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XL2 w/ External Recorder


Landon D. Parks

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Is there some way to use a off-camera recorder to capture the camera signal without compressing it to DV tape? I seen on canons website some kind of RAM recorder or something that fits onto the camera and records up to 2 and 4 hours of footage, but it didnt say if it was uncompressed, ect.

 

I'm looking for something to get the full camera resolution recorded 24p and uncompressed. Then transfer it via Firewire to the computer for editing.

 

Pretty much, to just avoid compression.

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Hi,

 

There's a hard disk recorder mod for the DVX-100 that will give you uncompressed recording (I'm sure we've discussed it, while you were around, actually.) Of course, the DVX lacks the true widescreen of the XL2, which is a shame.

 

I'm sure anything that can record several hours of footage is going to be compressed, it'll just be recording the firewire output. Uncompressed SD video is around 30Mbyte/sec, so two hours of it would be over two hundred gigabytes.

 

Phil

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The canon thing recorded 2 hours onto a 40gig Hard Drive. and 4 onto an 80gig Hard Drive. So if 2 hours is 200gigs, I highly doubt that its uncompressed. But still compression has to be better than recording to the MiniDv tape.

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It should be the same compression as the minidv tape using the dv codec. I ran across some website that promoted a uncompressed version of a firewire interface. I'll try to find it again and post it, but I remember the website looked like a homemade deal so I don't know how good a unit it would actually be.

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Hi,

 

> But still compression has to be better than recording to the MiniDv tape.

 

Why does it "have" to be? If it was, it'd be a pain - you'd need some different codec to read it in your NLE application, and possibly faster hard drives.

 

I think what you're looking at is the Firestore devices, or something like that, which do nothing more than record the DV compressed firewire output to a hard disk. This has definite advantages, but it's to do with workflow and editing without having to capture from slow tape. There's no image quality difference.

 

Phil

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Hi,

 

> I ran across some website that promoted a uncompressed version of a firewire interface.

 

I think you've seen the uncompressed output mod for the DVX-100. It's nothing to do with the firewire interface; it's a device designed to probe the RGB data directly off the ADCs just after the CCD assembly. To do this, you have to open up the case of the camera and place clips on the PCBs, but the results are pretty good. Much more room for creative grading and the images are vastly sharper.

 

Phil

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Why does it "have" to be?

I dont guess it does, but still. I can't see why just the lack of Compression would cause you to need a whole new Codec in your software. If its anything like my digital still camera, I can take a picture with a bunch of compression or non what so ever. But I can still load it into the same application to edit it.

 

I know it would take more hard drives, and faster ones for that matter. But still, I think one of the major set-backs of DV is its compression...

 

Although I dont know much about it, So I'll let the pro's have there say.

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Hi,

 

> I dont guess it does, but still. I can't see why just the lack of Compression would

> cause you to need a whole new Codec in your software.

 

The codec is, in this context, just a converter that sits between the way the video is stored on the hard disk (as a stream with DV compression, often) and the way the computer wants it in memory. A DV codec has to unscramble the DCT compression, upscale the U and V images (they're 4:1:1 or 4:2:0 reduced, remember) and most usually convert the image from YUV to RGB.

 

It's true that if you store your video as uncompressed, unsubsampled RGB the codec has a lot less to do - the poor performance of a DV workstation is actually a lot to do with the fact that undoing DV compression is actually hard work for the computer, so assuming you have the disk bandwidth, you will find that the rendering performance actually increases if you work uncompressed. Assuming you do store uncompressd RGB most systems come with a suitable codec - Quicktime calls it "none", and the Video for Windows architecture I believe calls it "uncompressed." You may still have issues in that it's probably at a higher-than-eight bit depth, so you might still need something else to decode it.

 

This isn't that huge a problem, other than one thing: working uncompressed you can't monitor it on a decent video monitor via your DV camera anymore, at least not unless you render it down to a DV stream.

 

> If its anything like my digital still camera, I can take a picture with a bunch of

> compression or non what so ever. But I can still load it into the same application to

> edit it.

