[MPlayer-users] How to find "technical differences" in MPEG?

[RC]

On Tue, 20 Feb 2007 04:12:10 +0100
karl-heinz-1950 at web.de wrote:

> assume further that there is a given colour depth, that way I have a
> fixed amount of bits I have to read per second. 

That would only be true if the video is uncompressed, and
all-key-frames...  which it never is.

Key and non-key frames are vastly different sizes, and the size of each
frame will vary constantly.  Some images are just more compressible
than others.

<blockquote>Reading faster would fill the buffer, reading slower will
stop the movie for a short time (if the buffer is empty).</blockquote>

Hardware players have no choice of speeds to read at.  The DVD-ROM spins
at 1X, no matter how much or little data it wants.  All the player can
tell the drive is to read X bytes, starting at position Y, then wait and
hope.  Presumably, X is how much free-space there is in the buffer.  If
the bitrate is too high, and the buffer isn't big enough to make-up the
difference, the video will be be corrupted.

> Secondly, what does a settop DVD recorder vary for the different
> recodring modes? (e.g. on one DVD either 1 hour or 4 hours of movie)

I can't say (don't have one, and never checked).  Given the constraints
of the format, it's probably some combination of video bitrate, and
video resolution.