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Deinterlacing after Transcoding with Compressor
Compressor seems to deinterlace no matter what settings I choose. I’m down converting from HDV to ProRes 422 letterbox for output to BetaCam SP and DV. After importing the resulting file into FCP and viewing on my NTSC monitor (via AJA IO) I should see interfield switching as evidence of interlacing. Instead it looks as if the two fields have been blended. I’ve turned off Frame Controls and verified that the deinterlace filter is unchecked in the filter tab. Any suggestions? Thanks.
Lee
Lee Berger
http://www.leebergermedia.com -
7 Replies
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Hi Lee,
I think you will always need the “Deinterlacer” ON. The Deinterlacer also manage the “Shift-Fields”.
Your HDV footage is Upper and your SD destination Lower.
In the Output Fields you must check: Lower First.
rafael -
[Rafael Amador] “The Deinterlacer also manage the “Shift-Fields”.”
I believe that Shift Fields is only relevant if you place the HDV footage in an SD timeline. I’m exporting to a self contained HDV file and using Compressor to transcode and down convert to SD, Letterbox, ProRes 422. Once I have the downonverted ProRes file, I import it back into FCP and place it in a ProRes timeline. No need for deinterlacing or field shifting as ProRes is upper field dominant and has no effect on my analog component output to Betacam.
I do this because I find the downconvert in the timeline to be very poor, resulting in a great deal of aliasing.
I discovered this in 2006. Here’s my post from another form with comparative images.
https://www.dvinfo.net/conf/789649-post6.htmlLee Berger
http://www.leebergermedia.com -
[Lee Berger] “I believe that Shift Fields is only relevant if you place the HDV footage in an SD timeline. I’m exporting to a self contained HDV file and using Compressor to transcode and down convert to SD, Letterbox, ProRes 422. Once I have the downonverted ProRes file, I import it back into FCP and place it in a ProRes timeline. No need for deinterlacing or field shifting as ProRes is upper field dominant and has no effect on my analog component output to Betacam. “
the codec has nothing to do with upper / lower field. It’s the format.
If you’re going to SD NTSC Betacam, then you are reversing the fields from Upper (HD) to Lower (SD). I don’t know that Compressor can do this cleanly. We use our AJA Kona boards to perform this conversion as it’s flawless.
If your ProRes file is truly upper field first, that’s in the wrong field order for NTSC SD. You can confirm this very easily in FCP by simply setting up a new ProRes SD Timeline. Look at the field dominance, it’s set to Lower.
Walter Biscardi, Jr.
Biscardi Creative Media
HD and SD Production for Broadcast and Independent Productions.STOP STARING AND START GRADING WITH APPLE COLOR Apple Color Training DVD available now!
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Thanks Walter. In the ProRes codec, if you select interlace, you can choose upper or lower fd.
After pondering my original issue, I began to suspect scaling.
I did a test, encoding an SD file to ProRes. It retained its interlacing, showing inter field flicker when paused on an object in motion. I then encoded an HDV file to ProRes with no scaling and it too retained its interlacing.
I assume that some field blending occurs during scaling.
Lee Berger
http://www.leebergermedia.com -
Hi Lee,
[Lee Berger] “I assume that some field blending occurs during scaling.”
With de-interlacing “Best and Better” you shouldn’t have any field blendingIn Compressor you need to follow the same rules about interlacing than in FC.
Compressor knows that your standard HDV is Upper, but doesn’t know that you want a Proress Lower first unless you tell him.
As Walter says, the codec have nothing to do. You could be doing Proress 720 x 480 Upper to make a NTSC MPEG-2 Upper first, perfectly legal.“I do this because I find the downconvert in the timeline to be very poor, resulting in a great deal of aliasing”
I’m doing that with very good results just setting FC with the best options.
Cheers,
rafael -
[Lee Berger] “Thanks Walter. In the ProRes codec, if you select interlace, you can choose upper or lower fd.
“Yes you CAN set it to upper, but that’s incorrect for NTSC SD. You’ll have reverse interlacing when you lay it out to Beta.
Walter Biscardi, Jr.
Biscardi Creative Media
HD and SD Production for Broadcast and Independent Productions.STOP STARING AND START GRADING WITH APPLE COLOR Apple Color Training DVD available now!
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[walter biscardi] “Yes you CAN set it to upper, but that’s incorrect for NTSC SD. You’ll have reverse interlacing when you lay it out to Beta. “
Exactly. You can change the field order of any file inside your computer just making a Shift-fields, but when printing to video you must keep the standard field order. Video desks have no “random access’ to the in tape information.
Rafael
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