Footage comparing Mpeg2 25Mb or 35Mb to Flash XDR higher bit rates?
 

Hey Mike and the CD Team:
I'm sure there are others like me very interested in recording from the uncompressed HD-SDI spigot to an on-camera source via a great codec, but the proof or value of the XDR will be in the quality difference between your 4:2:2/higher bit rates versus the cameras native codec and bitrate.

For instance, Sony's new EX1 records 4:2:0 35Mb VBR to SxS cards at $500 a pop for 8GB, which equates to 20+minutes in this HQ mode. OR I will be able to go out the sdi to Flash XDR and record to the same Sony codec (??) but at 4:2:2 and much higher bit rates (100 or 160Mb) but at the cost of $5000, plus the nominal costs of CF cards.

So, the BIG question for me and others (I presume) is:
is 50Mb, 100Mb, 160 Mb, 4:2:2 going to be that much better that I will want to buy ONE XDR instead of 10 SxS cards (or less and save money).

Quality is everything to me, so if quality is there - I will purchase. But the only way to tell if the quality of the Flash XDR substantially surpasses the cameras native codec is to see some side by side footage. I know you fellows have thought this through, and I'm curious when you think you may have some comparison footage to show us. (Cineform does a nice job of a Quality Analysis on their site that you may wish to peruse...)

Thanks for your time,
Lonnie

Lonnie,

mpeg2 based video has two major complaints against it.

1. 4:2:0 color space which is ok for true progressive but not so good for interlaced.
2. Bitrate starved with a 15 frame GOP. so video that rapidly changes a lot can get macro blocks.

What the Flash XDR does if get rid of both of these problems. There are many different flavors of mpeg2 which is why the format is so nice. The 4:2:2 color alone is going to be worth it for many people. The New high end XDCAMHD from SONY that is coming out will use 4:2:2 at 50 mbits/s. The only way to get this is going to be on $30,000 + cameras. For those who really want quality then 4:2:2 is really the way to go unless you shoot true progressive. If you shoot interlaced then in my opinion 4:2:2 is a must for high quality.

With the Flash XDR you get to either record in a higher bitrate for normal mpeg2 material or record in a I frame only format. I frame only means there is no 15 frame length GOP. All the video is encoded one frame at a time so complex motion will never have any macro blocks. This right here is a major deal for those who want high quality.

The max bitrate you can ever have for 15 frame GOP 4:2:0 mpeg2 is 80 mbits/s. At this bitrate we are talking almost perfect video when compared to raw uncompressed. The max for I frame only at 4:2:2 is 300 mbits/s which is even closer to raw uncompressed. The 160 mbits/s on the Flash XDR is lightyears beyond DVCPROHD or even HDCAM compression. Any range between 160 mbits and 300 mbits just gets rid of a tiny bit of mosquito noise for very complex scenes. I have encoded a lot of raw material using constant quality settings and it hardly ever goes beyond 160 mbits/s.

The EX1 at 35mbits/s still uses 4:2:0 and while 35 mbits/s is much better then HDV it can still run into problems. If you shoot a lot of simple scenes then you may find the 35 mbits/s works perfectly for you. If you ever shoot any stage productions with strobe lights and flares and stuff like that then you will insist on using either a much higher bitrate to deal with this or use a I frame only mode.

The beauty of the Flash XDR is that it gives you options. You are not locked into one form of mpeg2 recording but now have a choice based on the environment you are shooting in.

To be honest I could see a lot of people using this thing for 50 mbits/s 4:2:2 recording. It still gives decent record lengths but is a pretty good level of quality. I think a lot of people will find that 15 frame GOP at 80 or 100 mbits/s with 4:2:2 color is going to be pretty darn perfect even for complex scenes. This is a bitrate used by DVCPROHD but without the resolution reductions and a level of quality that could look like what DVCPROHD looked if it used 200 or 300 Mbits/s.

So in terms of quality this $5000.00 devices brings your current camera up to a recording format that is on par with much more expensive HD cameras. The camera itself may not be as good but the recording format will be. I have rendered a 160 mbit/s video and recorded it to HDCAM tape and the 160 mbit file blew away the HDCAM tape version when I recaptured it. So even using the Flash XDR on a HDCAM camera would be better then recording to HDCAM tape. HDCAM uses 1440x1080 with 3:1:1 color at 144 mbits/s. With the XDR you will get 1920x1080 4:2:2 color with a much better use of bitrates and quality.

