Why does a 2GB video file not fit on an iDVD project?

[TitanTiger]

I have a 2GB m4v file that I wanted to use iDVD to create a movie for. But even taking it off of Best Performance and instead using High Quality, the movie is too large to be burned. It's showing it as a 4.81 GB project.

I'll admit my ignorance here...what gives? How does a 2GB file grow that large when being encoded as a DVD?

 

[spinnerlys]

The 2GB .m4v file uses the H264 codec, an MPEG-4 variant.
Video DVDs use the MPEG-2 codec to encode the video.

MPEG-2 is older and less space efficient than MPEG-4, thus the transcoding process from MPEG-4 to MPEG-2 creates a larger file.

An SL-DVD can store up to 90 minutes with medium quality, an MPEG-4 video of the same size (4.37MB) can store much more than 90 minutes.

 

[PinkyMacGodess]

I figured it was a compression issue. I had no idea that the efficiency of the two was so dramatically different.