[MEncoder-users] "High Quality" H.264 at low bit rates ;)

[Grozdan Nikolov (openSUSE Linux)]

On Friday 22 February 2008 20:18, Gunter Ohrner wrote:
> Hi!
>
> I'm tyring to recode some MPEG2 streams to H.264 using mencoder and
> x264enc, my aim is to reduce the size significantly without a too severe
> quality loss. (Of course I'm aware that I'll lose quality in a
> lossy-to-lossy recoding in any case.)
>
> I'm using a post 1.0.rc2 mencoder (binary build of an svn snapshot from
> 20071207).

I get near DVD quality with a bitrate of 1100-1400... H.264 really shows its 
efficiency at high resolutions and low bitrates. You might also try out 
http://h264enc.sourceforge.net which has 38 different presets - use either 
the VHQ or the EHQ preset. If you want to futher improve the quality of your 
encodes in dark flat areas, then get the adaptive quantization patch for x264 
and patch & recompile x264

>
> What bitrate reduction factor should I be able to achieve?
>
> I'm asking as I read
> http://www.mplayerhq.hu/DOCS/HTML/en/menc-feat-x264.html, the mencoder man
> page and http://en.wikipedia.org/wiki/H264 .
>
> For my tests, I'm using bitrate-based three-pass encoding with variing
> encoding parameters.
>
> My source material is an 9.8 MBit MPEG2 stream. If I encode to 4 MBit
> H.264, there are still significant visual artifacts and a significant loss
> of detail in comparison to the source material.
>
> As I read that H.264 aims for at least twice the coding efficiency of MPEG2
> or more, I wonder if this is correct and to be expected, or what encoding
> parameters have proven themselves to optimize the perceived visual quality?
>
> There's probably no way to aim for 2 mbit H.264 video without experiencing
> severy quality losses, right?
>
> Greetings,
>
>   Gunter
>
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-- 
Regards