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How do I process this video? (all efforts are failing)

Specific to Premiere Elements Version 7.

Re: How do I process this video? (all efforts are failing)

Postby Bob » Sun Aug 01, 2010 4:22 pm

No, it's not the tracks. It has to do with how the video clip is created and played back. Movies shot on film and progressive video footage are the easiest to understand. Each frame of the movie is record as a whole and played back as a whole. However, interlaced video is different.

With interlaced video, each frame is divided into two half frames called fields. One field records the even numbered rows of pixels (called the bottom field because it contains the row at the bottom of the frame), the other records the odd numbered rows of pixels (called the upper field because it contains the row at the top of the frame). The two fields are not recorded simultaneously. They are recorded one after the other. When played back, the two fields are displayed one after the other and you see the complete frame.

The two fields need to be played back in the same order as they were recorded. If they are played back in the reverse order, the timing difference can show up as motion artifacts in the image. Where there is motion, the image can appear fuzzy or streaked and resemble the teeth on a comb (called appropriately enough "combing"). Interlaced standard definition video and high definition video are recorded using opposite field orders. If you mix the two together in the same timeline, you need to make sure you've addressed the field order of each clip to make sure all clips match the order used in the project setting.
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Re: How do I process this video? (all efforts are failing)

Postby ChancyRat » Sun Aug 01, 2010 5:24 pm

Bob wrote:No, it's not the tracks. It has to do with how the video clip is created and played back. Movies shot on film and progressive video footage are the easiest to understand. Each frame of the movie is record as a whole and played back as a whole. However, interlaced video is different.

With interlaced video, each frame is divided into two half frames called fields. One field records the even numbered rows of pixels (called the bottom field because it contains the row at the bottom of the frame), the other records the odd numbered rows of pixels (called the upper field because it contains the row at the top of the frame). The two fields are not recorded simultaneously. They are recorded one after the other. When played back, the two fields are displayed one after the other and you see the complete frame.

The two fields need to be played back in the same order as they were recorded. If they are played back in the reverse order, the timing difference can show up as motion artifacts in the image. Where there is motion, the image can appear fuzzy or streaked and resemble the teeth on a comb (called appropriately enough "combing"). Interlaced standard definition video and high definition video are recorded using opposite field orders. If you mix the two together in the same timeline, you need to make sure you've addressed the field order of each clip to make sure all clips match the order used in the project setting.


I appreciate your teaching. I guess I understand enough to know I need to pay attention. (weak smile).
Are we talking only about video clips, i.e., avi + m2ts (SD + HD)?
Or does it apply to m2ts + png + .wav? (audio and video, but where all video is HD)?
I see in PE, Field Options, but what do I turn on or off, and on which clips, and when?
Thanks.
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Re: How do I process this video? (all efforts are failing)

Postby Bob » Mon Aug 02, 2010 2:15 am

I know this can be confusing at first, but it will get easier as you gain more experience.

We are only talking about video -- in particular interlaced video. Still images and titles are not interlaced and do not have a field order; neither do audio files. Premiere Elements will correctly handle those types of files when you export or share your movie.

Field Options is where you control the field order. Select a clip and bring up the Field Options dialog box. At the top of the dialog box you'll see a checkbox labeled "Reverse Field Dominance". To reverse the clip's field order, all you need to do is check that box.

As for which clips and when, if you choose a project preset that matches the field order of all the interlaced clips you want to add, you generally don't need to reverse the field order. If you have some clips that match the project field order and some that don't, you need to reverse the ones that are opposite the project field order. If you play an interlaced clip backwards, the fields will be played back in reverse order as well. You'll need to reverse the field dominance of those clips too in order to play back the fields in the correct time sequence for each frame.
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