Render Problem, transparent GIF's

brant wrote on 11/10/2003, 11:32 PM
The problem: What you see rendered in the preview window is not the same as a render to file when using transparent GIF's.

Here's what I'm doing:
I have a video where there are lots of dropouts. I capture each broken frame, drop it into Photoshop (Version 6.) as a PNG. I fix the dropout area, then make most of the remaining frame transparent by deleting the areas around the fix. Then I save as a GIF to preserve the transparent areas. This creates a nice small file size (7k), because I have hundreds of dropouts that I have fixed.

My original video with dropouts is on track two. I place a repaired frame (the GIF file) on track one, right above the video track that has the frame with the dropout. When I play the video back in the preview window, the overlayed GIF file fixes the dropout perfectly. I've done this to hundreds of frames, and now I have a "restored video". (In preview window only).

Except - when I render the project (any any format - MPEG2, AVI, SVCD, etc), the dropouts re-appear in the final file. What is rendered in the final file is NOT what I see in the preview window. It's like the partially transparent GIF files were never there. I see nothing but the original video. All title, and other overlays work fine, and get rendered.

Any reason or clue as to why GIF files with transparency would not get rendered in the final output?

Using WIN98SE. VV4 4.0c

Comments

Grazie wrote on 11/11/2003, 2:05 AM
Good question . . I'm listening . . . .

. . .stupid question coming up .. . Do you think the dropouts are actually in the underlying video? I did say it was a stupid question . . humour me! ;-)

Grazie
brant wrote on 11/15/2003, 12:18 PM
The dropouts are in the underlaying video - but I drop a repaired frame on top- so the final product should be fixed. The fixed dropout line should 'lat over' the bad line in the original frame.

Each frame that I grab is of a bad frame with a droput form the original video. In Photoshop, I use the clone stamp to fix the dropout area, and save the repaired frame. The repaired frame is dropped on track one, above the 'broken' frame. I've tried this now using a PNG file instead of a transparent GIF, and leaving the repaired frame 'as-is". When I Preview the movie - all dropouts are fixed, yet when I render the file, any format, and playback in Windows Media player, Winamp, or preview in my Sonic DVD authoring program, the dropouts re-appear in the final product - it's like they were never fixed. But if I take the final rendered file and put in back onto Vegas, on track threee, and play it back all by it self - there are no dropouts.

I've been trying to figure this out for three days. Adjusting the compostiting modes on the tracks, adjusting the transparency, removing any transparency, etc.

But why it it that if you lay a 'repaired' frame over a broken one - you only get the original broken video? Is Vegas taking the original frame and not compositing it in the final render? Is it confused? Iv'e got to get at least 300 repaired frames to get back into this video.

What I've also tried is instead of using the "clone stamp" in Photoshop, I fill the white dropout pixels in with any other color, like black or blue. Now when I render ther final project, those black pixels show up. What it seems like to me is that Vegas ignores original cloned pixels if you composite a frame. If I can't clone the pixels on top of the dropout, then I can't repair the frame with the dropout.
BillyBoy wrote on 11/15/2003, 2:13 PM
We may have some confusion over terms.

A drop out? Normally as used it means litteraly that; a dropped frame or one that's no longer there. So as you're using the term I'm confused as to how your "fixed" what you don't have to begin with uless of course a drop out means something else to you.

How many tracks, what settings, muted, not muted, compositing, etc. do you have set?

Without any compositing, a track that's higher will totally block what's below it.unless some or all of it is transparent. Then what's below will bleed through. If you in effect create a mask in Photoshop whatever else is in the image if you select the correct file type or just set the Photoshop file to a transparent blackground will be transparent.

You can do it both ways either block what you want to preserve (mask it) then that object whatever its shape with "block" what's in a lower track allowing everything else to bleed through. Or you can mask everything but what you want to preserve, getting the inverse effect making it (the object) transparent.

Hope that made sense.
brant wrote on 11/16/2003, 6:19 PM
The "dropout" I refer to, is a tape dropout as in VHS tape. The little white line that streaks accross the frame whne playing back an old tape. Not a dropped frame. My original video is from an 8mm tape. Only using two tracks for video.

The latest experiment that I've done is to grab a frame in a PNG file format, edit it in Photoshop - which means - Clone Stamp the white line with adjacent pixels to fix it. Save the frame as a PNG (no transparency). Place the frame on track one above the original video frame. It blocks out the "bad" frame below - sort of. .... but not completly in the time alloted.

I then display the timeline showing just one frame accross the screen, and play it back. You can now see that during that 30th of a second, the overlay (repaired frame) does cover up the dropout - but only for 98% of that 30th of a second. It's like the PNG file created is not a full 30th of a sec, but a hair less. There is no option to change the Fame Rate of a media file.

I've tried the Force, Smart and Disable Resample options - no difference. And tried changing the Playback and Undersample rate, Field Order, Pixel Aspect Ratios, etc., of the PNG file - no difference either. Can't cover up that milisecond of white line dropout show through at the very end of the frame playback. I can see this perfectly on an external monitor.

Probably the only option I have left is to cut out the bad frame and replace them with a repaired frame.
brant wrote on 11/16/2003, 7:17 PM
Another append:

The 'repaired' frame PNG file has a Pixel Aspect ratio of 1.000 (Square), and the original video on track two (the one with the bad frames) had a .9091 NTSC DV aspect ratio. If I change the original 'broken' video to have a Pixel Aspect ratio of 1.000 (Square), now the repaired frame and the bad frame now match up in time. If both are .9091 (NTSC DV) the frame times would not still not match.

I guess I'll make my video on track two, 1.000 Square Pixel Aspect ratio instead of .9091 NTSC DV, and leave the PNG still frame as Square also.


brant wrote on 11/20/2003, 11:10 AM
Well, all the above stuff didn't work. I have eliminated droputs during preview playback - but alll the dropouts re-appear in the final rendered file.

I am convinced now that this has to be a Vegas bug. Something in the rendering process is 'confused'. (Along with me.....)

I'll put together a sample file and send it to them.