCAM 4:2:2 and EX to the group. He even brought monitors and gear with him on his demo. He showed us phase-inverted-canceled A&B shots to inspect artifacts....really cool stuff! In the end, we still didn't elevate XDCAM EX on our standard (because of the "numbers") and I think Sony was really upset by that.

Meanwhile, I know for a fact that we were airing a major show with boats and drama on the water that was shot mostly on HDV (25Mbp/s 1440x1080, non-square pixel) tape at that time. (go figure?) Ehh,...maybe I have said too much already ;-)

Anyhoo....I agree with you on your post Chris.

Re: Sony X70 4K - Lowest bit rate in the industry!
 

I think if Sony made the Prosumer/Professional difference as just SDI, Timecode in/out, Genlock , World camera specs, at each price point ( which would be features different ) it would make everyone's life a lot easier, including Sony.

Ron Evans

Re: Sony X70 4K - Lowest bit rate in the industry!
 

I'm perfectly OK with a paid upgrade sales model. I would certainly pay additional money for a second 100mbp/s liscense. I would certainly pay for an SLOG-2 X70 upgrade if the price was reasonable.

Speaking of SLOG-2....we are now seeing SLOG-2 make its way deep into the lower consumer markets. Multiple Sony Alphas and Cybershots now have it.

Who would have thought we'd all see the day when my Grandmother could go to a Best Buy and get her camera with an SLOG option it?

It's funny how cheap consumer cameras get things that many pro market cameras are not allowed to have.

SLOG-2...wonderful dynamic range recording! Get in on our high end super35 models or get it in the cheapest low end market! (Not available on any mid level pro market camcorder) $8k and higher or in several consumer $2.5k and below.

Strange?...

Re: Sony X70 4K - Lowest bit rate in the industry!
 

Well, not quite. Yes there are many XAVC modes, and yes they go up in bitrate..... but a large reason for that is to accommodate I-frame only versions of the codec. Such don't NECESSARILY give better quality, but there are reasons why they may be desired, right at the acquisition stage.

And unlike long-GOP, their bitrates are directly proportional to framerate, so up the framerate and ........
The maths is correct as far as it goes, but I'm afraid the reasoning is wrong on several levels.

Most importantly, you don't need twice the bitrate to code 4:2:2 chroma as you do 4:2:0. The reasoning is similar to why when you compress still images, for a given quality level the file sizes don't scale linearly with image size. If you've got a 4:2:0 chroma image, you can effectively "guess" at in between values. ("Guessed" 4:2:2.) So to code the true 4:2:2, you only need the values of how different the true values are from the guesses. Which can be represented by a lot less data than the original 4:2:0 chroma signal.

Secondly, Alister assumes the same compression ratio for luminance and chrominance, and for MPEG2 this is not necessarily true. It's frequently the case that the chroma signals get far harder compression than luminance - this is why when banding may sometimes be seen (esp on digital broadcast TV), it's frequently most noticeable on areas of plain saturated colour, more rarely on more monochrome scenes.

So you can't do a simple sum of total numbers of chroma and luma pixels, compared with total bitrate and reach any meaningful simple conclusion. It's far more complex than that.

Re: Sony X70 4K - Lowest bit rate in the industry!
 

Off topic question but I cant resist.

"The reasoning is similar to why when you compress still images, for a given quality level the file sizes don't scale linearly with image size."

I dont know the answer to this at all, but maybe you do...

Two files:

1.) If you encode a 500x500 frame size image with specific h.264 setting and achieve "X" quality.
2.) If you encode a 1000x1000 frame with the same exact h.264 setting to achieve the same "X" quality.



A.) Will file #2 require 2 times the bit rate to achieve the same "X" quality? (because its frame is 2x larger?)

