====== ffmpeg - Decoding - Extract some streams ======

===== Check what streams exist =====

<code bash>
ffmpeg -i inputfile
</code>

returns:

<code>
Stream #0:0: Video: hevc .....
Stream #0:1(eng): Audio: aac ....
Stream #0:2(eng): Subtitle: ...
Stream #0:3(fre): Audio: aac ....
Stream #0:4(fre): Subtitle: aac ....
</code>

----

===== Extract some streams =====

<code bash>
ffmpeg -i inputfile.mkv -map 0:0 -map 0:1 -map 0:2 -c:v libx264 -preset fast -crf 25 -c:a copy -c:s copy english-output.mp4
</code>

<WRAP info>
**NOTE:**  This extracts only the Video, English audio and Subtitles; but encodes the video (fast crf 25):

  * Processing what you mapped is done sequentially.
    * **-map 0:0** is the Video stream; because the **-c:v** is the first action and therefore goes to this 1st mapping.
    * **-map 0:1** is the Audio stream, because the **-c:a copy** is the second action and therefore goes to this 2nd mapping.
    * **-map 0:2** is the Subtitles stream, because the **-c:s copy** is the third action and therefore goes to this 3rd mapping.

  * There are shortcuts too, that could be used:
    * **-map 0:v** selects all the video type streams.
    * **-map 0:a** selects all the audio type streams.

</WRAP>