With all of that great information said, I still think Lonnie has a point.

All of us who are involved in technology have come to learn to only trust what actually comes into reality.

Not to say the XDR is in any type of jeapordy, but we are in the stated "delivery" timeframe and the convergent designs website has hardly changed from last year.

At $5,000, I as well will need to see proof that the money will yield a noticeable difference in the final product.

Another factor for me is availability.

To me, the best time to buy this device is at the same time one buys a camera. That way one can skip buying thousands of dollars worth of camera memory.

The XDR would be permanently mounted to the camera and the CF cards would be the only memory used.

So for this to work, one would need to be confident about the XDR purchase decision before the camera purchase, meaning web examples are the only way to judge.

I am excited to see what this unit paired with an EX-1 can produce.

Hopefully we can get some info soon!

Tom - thank you very much for your details. I have been educated and now stand armed with more questions to go research (the more you know the more you don't know kind of thing...) I really appreciate the time!

Tim - we are in utter agreement. Regardless of how the white papers or specs will tell me of one's quality superiority over the other... even Adam Wilt uses comments like, "looks better than it has any right to..."

And that's what I'm asking for - the "looks" part of the equation. ConvergentDesign will have plenty of big boys buying their gear. But I'd imagine that there is enough of a market share of customers like me where 5k is a substantial investment. BUT, they will gladly get my money if there is visual evidence that hey, this 5k buys me so much better quality plus now knowing what Tom said - It even will make big boys cameras look better too - then this purchase would also be a future proof investment which I'm always a fan of.

Again, thanks to you both and I look forward to hearing from the CD Team.
Lonnie

Thomas-
Thanks for the very detailed explanation, I don't think we could have explained the benefits of Flash XDR better!

First, some quick updates on our development. We have the prototype boards on the bench with HD-SDI I/O working as well as HD encode through the Sony MPEG2 CODEC Module. We expect to stream out the 1394 port next week, followed shortly by reading and writing the stream to the Compact Flash cards (in MXF format). Given that we are only into the third week of actual hardware debug, we are making remarkable progress.

Next week, we will have an extensive update with new images of the box, which is now in black! We have a top notch mechanical engineer designing the box to ensure a rock-solid enclosure. Since Flash XDR will be used in Fighter Jets and NASCAR events, ruggedness, small size and weight are top priorities.

We are working double-time to complete the enclosure and the final PCB design. An NAB introduction still looks likely.

The creation of comparison video clips (at various bit-rates), remains a top priority. As soon as we can stream MPGE2 data out the 1394 port or write into a CF card, we plan to capture video at 25, 50 and 100 Mbps (Long-GOP) and 100 / 160 Mbps (I-Frame). We will be using a Canon XL-H1 as our source. We will post these clips on our website for download.

We certainly agree with Thomas, that most user will find the 50 Mbps 4:2:2 Full-Raster format to be more than adequate for many applications. This is the recording format of the $35K PDW700! We also agree that the 100Mbps Long-GOP rate is roughly equivalent to 300 Mbps DVCProHD, due the added efficiencies of the temporal and spacial compression found in Long-GOP. (More info coming in a white paper on this subject).

Flash XDR uses the same MPEG2 CODEC as the PDW700 (we buy the CODEC module directly from Sony). But because our recording media (CF cards) can accept much higher data-rates, we can re-program the module for the higher bit-rates. We understand that this is the 6th generation MPEG2 encoder/decoder from Sony. Due to advances in semiconductor technology and better compression algorithms, bit-rates have dropped approximately 50% in the last 10 years for the equivalent video quality. We are amazed at the size and power consumption of the Sony module, it is unquestionable the best of breed in MPEG2 encoder/decoders.

But, some applications demand even higher quality, so sometime this Fall, we will introduce a much much higher bit-rate 10-bit 4:2:2 recording option (not based on MPEG2). It will be available as an optional software upgrade. More info to follow.

On the recording media front, we have some very exciting news. High-speed (40/45 MByte/sec) CF cards will soon be available from Delkin (32 GB) and Pretec (24GB). Using four CF cards you will get 5 hours of recording time at 50 Mbps or 90 minutes at 160 Mbps. These cards are expected to be priced in the $400 to $500 range, initially. But prices should continue to drop, as they have over the last 3-4 years.