B.) Does H.264 "gain" higher and higher efficiency levels as frame size increases? (So maybe it only needs 1.5 times the bitrate instead of 2 times to achieve "X" quality)

C.) I believe that H.264 operates in fixed block sizes. Or is this wrong and are these block sizes (4x4 or 8x8 or 16x16...etc) are infinitely scalable? I know that h.265 operates in different block sizes and supposedly is a major advantage over h.264 because of that. (one simple reason on many) If block sizes are fixed, than that would suggest a more linear or proportional scaling bit rate???

I'm not sure about any of these questions but maybe you or Jody or anybody else knows?

Re: Sony X70 4K - Lowest bit rate in the industry!
 

Might I suggest someone do a short recording using the AX100 and x70 in 4k and open and compare the files in MediaInfo. While it won't tell the whole story it will tell you what OTHER differences there are besides bit rate. Things like Entropy and GOP Structure can result in a lower bit rate file looking better than a higher bitrate file.

Re: Sony X70 4K - Lowest bit rate in the industry!
 

And - like with a lot of things(!) - I don't think the answer is simple.....

Firstly, I think you mean "Will file #2 require 4 times the bit rate to ......", don't you? You're quadrupling the number of pixels, so "common sense" would seem to indicate you'd need 4 times the bitrate?

The answer is generally taken to be "no", but it depends a lot on what variables change. You're changing the image resolution - but are you changing the size of the viewed image as well? If your original image is viewed in a frame 8"x8", the answer will vary depending on whether file#2 is also viewed as 8"x8" - or scales up proportionally to 16"x16".

That's important when you think of the difference between 4:2:0 and 4:2:2 chroma sampling. In such a case you are far more analogous to "fixing the size of frame" - as the 1920x1080 luminance aspect is unchanging. And it then follows that although there is a doubling of chroma samples, it shouldn't necessarily be thought of as needing a doubling of bitrate for equivalence - it should be less.

Re: Sony X70 4K - Lowest bit rate in the industry!
 

As reported earlier (in this unnecessarily very long thread) I've done that with a colleague's AX100 and my 4K X70 in a 4K color grading suite at Roush Media in Burbank, CA. Projected in 4K on a 15-foot screen. They both looked very good (for what they are... I'm used to seeing F55, RED, or Alexa 4K up there.) The X70 graded better, chroma noise was a bit less, the compression appeared to be superior as there was slightly more digital artifacting in the AX100.

I have no way of sharing this as we did not have opportunity for outputting, much less doing so in a comparative side-by-side edit. (You'd not be able to evaluate it online anyway do to compression and the wide variance in monitoring.) I have posted some 4K X70 that Roush Media graded on this website. It'll give you some idea of what you can do. Here again is the link:

Re: Sony X70 4K - Lowest bit rate in the industry!
 

No prob. Hope to see you there.

Re: Sony X70 4K - Lowest bit rate in the industry!
 

Can you imagine the reaction 10 years ago if someone said those images were from cameras cost around $2000 ?

Ron Evans

Re: Sony X70 4K - Lowest bit rate in the industry!
 

Jody, Cliff doesn't believe eyeballs. That's why I mention a comparison using MediaInfo. That will provide the "numbers" Cliff loves. My own hunch is there might be things other than the data rate that are different which may show why a lower data rate file can be better than a higher data rate file.

Re: Sony X70 4K - Lowest bit rate in the industry!
 

Good idea. Will do that in the next day or so!

Edit: Had the files and exported the metadata form MediaInfo as text. I included the AX100@100Mbp/s too

Re: Sony X70 4K - Lowest bit rate in the industry!
 

Yeah,..., total brain fart on my part. Good catch.

I'm thinking of the general scalability of h.264. (either 4:2:0 or 4:2:2) Let me put it a better way than my original bone-headed explanation:

If you took 15Mbp/s, h.264, 8bit, 4:2:0 at High profile with CABAC at whatever long GOP structure you want at 1920x1080 frame size. The would give you a certain quality level.

