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Old October 30th, 2007, 09:55 AM   #1
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Updated Convergent Designs Flash XDR F.A.Q.

Howdy from Texas,

Mike Schell of Convergent Designs has graciously consented to let DV Info Net make available for download their recently released F.A.Q. document in .PDF format which covers their forthcoming Flash XDR Portable HD Recorder Update:

"Since the introduction at IBC of Flash XDR, the first ultra-portable Compact Flash based HD Recorder; we have received a large number of inquiries and questions. We have summarized these questions and created a lengthy FAQ document for your review.

Also, we have made a number of very exciting changes / enhancements to the design:


1. The maximum MPEG2 compressed data-rate has been increased
to 160 Mbps 4:2:2 I-Frame or 100 Mbps 4:2:2 Long-GOP.

2. The number of Compact Flash Card slots has been increased from 2 to 4,
so the record times are now doubled or you can set up the system in a RAID 1 configuration
and automatically write the same video data to 2 cards simultaneously (auto-backup).

3. Added the capability to automatically remove the pulldown on 1080i60/59.94
HD-SDI stream and create a 1080p23.98/24 recording. Also, the image can be
flipped to compensate for the effect from some cine lenses.

4. AES digital audio has been replaced with balanced analog audio inputs / outputs,
which is the more common production format. The balanced audio inputs are switch-
able between line-level and microphone level. A 48V phantom power can be enable
with microphone inputs. Also, a microphone pre-amp is included with programmable
10 to 65 dB gain.

5. We have settled on FAT32 file system and MXF file format for storage
on Compact Flash. MXF is widely supported by major NLE programs.

6. DC power input plug is now an industry standard 4-pin XLR. We are
working on cabling and mounting options for different camcorders and
battery options.

"All the technology for Flash XDR is available now (we’re not waiting for some “magic” new chip). So, we are pouring the coffee and working as fast as possible to complete the design. We plan to have shippable units sometime in Q1 2008."

Here's the Updated Flash XDR F.A.Q. document for download (16 pages; about 690kb):
Attached Files
File Type: pdf Flash XDR Spec and FAQ.pdf (690.9 KB, 1062 views)
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Old October 30th, 2007, 12:30 PM   #2
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Quote:
Originally Posted by Michael Galvan View Post
I have a question ... if shooting 1080p24, when you mics connected directly to the XDR, does it record the audio to match the frame rate of the video?
Hi Michael-
Good question. Yes, we have taken this issue into consideration. When going from 1080i59.94 to 1080p23.98 you have to spread the audio samples over fewer frames. It's not difficult, but absolutely required to make the audio sound proper.

Mike Schell
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Old October 30th, 2007, 12:50 PM   #3
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Hi Mike,

So I am assuming you will have this implemented in your final device? Will it be automatic? Or will it have to be switchable?
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Old October 30th, 2007, 02:39 PM   #4
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Mike,

As someone who has been working a lot with I frame only mpeg2 video what was the reason for sticking with a max of 160mbits/s and 100 mbits/s GOP?

I usually work with 300 mbit/s I frame only files but find this is a little overkill. I have been trying to find the sweet spot between size and quality and was just curious as to how you felt 160 was a great level for quality? To be honest I also use a lot of 150 mbit I frame only encodes and they look pretty darn close to the 300 mbit versions. Have you also found there really isn't much gain between 150 and 300 or is it more of a balance between record time and great quality? Really the only thing I ever noticed that got any better with higher then 150 bitrates was high contrast edge noise artifacts. Then again I am mostly encoding 3D and particle effect graphics to use inside of Liquid so they don't push the encoder as hard as realworld footage would.

I am very excited about the 160 mbit mode to use with a new SONY EX1.
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Old October 30th, 2007, 04:05 PM   #5
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Quote:
Originally Posted by Michael Galvan View Post
Hi Mike,

So I am assuming you will have this implemented in your final device? Will it be automatic? Or will it have to be switchable?
Hi Michael-
The re-distribution of audio samples from 1080i59.94 to 1080p23.98 rate will be done automatically in the Flash XDR box. This occurs whenever you invoke the inverse telecine funtion. It's all transparent to the user.

Mike Schell
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Old October 30th, 2007, 04:10 PM   #6
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Quote:
Originally Posted by Thomas Smet View Post
Mike,

As someone who has been working a lot with I frame only mpeg2 video what was the reason for sticking with a max of 160mbits/s and 100 mbits/s GOP?

I usually work with 300 mbit/s I frame only files but find this is a little overkill. I have been trying to find the sweet spot between size and quality and was just curious as to how you felt 160 was a great level for quality? To be honest I also use a lot of 150 mbit I frame only encodes and they look pretty darn close to the 300 mbit versions. Have you also found there really isn't much gain between 150 and 300 or is it more of a balance between record time and great quality? Really the only thing I ever noticed that got any better with higher then 150 bitrates was high contrast edge noise artifacts. Then again I am mostly encoding 3D and particle effect graphics to use inside of Liquid so they don't push the encoder as hard as realworld footage would.

