Digital Video.. at DVinfo.net

Andreas Fernbrant · November 27th, 2003, 06:23 AM

I have som questions for those who have experience with larger digital video camera like DigiBeta.

When you load you video in to the computer? is it done by FireWire? What format and compression do you get and edit with?
DV= DV Codec. But I can't see how that would fit to a Digi Beta?
Do you edit and render it as an uncompressed videofile?

DV is about 13-14 gigs per hour, what about digibeta?

/Andreas

Graeme Nattress · November 27th, 2003, 06:34 AM

DigiBeta uses a motionJpeg type codec at 50% compression. At those rates, it's practically lossless. It is generally connected to a computer NLE via SDI, and output via SDI. The SDI does not carry the "dub" signal (the compressed version of the video data) like with firewire, but a fully uncompressed 4:2:2 SMPTE 601 video stream, and hence is generally edited uncompressed.

SDI can carry the dub signal on other formats - BetaCamSX and (perhaps HDCAM will give access to the dub signal) because it can be used as a wrapper for any video data stream that fits within it's bandwidth.

Graeme

Jeff Donald · November 27th, 2003, 06:49 AM

SDI and FireWire are just pipelines. You can send whatever signal will fit within their bandwidths. Manufactures are adding FireWire compatibility to many of their new camera models. Transcoders are available to convert many different signals, using FireWire and SDI.

Graeme Nattress · November 27th, 2003, 07:07 AM

Yes - with boxes like the AJA IO, you can transmit uncompressed video over firewire - it has the bandwidth to cope.

Graeme

Jon Yurek · November 30th, 2003, 10:30 AM

Just to point something out though... even though you can transfer "uncompressed" video through a FireWire or SDI link, you're still getting only what you would have gotten if you had copied the DV or MJPEG stream directly and then converted to uncompressed 4:2:2 on your computer. Once it's compressed (as it is when it's stored to tape), you're not getting the information back that it threw away to compress it.

Speaking of which... if DigiBeta only compresses 50%, why not use something like the HuffYUV codec which is lossless and compresses around 2:1?

Rob Lohman · December 2nd, 2003, 06:05 PM

That's a good question Jon. Might have to do with bit allocation
and colorspaces. But then again I know everbody is using MJPEG,
it has been around for a long time.

Yes, we edit in DV. Our DV camera's encode directly to DV (25 mbps)
and this information gets transferred over the firewire in its
native compressed format.

So the capture is in fact just a "copy". On the computer we edit
this footage indeed with a DV "codec".

Dan Bohman · December 24th, 2003, 05:56 PM

does this mean there is no compression or decompression between the tape and the harddrive? i mean to say - when i capture into fcp4 via firewire from my gl2, is there no real codec being used? the appleDV codec that is used is really just for playback on the computer, right? is there a codec built into the camera for it to playback the digital tapes, or through the analog output? maybe i'm confused. hmm....

Glenn Chan · December 24th, 2003, 06:15 PM

The apple codec does 2 things: COmpress, and DECompress. When you are playing back DV footage on the timeline, it decompresses the DV footage into a format that plays on your monitor.

Suppose you add some effects to your footage. FCP decompresses the footage, applies the effects, then compresses the footage using the Apple DV codec.

Cameras/decks should have some sort of codec built in presumably (to play back and record DV).

Edward Troxel · December 24th, 2003, 09:59 PM

Quote:

does this mean there is no compression or decompression between the tape and the harddrive? i mean to say - when i capture into fcp4 via firewire from my gl2, is there no real codec being used?

This is TRUE. It is simply a file copy from the tape to the hard drive via a firewire connection. NO codec is involved in this process.

Ben Wiens · December 25th, 2003, 08:52 PM

Graeme mentioned that "DigiBeta uses a motionJpeg type codec at 50% compression. At those rates, it's practically lossless". This must be 1/4 or less compression than MiniDV. Is this a major reason why big camera productions have so much better qualilty than those shot with MiniDV. Also is this the key big camera format or are there others?

Dan Bohman · December 27th, 2003, 10:28 AM

i appreciate the answers everyone. definitely helped to clear up some questions. just one last semi-related question. all the talk about lossless editing, that not mini-dv is it? are they talking about larger format cameras? even older analog cameras at times?

