, can be a string of the form
<var>width</var>x<var>height</var> or a video size abbreviation.
If not specified it defaults to the size of the input video.
</p>
</dd>
<dt>&lsquo;<samp>driver</samp>&rsquo;</dt>
<dd><p>Set display driver.
</p>
</dd>
<dt>&lsquo;<samp>algorithm</samp>&rsquo;</dt>
<dd><p>Set dithering algorithm. Dithering is necessary
because the picture being rendered has usually far more colours than
the available palette.
The accepted values are listed with <code>-list_dither algorithms</code