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--- ffmpeg:decoding:extract_some_streams [2023/11/02 22:54] – created peter
+++ ffmpeg:decoding:extract_some_streams [2023/11/02 23:03] (current) – peter
@@ Line 1: / Line 1: @@
 ====== 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>