40k.
The second instance is downmixed to 2 channels and encoded with codec aac. A bitrate of 128k is specified for it using
absolute index of the output stream.
</p>
<p>Note: the &lsquo;<samp>-nooption</samp>&rsquo; syntax cannot be used for boolean
AVOptions, use &lsquo;<samp>-option 0</samp>&rsquo;/&lsquo;<samp>-option 1</samp>&rsquo;.
</p>
<p>Note: the old undocumented way of specifying per-stream AVOptions by
prepending v/a/s to the options name is now obsolete and will be
removed soon.
</p>
<a name="Ma