Wait!,...do we agree that 15Mbp/s for the above specs for 1920x1080 are not too good? (I hope so...it's actually way below AVCHD's h.264, High profile, CABAC, 24Mbp/s)

Now, take this video, multipy it's bitrate and frame size times 4 and you get 60Mbp/s UHD. NOW!,...take your 70inch UHD TV, get a piece of cardboard and cover the bottom half of your screen as well as the top left 1/4. This leaves you watching a single 1/4 size or ""1080" quadrant of your 4k video. When you watch this, will you see video that equals the same "15Mbp/s" of quality or artifacts that you see in a normal 1080 video??

The short question: Is h.264 "proportionally" scalable in quality as you increase it's frame size and bit rate?

Or,..does it GAIN or LOSE bit rate effeciency as you increase or decrease it's frame size with the bitrate?

I do not know the answer. I only suspect that because it operates in fixed block calculations that you MUST increase the bitrate TOGETHER in a direct "linear" or "proportional" fashion with a proposed frame size increase. Both factors must increase "evenly" together??

So, UHD h.264 @ 60Mbp/s = FOUR 15Mbp/s "1080" quadrants in your UHD TV???

Again, yes, yes, yes this is speculation on my part. No doubt. But I have always wondered h.264's scalability and efficiency for years.

Anybody know? Anybody care?.. or maybe it's just too geeky of me to think about. lol

Re: Sony X70 4K - Lowest bit rate in the industry!
 

My eyeballs tell me that my X70's 4k looks good today. I think Sony will make it look better in the 100Mbp/s codec update they are working on. (hopefully they succeed)

I wonder why Sony is even trying this?

Official Sony statement = *We are looking to support a higher bit-rate recording mode than 60 Mbps for 3840x2160 XAVC-L in the future.

What is Sony thinking here?? I don't think Sony understands yet that nobody want's it and it's really not needed? ;-)

Are we really arguing against the reasons for something that Sony is trying to do?



On a completely different note: Just took my new RX10-II for a 30 min spin. The new stacked 1 inch-type sensor has NO rolling shutter in 4k!!...it's GONE! Woah! SLOG-2 looks fantastic, highlight handling is a HUGE improvement....dynamic range is EASILY way better than previous 1 inch-type models I have used (RX10, AX100 and X70) with SLOG-2 turned on. (rec 709 highlights seems the same as previous 1inch-type) Way to go Sony...you fixed it!!

The high speed frame rates are spectacular for a cheap $1,300 camera.

This thing is a little MONSTER!

Re: Sony X70 4K - Lowest bit rate in the industry!
 

David ~

Agreed and I believe that is why Sony settled on 50-mbit for its XDCam MPEG-2 422 Profile@High Level as opposed to its 35-mbit 420 version MPEG-2 Main Profile@High Level.

This I believe to be correct for MPEG-2 420 in the transmission chain but this is at a considerably lower bit rate than typical camera compression rates. I believe Alistair to be correct with regards to Sony's proprietary camera 422@HL and MPEG-2 Main Profile@High Level implementations as they use the same compression algorithm for both luminance and chroma. The same goes for Canon's and Convergent Design's use of these codec as they was licensed from Sony. In Alistair's mathematical examples I think he was keeping it reasonably simple to understand for those who want an overview of compression schemes relating to cameras but without drowning them.

With regards to artifacts. Even with the newer DBS transmission systems based on DVB-S2 we are now seeing 420 HD bit rates between 8~19Mbps with a mean average of 12Mbps for both MPEG-2 and MPEG-4 AVC transmissions so it it hardly surprising we are seeing banding artifacts. With many broadcasters now using rate shaping to fit three 1080i channels on a 31.6Mbps DBS transponder I think we will see more of these compression banding artifacts. Without laboring the point I think to compare low bit rate transmission compression artifacts with some of the later compression schemes used in more recent camera designs is probably not the best example to put forward.

Chris Young
CYV Productions
Sydney

Re: Sony X70 4K - Lowest bit rate in the industry!
 

