[MEncoder-users] Different parameters in two-pass encoding

Guillaume POIRIER poirierg at gmail.com
Sun Feb 1 23:26:45 CET 2009


On Sun, Feb 1, 2009 at 11:12 PM, Stjepan Brbot
<stjepan.brbot at zg.t-com.hr> wrote:
> Hi,
> several times on Internet and this mailing lists archive I found that
> people recommend setting parameter "turbo" in 1st pass encoding while
> omitting it in 2nd pass.

That's silly. turbo option as an effect only if it's specified in the
first pass. Otherwise isn't a non-op.

> Or even, to define only subset of parameters in
> 1st step and put several additional parameters (like mdb=2:vhq=4) in 2nd
> pass. Generally speaking, is this correct?

Well, the whole purpose of turbo is that you keep the same options for
all passes, and let turbo remove the most expensive ones that have a
very little or no impact on the resulting 2-pass encode.

> In my opinion 1st pass log is
> used for better redistribution of bitrate in 2nd pass encoding but 1st
> pass log should be created with exactly the same conditions (encoding
> parameters). Isn't it?

That's correct, but it's all a matter of trade off IMHO. I prefer to
speed-up the first pass, and invest the time I saved in the first pass
to use higher quality encoding options. In the end, for given the same
overall time, I get better quality.

Only a very small fraction of our DNA does anything; the rest is all
comments and ifdefs.

Samuel Goldwyn  - "I had a monumental idea this morning, but I didn't like it."

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