flipped .avi video jagged playback

M. Krishna Babu · March 14th, 2006, 05:08 AM

dale,
meanwhile i did a small test on the footage.it goes like,
1.take a clip apply adam's flip and render to new track
playing back the track makes the video shimmer
2.now apply the same flip to the newly rendered track and render to .avi
surprisingly, the shimmer is gone (though the video is upsidedown). its like the video has some back to normal.

then i did the same test with pan/crop flip mechanisms discussed in previous posts, but the final video has shimmer.

umm...some thing is defnitely happening here.
i think its time i look at 'flipping the camera' mechanism
dale & Douglas, i appreciate your effort to help me out.

thank you very much.
krishna.

Douglas Spotted Eagle · March 14th, 2006, 08:15 AM

No comment, I give up. Uncle.

Dale Paterson · March 14th, 2006, 10:55 AM

Douglas, I waited all day for your input!

Please at least see one of my previous posts detailing a 'theory' that I have.

Regards,

Dale.

Hornady Setiawan · June 3rd, 2006, 09:03 AM

* when your project settings is interlaced, vegas will process it field-by field.

* when you flip a frame, the field order is also flipped. eg. odd become even and even become odd. To visualize this easily, just draw 2 lines. Once u flip it, the upper line becomes the lower line. Hence the field flipped. To overcome this, u must flip the frame, then shift the frame 1 pixel up or down. This will recorrect the field order.

* somehow, vegas flip the frame before outputing the fields to the encoder. Remember in 1 frame there are 2 fields. Actually, vegas should separate the fields first, flip them, then re-interlace the fields into 1 frame, then output to encoder.

* i think Krishna's media player is playing the avi file in 50 fields per second. That's why he sees it 'shimmer' back & forth. Some codec allows playing back in 50 field/sec, separating the field first for viewing. Some other codec plays back in 25 frames/sec, either discarding 1 field or displaying both fields in 1 frame.

* there are tools for field processing in virtualdub. You can reverse field order, or shift the fields 1/2 a frame, etc. Also in avisynth (& in most compositing app). In vegas, you may want to try intrepreting the DV file as upper field first or set the project as upperfieldfirst, or another workaround is to set the project as progressive & turn on reduce interlace flicker.

hope this clears something...

Adam Woodworth · June 6th, 2006, 06:26 PM

Did someone say my name? :)

First off, what is your target medium for your video output? TV/DVD, or computer/internet?

If it is for TV, then burn a sample DVD, or print a sample to tape. Play it back on your TV. Does it look fine on the TV? Then you're all set.

If it is for computer, then your final render should NOT BE interlaced! Computers are progessive, not interlaced, so you really should be rendering it out as progressive footage. That's not to say that you need to loose any sharpness -- just render it as the full frame-per-second rate for your source (e.g., 29.97 for NTSC). That way the 2 fields are just stored as one frame. When you playback interlaced footage on your computer it's doing this anyways, but some media players don't do it so well.

Whether or not this will fix your problem I'm not sure, as I haven't seen this problem.

Also, don't trust Windows Media Player. It's got bad karma. I suggest the freely available VLC player at www.videolan.org.

Of course, you can always upgrade to a 24p capable video camera. :)

March 14th, 2006, 08:15 AM	#17
Douglas Spotted Eagle VASST Join Date: Jan 2004 Location: Stockton, UT Posts: 5,648	No comment, I give up. Uncle. __________________ Douglas Spotted Eagle/Spot Author, producer, composer Certified Sony Vegas Trainer http://www.vasst.com

June 6th, 2006, 06:26 PM	#20
Adam Woodworth Regular Crew Join Date: Jan 2005 Location: Cambridge, MA Posts: 55	Did someone say my name? :) First off, what is your target medium for your video output? TV/DVD, or computer/internet? If it is for TV, then burn a sample DVD, or print a sample to tape. Play it back on your TV. Does it look fine on the TV? Then you're all set. If it is for computer, then your final render should NOT BE interlaced! Computers are progessive, not interlaced, so you really should be rendering it out as progressive footage. That's not to say that you need to loose any sharpness -- just render it as the full frame-per-second rate for your source (e.g., 29.97 for NTSC). That way the 2 fields are just stored as one frame. When you playback interlaced footage on your computer it's doing this anyways, but some media players don't do it so well. Whether or not this will fix your problem I'm not sure, as I haven't seen this problem. Also, don't trust Windows Media Player. It's got bad karma. I suggest the freely available VLC player at www.videolan.org. Of course, you can always upgrade to a 24p capable video camera. :) __________________ Bourbon: It's hard being a small time gangster. http://www.bourbonmovie.com

March 14th, 2006, 05:08 AM	#16
M. Krishna Babu New Boot Join Date: Sep 2005 Location: Hyderabad. India Posts: 20	dale, meanwhile i did a small test on the footage.it goes like, 1.take a clip apply adam's flip and render to new track playing back the track makes the video shimmer 2.now apply the same flip to the newly rendered track and render to .avi surprisingly, the shimmer is gone (though the video is upsidedown). its like the video has some back to normal. then i did the same test with pan/crop flip mechanisms discussed in previous posts, but the final video has shimmer. umm...some thing is defnitely happening here. i think its time i look at 'flipping the camera' mechanism dale & Douglas, i appreciate your effort to help me out. thank you very much. krishna.

March 14th, 2006, 10:55 AM	#18
Dale Paterson Major Player Join Date: Jun 2005 Location: Johannesburg, South Africa Posts: 200	Douglas, I waited all day for your input! Please at least see one of my previous posts detailing a 'theory' that I have. Regards, Dale.

June 3rd, 2006, 09:03 AM	#19
Hornady Setiawan Regular Crew Join Date: May 2005 Location: Jakarta, Indonesia Posts: 103	* when your project settings is interlaced, vegas will process it field-by field. * when you flip a frame, the field order is also flipped. eg. odd become even and even become odd. To visualize this easily, just draw 2 lines. Once u flip it, the upper line becomes the lower line. Hence the field flipped. To overcome this, u must flip the frame, then shift the frame 1 pixel up or down. This will recorrect the field order. * somehow, vegas flip the frame before outputing the fields to the encoder. Remember in 1 frame there are 2 fields. Actually, vegas should separate the fields first, flip them, then re-interlace the fields into 1 frame, then output to encoder. * i think Krishna's media player is playing the avi file in 50 fields per second. That's why he sees it 'shimmer' back & forth. Some codec allows playing back in 50 field/sec, separating the field first for viewing. Some other codec plays back in 25 frames/sec, either discarding 1 field or displaying both fields in 1 frame. * there are tools for field processing in virtualdub. You can reverse field order, or shift the fields 1/2 a frame, etc. Also in avisynth (& in most compositing app). In vegas, you may want to try intrepreting the DV file as upper field first or set the project as upperfieldfirst, or another workaround is to set the project as progressive & turn on reduce interlace flicker. hope this clears something...