If you do not receive our e-mail updates, please register on our home page or send an e-mail to sales@convergent.com

Mike Schell and the Convergent Design Team

Thanks for your update Mike!

If I could request, (which I am sure you have already thought about) that some the video samples be geared around showing dynamic range?

Like a properly exposed scene with a hot area like a lamp or outdoor light streaming in repeated with different bit rates so we can see how much the higher bit rates help or do not help with retaining image integrity.

To me, this is the area I hope the XDR will be able to transform mid-priced cameras to higher level devices.

Looking forward to the footage!

Thanks Mike - look forward to the footage and future updates from
you and the CD Team - it all sounds very promising!

Lonnie

Mike, this is the most exiting news. You're proving the Flash XDR will have a firmware upgrade path to newer, even better codecs! Wonderful news.

I second Christophers comments above, and also think Thomas did an excellent pull together a few posts back. But I did feel Thomas's post was missing one important issue - any comment on bitdepths, and if there was anything lacking in the XDR it was the fact it was still only making an 8 bit recording. Mike's comment above obviously changes all that, and I don't think it's significance can be understated - some may feel that 10 bit v 8 bit is more significant than 4:2:2 v 4:2:0, certainly in progressive mode.
The speed of advance of solid state memory technology is remarkable. That's the sort of price/GB I'd expect to have been paying for 20MBs CF quite recently.

Editing 10 bit 4:2:2 HD video sounds great, but a computer as well as software upgrade would need to take place.

Do desktop NLEs edit 10 bit footage?

FCP ProRes?

Yes, as David pointed out, NLEs edit 10bit - Prores is a 10bit codec, and FCP has been able to do 10bit uncompresed for a while too.

Mike, are you contemplating using the DNxHD codec? I'd hate to hype if it isn't your plan, but I can see that being implemeneted - great codec, planned to be HD codec standard, free(?). I have no idea what hardware would be needed, but I think DNxHD is a codec that can't really be disputed! I use Prores (DNxHD cousin as far as I'm concered), and no complaints.

Another sample footage request/suggestions to show off the XDR improvements:

- Shot of leaves blowing it the wind

- Water in a river or sunlight reflection on a moving water surface

- CU of fire

Long GOP just hates these type scenes

(and the 10 bit software upgrade coming down the pike is awesome! Makes our Que Investment even more valued - kicking around a second one)

Hey 10bit is great but does your camera pump out 10 bits from HD-SDI? The only sub $10,000.00 camera that does is the SONY EX1.

Also 10 bit is great but pros have been dealing with 8 bit DVCPROHD and HDCAM footage tape material for years. I do find 10 bit to be better but it isn't as earth shattering better as some would think it is.

Take the SONY PDW700 for example. This still shoots in a 8 bit format and it is not cheap and will be used on some pretty high budget projects. The camera or format is nothing to laugh at either. Even at 8 bit it will create material that will blow people away. There is nothing wrong with 8 bit material. If you have a 8 bit camera then 10 bit recording is going to do nothing for you at all.

The XDR allows you to shoot material that compression wise is equal or better to 8 bit material from a $35,000.00 camera.

If a $100,000.00 Cinealta F900 shoots 8 bit to tape is 8 bit really all that bad? I'm sure none of you would complain if somebody gave you a F900 to shoot 8 bit tapes with.


Tim,

What does the recording format have to do with dymanic range? A recording tool just dumps what the camera sees into a format we can use. mpeg2 or pretty much any other codec try to mirror what comes in as best they can. If your camera itself doesn't handle dynamic range very well then the XDR cannot make your camera better. If your camera has great dynamic range then the XDR should record it as that.



If you guys want to see how good higher bitrate mpeg2 is then take some SD footage you have that has a hard time compressing on a DVD and encode it at 15 mbits/s main level/main profile with your encoding software. You will see those areas that break up at 8 mbits are now rock solid. 15mbit/s SD mpeg2 footage is like 80 mbit/s HD mpeg2 material.

