Thanks.
Unfortunately, it doesn't matter what you do on the timeline. The ouput PNG sequence is always 32bit.

I should say, I'm using Vegas Pro 10.

I think PNG exported from Vegas does always include alpha channel.
I had same problem when I needed frames for a Sony MVS6000 switcher which does not accept alpha channel. I either needed to reformat the PNGs outside Vegas Pro to 24 bit or switch to BMP export.

The alpha is what shows emptiness, so adding a solid background like said above would have nothing in the alpha channel. A solid black would do the same thing as white, except be black.

Thanks everyone.

Marco, I have the same problem as you - software that needs 24bit, not 32. My Vegas data is 4k, 46000 frames long. So now I have to spend another 16 hours converting to 24bit.

Strange something would accept a 24-bit png & not a 32 & just ignore the alpha.

I just tested though, infranview can strip the alpha from the image. It will be replaced with color 0,0,0. I'd say render as a bmp instead & convert that to a ping. Might be faster because it won't need to uncompress when converting.

Thanks.
I haven't tried BMP because of the potential files sizes. I'll give it a test.

I'd also suggest IrfanView for batch converting. The choice is up to you if you'd like converting to BMP or to 24 bit PNG within IrfanView.

Thanks. I'll give it a try.

Blender is free and allows you export by selecting the PNG levels you want, RGB or RGBA is selector in the render panel. Just a thought.