I confess I don't know whether the compression ratios in XDCAM for luminance and chrominance are the same or not. They may use the same algorithms but does that automatically mean the ratios will be the same? The point I was trying to make is that it's dangerous to assume they are - they need not be for MPEG2, and in various implementations they are not.
But "keeping it simple" shouldn't mean saying anything incorrect, and I'm afraid here it does. It "proves" that the basic compression ratios between XDCAM EX and 422 are the same (the only difference between them is the 4:2:0/4:2:2 aspect) and regardless of the truth about differing luminance/chrominance compression ratios, there is still the fact that doubling the number of chrominance samples won't mean a doubling of bitrate. And that's before we even start to consider any other factors that may differ between them.

It's similar to the comparisons made some time ago between XDCAM EX when it first came out and HDV. Same basic codec (MPEG2) and XDCAM EX not that much higher bandwidth...... True as far as it goes, but totally failing to take into account less quantifiable factors, of which I believe the dynamic bitrate allocation between Intra and difference frames of XDCAM was one major fact.
I was trying to illustrate a different point - that there is no need whatsoever for luminance and chrominance compression within a codec to have the same ratio, and in some cases they don't. Hence taking the combined number of samples per frame and dividing by bitrate doesn't (by itself) prove very much.

Re: Sony X70 4K - Lowest bit rate in the industry!
 

I'll say again, beware of simple headline numbers.

As far as AVC-HD goes, then I understood that the 24Mbs figure (for 720p and 1080p/25, 1080i/25) is a peak value, not an average value. I seem to remember when the first Panasonic AVC-HD cameras came out that the average value I was seeing reported was far more around the 17-19Mbs mark?

And that was for early implementations, not using anything like all the tricks that AVC-HD is capable of. So my first question to you is this 60Mbs XAVC implementation you are unhappy about an AVERAGE of 60Mbs or a PEAK of 60Mbs? Because without being absolutely crystal clear about that, this entire debate becomes meaningless!

Secondly, for AVC-HD we may be talking about interlace (1080i/25) - with what you're referring to (XAVC for 4K) it's progressive. It has to be - 4K is always progressive. And progressive lends itself better to compression than interlace.

Thirdly, XAVC is a more advanced codec than AVC-HD. It's more recent - so requires a more recent decoder version - but that allows it to be more complex than earlier H264 incarnations (like AVC-HD).

Take all that together and it all becomes feasible that a quadrant of such a 60Mbs QFHD image *MAY* indeed be better than an AVC-HD single image. Frankly, there are so many variables that I wouldn't like to predict. All I will really say is DON'T rely on "simple" headline numbers.

(And note also that as Chris says, digital broadcasting of 1080i/25 is indeed using bitrates averaging around 12Mbs, and I can't remember seeing any noticeable artifacting on BBC One HD at home for a long time. OK, they've got statmuxing with other channels in the multiplex to help get it so low, along with expensive broadcast encoders, but the implementation is unlikely to be able to be as sophisticated as XAVC (to maintain backwards compatibility with all existing decoders), and it's for an interlaced system.)

Re: Sony X70 4K - Lowest bit rate in the industry!
 

I think the thing about XAVC either S or L's published 60Mbps being the peak or average sustainable bit rate is the key. I myself still have had no idea that being one or the other after all these times!

Re: Sony X70 4K - Lowest bit rate in the industry!
 

I have seen the following.
AX1 QFHD 60P 150Mbps shown as 155Mbps in Catalyst Browse and 149 to 152 in VLC player tools
AX1 QFHD 30P 60Mbps shown as 59 in Catalyst browse and 59 in VLC
AX1 QFHD 30P 100Mbps shown as 99 in Catalyst Browse and VLC player

AX100 QFHD 30P 60 and 100 show the same as the AX1

AX100 HD nominally 50 Mbps show as 50 to 53 in VLC player and 53 in Catalyst browse.

Same clips used of course to compare in Catalyst browse and VLC player. Not sure if Catalyst Browse just gives the maximum data rate as one can watch the data rate as the clip plays in VLC player.

