HDSDI out on a PDW 350....

[Godfrey Kirby]

I have seen elsewhere on DVi a thread, a solid state recorder that connects to the HDSDI output from the EX.1 - 'fraid I have forgotten the name of the manufacturer - and records at a greater rate than the 35 Mbps that is standard. Is this device any use connected to the 350 or is it that the EX 1 has a different output. Any words of wisdom welcome....

[Greg Boston]

That would be the Convergent Designs Flash XDR recorder. It's not available just yet, but hopefully soon.

-gb-

[Steve Phillipps]

Flash XDR will work with any cam with HD SDI out I believe - Canon XL-H1, JVC HD250 etc., all the way up to PDW700.
A much anticipated product! Roughly $5000 / £2600.
Steve

[Godfrey Kirby]

Just wondering if the HD-SDI on the 350 is pre. or post compression and whether the fact that it is not like the EX1, in that it is 1440 x 1080 not 1960(?)x 1080, has implications. I can see loss of detail in movement on my LMD 9050 LCD monitor when it's plugged into the HD-SDI i/o - or is this a feature (failing) of LCD technology. Again - any words of wisdom welcome......

[Greg Boston]

HD-SDI out is post compression if playing back recorded media. That's pretty much how all of them work. HDSDI taken live from the camera head is uncompressed 4:2:2 and that's why all the hoopla about being able to mount a device like the Flash XDR which will record that uncompressed signal to a more modest compression such as 160mb MPEG2, among others onto Compact Flash cards.

The native resolution of the F350 sensors is 1440x1080, not 1920x1080 as the EX-1 has.

-gb-

[Dan Brazda]

Originally Posted by Greg Boston

HD-SDI out is post compression if playing back recorded media. That's pretty much how all of them work. HDSDI taken live from the camera head is uncompressed 4:2:2 and that's why all the hoopla about being able to mount a device like the Flash XDR which will record that uncompressed signal to a more modest compression such as 160mb MPEG2, among others onto Compact Flash cards.

The native resolution of the F350 sensors is 1440x1080, not 1920x1080 as the EX-1 has.

-gb-

So we are really talking about true "uncompressed" HD here? If there is no compression whatsoever we'd be talking about massive file sizes wouldn't we?

[George Kroonder]

What comes out of the HD SDI is a stream of data. It is not a "file" (yet).

Connect a monitor to it and you can see the video, hear the audio. Connect it to a computer and capture the stream or use a dedicated capture device (tape, memory card) and that will create a file.

If you capture without compression, file sizes will be really big. Therefor you usually capture using some codec that involves compression. This could be ProRes or DVCPRO HD or Cineform (or anything else). The Flash XDR uses MPEG2 to compress the stream down into a more managable filesize. Wafian offers a direct-to-disk recorder and uses the Cineform Intermediate Codec to capture "visually lossless" 4:2:2 10-bit.

Most codecs offer different compression levels, where more compression (or smarter compression) results in a lower datarate and smaller filesize, but some information is lost. How much the quality actually "suffers" and if it s acceptable depends on the codec and the intended use.

George/

[Dan Brazda]

I hear there will be an uncompressed option for the nanoFlash. Will the F350 be able to take advantage of that technology or will the limitations of the 1440x1080 chips and S/N ratio negate any advantages between the uncompressed and compressed versions of this product?

[George Kroonder]

Originally Posted by Dan Brazda

I hear there will be an uncompressed option for the nanoFlash

I think you heard wrong. There will be an uncompressed option for the Flash XDR.

http://www.dvinfo.net/conf/showthread.php?t=124296

George/

[Greg Boston]

Originally Posted by Dan Brazda

So we are really talking about true "uncompressed" HD here? If there is no compression whatsoever we'd be talking about massive file sizes wouldn't we?

Yes, the data rate is right at 1.4 gigabits/second. That's why it requires a dedicated capture board and RAID'ed discs to handle such a high data rates involved.

Some higher end cameras have dual HDSDI output which can be recorded to HDCAM SR at 4:4:4. So in truth, there is some loss of red and blue chroma in a 4:2:2 output scheme.

-gb-

[Alister Chapman]

An F350 recording to a Convergent Flash XDR or nano flash at 50mb/sec MPEG 2 would be an interesting proposition. I have done various tests recording the HDSDi out on to a Mac as uncompressed and then encoding that as 35Mb 4:2:0 and 50Mb 4:2:2. There is very little difference between the 50Mb 4:2:2 and the uncompressed 8 bit original. having said that it still surprises me how little difference there is between the 35Mb and uncompressed signal. The 50Mb 4:2:2 shows more chroma detail (as expected) and in my multi generation tests is a little more robust than 35Mb. The Convergant devices are really going to allow users of lower cost cameras to squeeze out every ounce of quality.

[Mike Schell]

Originally Posted by Alister Chapman

An F350 recording to a Convergent Flash XDR or nano flash at 50mb/sec MPEG 2 would be an interesting proposition. I have done various tests recording the HDSDi out on to a Mac as uncompressed and then encoding that as 35Mb 4:2:0 and 50Mb 4:2:2. There is very little difference between the 50Mb 4:2:2 and the uncompressed 8 bit original. having said that it still surprises me how little difference there is between the 35Mb and uncompressed signal. The 50Mb 4:2:2 shows more chroma detail (as expected) and in my multi generation tests is a little more robust than 35Mb. The Convergant devices are really going to allow users of lower cost cameras to squeeze out every ounce of quality.

Hi Alister-
Our tests indicate virtually no visual difference between uncompressed and 100Mbps 4:2:2. Given the low-cost of the 32GB Compact Flash cards (US$135) and the ability to record 35 minutes @ the 100Mbps rate, we think the nanoFlash/Flash XDR could raise the quality level of almost every HD-SDI camera.

We are simply amazed at the quality of the EX1 camera with it's 1920x1080 sensors. The EX1 + nanoFlash (under $US 10K for the combo) will certainly rival the quality of cameras costing 3X to 4X more.