[MEncoder-users] Flashvideo for YouTube using mencoder

[Reimar Döffinger]

On Fri, Feb 22, 2008 at 06:28:35PM +0100, Ben wrote:
> On Fri, Feb 22, 2008 at 5:18 PM, Reimar Döffinger
> <Reimar.Doeffinger at stud.uni-karlsruhe.de> wrote:
> 
> >  Uh... I thought it was rather obvious that the question is quality _at a
> >  fixed bitrate_.
> 
> Not entirely by the way, the YouTube low-quality requirement
> is a maximum of 349 kbit/s (for both Audio + Video).
> When I put less keyframes in, the videorate lowers,
> for example from 262 to 200 kbit/s which is wasting
> 62 kbit/s of room for extra quality, obviously.

When you specified a bitrate of 349kbit/s and your video rate lowers
that means that either 1) your codec sucks 2) you did not do two-pass
and quality will probably be bad anyway.

> So this is not working with a fixed bitrate, but with a maximum.

uh.. What would be the difference between fixed bitrate and maximum? Do
you usually say "well, the maximum is x, but then my video would not
look ugly so let's encode at a bitrate of x/2" or w

> Check out what Jeroen Wijering (we all know him from his
> great free flashplayer code) has to say about it:
> http://www.jeroenwijering.com/?item=FLV_Video_Compression
> He prefers a keyframe every 2 seconds.

His reasons are not clear though. For quality this makes only sense if
you only do one pass or the encoder is stupid and can not realize when
to insert a key-frame (keyint is the _minimum_ interval for keyframes,
a good encoder will of course insert more if this is the most efficient
way to code the video).