# FFmpeg

Just some useful FFmpeg commands I sometimes use.

## Show file information

    ffmpeg -i input.mp4

Lists (among other things) the streams contained in the file, like `Stream #0:0: Video: h264..` or `Stream #0:1: Audio: aac..`.

## Extract Audio

Extract as WAV:

    ffmpeg -i input.mp4 -map a output.wav

Extract without re-encoding (-c(odec) copy, container format depends on what the original audio encoding is):

    ffmpeg -i input.mp4 -map a -c copy output.aac

If there's more than one audio track you can select a certain stream in the file (in this example the 3rd track in the first file):

    ffmpeg -i input.mp4 -map 0:2 -c copy output.aac

## Exchange Audio

Use several input files and select which streams you want to have in there:

    ffmpeg -i input.mp4 -i audio.aac -map 0:0 -map 1:0 -c copy output.mp4

In this example, it's using the first stream from the first file (`-map 0:0`) and the first stream from the second file (`-map 1:0`). And it's still just making a copy of the streams instead of encoding them (`-c copy`).

## Mute Audio

To mute part of the audio of a video, you can use the following:

    ffmpeg -i input.mp4 -af "volume=enable='between(t,10,30)':volume=0" -c:v copy output.mp4

The audio filter mutes the audio between 10 and 30 seconds into the video. The `-c:v copy` directly copies the video only, the audio has to be re-encoded. You can also mute more than one section:

    ffmpeg -i input.mp4 -af "volume=enable='between(t,10,30)':volume=0, volume=enable='between(t,120,180)':volume=0" -c:v copy output.mp4

This would mute the parts between 10 and 30 seconds and between 2 and 3 minutes into the video.

## Cut

To cut out part of a video (without re-encoding), for example starting at 12 minutes to 12 minutes 10 seconds, all of the following are equivalent:

    ffmpeg -i input.mp4 -c copy -ss 0:12:00 -t 0:00:10 output.mp4
    ffmpeg -i input.mp4 -c copy -ss 12:00 -t 0:10 output.mp4
    ffmpeg -i input.mp4 -c copy -ss 0:12:00 -to 0:12:10 output.mp4

-ss starttime offset
-to endtime offset
-t duration

### cut.bat

To make things a bit easier the following very simple .bat-file can be used:

    ffmpeg -i %1 -ss %2 -to %3 -c copy output.mp4

Usage:

    cut.bat IN_FILE.mp4 10:00 1:05:00

## Put together video parts

This is useful when a video is in several parts and you want to put it together without re-encoding (e.g. old Twitch VOD parts). Create a text file called e.g. `concat.txt`, containing the lines:

    file 'live_user_joshimuz_1408262284.flv'
    file 'live_user_joshimuz_1408263805.flv'
    file 'live_user_joshimuz_1408265325.flv'

Then use the command:

    ffmpeg -f concat -i concat.txt -c copy output.mp4