Hi John-
Thanks for the explanation! It makes good sense to me. I think the histogram offers a more qualitative view of how compression affects the quality of the images. It certainly collaborates our earlier findings, that 50Mbps MPEG2 outperforms DVCProHD, at least on a still image.

A local EX1 user, Jim Arthurs, sent me a Photoshop file of the compressed images, as individual layers. By turning on one layer in normal mode and a second layer in difference mode, you can easily see the effects of compression. Again the results show the superior results of the 50 Mbps rate and near ideal results with 100 Mbps (you see almost no differences to the uncompressed).

Yes, to the first bit of that, but an 8 bit structure inherently gives 2 to the power 8 levels - 256 - hence the 8 bit aspect doesn't explain the gaps.

If I import 8 bit DSLR images into Photoshop, the originals show a smooth histogram structure. Manipulating those images by such as gamma, black level or colour correction then produces histogram "gaps", as the process favours some levels over others. (Start with a 10 bit original, and this will obviously be much diminished.)
I'd recommend this as an excellent way of quantifying the differences, and treating Y,U,V separately can help to show what's going on. Normally the compressed signals are subtracted from the corresponding uncompressed ones, and mid grey added. Perfect compression will show up as a plain grey, the more detail that can be seen, the more errors the compression is introducing.

It can also show up compression effects due to motion, if the filmstrip feature within Photoshop is used.

David:

Please excuse my math ignorance. I surely would appreciate a little more help understanding your explanation:

"Yes, to the first bit of that, but an 8 bit structure inherently gives 2 to the power 8 levels - 256 - hence the 8 bit aspect doesn't explain the gaps."

My thoughts on thinking the gaps were due to an 8 bit photo were due to their inclusion in the standard Photoshop 24 bit histogram.

Maybe I should do some of my own screen grabs of HDV material from our Canon H1. Could it be that the gaps are created by the fact that even though the H1 is putting out a 10 bit signal from the HD-SDI, 2 of those 10 bits actually have no data reportedly?

When you talk of Photoshop being 24 bit, that refers to 8 bits each for red, green and blue channels, hence each channel is 8 bits, or 256 levels. For video, it's different in so far as it is normally recorded as 3 component signals: luminance (Y), and difference signals (U and V), which show the difference between luminance and blue and red. From the three, red, green and blue can be reconstructed.

But each of Y,U,and V is recorded as an 8 bit signal, so video could also be described as 24 bit if you looked at the total.

It's conceivable that the gaps are due to a Y,U,V=>R,G,B conversion within Photoshop. It may be more valid to look directly within Photoshop at the Y,U,V histograms.

Mike,

Am I right assuming that with Flash XDR, having the 2 audio tracks embedded in the HD-SDI output from the EX1, by also using the Flash XDR's XLR audio inputs one can achieve 4 channels of audio at the ouput?

This is quite important when considering between the XDR and the nano versions, while only having a camera with 2 audio channels.

Dear Piotr,

Your question is very interesting.

Mike will be able to give you the proper answer.

But, in the meantime, I want to post the following observations for discussion purposes.

We believe that most camera audio circuits will not be as high in quality as the audio circuits in the Flash XDR.

So for the highest quality audio, one should choose the Flash XDR external audio inputs as opposed to routing the audio to the camera first.

(The audio outputs from the Flash XDR can then be routed to your cameras inputs, if you so desire.)

Few cameras support 24 bit audio, but the HD-SDI specification does include both 16 bit and 24 bit audio.

So, in use with most cameras, the embedded audio in the HD-SDI signal will normally be 16 bit.

Whenever possible, I highly recommend using 24 bit audio. 16 bit audio can give great sound, but 24 bit audio gives you the luxury of recording great audio, even if the levels are not optimum.

A 16 bit audio recording, with the audio levels set low, leaves something to be desired. But, a 24 bit audio recording, with low levels, can be optimized in post while maintaining very high quality. Recording in 16 bit audio, with the audio levels set for the expected audio level, will not be able to handle unexpectedly loud sounds.

