Why can't anything do a lossless rotation?

[jimrooney]

I'm curious.
I've done a bit of looking around, but it seems that nothing can do a lossless 180deg rotation.

AVIDemux does essentially what I need if I match up the video codecs, but I'm curious why it can't simply "copy" the video type?

My interest is in speed btw.
I have to mount my cameras upside down and wish to flip the video before I do any editing. I'm not a fan of monolithic editors (AVIDemux is a godsend), so "do it all in FinalCut" (or similar) just doesn't do it for me.

Like I said, I've got a process that works, I'm just curious.
Thanks
Jim

[jagabo]

Because the image data needs to be decompressed, rotated, and recompressed.

[poisondeathray]

There is a trick you can do in Quicktime Pro, and you can losslessly rotate most videos in the mov container. But it only works in QT Player, other players won't accept this (except MPC seems to work, because it's using the installed QT directshow components). I think it is a container level signalling modification, not sure of the mechanism.

In movie properties => highlight the video track => visual settings => flip/rotate. And you can save the changes.

[jagabo]

Yes, that just sets a metadata flag in the header. It tells the player to rotate the video during playback. It doesn't really rotate the image within the video file.

[creamyhorror]

Why not include the rotation as part of your editing step, so you don't have to recompress? (Unless, that is, you don't do a full recompression during the edit...)