HDV export to tape lossless? at DVinfo.net

Michael Barrette · March 27th, 2007, 06:36 PM

If importing HDV then exporting back to tape, is the footage as high quality as the original footage after it's gone through both the import and the export transcoding to make it HDV? Or is the only way to keep it lossless quality to import and export using HDMI?

Thanks!
Michael

Steven Gotz · March 27th, 2007, 07:21 PM

There will be loss, but less loss if you use Cineform Aspect HD. In any case, there is loss when encoding it back to HDV.

Don Blish · March 27th, 2007, 09:23 PM

As you can see from this post, the export back to tape is tripped up by scene boundaries.

http://www.dvinfo.net/conf/showthread.php?t=89585

The original footage always starts with a full "I frame", thats one reason why our HDV cameras take a few heartbeats to start recording. On reexport, scene boundaries will often badly miss "I frame boundaries". At least thats my interpretation. In Blu-Ray authoring, using VBR lets software ramp up speed for such.

Pete Bauer · March 27th, 2007, 09:24 PM

Steve is definitely correct if you've edited and then rendered out for export to tape.

I was under the impression that if you just captured and then exported back to tape without doing anything more than cuts -- (no color correction, etc that would require a render), you shouldn't lose image quality. There's probably a caveat for HDV, though, in that if you've cut in the middle of a GOP, it presumably would force a render of at least some adjacent frames to create new GOP's, but this is about as far as I can go with it. Steve and others can probably write more authoritatively on that.

EDIT: That was fast...see Don's post just before mine!

March 27th, 2007, 06:36 PM	#1
Michael Barrette Regular Crew Join Date: Feb 2007 Location: calgary, Canada Posts: 48	HDV export to tape lossless? If importing HDV then exporting back to tape, is the footage as high quality as the original footage after it's gone through both the import and the export transcoding to make it HDV? Or is the only way to keep it lossless quality to import and export using HDMI? Thanks! Michael

March 27th, 2007, 07:21 PM	#2
Steven Gotz Trustee Join Date: May 2002 Location: Clermont, FL Posts: 1,520	There will be loss, but less loss if you use Cineform Aspect HD. In any case, there is loss when encoding it back to HDV. __________________ Steven Gotz http://www.stevengotz.com

March 27th, 2007, 09:23 PM	#3
Don Blish Major Player Join Date: Oct 2003 Location: Portland OR Posts: 227	Loss at scene boundaries As you can see from this post, the export back to tape is tripped up by scene boundaries. http://www.dvinfo.net/conf/showthread.php?t=89585 The original footage always starts with a full "I frame", thats one reason why our HDV cameras take a few heartbeats to start recording. On reexport, scene boundaries will often badly miss "I frame boundaries". At least thats my interpretation. In Blu-Ray authoring, using VBR lets software ramp up speed for such.

March 27th, 2007, 09:24 PM	#4
Pete Bauer Wrangler Join Date: May 2003 Location: Eagle River, AK Posts: 4,100	Steve is definitely correct if you've edited and then rendered out for export to tape. I was under the impression that if you just captured and then exported back to tape without doing anything more than cuts -- (no color correction, etc that would require a render), you shouldn't lose image quality. There's probably a caveat for HDV, though, in that if you've cut in the middle of a GOP, it presumably would force a render of at least some adjacent frames to create new GOP's, but this is about as far as I can go with it. Steve and others can probably write more authoritatively on that. EDIT: That was fast...see Don's post just before mine! __________________ Pete Bauer The most beautiful thing we can experience is the mysterious. It is the source of all true art and science. Albert Einstein Trying to solve a DV mystery? You may find the answer behind the SEARCH function ... or be able to join a discussion already in progress!