HDV is like a DVD at 6.25 Mbits/s.
XDCAM HD is like a DVD at 8.75 Mbits/s.
XDCAM HD EX1 is like a DVD at 6.55 Mbits/s. (due to higher rez then normal XDCAM HD)

Encode a complex SD scene at 6.55 mbits/s and then encode that same scene at 15mbits/s and compare them. Simple segemtns should look very close but once the video gets complex the higher bitrate will shine.

Thomas - you lost me.

You're points are terrific and I got the education except how:
15mbit/s of SD mpeg2 = 80mbit/s HD mpeg2

Is HDmpeg2 almost 6x worse than SDmpeg2?

It depends what you're doing with the footage. 8 bit certainly is not "bad", and for straight viewing I doubt you'd see much difference between 8 and 10 bit. But it's when the footage comes to be graded that 10 bit comes into it's own, and allows adjustments to be done that would cause contouring etc in an 8 bit system.

When used in conjunction with the EX, a device like the XDR theoretically can allow three areas for improvement: lower compression (including I-frame only), better colour space, and better bitdepth. Colour space improvements will be of most benefit for keying etc, bitdepth for grading.

Until Mikes announcement above ("sometime this Fall, we will introduce a much much higher bit-rate 10-bit 4:2:2 recording option") it looked as if the XDR would offer the first two out of those three options over a raw EX1. That wasn't "bad" by any means, but 3 out of 3 is better still.

Hi Thomas-
Thanks again for the detailed explanation! Just as an additional clarification, all MPEG2 video is by definition, only 8-bit. So the recording mechanism in HDV, XDCAM and HDCAM is only 8-bit. However, for a mere $90K, you can use the HDCAM SR deck to get 10-bit recording.

I think most users will find that 50 or 100 Mbps 4:2:2 Long-GOP will provide outstanding video quality. At 100 Mbps we're talking 4X the bit-rate of HDV and 3X that of the EX1. A 3X to 4X increase in bit-rate, combined with 4:2:2 color space and full-raster (1920x1080) will make a dramatic reduction in motion artifacts and mosquito-noise. Due to the added advantages of spacial and temporal compression, I expect we will find that 100 Mbps Long-GOP = 300 Mbps I-Frame. XDR offers both Long-GOP and I-Frame modes, but Long-GOP will likely outperform I-Frame in most applications.

Sony has a very interesting white paper on MPEG2 technology with a comparison to AVC Intra at: http://bssc.sel.sony.com/Broadcastan...overview.shtml
go to support and Tech info and download the CODEC technology paper.

We agree that some applications demand ultimate quality, so we are working on a very high bit-rate 4:2:2 10-bit capture. I hope to have details this week after some more tests.

That said, I think most users will be more than satisfied with the 50 / 100 Mbps 8-bit 4:2:2 1920x1080i/p results. Remember, we're using the same Sony CODEC found in the $35K PDW700, with the option to dial up the bit-rate.

Mike, I have a small question:

Since it will be quite hard to edit those capture codecs natively (FCP, which is the system I use, doesn't support nativelly any of the high bitrate codecs, does it?) will there be any sort of conversion software available? I do not mind long conversion times, as long as the material is in the best quality possible... Do specially include a software that can convert the Long GOP and High Bitrate files to Prores in a "lossless" manner! I believe Avid Users will want an Avid codec converter...

I am talking about the amount of compression for that type of video. SD resolution material needs less bits because there is less information there. A SD resolution video at 15 mbits/s is about equal to HD resolution material at 80 mbits/s. Since HD can have as much as 6x the amount of pixels it needs around that many more bits to have an equal level of compression.

If you want to see "about" what HD material would look like at 80mbits/s you can see what SD material looks like at 15 mbits/s. This will give you a visual on how good the compression is.

10-bit could make or break a purchase of the Flash XDR for a company intending to use this in high-end commercial production. Glad you're planning this kind of depth for your product, Mike!

And besides, who say we have to own a 10-bit camera? It'd make a lot of sense to own the XDR and if need be, when the time comes, rent that higher end so you can do proper 10-bit.

And since 10-bit will no doubt become standard across the board for video electronics over the next 5-10 years, it'd be unwise to limit a device to 8-bit. I do agree though - 10-bit, despite being at 1024 vs the 256 (and yes, these numbers are less in the real world) isn't as ground-breaking as it sounds, but I'd take it if I could get it, no doubt about that.