I am very excited about the 160 mbit mode to use with a new SONY EX1.
Thomas-
To be perfectly honest, the 100 Mbps Long-GOP and the 160 Mbps I-Frame only modes are maximum rates available from the Sony MPEG2 CODEC. So, that's how we chose these rates. We do plan to post some comparison video shot at 25, 50, 100 and 160 Mbps rates (we'll feed the same HD-SDI stream to four of our boxes). So, you should be able to make some good visual comparisons.

Mike Schell
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Old October 30th, 2007, 06:10 PM   #7
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Quote:
Originally Posted by Mike Schell View Post
Hi Michael-
The re-distribution of audio samples from 1080i59.94 to 1080p23.98 rate will be done automatically in the Flash XDR box. This occurs whenever you invoke the inverse telecine funtion. It's all transparent to the user.

Mike Schell
That is awesome!

I know we may have not met in person before, but I think I've loved you for a very long time ...

LOL
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Old October 30th, 2007, 07:47 PM   #8
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Originally Posted by Michael Galvan View Post
I know we may have not met in person before, but I think I've loved you for a very long time ...
Well I've met him in person, and trust me he really is quite a dreamy hunk of a man.

So if you want him, you'll have to get in line.
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Old October 30th, 2007, 07:55 PM   #9
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Originally Posted by Chris Hurd View Post
Well I've met him in person, and trust me he really is quite a dreamy hunk of a man.

So if you want him, you'll have to get in line.
Well working in this industry, you have to be flexible and open about adapting to any situation that may arise ...

LOL
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Old October 31st, 2007, 08:08 AM   #10
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Originally Posted by Chris Hurd View Post
Well I've met him in person, and trust me he really is quite a dreamy hunk of a man.

So if you want him, you'll have to get in line.
Trust me, there is no line. If you ask my wife, I qualify as the biggest nerd on the planet.

Mike
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Old October 31st, 2007, 08:17 AM   #11
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Believe me Mike, that's a big part of your tremendous appeal.

I'm really pleased with your decision to increase the number of CF slots from 2 to 4 with an option to configure as RAID 1. I'm wondering if you guys have looked closely at the current availability of high-speed CF cards; they seem to be in very high demand right now. Congrats on taking a bright idea and making it even better,
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Old October 31st, 2007, 04:00 PM   #12
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Quote:
Originally Posted by Chris Hurd View Post
I'm really pleased with your decision to increase the number of CF slots from 2 to 4 with an option to configure as RAID 1. I'm wondering if you guys have looked closely at the current availability of high-speed CF cards; they seem to be in very high demand right now. Congrats on taking a bright idea and making it even better,
Thanks. Increasing the number of CF slots turned out to be fairly straighforward and gave us the added benefit of either doubling the record time (now around 6 Hours at HDV rates) or recording the same data to two CF cards simultaneously (auto back-up).

There should be no problem getting plenty of high-speed CF cards, as there is a glut of NAND Flash chips on the market and the prices continue to fall.

Mike
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Old October 31st, 2007, 04:57 PM   #13
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Originally Posted by Mike Schell View Post
There should be no problem getting plenty of high-speed CF cards, as there is a glut of NAND Flash chips on the market and the prices continue to fall.
My understanding has been that the 100Mbs mode doesn't need the highest spec of CF card, but that Sandisk Extreme III or equivalent should work fine, though download is unlikely to be much better than real time.

Can you confirm 100% whether this is indeed the case?
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Old October 31st, 2007, 05:57 PM   #14
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Originally Posted by David Heath View Post
My understanding has been that the 100Mbs mode doesn't need the highest spec of CF card, but that Sandisk Extreme III or equivalent should work fine, though download is unlikely to be much better than real time.

Can you confirm 100% whether this is indeed the case?
Hi David-
Your understanding is correct. The SanDisk Extreme III card has a read / write speed of 20 MBps (or about 160 Mbps). That should be sufficient for 100 Mbps MPEG2 video + 2 channels of audio. Under these conditions, the download time is not much faster than 1:1.

A 16BGyte Extreme III Card is about $220, while the higher speed 8GByte Extreme IV card is about $190. So, you do pay a hefty price for the higher speed improvement. But the Extreme IV card with a FireWire 800 reader would reduce the download time in half.

Mike
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Old November 1st, 2007, 04:13 AM   #15
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Great work guys- really good.

In terms of card slot design, would this be similar to a card reader type- push and go with the card sticking out a bit or a recessed card, mechanical release.
Also would there be a "VTR" translucent styled flap- rubber sealed (dsr 450) once again with mechanical spring latch, entire design like a cigarette box.

With user interface and display how will you determine the end of "tape" warning- would this be user configurable- eg from 5mins -1min. switchable TC display- R Run etc and a "tape" counter with countdown option.

maybe an optional Portabrace protective cover.

modular design where you can stack the XDR's

simple led status- red=recording , green=card full for each slot.

and finally would information be displayed in the viewfinder.

its the red bull doing this...
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