It is possible to record in the Flash XDR at 16 bits. This would match the audio format from the camera. It would be nice if the Flash XDR combined both sources to give you four channels of embedded audio, as you suggested.

At this time, I do not know if the HD-SDI specifications allows for two channels at 16 bit and two channels at 24 bit. We will need to determine if this is the case.

Please note that if

1. You send an HD-SDI signal, without embedded audio, to the Flash XDR, and
2. You send two channels of audio to the Flash XDR via the external audio inputs, the Flash XDR HD-SDI outputs will have the audio embedded in the signal.

In other words, the Flash XDR acts as an audio embedder. I feel that this is an important feature. The same applies to the external timecode input.

I am certain that Mike will answer your original question as soon as possible.

Hi Piotr-
I just spoke to the hardware designer, who wondered when this question would arise. Yes, you can take 2 channels of embedded audio and mix with 2 channels of analog audio on the XDR. Of course this is not possible on the nanoFlash.

Dan & Mike,

Thanks for this answer, as well as the interesting considerations re 24 vs 16 bit audio.

Any news on proposed XDR mounting options with the EX1?

Any closer?
 

Just curious if there were any updates on the FAT32 code? The still images are fun but I am a video guy and I need to see these .mxf files work in FCP. This may be the greatest recorder in the world but it is a paper weight unless NLE's can read the video files.

David Schmerin

one thing i think that might be important to keep in mind when comparing codecs especially through histograms is that the XDR is probably the only codec that isnt scaling the input*. seems pretty likely that the differences in the histogram might be related to the fact that different pixel values are being created through the combining/filtering/averaging of surrounding pixel values. that might be all you are seeing in the histograms. of course that is a wonderful thing, since scaling introduces various kinds of artifacts and of course softening itself, but im not sure those histograms tell us much about the compression codecs and how they compare. perhaps you could throw in another codec for comparison that supports 1080p without scaling, such as 50 or 35mbps xdcam or even something more competative like hdcamsr or cineform (especially relevant if cineform ever comes out with their similar solid state recording device)?

*for reference, dvcprohd scales the image to 1280x1080 and hdv scales it to 1440x1080, whereas xdr maintains the full 1920x1080 frame

Yeah I'm bothered by the fact that Cineform haven't given an ETA on when their device might be coming to market, which is why I'll probably end up buying this NanoFlash XDR. For me it's kinda, whichever comes first. Codec isn't TOO important with me, because they're both 4:2:2, perform inverse-telecine, and offer very high bitrate/quality.

Rec. Start/Stop via Canon XL H1 Rec. Button/Trigger
 

I really like the specs on the Flash XDR... One very important factor for me... Will I be able to start/stop the unit via the built in start/stop rec. button (handgrip) on the camera?

If yes, how will this be achieved (time code movement or firewire out to trigger start/stop)?

Thanks,
Thomas

Dear Thomas,

If you set your camera to "Record Run" timecode, the Flash XDR will detect when the timecode starts (via the timecode embedded in the HD-SDI signal or the External Timecode Input) and then automatically start recording.

Hi David-
We're very close on the FAT32 and MXF file formats. We have the MXF code working on the MAC, just need to transfer the code to the MCU inside XDR. We will post files on our website ASAP and I'll post a message on this forum when they are avaialble.

Hi Piotr-
Yes, we have some updates on the mounting options. I will try to post next week.

Hi Noah-
I think you analysis is spot on. I also suspect that the changes in the histograms are largely caused by the horizontal sub-sampling used in HDV and DVCProHD. You can really see the differences on resolution comparison charts. The EX1/EX3 should really shine given the full 1920x1080 sensors combined with the full-raster MPEG2 CODEC used in XDR. This combo will completely eliminate any horizontal resizing (up or down) through acquisition and post production.

