ated from it by a colon. E.g. <code>-codec:a:1 ac3</code> contains the
<code>a:1</code> stream specifier, which matches the second audio stream. Therefore, it
would select the ac3 codec for the second audio stream.
</p>
<p>A stream specifier can match several streams, so that the option is applied to all
of them. E.g. the stream specifier in <code>-b:a 128k</code> matches all audio
streams.
</p>
<p>An empty stream specifier matches all streams. For example, <code>-codec copy</code>
or <code>-codec: copy</co