November 27th, 2003, 06:23 AM	#1
Andreas Fernbrant Major Player Join Date: Oct 2002 Location: Sweden - Helsingborg Posts: 283	Digital Video.. I have som questions for those who have experience with larger digital video camera like DigiBeta. When you load you video in to the computer? is it done by FireWire? What format and compression do you get and edit with? DV= DV Codec. But I can't see how that would fit to a Digi Beta? Do you edit and render it as an uncompressed videofile? DV is about 13-14 gigs per hour, what about digibeta? /Andreas

November 27th, 2003, 06:34 AM	#2
Graeme Nattress RED Problem Solver Join Date: Sep 2003 Location: Ottawa, Canada Posts: 1,365	DigiBeta uses a motionJpeg type codec at 50% compression. At those rates, it's practically lossless. It is generally connected to a computer NLE via SDI, and output via SDI. The SDI does not carry the "dub" signal (the compressed version of the video data) like with firewire, but a fully uncompressed 4:2:2 SMPTE 601 video stream, and hence is generally edited uncompressed. SDI can carry the dub signal on other formats - BetaCamSX and (perhaps HDCAM will give access to the dub signal) because it can be used as a wrapper for any video data stream that fits within it's bandwidth. Graeme __________________ www.nattress.com - filters for FCP

November 27th, 2003, 06:49 AM	#3
Jeff Donald Warden Join Date: Mar 2002 Location: Clearwater, FL Posts: 8,287	SDI and FireWire are just pipelines. You can send whatever signal will fit within their bandwidths. Manufactures are adding FireWire compatibility to many of their new camera models. Transcoders are available to convert many different signals, using FireWire and SDI. __________________ Jeff Donald Carpe Diem Search DVinfo.net for quick answers \| Where to Buy? From the best in the business: DVinfo.net sponsors

November 27th, 2003, 07:07 AM	#4
Graeme Nattress RED Problem Solver Join Date: Sep 2003 Location: Ottawa, Canada Posts: 1,365	Yes - with boxes like the AJA IO, you can transmit uncompressed video over firewire - it has the bandwidth to cope. Graeme __________________ www.nattress.com - filters for FCP

December 2nd, 2003, 06:05 PM	#6
Rob Lohman RED Code Chef Join Date: Oct 2001 Location: Holland Posts: 12,514	That's a good question Jon. Might have to do with bit allocation and colorspaces. But then again I know everbody is using MJPEG, it has been around for a long time. Yes, we edit in DV. Our DV camera's encode directly to DV (25 mbps) and this information gets transferred over the firewire in its native compressed format. So the capture is in fact just a "copy". On the computer we edit this footage indeed with a DV "codec". __________________ Rob Lohman, visuar@iname.com DV Info Wrangler & RED Code Chef Join the DV Challenge \| Lady X Search DVinfo.net for quick answers \| Buy from the best: DVinfo.net sponsors

November 30th, 2003, 10:30 AM	#5
Jon Yurek Regular Crew Join Date: Sep 2003 Location: Worcester, MA Posts: 64	Just to point something out though... even though you can transfer "uncompressed" video through a FireWire or SDI link, you're still getting only what you would have gotten if you had copied the DV or MJPEG stream directly and then converted to uncompressed 4:2:2 on your computer. Once it's compressed (as it is when it's stored to tape), you're not getting the information back that it threw away to compress it. Speaking of which... if DigiBeta only compresses 50%, why not use something like the HuffYUV codec which is lossless and compresses around 2:1?

December 24th, 2003, 05:56 PM	#7
Dan Bohman New Boot Join Date: Oct 2003 Location: Stafford, VA Posts: 8	clarify me.... does this mean there is no compression or decompression between the tape and the harddrive? i mean to say - when i capture into fcp4 via firewire from my gl2, is there no real codec being used? the appleDV codec that is used is really just for playback on the computer, right? is there a codec built into the camera for it to playback the digital tapes, or through the analog output? maybe i'm confused. hmm.... __________________ dB. Cannon GL-2 Sennheisser k6: ME64, ME66 FCP4 on a G4 Life is one big gamble. You just have to choose your bets.

December 24th, 2003, 06:15 PM	#8
Glenn Chan Inner Circle Join Date: Jun 2003 Location: Toronto, Canada Posts: 4,750	The apple codec does 2 things: COmpress, and DECompress. When you are playing back DV footage on the timeline, it decompresses the DV footage into a format that plays on your monitor. Suppose you add some effects to your footage. FCP decompresses the footage, applies the effects, then compresses the footage using the Apple DV codec. Cameras/decks should have some sort of codec built in presumably (to play back and record DV).

December 25th, 2003, 08:52 PM	#10
Ben Wiens Regular Crew Join Date: Dec 2002 Location: Vancouver BC Canada Posts: 56	DigiBeta Graeme mentioned that "DigiBeta uses a motionJpeg type codec at 50% compression. At those rates, it's practically lossless". This must be 1/4 or less compression than MiniDV. Is this a major reason why big camera productions have so much better qualilty than those shot with MiniDV. Also is this the key big camera format or are there others?

December 27th, 2003, 10:28 AM	#11
Dan Bohman New Boot Join Date: Oct 2003 Location: Stafford, VA Posts: 8	thanks for the help i appreciate the answers everyone. definitely helped to clear up some questions. just one last semi-related question. all the talk about lossless editing, that not mini-dv is it? are they talking about larger format cameras? even older analog cameras at times? __________________ dB. Cannon GL-2 Sennheisser k6: ME64, ME66 FCP4 on a G4 Life is one big gamble. You just have to choose your bets.