does the "Uncompressed" codecs actually ad compression? at DVinfo.net

Mike Barber · December 1st, 2008, 01:53 PM

I am trying to deal with some "FUD" about Final Cut Pro/QuickTime codecs and compression.

I was just told that capturing the incoming HDCAM tapes through FCP is not giving us the best quality. It has been claimed that the "Uncompressed" codec still compresses the image.

I am capturing from HDCAM to FCP6 through a Kona 2 card using Kona Uncompressed settings.

I realise that there is already some loss from the HDCAM tape, which is 4:2:2 (the original source is 4:4:4 ), but I don't understand why I am not (according to others) getting the best quality we can out of the tape with this method.

Noah Kadner · December 1st, 2008, 02:17 PM

How are you judging the quality. Uncompressed is what it says. As long as you're sending the right signal and routing it into the right input that's as good as it gets. Perhaps it's a color space issue? What you see in FCP is just a proxy. What goes out to the HD-SDI monitor from the Kona is the actual quality.

Noah

Mike Barber · December 1st, 2008, 02:42 PM

Quote:

Originally Posted by Noah Kadner

Uncompressed is what it says. As long as you're sending the right signal and routing it into the right input that's as good as it gets. Perhaps it's a color space issue?

Well, that's what I thought but someone else seems to have a strong opinion otherwise, though I am not sure from where his opinion comes. He's a smart guy, but maybe there is some confusion... well, there's no "maybe"... there is confusion, but on who's part?

[QUOTE=Noah Kadner;971262]How are you judging the quality. […] What you see in FCP is just a proxy. What goes out to the HD-SDI monitor from the Kona is the actual quality./QUOTE]

I'm looking at the footage on a nice 24" Sony HD CRT monitor and it looks great. The online editor (at a different facility) is the one complaining.

Just out of curiosity... I have seen some QT files that has "None" as its "Format" (in the QT player Inspector). What is the difference between that and uncompressed? I notice a difference in filesize as well as colour when a file is exported to both.

Andy Mees · December 2nd, 2008, 12:09 AM

Mike, this is darn tricky ... as I understand it, the image data on tape is already compressed to the proprietary HDCAM codec, this image data is of course then decompressed in camera/deck and that baseband image data is then sent via HD-SDI to your capture hardware, then the capture hardware will encode (or "compress") that baseband image data using an assigned codec, where that assigned codec can include the "Uncompressed" codec. As an example of the possible compression involved in Uncompressed, where a fully decompressed image data might be represented as 4:4:4 the Uncompressed codec may be 4:2:2 so in such a scenario there can be some compression in the color sampling going on.
All that said, HDCAM (not HDCAM SR) is a proprietary Sony codec which itself is generally held to be a compressed 3:1:1 format.
If you want truly uncompressed then I think you need to go with "None" ... which is pretty aptly named :-)

December 1st, 2008, 01:53 PM	#1
Mike Barber Major Player Join Date: May 2006 Location: Toronto ON Canada Posts: 731	does the "Uncompressed" codecs actually ad compression? I am trying to deal with some "FUD" about Final Cut Pro/QuickTime codecs and compression. I was just told that capturing the incoming HDCAM tapes through FCP is not giving us the best quality. It has been claimed that the "Uncompressed" codec still compresses the image. I am capturing from HDCAM to FCP6 through a Kona 2 card using Kona Uncompressed settings. I realise that there is already some loss from the HDCAM tape, which is 4:2:2 (the original source is 4:4:4 ), but I don't understand why I am not (according to others) getting the best quality we can out of the tape with this method. __________________ Mike Barber "I'm laughing to stop myself from screaming."

December 1st, 2008, 02:17 PM	#2
Noah Kadner Better than Halle Berry Join Date: Feb 2004 Location: Los Angeles, CA Posts: 435	How are you judging the quality. Uncompressed is what it says. As long as you're sending the right signal and routing it into the right input that's as good as it gets. Perhaps it's a color space issue? What you see in FCP is just a proxy. What goes out to the HD-SDI monitor from the Kona is the actual quality. Noah

December 2nd, 2008, 12:09 AM	#4
Andy Mees Major Player Join Date: Mar 2006 Location: Kuala Lumpur, Malaysia Posts: 645	Mike, this is darn tricky ... as I understand it, the image data on tape is already compressed to the proprietary HDCAM codec, this image data is of course then decompressed in camera/deck and that baseband image data is then sent via HD-SDI to your capture hardware, then the capture hardware will encode (or "compress") that baseband image data using an assigned codec, where that assigned codec can include the "Uncompressed" codec. As an example of the possible compression involved in Uncompressed, where a fully decompressed image data might be represented as 4:4:4 the Uncompressed codec may be 4:2:2 so in such a scenario there can be some compression in the color sampling going on. All that said, HDCAM (not HDCAM SR) is a proprietary Sony codec which itself is generally held to be a compressed 3:1:1 format. If you want truly uncompressed then I think you need to go with "None" ... which is pretty aptly named :-)