[MPlayer-users] Mencoder fails: Cannot initialize video driver

[Rich Felker]

On Thu, Jan 24, 2008 at 03:19:36AM +0000, Da Rock wrote:
> Thanks for the very concise answer on that. So I frames are key
> frames and the keyint is like (forgive the example) the frames used
> for tweening in flash.

Yes.

> What are the B frames if I can press you further? Are they the
> interval frames?

B frames are bidirectionally-predicted frames, that is, they're
encoded as difference from both past and future frames.

> How much effect on quality does changing this variable make? Is the
> quality of the video improved or only the seeking?

At a fixed bitrate, the quality will be lowered by using a smaller
keyint, since more bits will be spent on encoding the I-frames "from
scratch" which does not contribute to quality, only seekability.

On the other hand, if you use any sort of "fixed quality" type
encoding, lower keyint will not affect quality; it will just make your
file come out larger.

Rich