You're giving your product expandability Mike! It's potentially almost too good - a product that lasts forever limits your future sales ;)

Kidding - I own your HDMI to HD-SDI convertor (nanoConnect) - great device. Of course, it's 8-bit HDMI, so if a 10-bit HDMI camera comes along, I'll have to upgrade my nanoConnect... ;)

Sounds reasonable, but there is a caveat along the lines of "all else equal" that needs adding to that, as all compressors are not equal. A given MPEG2 bitrate does not by itself define quality, it depends on the codec implementation as well. As Mike said earlier:
Hence this module may achieve a quality at 7.5Mbs that an early MPEG2 encoder would only have been able to manage at 15Mbs.

Well I guess I am coming from the point that the 4:2:0 color space is limiting dynamic range due to less color information.

Or maybe I should be using the term lattitude instead.

Upon speaking with a Sony tech on the phone, he told my dynamic range is a factor of chip size and chip attributes as well as the codec that stores information recorded.

When the mod for the DVX-100 took the signal straight off the sensors, they supposedly got 9 stops from that camera.

Maybe I am wrong here, and please tell me if I am.

I just hope to see more of an image improvement from the XDR than just eliminating artifacts from the tenth wheat stalk from the left. :)

yes but the only time there is a big quality difference between encoders is when the bitrate is too low.

This is why XDCAMHD at 25mbits/s or even 18 mbits/s usually looks better then HDV at 25 mbits/s. A $1,000.00 HDV camera is not going to use the same expensive mpeg2 encoding chip that a $20,000.00 camera uses. I always tell people mpeg2 is not all the same. Just as all software mpeg2 encoders are different so are hardware encoder chips. This is why AVCHD cameras are so bad right now. The encoding chips just are not very good right now. It costs money to have an encoding chip and AVC encoding is so much harder then mpeg2 encoding. So we have a much more complex encoding chip in cameras that cost the same as the mpeg2 based cameras. Clearly many quality corners were cut to keep the cost of those AVC encoding chips down.

One of the reasons I assume the XDR is at the price it is is because they are using a very high quality mpeg2 encoder. This is the same encoder used in the PDW700 so you know even at 25 mbits/s it will already look better then what your HDV camera can do. This is why Mike keeps telling everybody that he thinks a lot of people will enjoy the 50 mbits/s 4:2:2 mode because it will be very rock solid with this encoder. If you are shooting a extreme environment such as a massive amount of camera flashes on a red carpet event then you should maybe bump that up a few notches.

So my post about trying it with 15mbits is just for people to be able to see what video looks like at the max level. The only reason I said this is because a lot of people have never really seen HD at 80 mbits/s or higher so this would give them a rough idea of what they could expect. A lot of people think all forms of mpeg2 are bad because it has been drilled into their heads for the last couple of years. Mpeg2 is not bad at all and the only reason HDV wasn't all that great was because it had too low of a bitrate based on the cheap encoder that was used.

Thomas -
thanks for your time and replies...
it is very much appreciated!
Lonnie

Hi Sergio-
We are working with Apple and Avid to get native support of all our MPEG2 CODECs. Both companies are implementing the 50Mbit 4:2:2 full-raster MPEG2 CODEC found in the Sony PDW700. All our 4:2:2 modes are based on this same CODEC, just at a higher bit-rate (100 vs 50) and I-Frame only, instead of the IPB long-GOP. We don't believe and neither does Apple or Avid, that these are significant development projects. Most MPEG2 CODECs, either hardware or software, will already support I-Frame only, at least in decode.

Once these higher bit-rates are supported, it should be a fairly simple task to transcode to ProRes or DNxHD. However, you should be able to play back in the native format and only transcode regions which have effects added. I know that FCP has very good support now for multiple CODECs on the same timeline. Effects are rendered in ProRes, but all the other video can remain in it's native format.

Hi John-
Excellent suggestions! I too am most interested to see how well the 100 Mbps Long-GOP holds up in these conditions. I am betting that we will be surprised and the Long-GOP will perform quite well at these higher rates.

I also want to test with a camera flash, which can really test the Long-GOP as you can generate 1-2 frames in the middle of the GOP which are completely different from the I-Frame.

