De-interlacing 30p?
- Thread starter Joe_Hicks
- Start date
Joe,
Can you clarify what you mean about capturing as interlaced? Do you mean that you shot the footage in 30p? A NTSC-version DVX records all footage to tape as if it were standard 60i NTSC footage. As I understand it, when the footage is captured and written to harddisk, it is not altered. That's why you can use any miniDV camcorder to upload a tape recorded by a DVX; even 24p footage. Once it's on disk, it's up to the program you're using to interpret the footage as 60i, 30p, 24p, 24pa, etc.
If you can provide more detail on what you're doing or trying to do, I might be able to provide more specific answers.
-Dan
Can you clarify what you mean about capturing as interlaced? Do you mean that you shot the footage in 30p? A NTSC-version DVX records all footage to tape as if it were standard 60i NTSC footage. As I understand it, when the footage is captured and written to harddisk, it is not altered. That's why you can use any miniDV camcorder to upload a tape recorded by a DVX; even 24p footage. Once it's on disk, it's up to the program you're using to interpret the footage as 60i, 30p, 24p, 24pa, etc.
If you can provide more detail on what you're doing or trying to do, I might be able to provide more specific answers.
-Dan
Hey Dan-
When setting up a new project under 'General Settings' Premiere gives you the option of 'Lower Field First', 'Upper Field First', or 'No Fields (Progressive Scan)'.
I captured footage shot in 30p mode in a project that was set-up with 'Lower Field First'. Is this an issue or do I not need to worry about it and be sure to de-interlace all my footage.
I get a bit confused on progressive vs. interlaced when it comes to post-production.
When setting up a new project under 'General Settings' Premiere gives you the option of 'Lower Field First', 'Upper Field First', or 'No Fields (Progressive Scan)'.
I captured footage shot in 30p mode in a project that was set-up with 'Lower Field First'. Is this an issue or do I not need to worry about it and be sure to de-interlace all my footage.
I get a bit confused on progressive vs. interlaced when it comes to post-production.
Hey Joe,
I'm with you now. I think you could just start a new 30p project and import the same AVI files from disk. I normally use a separate capture program to load to disk and then import the files into my project. The capture program doesn't really understand or care if the footage is interlaced or not. Even if you stick with a 60i project, if you export with the Adobe Media Encoder, you can still choose a progressive output preset.
-Dan
I'm with you now. I think you could just start a new 30p project and import the same AVI files from disk. I normally use a separate capture program to load to disk and then import the files into my project. The capture program doesn't really understand or care if the footage is interlaced or not. Even if you stick with a 60i project, if you export with the Adobe Media Encoder, you can still choose a progressive output preset.
-Dan
Hey Dan,
Ok, so indeed choosing properly matched settings does make a difference with the final product. If I have progressive footage then I should create a project with the field settings set for progressive and 60i would be lower field first.
Ok, now, what's the proper method when you have mixed footage (this subject is probably all over this forum) such as 30p and 60i, and for that matter maybe there's some 24p I need to get in-- how is this handled? And getting back to the first question, does 30p footage need to be de-interlaced?
Ok, so indeed choosing properly matched settings does make a difference with the final product. If I have progressive footage then I should create a project with the field settings set for progressive and 60i would be lower field first.
Ok, now, what's the proper method when you have mixed footage (this subject is probably all over this forum) such as 30p and 60i, and for that matter maybe there's some 24p I need to get in-- how is this handled? And getting back to the first question, does 30p footage need to be de-interlaced?
Joe,
I think the simple answer to your 30p question is that you do not need to de-interlace it. If you have a 60i project and you import footage shot at 30p, PPro will simply treat it has 60i footage with a lower and upper field. When you export it, just export it as 30fps progressive if that's what you want. You certainly don't want to use the de-interlace option in the 'field options' menu. I believe is discards one field and does a line doubler. You wind up losing a lot of resolution.
-Dan
I think the simple answer to your 30p question is that you do not need to de-interlace it. If you have a 60i project and you import footage shot at 30p, PPro will simply treat it has 60i footage with a lower and upper field. When you export it, just export it as 30fps progressive if that's what you want. You certainly don't want to use the de-interlace option in the 'field options' menu. I believe is discards one field and does a line doubler. You wind up losing a lot of resolution.