Not sure if these mean the 60 and 100 are maximum or not but the 50 for HD and the 150 for 60P QFHD are not the maximum as I have observed more in several clips. I have not shot XAVC-S HD in the AX1 to try but will do some time. Expect it is just like the AX100.

Ron Evans

Re: Sony X70 4K - Lowest bit rate in the industry!
 

Looks like we could say that at least for Sony cameras' published XAVC bit rates the numbers actually mean "around xxxMbps". They mean neither peak nor average but it seems safe to refer to for the sake of arguments since the variances, as Ron has found out, are pretty small.

The definition aside, my experience shooting with my AX100 at both 60Mbps and 100Mbps for the past 2-3 months has yet to reveal any clear proof the higher bit rate files have any noticeable IQ improvement in moving (either the camera itself moving or shooting at moving subjects) shots. In static shots or shots with little movement, they look exactly identical.

Re: Sony X70 4K - Lowest bit rate in the industry!
 

I am not a big fan of slow frame rates being particularly sensitive to judder. I can tell the difference on a very slow pan at 30P on the AX100 and the AX1 between 60Mbps and 100Mbps but it is almost insignificant. Noticeable if the pan is across grass or leaves. Also very little difference between the two cameras. For relatively still frame there is no difference that I can see between 60 and 100 Mbps maybe as one would expect. 30P frame rate motion cadence is more dominant. For me there is a big improvement in moving to 60P at 150Mbps.

Ron Evans

Re: Sony X70 4K - Lowest bit rate in the industry!
 

In the side by side test I posted a pager earlier in this thread, there are only "mild" difference between 60 and 100Mbp/s on the AX100. However, all those test scenes were on a tripod pointed at palm trees and a very gentle breeze. So obviously, both bit rates were relatively close. Neither one was too stressed.

I must admit that I'm a little surprised at how many people had a strong reaction to this topic. I figured we'd all jump on the band wagon with our pitch forks and shout for 100Mbp/s. I guess it didn't really happen that way and some disagreed completely with the general concept that less compression is a good thing.

I also had a really difficult time explaining to people that I think 60Mbp/s looks "OK" (they think I hate it...I dont) but that I strongly agree with Sony on their attempt to add higher bit rates to the X70. I think that with the rest of Sony's models and the rest of the industry doing 100Mbp/s, the X70 was left all alone at 60Mbp/s.

I think Sony is attempting to do the right thing with the X70. (I guess some see it differently)

I guess we can all agree to disagree. That is what makes this forum so much fun.

CT;-)

Re: Sony X70 4K - Lowest bit rate in the industry!
 

It depends which way you look at it. Higher compression rates may indeed be seen as a "good thing" in respect that they mean lower file sizes, and lower data rates - which taken together can mean smaller memory card sizes, and speed performance is less critical - so much lower per GB costs as well. But yes, go too far and quality may suffer. And the question becomes where you draw the line. That's the question constantly confronting designers and manufacturers. Compress too high and people complain about the quality. Compress too little and people complain about media costs.

It's easy enough to simply say "less compression is a good thing" - but higher bitrates come at a cost. If it makes a noticeable difference, well, fair enough, but if any difference is marginal then you have to strike a cost/benefit deal.

For my own part, I was really just trying to get over the general concept that drawing strong conclusions on headline numbers is dangerous. The more I find out about the whole subject, the more I realise I don't know - but I do now realise that simplistic assumptions can be seriously wrong. Which is why I haven't given any direct opinion to your fundamental question - I don't know the answer.

In the very first post you said:
But I put it to you - what if investigations showed that the 60Mbs was an average, and the 100Mbs of the other cameras was their peak value? Indeed, what if it turned out that for that "100Mbs" codec the AVERAGE rate was only (say) 50Mbs? Would you still be pushing for it?

Or what if the 60Mbs footage had a different GOP structure - more difference frames between I frames?

