-
When exporting to DVD, random problems with Alpha channel
I created some lower-third graphics in After Effects and rendered as “Lossless with Alpha” Quicktime files. I imported them to Premiere Pro 1.5 and put them in a video layer above my DV footage in the timeline. When I press spacebar to play the sequence, everything looks fine (ie. the graphics are overlaid on top of the video with the alpha channel being transparent.). I have a 13-minute video sequence, so I have a graphic come on then wipe off. Then another graphic comes on later then wipes off and so on.
But when I export to DVD, sometimes everything looks fine, other times the graphic comes on with the alpha channel black instead of transparent blocking out the video behind it. I use exactly the same technique throughout the video sequence. I have tried encoding with different bitrates but to no avail. It seems random. One time I burn to DVD and the problem occurs in one part of the video, another time I burn and the problem occurs in a different part of the video but the first part is fine again. Is this a glitch with the Premiere Pro software? What do I do to fix it?
-
2 Replies
-
I have seen this, but could not reproduce the problem dependably. The workaround is to export those sections of the timeline as a DV.AVI and then overlay these above the original footage. I suspect a bug in the Mpeg 2 encoder.
-
I had something similar, though not with alpha channels. I dont think it’s an mpeg but, I think it has soemthing to do with the fact that dvd doesnt work with frames like premiere does but with blocks of encoded data (dont quote me on this, cant explain it in a different way).
So synch between channels containing such stuff can be a problem.
I had a short sequence of frames which were resulting in an animation but they were cut short and the animation was no longer smooth enough.
Maybe this will give u any idea of where to look to fix the problem.
Good luck and if u find the sollution, maybe u post it here as well.
Reply to this Discussion! Login or Sign Up