[MEncoder-users] Help with MPG video encoding

[Walter Belhaven]

Hi,

I've got a question on how to get the best possible MPG encoding of a
movie source, "at any price" so to speak -- i.e., as many bits as the
encoder needs to get the highest possible video quality.

It appears to me that the MPG encoding process is introducing artifacts
that are present regardless of the amount of "free reign" I give to the
encoder with respect to quantization, bitrate, and the like.  My bottom
line question is thus: "Are these artifacts inherent in MPG encoding,
or am I just not twiddling the knobs and dials on the encoder
correctly?"

Here's all the details ...

My source is a mixed hard- and soft-telecined "movie" at 1080/60i that
I'm trying to tanscode to 480/24p, soft telecined to 480/60i, for
ultimate burning to an NTSC DVD-Video.

When I use mencoder to inverse telecine, crop out the crud, expand back
to the original letterbox ratio (it's 2.35:1, not 16/9), and 'encode'
the video with HUFFYUV (422P), the resulting video looks stunning, with
no 'blocking' artifacts to speak of.  This, of course, is as expected.

But when I encode the video in MPG2 or MPG4, even with vqscale=1 or
vqscale=2, I see sometimes severe blocking in the resulting video.  Is
this because the chroma is being subsampled vertically and horizontally
(4:2:0), or is it because 'vqscale' is (perhaps necessary but) not
sufficient to get "maximum quality at any price" encoding?

Thanks,
WB



 
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