Yes, those scenarios are unlikely to be true - I'm certainly not saying they are - but..... it just shows how headline number "reasoning" COULD lead to very wrong conclusions. That's the point.

And same with comparing one quadrant of the 4K image with a 1920x1080 image. Factor in that XAVC bitrates are average, AVC-HD are peak, then add in the fact that 4K is progressive (so will compress better), and a modern XAVC encoder is almost certain to be more efficient than an early AVC-HD one, and the conclusions become very different. (And there may well be other factors I'm not accounting for, which may work either way.)

What you're asking for (100Mbs instead of 60Mbs, all else equal) may well give an improvement - but if it's only very slight, then is it worth it? That's why we're not picking up the pitchforks and marching...... :-)

Re: Sony X70 4K - Lowest bit rate in the industry!
 

Indeed, as long as it's done with tact and respect. Good discussions about the merits or downsides of a subject are often enlightening to both sides of the table. It's just sad to see how despicably it often plays out on social media or as comments under news stories.

-gb-

Re: Sony X70 4K - Lowest bit rate in the industry!
 

For me, I'm shooting in a rec709-ish profile that is "pre-graded" with fairly high contrast and color saturatiuon, than 60Mbp/s concerns me less. And make no mistake, the fact that all (I think) Sony cameras have it along with 100Mbp/s is great. (60mbp/s needs to be there)

However, if shooting in flat de-saturated colors to help protect RGB channels form clipping and grading is necessary? I really feel strongly that Sony is doing the right thing in trying to support higher PXW-X70 bit rates.

As a general rule of thumb for almost all compression schemes...higher bit rates provide less and less quality loss. We know that many compression types allocate bandwidth to the most vital and visible areas if an image...mid tones. Shadows and the darkest areas often get less bits because of this. If you want to lift the shadows of an image, you will typically find more macro blocking, large block rounding and banding in those tones.

So for me to declare that less compression is a good thing for image quality and grading in post. (in general). I don't see how anybody can say that is nutts.

Yes,..if Sony succeeds in getting the X70 100Mbp/s....YES!,..I will still use 60Mbp/s on occasion for certain applications!

I just got the new RX10-II and I'm loving the SLOG-2 on it so far. This little monster has 100mbp/s and I NEVER would want to try and grade/normalize SLOG-2 from a 60Mbp/s codec. That is too much bending and stretching for 8bit 60Mbp/s. Can we at least all agree with that? H.264 is great but it DOES have it's limitations.

Re: Sony X70 4K - Lowest bit rate in the industry!
 

Is the slog2 from the rx10II also not 4:2:0 8bit?

Re: Sony X70 4K - Lowest bit rate in the industry!
 

The RX10-II is 8 bit, 4:2:0. Like all Sony 4k/UHD cameras today, it can shoot in 60mbp/s and 100mbp/s. (Whoops,...with the only exception being the PXW-X70)

Almost forgot there.

CT :-)

Re: Sony X70 4K - Lowest bit rate in the industry!
 

Yes, but you said you never would grade/normalize SLOG-2 from a 60Mbp/s codec, do you think 100mbs would make such an enourmous difference?

Re: Sony X70 4K - Lowest bit rate in the industry!
 

I'll let you know when I try on the RX10-II. My SLOG-2 experience so far only comes from the A7s and ProRes from the Shogun. I typically use the 600Mbp/s flavor of Prores. (is that right?...yeah, it's somewhere around the 600Mbp/s area)

That is only 8bit as well. I have to admit though, ProRes is tough as nails, even in 8bit.

I have only done a few minutes of SLOG-2 footage and that was just to see how much dynamic range I could see in the RX10-II's sensor

Will let you know!

60Mbp/s average bit rate = 7.5 megaBYTEs ber second.

100Mbp/s average bit rate = 12.5 megaBYTES per second.

That's an average of 5 additional megaBYTES per second across 30 frames using this higher bit rate.