 

Sure, but that's only because Photoshop or whatever you're using ships with support for many image formats including JPEG, TIFF, RAW, or whatever your camera shoots. It still requires the software to explicitly know how to handle the format.

 

> I know it would take more hard drives, and faster ones for that matter.

 

You can put a pair of drives on a motherboard RAID controller and do uncompressed SD, so it doubles the cost, but it's not so horribly unattainable.

 

> But still, I think one of the major set-backs of DV is its compression...

 

No kidding.

 

Phil

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Isn't there some way to run a signal directly to a D5 or so VTR or maybee even HDCAM VTR? That would take care of the compression problem, although then you have an HD image to edit, which means a more powerful PC.

 

Maybee a DVCPRO50 VTR is the answer?

Edited by Landon D. Parks
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There's not a firewire based VTR that I'm aware of that doesn't use DV material only. You could use an external deck but then you'd have to use your analog outputs, and the XL series only have a composite and S-Vid output. So you certainly wouldn't get a better quality image. If anything it would be reduced in quality. What they need to make is a firewire device that either converts the firewire output to an 8 or 10 bit uncompressed SDI signal or something like the DVX100A uncompressed DTE has where you record a signal not long after it leaves the CCD's. I think with current technology you'd need a raid system just to write the uncompressed file but certainly someone should come up with a way around that. I'm very displeased with the dv codec and wouldn't mind venturing into some different setups for uncompressed footage. I know some people are thinking "why don't you just buy a D9 camera?" but the cost just isn't worth the ability to work with uncompressed footage. It seems like a rather simple solution that hopefully some engineer will answer. And thanks for the info Phil.

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Hi,

 

> What they need to make is a firewire device that either converts the firewire output to

> an 8 or 10 bit uncompressed SDI signal

 

Already exists, but what's the point? It's already been compressed.

 

> There's not a firewire based VTR that I'm aware of that doesn't use DV

> material only.

 

There are DVCPRO-100 VTRs that have firewire, but that's a special link to talk to Macs with FCP. In any case - again, by the time it gets out of the camera it's compressed.

 

There is no way to do this without ripping the case off the camera and patching some fairly high technology onto the PCBs.

 

Phil

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Phil,

 

Who makes the uncompressed firewire DTE and where could I get one if I so choose?

 

I talked about the benefits of transferring dv footage to other digital formats in another thread titled "The Competitive XL1s" in the XL forum. I'd appreciate your insight into some of the questions brought up in that discussion. To summarize I stated you could achieve better results by transferring your dv footage to a format that could be edited uncompressed. Of course you can't change or modify the fact that you're starting out with dv material but while editing (FCP in my case) you can tell a noticeable improvement in color information, when color correcting, and sharpness. This isn't brought about necessarily from the tape transfer but rather avoiding the Quicktime DV codec.

 

Thanks,

AT

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Hi,

 

> Who makes the uncompressed firewire DTE

 

Someone makes an uncompressed DTE recorder, but it's specific to the DVX-100 and nothing to do with firewire.

 

What you may be thinking of is "a firewire device that either converts the firewire output to an 8 or 10 bit uncompressed SDI signal", and you can buy such a 1394 to SDI convertor from any number of people, but I don't understand why you'd want to. It'd offer no advantage over just working uncompressed with it on your computer - which is certainly something I'd encourage you to do.

 

> To summarize I stated you could achieve better results by transferring

> your dv footage to a format that could be edited uncompressed.

 

Yes, sure, it helps if you don't keep recrunching it.

 

Phil

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working uncompressed with it on your computer - which is certainly something I'd encourage you to do.

 

Hi;

 

This is something I've been confused by for a while Phil, If I need to colour correct Minidv in say Final Cut Pro why will I achieve better results if I change the timeline to uncompressed 10bit if the colour and compression on the dv is already 4:2:0 and 5:1? I'm assuming that I'd need to stay in uncompressed 10bit and output to say digibeta for this to be worth while too rather than going back to minidv? Thanks for any scraps o' wisdom.....

 

Olly

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