When is Digital not Digital? Firewire or SDI?

[Shane Ross]

IF YOU ARE WORKING WITH DV ONLY…

Capture via firewire is lossless. Capture via SDI adds compression. Slight compression, but compression. DV natively is compressed 5:1

BUT…the BIG advantage of SDI at the uncompressed codecs is that your graphics, titles, stills all benefit from the 8 or 10 bit uncompressed rate. Thus while your tape footage is still compressed 5:1, your graphics, stills and text isn’t…and will be far sharper.

PLUS…you benefit tons for being able to color correct and add filters at uncompressed 4:2:2, as opposed to DV 4:1:1.

Will you notice the difference in the Firewire vs SDI capture on the tape footage? Doubtful. Will you notice a difference in your text and graphics…most definately.

Shane Ross
Alokut Productions
http://www.lfhd.net

[Walter Biscardi]

[Andy Taplin] “Is there a provable, definitive answer to the question about which input to an NLE like FCP (via a card of your choice) is better – Firewire or SDI?”

What format are you talking about?

For DV and DVCPro HD there’s no reason to come in SDI, it’s an identical capture to bringing in the footage via Firewire. I work with DVCPro HD all day long and we bring it in and master out via Firewire.

For Uncompressed SD and HD, then you need to come in via SDI to work in those formats (or component if your system supports that). Firewire doesn’t support uncompressed HD, though it will support uncompressed SD with the AJA Io series.

[Andy Taplin] “This would appear to not be the case with DV? So when is digital not digital? And how does all this affect the move to HD?”

I don’t understand this “when is digital not digital?” Firewire and SDI are both digital formats. Regardless of which input you’re using, you’re working in digital. Digital is not digital when you work in an analog format such as component, composite or S-Video.

Walter Biscardi, Jr.
https://www.biscardicreative.com

Director, “The Rough Cut”
https://www.theroughcutmovie.com

Now Posting “Good Eats” in HD for the Food Network

“I reject your reality and substitute my own!” – Adam Savage, Mythbusters

[Andy Taplin]

Thanks Shane

The main reason for the post is that currently I’m working with DVCAM (PAL) on Media 100 but will be moving to FCP this year. In M100 I’m capturing via Firewire and this then gets converted to M100’s MJPEG codec. Results are good but it’s still converting from DV to MJPEG which I would imagine adds errors.

Are you saying you can captre DV or DVCVAM into FCP via Firewire (which is compressed at 5:1 on the tape) and then uncompress it to a new uncompressed codec? This is no doubt a stupid question but where does the extra information to turn it from 5:1 to 1:1 come from?

Andy

[Walter Biscardi]

[Andy Taplin] “Are you saying you can captre DV or DVCVAM into FCP via Firewire (which is compressed at 5:1 on the tape) and then uncompress it to a new uncompressed codec? This is no doubt a stupid question but where does the extra information to turn it from 5:1 to 1:1 come from?”

There is no extra information to turn it into 1:1. 5:1 compressed stays 5:1 compressed no matter how you bring it in. If you come in via Uncompressed SD, the footage is still going to be 5:1 compressed in the camera and you just have a much larger file in FCP.

Capturing DV / DVCAM via Firewire is considered a “lossless” capture. That is FCP adds no additional compression to the footage and original quality is maintained.

Walter Biscardi, Jr.
https://www.biscardicreative.com

Director, “The Rough Cut”
https://www.theroughcutmovie.com

Now Posting “Good Eats” in HD for the Food Network

“I reject your reality and substitute my own!” – Adam Savage, Mythbusters

[Andy Taplin]

Hi Walter

Using DVCAM you’re saying there is no difference between Firewire and SDI? Maybe it looks the same but surely there are technical differences with compression and suitability for various post work – even with SD? That’s why I

[Mike Smith]

Hi Walter

I guess the plus of going to uncompressed comes in the extra colour space for grading / timing, and for effects and graphics work.

Of course the (DVCAM) camera footage gains no extra info in going uncompressed (via SDI if you have a DVCAM deck with SDI out, or via software conversion), but for broadcast the additional colour information will allow better results when the final color correction, effects and graphics have been added.

But you add a lot of extra data handling, storage requirement and system load for your gains. So if your output requirements are corporate / DVD / vhs, as Andy’s seem to be from his website, then I guess those costs may outweigh the benefits.

[Andy Taplin]

So if Firewire capture is lossless why capture SD via SDI as some people are suggesting?

[Walter Biscardi]

[Andy Taplin] “Using DVCAM you’re saying there is no difference between Firewire and SDI?”

Nope, capture quality will be exactly the same.

[Andy Taplin] “Maybe it looks the same but surely there are technical differences with compression and suitability for various post work – even with SD? That’s why I

[Walter Biscardi]

[Andy Taplin] “So if Firewire capture is lossless why capture SD via SDI as some people are suggesting?”

If you want to edit in an uncompressed 720×486 timeline, then you come in via SDI. Other than that, there’s no reason to do this.

Walter Biscardi, Jr.
https://www.biscardicreative.com

Director, “The Rough Cut”
https://www.theroughcutmovie.com

Now Posting “Good Eats” in HD for the Food Network

“I reject your reality and substitute my own!” – Adam Savage, Mythbusters

[Andy Taplin]

Thanks for the advice guys

Most of my stuff involves some working in AFX (or maybe now Motion) as well as the NLE and then importing AFX renders back into the NLE. I tend to produce DVD masters nothing goes out on tape anymore.

Would you therefore reccommend capturing via SDI uncompressed to get better quality after rendering in AFX? What codec would you render out with (Sheer?) and lastly, how much bigger are the files capturing using SDI uncompressed compared to Firewire DV – which I guess comes into FCP at 3.6MB per sec?

many thanks

Andy