Mike Schell

PS I was obviously "asleep at the wheel" when I posted the e-mail address to get on the newsletter. So, if you want to be added to the Flash XDR e-mail list, send a note to sales@convergent-design.com

As an XL -H1 owner, I have been following this for awhile - I am super excited to hear it's progressing well.
I may go to NAB, just to see it .
John

Hi John-
Thanks! We are working double time to get it finished. Debug is going extremely well. We will keep you posted on the progress, but NAB is looking good.

Best-
Mike

Mike,

Even from your preliminary brochure, I can see your favourite mounting option for the Flash XDR is the back of the XL-H1 camera... While this is understandable, please tell me: having the PMW-EX1, what will my mounting options be? Between the camera and tripod - OK, but how about shooting handheld? Also, I am using PAG batteries without V-mount (Powerpack 100 Wh model 9370), attached to the plates which either goes to the back of my PAG Orbitor shoulder support, or to my waist with the belt clip (the plates have two PP90 socekts - one is used for the PAG lamp).

Another question is this: on your web site it's possible to preorder with a deposit, but I'd like to buy from your EUR distributor (www.symbiosis.eu), and they don't take pre-orders. What do I do to get the Flash XDR as soon as possible (would like to get the Invoice, dated before the end of March - even if the actual delivery is going to take some more time).

I'll apreciate you answer.

PS Is it viable to record from the EX1's HD-SDI to the Flash XDR, while monitoring on a HD laptop, using Flash XDR's 1394 output?

Obvious Question?
 

Anyone talked to you about taking the XDR and making it the building block for a camera?

Just trying to think of how many 10-bit 4:2:2 uncompressed cameras there are available...

Every camera with HD SDI output.

I meant a one piece camera utilsiing XDR technology for onboard recording.

Mike this question maybe redundant
 

forgive if it's already been addressed, but it occurred to me yesterday, will the xdr also capture uncompressed audio, or is it only a video stream?

thanks

Adam

Dear Adam,

The Flash XDR provides for recording 4 channels of audio embedded in the HD-SDI data stream, or 2 channels of analog XLR input (microphone or line level), with microphone gain up to 65 db.

The analog audio data is recorded at 48,000 samples per second with a word size of 16 or 24 bits (user selectable).

So, yes, the Flash XDR records uncompressed audio (in the usual meaning of the term).

Being able to record 48K/24 Bit can be a real advantage over the usual 48K/16 Bit recording standard.

Note that the analog XLR inputs, direct to the Flash XDR, completely eliminates any issues with less than optimum audio sections of the camera.

Which is an advantage provided the XDR's own section is of higher quality :)

On another note: has anyone got any update about the mounting options with the Sony EX1, and the PAGlock battery system?

Thanks Dan
 

my bad,

It was one of those I'm too exhausted and didn't go through the thread to find out what might have been mentioned in other posts. And I should have looked at the pdf.

Good news though, really amped with part as my HD251 only has 384kbps compressed audio.

Question with that then, does it work in the same manner as the video stream that if it's SDI output, the audio isn't already compressed, or is this possibly hardware restricted within the camera?

thanks

Adam

Dear Adam,

The embedded audio from your camera, output via HD-SDI, should be uncompressed 48k PCM (Pulse Coded Modulation). In other words, it should be uncompressed.

The HD-SDI standard provides for up to 8 pairs (16 individual channels) of embedded audio at 48k 24 bits. 16 bit audio is also accommodated.

You do not need to worry about the 384k compressed audio, it does not apply when using HD-SDI.

Hi Adam-
Just to expound further on Dan Keaton's excellent summary of the Flash XDR analog audio, I would add that we are using top of the line components in this design. The 24-bit audio A/D is a very high-end device with >120 dB dynamic range and very low harmonic distortion. Even the headphone amplifier is a very high-grade design, arguably a notch above the headphone driver circuit in most camcorders.

Hi Piotr-
Our mechanical engineer has completed the Flash XDR box design and is now concentrating on mounting options. We are actively working on support for the Sony EX1.

Also, we are adding numerous threaded inserts into the box to support various monting options. More details soon.

Thanks Dan and Mike
 

mate this is all good news, I'm constantly thinking "If only I didn't have sucky compressed audio for this situation". This will help when I'm soloing in documentary and events land and have no sound man.

Cheers

Adam