[MPlayer-DOCS] Interested in contributing case studies

[Loren Merritt]

On Fri, 20 Oct 2006, Mark Pilgrim wrote:

> Draft 2 attached. Incorporated all of Jeff's feedback -- corrected
> factual inaccuracies, added turbo, removed default options, rephrased
> text on scaling and multithreading, etc. Feel free to critique

>+ The next step is truly heartbreaking.
>+ <application>QuickTime</application> 7 does not support MPEG-4 videos
>+ with a display aspect ratio different from the sample aspect ratio,
>+ so you will need to scale the video to square pixels.  This wastes a
>+ lot of disk space, but it simply can not be avoided if you want your
>+ video to be playable by <application>QuickTime</application>.

"...does not support MPEG-4 videos with a sample aspect ratio other than 1."
Your statement meant instead that the whole video must be square.

>+ Of course you want a full-resolution video, so you will not be scaling
>+ vertically.  To scale horizontally, you first need to know what aspect
>+ ratio the source DVD uses.  <application>MPlayer</application> can tell
>+ you this:

You don't actually need to know that. "-vf scale=-10:-1" will pick the 
right width for the current height, rounded to a multiple of 16 for 
optimal compression.

>+ The second pass is the same, except that you specify
>+ <option>pass=2</option> and remove the <option>turbo</option> option.

You don't have to remove turbo, it automatically disables itself on the 
2nd pass.

>+ I have a dual-processor machine, so I usually add
>+ <option>threads=2</option>.  This can result in slightly larger files,
>+ but it increases encoding speed by 20-30%.  Real multithreaded support
>+ requires that <systemitem>libx264</systemitem> be compiled with
>+ <option>--enable-pthreads</option>.

"Real multithreaded support" as opposed to what, fake multithread? 
Imo, --enable-pthreads doesn't need to be mentioned anymore, since x264 
has had autodetection for such libraries for a long time. Yes, it's 
possible to compile x264 without multithread support, but only by adding 
--disable-pthreads or by using some os other than linux, windows, and bsd.

--Loren Merritt