-Dan
Rick Meyer
Veteran
TeleDan said:
Okay, you're confusing me now....I have been painfully, and I mean, PAINFULLY struggling with the technical difficulties of my sisters wedding footage; more specifically a chapter in her wedding video. I shot it in 30p. I was also using magic bullet. Now, one of the main problems (of several) I was having was flicker or strobing that was VERY apparent in the footage. This seemed to appear one day and I could NOT for the life of me figure it out. Someone suggested I right click on the clip and go into FIELD OPTIONS and make sure ALWAYS DEINTERLACE was check. Now, in a way, this makes sense. 30P footage is NOT interlaced. So in that sense, it is deinterlaced footage. So, I tried it and voila', the footage lost its strobing. Now, it struck me as odd that this was not a default setting but beggers cannot be choosers. It worked. That's all I needed.
Rick
Rick,
Sorry if my response to Joe is confusing. There's more than one factor/setting involved so it's hard to give a simple answer that covers all situations. First, there's how the footage was shot (60i, 30p, 24p, 24pa, etc). Then, when you create a new project, you specify what the timeline will be. PPro will then attempt to conform the clips to the timeline based on how it interprets each clip. Then there's what you finally export the timeline to be.
In Joe's case, he said he captured 30p footage and loaded it into a 60i project/timeline. I've done this a lot without any problems. However, I typically don't do much to the footage beyond edits, transitions, and color correction. There are some plugins that are sensitive to whether they are processing interlaced footage or not. Twixtor, for one, prefers to work with non-interlaced footage.
I scanned through your thread about the problem you encountered and if I understood correctly, the strobing motion had more to do with trying to slow down 30p footage. Plus you were using a heavy duty plugin like Magic Bullet. Plus I missed where you said what your PPro project characteristics were (interlaced or progressive). Your situation was a more complex.
-Dan
Sorry if my response to Joe is confusing. There's more than one factor/setting involved so it's hard to give a simple answer that covers all situations. First, there's how the footage was shot (60i, 30p, 24p, 24pa, etc). Then, when you create a new project, you specify what the timeline will be. PPro will then attempt to conform the clips to the timeline based on how it interprets each clip. Then there's what you finally export the timeline to be.
In Joe's case, he said he captured 30p footage and loaded it into a 60i project/timeline. I've done this a lot without any problems. However, I typically don't do much to the footage beyond edits, transitions, and color correction. There are some plugins that are sensitive to whether they are processing interlaced footage or not. Twixtor, for one, prefers to work with non-interlaced footage.
I scanned through your thread about the problem you encountered and if I understood correctly, the strobing motion had more to do with trying to slow down 30p footage. Plus you were using a heavy duty plugin like Magic Bullet. Plus I missed where you said what your PPro project characteristics were (interlaced or progressive). Your situation was a more complex.
-Dan
Rick Meyer
Veteran
TeleDan said:
Thanks Dan. Yes, that makes sense; there are usually many factors involving each project making the troubleshooting process tricky.
I still get strobing on two of my clips. I have given up on them. They are not monumentally distracting so the strobing stays. But you are right, each step is an important one and can save LOADS of time in the longrun as long as you know what you are doing. What are you filming? 24p? 30p? 60i? How are you capturing? How have you set up your project? What types of effects are you doing or using? The list goes on and on. Shoot, someone should just create a checklist; a form that asks all the basics then have a spot where the question can be asked. That way, anyone so inclined to help will not have to tear their hair out trying to figure out what the problem might be.
Rick
overnighttolondon
Well-known member
General note to Magic Bullet users: please note that there's an update for the plugin that resolves strobing issues encountered when crossfading between two clips or when using MB with other effects.
I sort of want to take this discussion back to a very basic level. 30p is for all intents and purposes, de-interlaced footage-- it's frames are not broken into two fields, so it does not need to be de-interlaced. On the other hand, 60i footage is interlaced, and so if the final output is going to be for NTSC televsion, such as a commercial for example, then the footage will need de-interlacing to show properly on an NTSC television.
