[MPlayer-DOCS] [PATCH] XviD documentation reaching almost completeness

[Dominik 'Rathann' Mierzejewski]

On Tuesday, 07 September 2004 at 14:40, Guillaume POIRIER wrote:

> --- main/DOCS/man/en/mplayer.1	2004-09-07 11:56:20.000000000 +0200
> +++ mplayer.1.latest_xvid_patch 2004-09-07 14:37:59.000000000 +0200
> @@ -6027,8 +6027,8 @@
>  .TP
>  .B rc_reaction_delay_factor=<value>
>  This parameter controls the delay in frames before the CBR rate
>  controller
> -will react to bitrate changes and will try to compensate the change
> to obtain
> -a constant bitrate over an averaging range of frames.
> +will react to bitrate changes and will try to compensate for the
> change to
> +obtain a constant bitrate over an averaging range of frames.
>  .
>  .TP
>  .B rc_averaging_period=<value>

Maybe "compensate for them", because "changes" were mentioned a few
words before. Repeating the auxillary verb is also unnecessary. And
I'd rephrase it even further to be completely clear:

This parameter controls the number of frames the CBR rate controller
will wait before reacting to bitrate changes and compensating for them
to obtain a constant bitrate over an averaging range of frames.

One more question: what's an "averaging range of frames"? Is it the
number of frames specified in rc_averaging_period?

> +Sometimes B frames do not look good, and introduce artifacts when
> most of
> +the frame is static and some small zones have high motion (in a static
> +scene with a man talking, his mouth will probably look bad if what is
> +surrounding the man and his mouth is completly static).
> +This setting allows you to favorize or not, the use of B frames.
> +The higher the value, the higher the probability of B frames being used.
> +(default: 0)

As spotted by Wanderer, there's no such verb as favorize. Use favour (do
we use British or American spelling?). And I'd say:

This setting controls the probability of B frame being used in such cases.
The higher...

> +.B frame_drop_ratio=<0\-100>
> +XviD keeps track of block coding type (skipped, predicted, intra).
> +The skipped block counter can be used to choose whether a frame is
> so close
> +to its reference that it can be
> +.I completly
> +skipped.
> +This setting allows you to choose the (100 \- value) threshold for
> skipping
> +a frame.

This isn't clear to me. Please rephrase and make it clearer. What is this
threshold and when is a frame skipped? What does it mean it's skipped? Is
it simply not encoded or is reference frame used instead of it?

> +.TP
> +.B curve_compression_high=<0\-100>
> +This settigs control how much the upper part of the curve has to get
> +closer to the average bitrate value.

control_s_

Better: This setting controls how close the upper part of the curve has to
get to the average bitrate value.

But, docs on the net (for example http://nic.dnsalias.com/XviD_Options_Explained.pdf)
say when you set it to 0, you get prefect VBR. Higher settings will take away
specified percentage of bits from high motion scenes, while lower will give
them additional bits. This pdf, however, describes VirtualDub's interface to XviD,
so this may not be the same. So which is it?

> +The upper part of the curve is the set of values that are higher than
> +the curve average.

Huh? This doesn't make sense to me. Values of what?

> +Think of that setting like a shrinking factor for the upper part of
> +the curve (default: 0).

"Think of ... as", not "like". 

> +.
> +.TP
> +.B curve_compression_low=<0\-100>
> +This settigs control how much the lower part of the curve has to get
> +closer to the average bitrate value.
> +The lower part of the curve is the set of values that are lower than
> +the curve average.
> +Think of that setting like a growing factor for the lower part of
> +the curve (default: 0).

Same as above.

> +MPEG4 defines 5 standard Pixel Aspect Ratio and one extended
> +one, giving the opportunity to specify a specific pixel aspect
> +ratio.

You missed Diego's suggestion: 5 standard pixel aspect ratio_s_.

R.

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