Ok this is like agony now
 

I can't wait, I just had to post, I waited almost a week (pat myself on the back).

But Mike can you post some footage, and to raise the stakes and see what a change it'll make for us, and yes its a bias request, but can you shoot something with a JVC HD251 in lowish light without gain, and heck, why not with maybe 3db gain.

Forgive my impatience, but I look at my noisy JVC footage, as great a camera as it is, and think "More", I need "More" (which when it comes to noise actually means "Less" I need "Less"!)

The Canon XLH1 and EX1 are great cameras, but they have a lotter lower noise levels than the JVC, so that's also why I think it would be a good test, and maybe if you record simultaneously hdv to tape and sdi to CF, then post both avi's, we could see back to back what kind of difference to expect?

I haven't yet used my SDI output, so I don't know if you can simultaneously do both tape and SDI, I presume because you can do firewire out and tape that you can.

Hey there's one born every minute, but if you want some beta testing in severe hot and dusty enviroments, I'll volunteer, I'll be in Australia's Outback shooting a doco possible to become TV series soon.

cheers

Adam

And sorry for being too zealous here

:-P

Dear Adam,

We share your excitement.

We are making solid progress in our final steps to deliver the Flash XDR.

We have an XL H1 and an XH G1 in house for testing. We also have access to the Sony EX1.

We plan on recording footage, using a few cameras, using the Flash XDR, recording to Compact Flash. Then we plan on posting the resulting files so that others can see and work with the footage.

If we can arrange access to the JVC HD251, then we should be able to perform some tests, as soon as we can find the time. When we do so, we will be happy to record under the conditions you specify, if at all possible.

I have not studied the JVC HD251, but I feel confident that you should be able to record to tape and output HD-SDI simultaneously.

NLE Question
 

Just catching up on this product. This looks very interesting! When NLE support is up an running are you expected to be able to use the XDCAM software or the FCP P2 log and capture window. I am looking at the Sony EX3 with a Letus Extreme setup. Just wondering how to get the footage in to FCP.

The XDR looks like a great product... a question I keep asking myself...

How do you see Cineform working with the XDR...

Dear Ray,

I assume that if you are using Cineform now, you do one of the following:

1. You capture your footage creating a file on your hard disk drive, then use Cineform to encode/transcode the footage.

2. You bypass the capture process by using a memory medium other than tape that can be read by your computer and use Cineform to encode/transcode your footage directly from your source footage.

The Flash XDR allows you to use both of the above methods to encode/transcode your footage into the Cineform codec.

The XDR uses an MPEG2 codec, so if you need Cineform for your workflow you can transcode it using Prospect.

George/

Hi Matthew-
We are working with the Final Cut Pro team now to seamlessly allow you to bring footage into the log and capture window. I hope to have a press release this week detailing the planned integration.

720 25p
 

Mike I can't see anywhere 720 25p support, I know you can drop 720 50p onto a 25p timeline, but is there a reason for this?

Or maybe simply I can't find it, the convergent site doesn't have it listed in the specs

thanks

Adam

Hi Adam-
Currently, FCP only supports 720p50 and 720p60 with the 50Mbps 4:2:2 CODEC, so we have limited are support accordingly. I think our CODEC will support the 720p25, but we really need the corresponding NLE support.

That said, we may see expanded support in the future. Also I don't know about the support of 720p25 (at 50 Mbps) from other NLE programs at this point.

Wouldn't 720p50 be preferred over 720p25 in most applications? Or do you plan to go to film?

I would like to throw in a vote for 720P25. If you want a more film like cadence, you can get better quality per frame at the same data rate.

Also DnxHD (Avid) supports this (and I would guess Prores as well but don't have FCP) so although the footage would have to be transcoded it still seems like a good acquisition format...

keep up the good work Mike.

