[MPlayer-users] Re: Mpeg2 encoding results

Nico nsabbi at libero.it
Mon Sep 1 18:56:04 CEST 2003



Jonathan Rogers wrote:

> [Automatic answer: RTFM (read DOCS, FAQ), also read DOCS/bugreports.html]
> Nico wrote:
>
>> Well, the quality was very good, but both movies showed the usual 
>> problem that I find in every lavc encoding (mpeg1/2/4):
>> black areas show many visible greyish blocks, at least when read from 
>> a DVD player.
>
>
> Just out of curiosity, have you found an MPEG-4 encoder that doesn't 
> have this problem as much at the same BPP? 


yes, Xvid satisfies me much more, especially because it almost never 
shows this problem.
I also made some movies with both  xvid and lavc (and the same 
settings),  and I always liked much more the one made xvid;
now that I think of it lavc seems to suffer from another main problem: 
wormito noise;
I call it wormito because it's not like mosquito that is spread in dots 
without continuity; wormito shows continous  lines like worms moving
around outlines.

> I haven't noticed XviD or DivX doing much better, but maybe I just 
> haven't looked closely enough. Maybe lavc doesn't scale up to high 
> bitrates as well as other encoders?
>
>> Mplayer is so good at decoding that it  deceives the eyes, showing a 
>> good picture (blocks show less) even when it's bad :)
>
>
> It seems to be somewhat accepted that video quality is a function of 
> both the encoder and decoder, though there is clearly more of 
> challenge in the encoding. Maybe it's that MPEG-4 gives much more 
> freedom for the decoder to enhance quality than MPEG-2 and the lavc 
> encoder and decoder are essentially MPEG-4 encoders, even in MPEG-2 
> mode. Or, perhaps DVDs allow for such high bitrates that they don't 
> typically need good decoders to get good results.

I guess that DVD players expect to have near-perfect, and high bitrate, 
movies that don't need post-processing.

>
> Jonathan Rogers
>
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Nico




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