Can anybody actually say with a straight face that all that extra image data (40Mbp/s additional information) is "useless"...or "worthless"??

The Sony XAVC engineers and marketing departments certainly wont say that!!! ;-)

Re: Sony X70 4K - Lowest bit rate in the industry!
 

If you can show what that 40mbs means in the real world, like showing actual footage that would support your statement, then it would not be necessary to talk numbers again. Also If that slog2 from the rx10 would be 10bit 4:2:2 this would help a lot more when you want to grade your footage then a higher bitrate only.

Re: Sony X70 4K - Lowest bit rate in the industry!
 

OK. So to clear all this up for everybody, I'll setup a nasty stress test for both 60Mbp/s and 100Mbp/s. I guess we can all inspect the results. (whatever that may be)

I can only do this with the h.264 XAVC-S .MP4 wrapper. (AX100 or RX10-II) I'd love to try it with the .MXF wrapper but the X70 wont do 100Mbp/s and I dont have any other .mxf 4k camera.

Will post something this weekend. I think it will be a nice test to possibly put this all to rest. One way or the other.

Who knows? Maybe the "60Mbp/s is already the best in 4:2:0, 8bit long GOP and no more is needed" crowd is right!

Let's break them and see what happens!

CT ;-)

Re: Sony X70 4K - Lowest bit rate in the industry!
 

But is it extra information - or just extra bitrate?

Think of a word document and using a zip file to compress it. You'd expect the file size to decrease substantially wouldn't you?

So does that mean that it's therefore losing a lot of information in the zip process? The answer's no. In this case none at all. The file size is smaller but no information has been lost. Unzip the file and reopen and the document will be identical to the original.

It's the difference between lossless and lossy compression that's significant, and as I've been trying to say all along, don't draw too many conclusions from headline numbers.

For the record, my bet on such as this is that the 100Mbs sample is likely to be better - but not such a night and day difference as might be first expected. The question then is whether any difference is worth the extra overhead.

Re: Sony X70 4K - Lowest bit rate in the industry!
 

Well, ZIP works totally different. If you zip a book of text, you will get huge gains. What is rebuilt on the unZip is identical to the original text. 0% loss. Text and other types of data compress very well.

Try to Zip a .jpg or an .mp4 file. What happens? Almost nothing. The only way to compress "video" is to throw away image data to make it smaller. When it's uncompressed, it doesn't equal the same as the source. Very very different than zip.

Yup,..numbers alone don't tell all the story. 60Mbp/s on the X70 is not bad, I know this.

I'm actually curious to see a real world stress test between the two. Let's see how far we can push each one in a really complex moving scene.

I'm doing a side by side test between the PXW-X70 "XDCAM" at 60Mbp/s .MXF against the AX100 "HandyCam" at 100Mbp/s .MP4.

I have no evidence of this but I strongly believe they use the exact same encoder chip. It's the same h.264 codec inside two different wrappers.

It will be a good fight. Let's see how they fair this weekend.

Re: Sony X70 4K - Lowest bit rate in the industry!
 

Yes, true - a .jpg or an .mp4 file is already compressed.
Not true. Not if you start with the uncompressed original.

You'll be able to compress *to a certain extent* without any loss at all (same as zipping) and then the uncompressed signal will be exactly the same as source. You're taking advantages of redundancies in the signal. Preserving all the information, but in a smaller file size. And if you take advantage of similarities between frames it works even better - which is why interframe compression will give better results than intra for a given bitrate.

Practically, it's still likely to end up too large a file to be practical. So to compress further then yes, you have to discard information. The trick of a good coder is to lose bits which are least important, and it's quite surprising how far you can go before it becomes noticeable.

But it's an exponential graph. No loss at all initially, then very little, even for quite big bitrate reductions, then eventually even a small decrease in bitrate will make a big difference. The trick is to choose the most sensible point on the curve. It'd be lovely to do as zip files do - as much as possible but remain lossless - but impractical.