Teledan states that using the "Field Options" for de-interlacing is not a good idea as it is only a line doubler so to speak. So, if this is the case, then what is the proper and highest quality method of de-interlacing?
Are these problems inherent in Premiere only or do other NLE's experience the same issues? I've been strongly considering going to Avid Xpress Pro as I seem to constantly be running into issues with Premiere and having to worry about work arounds. For a "professional" software, I'm not impressed.
Teledan states that using the "Field Options" for de-interlacing is not a good idea as it is only a line doubler so to speak. So, if this is the case, then what is the proper and highest quality method of de-interlacing?
Are these problems inherent in Premiere only or do other NLE's experience the same issues? I've been strongly considering going to Avid Xpress Pro as I seem to constantly be running into issues with Premiere and having to worry about work arounds. For a "professional" software, I'm not impressed.
Rick Meyer
Veteran
overnighttolondon said:
Yes thank you overnighttolondon...You pointed me into the right direction of this plugin. However, I was unable to get it to work. Even after I contacted the guys at Magic Bullet directly, they did not offer a workaround. I finally had to render out clips individually and bring them back in.
overnighttolondon
Well-known member
No. NTSC television signals are interlaced. That's why the image flickers when you pause your VCR (it alternates between the 2 60i fields that make up the frame you're on), and why when you're watching football and they pause at the beginning or end of a replay you can see the image lose half of its resolution (they're doubling a field).Joe_Hicks said:
In NTSC, 60 interlaced fields get shown to you one-at-a-time (changing the image 60 times per second). On a computer monitor, both fields in a frame (each frame is a pair of fields) are shown to you simultaneously instead of one-at-a-time, giving you those gross interlacing artifacts that we all love so much. The artifacts you're seeing in high motion clips will look perfectly fine on a television, it's only on a computer monitor that they look dumb.
All footage displayed on an NTSC television is 60i. 30p is different from standard 60i because its two fields are captured at the same moment in time, instead of 1/60th of a second apart. But that doesn't change how it's displayed on a TV. When you put it on a TV, each frame still has two fields, and they get displayed just like any other NTSC footage - 1/60th of a second after each other. But you'll get a bit of a different motion feel because of them having been recorded at the same moment.
Now, computer monitors are a different story altogether, and you probably want to stay away from interlaced footage as much as possible if TV isn't your final format.
The problem is not with Premiere - this is how NTSC works.Joe_Hicks said:
Joe_Hicks said:
Joe,
When the final result is destined for a progressive display. Also, as I mentioned earlier, when a particular effect/plugin you want to use works best with de-interlaced footage.
As for the best method, that's a good question. If the original footage was actually captured interlaced, then the two fields will have a time displacement. Have you seen video where a vertical or diagonal edge is in movement and you see a combing effect? De-interlacing that kind of footage is the real challenge. Here's an article that might help. It's a little dated but is useful for demonstrating the problem and different ways of addressing it:
http://forums.creativecow.net/cgi-b...cles/onneweer_barend/deinterlacing/index.html
From this you can see that the simplist approach is to simply throw out one of the fields and duplicate the remaining one. Simple but you loose half of your vertical resolution. That's why I cautioned against using the de-interlace field option in PPro. I'm not sure exactly what technique PPro uses.
I tend to shoot in progressive mode but I get interlaced footage from other sources. When necessary, I use the RE:Vision Effects de-interlacer mentioned in the above article. It makes motion estimates across a number of frames to do the job a little more intelligently. There are other products for doing this.
Going back to your original question, if your original footage was shot in 30p mode, the DVX still records each frame to tape as two separate fields. However, since both fields were captured at the same instant, 'de-interlacing' a frame is just a matter of recombining the two fields since there's no combing effect to deal with. In PPro, if the project you created was not progressive, I think you will still get progressive output if you specify it when you export.
My apologies if my initial response was overly simplistic and ultimately confusing. I think you can see from this discussion it's not a simple topic.
-Dan
Hey Overnight,
Thanks for your repsonse. I started to reply last ngiht and kept getting bogged down. You said it better than I could have. :beer:
-Dan