720 25p
 

Is the main format I shoot in, the cadence is very film like even if it's not a film out, everybody who sees my stuff thinks it's very 'film' like. And even though by no means do I knock the 'video' look, but people love the whole my video looks like a movie thing.
So yes a definite can we have it please.

Thanks

Adam

Same opinion from here, Mike.

The EX1's 720/25p is a great format; it'd be a pity having to drop it with nanoFlash...

Is FCP the only NLE you are supporting now? Hey FCP doesn't support 160 mbits either but that is still in the XDR. I know a lot and I mean a lot of people that shoot 720p 25p and 720p 50p that turn it into 25p slow motion. I thought the whole point to the XDR was to make it universal for everybody.

Hi Everyone-
OK, I get the message, we'll put in all the formats regardless of the NLE support. It is actually quite simple to add all the formats, but we'll likely have to pony up for an Iconix camera since it's about the only device that can generate all the various flavors for HD-SDI.

You could do it with a Blu-ray player and an HDMI to HD-SDI converter (eg nano-connect:-).

Does that make sense?

Hi John-
Yes, that might work fine. But I think we'll need to get an Iconix anyway for long-term compatibility testing. A considerable number of customers plan to use the Flash XDR / nanoFlash with the Iconix camera.

Maybe Iconix would be smart to provide C-V with a loaner since their camera and the XDR/Nano are a perfect marriage for their miniaturized system.

Couldn't you just drop every other frame from a 720p 50p SDI signal? Like you said most cameras even if the user is shooting 25p will still output as 50p via SDI but that user would still want the video encoded as 25p to save bandwidth or boost quality. 720p 25p at 50 mbits/s is really awesome looking.

Hi Thomas-
Yes, this is certainly a possibly solution. Dropping every other frame would be a simple answer.

Do the new Sandisk Extreme III 16G cards meet the Flash XDR's specs?... noticed Sandisk have a good rebate deal going for US users (bit strange because you get it inthe form of a pre-paid Visa card so it ain't cash)...

Details on B&H's website.

http://www.bhphotovideo.com/c/produc...pactFlash.html

The minimum data rate on the new Extreme IIIs is 30MB/s or 240Mbps which is more than enough for any of the MPEG 2 data rates.

Dear E. J.,

Currently, the Transcend 16 GB 300x and the Transcend 32 GB 133x are the fully qualified and recommended CompactFlash Cards.

The Transcend cards more than meet their specifications. Mike calls these cards "Overachievers”!

We are waiting to test the Microdia 64 GB card. I assume that this will be the first of many 64 GB cards. The Microdia one is rated at 300x both read and write, but we do not know the price at this time.

The SanDisk may work just fine.

E.J, I know you know this, but for others that are reading this: The speed ratings of many manufacturers cards, such as 133x, usually indicate the fastest that the card can be read under ideal conditions, while the write speeds are usually much slower.

For certain premium cards, the read and write speeds are essentially the same.

For the Flash XDR and nanoFlash, the write speed is much more critical.

Sound Devices, on their website, has the detailed results of their testing of CompactFlash cards.

Please note that Sound Devices' tests are great for general comparison of various CompactFlash cards. When the same card is used within the Flash XDR or nanoFlash, the speeds will be different since we do not have to go through a Firewire interface.

http://www.sounddevices.com/notes/re...ats/cf-speeds/

I am certain that we have tested the SanDisk Extreme III 16 GB card, I just do not have the specific results with me at this time.

This is true for Sandisk as they rate their cards based on minimum write speeds. This is why Sandisks are the only cards that consistently perform in a RED. It's nice that unlike most other manufacturers, they don't market their cards based on the highest achievable read speed.

Although I completely understand the need to tell people which cards are 'qualified and recommended' I know that our Extreme III/IVs will have absolutely no issues in the XDR.

Dear E.J.,

The $90 rebate on the SanDisk Extreme III 16 GB card certainly makes this attractive.

I will get an answer as soon as possible.