fading out last 50 frames - but no keyframe.

[davexnet]

Hello - I'm playing with an old music video in Virtualdub.
I have the video and audio sync'd up and it looks good. (Call it video 0)

The thing is 4000 frames or so, I want to fade to black the last 50 frames -
however, I don't want to re-encode the whole thing and incur another quality loss.

Trouble is, there is no keyframe near that point at which I want the fade to start.

The best I have so far (and it's not too bad) is to save frame 1-3950 as direct stream copy. (Call it video 1)
Then I used avisynth to access video 0 and use
trim(3950,4000)
fadeout(50)

Open this in Virtualdub and save it as video 2. Close, it reopen video 1 and append video 2.
Save as direct stream copy.

Is there a better way to do this? I tried to do the fade part completely in virtualdub, but couldn't get the
"smart rendering" and the fade filter to work.

[guns1inger]

Use a newer version of Virtualdub and you can use smart rendering. It will render just the section you change, without being tied to keyframe boundaries the way the old one was.

[davexnet]

OK - I'll give it a try.
The other thing that occurred to me was,
the MPG file from which I created the "video 0" avi (completely in Virtualdub)
- I should have done the fade then - then no further changes to the video
would have been needed..
Then I could have concentrated on the audio time stretch and mix to
fit the video (which took up most of my time!). Then video 0 could be
used as Direct stream copy with the new audio...

[DarrellS]

Also, use the Fill filter in Blend mode and use the Curve Editer to fade the video exactly where you want to fade it. Then use Smart Render to encode only the filtered section and direct stream copy the rest of the clip. You'll need to select the original codec (DivX?) to get Smart Render to work.