Uncompressed from HM700? at DVinfo.net

Joe Carney · November 1st, 2009, 07:13 PM

Has anyone captured footage from the HM700 via the HDSDI output? Possibly to a NanoFlash or AJA KI Pro or directly to a computer via one of the popular SDI capture cards?

Just wondering how the noise issues are via that route.

Steve Phillipps · November 2nd, 2009, 02:20 AM

Bear in mind that these things are still not "uncompressed".
Steve

Tim Dashwood · November 2nd, 2009, 03:16 AM

A live feed from the HD-SDI output can be considered "uncompressed" with respect to the fact that it has not gone through the mpeg2 encoder, however it is still chroma-subsampled to 4:2:2 at 8 bits/pixel.
If you digitize this live signal using an uncompressed codec then (in theory) the resulting media will an exact pixel for pixel clone of the original HD-SDI signal. I have done some tests with the uncompressed codec as well as the Apple ProRes codecs and they are available in the FCP forum.

But what about noise? The mpeg2 encoder isn't actually adding video level noise at the compression stage. Yes there will be added compression artifacts (and chroma is sub-sampled to 4:2:0) but if anything you will probably see slightly less overall noise in the B & R channels after encoding because the of the added amount of subsampling. This difference is negligible and difficult to see even when carefully analyzing the separate channels.

The latest HM700 firmware update addressed noise reduction (among other things) but I have yet to empirically analyze a before and after.

Paul Shapiro · November 2nd, 2009, 05:11 AM

Tim,
Does all of that also apply to the HM-100? I have asked JVC directly several times with, predictably, no response.

Joe Carney · November 2nd, 2009, 06:46 AM

Tim, I was under the impression the output on the HDSDI is 10bit. Not so?

Paul Shapiro · November 5th, 2009, 07:55 PM

Quote:

Originally Posted by Paul Shapiro

Tim,
Does all of that also apply to the HM-100? I have asked JVC directly several times with, predictably, no response.

Okay, has ANYONE been able to find this out? Can we get full uncompressed from the HM-100 HDMI?

Andy Urtusuastegui · November 6th, 2009, 12:27 AM

Paul, I am also interested in the output from the HM100 HDMI port. I am thinking of getting a blackmagic card.

I found this link on the JVC US page.
http://usjvc.com/faq/index.php?actio...123&artlang=en

It states HDMI is produces uncompressed output. I am not sure this is official.

Paul Shapiro · November 6th, 2009, 05:54 AM

Thanks very much Andy; I overlooked that JVC page. I guess the CD nanoFlash would also be an option. The nano would also add timelapse to the humble HM-100 -- although at quite a price!

Craig Yanagi · November 20th, 2009, 10:51 PM

Quote:

Originally Posted by Andy Urtusuastegui

Paul, I am also interested in the output from the HM100 HDMI port. I am thinking of getting a blackmagic card.

I found this link on the JVC US page.
JVC Pro FAQ

It states HDMI is produces uncompressed output. I am not sure this is official.

It is official.

Andy Urtusuastegui · November 20th, 2009, 11:23 PM

Craig, thank you for clarifying this. I am going to move forward with my plans to get a blackmagic card.

Tim, seems this should be in a FAQ or sticky.

November 1st, 2009, 07:13 PM	#1
Joe Carney Inner Circle Join Date: Jul 2002 Location: Centreville Va Posts: 1,828	Uncompressed from HM700? Has anyone captured footage from the HM700 via the HDSDI output? Possibly to a NanoFlash or AJA KI Pro or directly to a computer via one of the popular SDI capture cards? Just wondering how the noise issues are via that route. __________________ Boycott Guinness, bring back the pint!!!

November 2nd, 2009, 03:16 AM	#3
Tim Dashwood Wrangler Join Date: Aug 2005 Location: Toronto, ON, Canada Posts: 3,637	A live feed from the HD-SDI output can be considered "uncompressed" with respect to the fact that it has not gone through the mpeg2 encoder, however it is still chroma-subsampled to 4:2:2 at 8 bits/pixel. If you digitize this live signal using an uncompressed codec then (in theory) the resulting media will an exact pixel for pixel clone of the original HD-SDI signal. I have done some tests with the uncompressed codec as well as the Apple ProRes codecs and they are available in the FCP forum. But what about noise? The mpeg2 encoder isn't actually adding video level noise at the compression stage. Yes there will be added compression artifacts (and chroma is sub-sampled to 4:2:0) but if anything you will probably see slightly less overall noise in the B & R channels after encoding because the of the added amount of subsampling. This difference is negligible and difficult to see even when carefully analyzing the separate channels. The latest HM700 firmware update addressed noise reduction (among other things) but I have yet to empirically analyze a before and after. __________________ Tim Dashwood

November 2nd, 2009, 06:46 AM	#5
Joe Carney Inner Circle Join Date: Jul 2002 Location: Centreville Va Posts: 1,828	Tim, I was under the impression the output on the HDSDI is 10bit. Not so? __________________ Boycott Guinness, bring back the pint!!!

November 2nd, 2009, 02:20 AM	#2
Steve Phillipps Inner Circle Join Date: Apr 2006 Location: Wales Posts: 2,130	Bear in mind that these things are still not "uncompressed". Steve

November 2nd, 2009, 05:11 AM	#4
Paul Shapiro Regular Crew Join Date: Apr 2009 Location: Paget, Bermuda Posts: 52	Tim, Does all of that also apply to the HM-100? I have asked JVC directly several times with, predictably, no response.

November 6th, 2009, 12:27 AM	#7
Andy Urtusuastegui Regular Crew Join Date: Oct 2007 Location: Foothill Ranch, CA Posts: 166	Paul, I am also interested in the output from the HM100 HDMI port. I am thinking of getting a blackmagic card. I found this link on the JVC US page. http://usjvc.com/faq/index.php?actio...123&artlang=en It states HDMI is produces uncompressed output. I am not sure this is official.

November 6th, 2009, 05:54 AM	#8
Paul Shapiro Regular Crew Join Date: Apr 2009 Location: Paget, Bermuda Posts: 52	Thanks very much Andy; I overlooked that JVC page. I guess the CD nanoFlash would also be an option. The nano would also add timelapse to the humble HM-100 -- although at quite a price!

November 20th, 2009, 11:23 PM	#10
Andy Urtusuastegui Regular Crew Join Date: Oct 2007 Location: Foothill Ranch, CA Posts: 166	Craig, thank you for clarifying this. I am going to move forward with my plans to get a blackmagic card. Tim, seems this should be in a FAQ or sticky.