How to remove one track from video file using ffmpeg?

Question

How to remove only one track (not all) from video file container (.vob or .mkv) using ffmpeg?

I know I can just copy video (-c:v copy -an) and specific audio track from container into two separated files and then join them.

But is there an easier way? Can I just remove specific audio track from container? ffmpeg command?

Answer 1

The most efficient method is to use negative mapping in the -map option to exclude specific stream(s) ("tracks") while keeping all other streams.

Remove a specific audio stream / track

ffmpeg -i input -map 0 -map -0:a:2 -c copy output 

• -map 0 selects all streams from the input.
• -map -0:a:2 then deselects audio stream 3. The stream index starts counting from 0, so audio stream 10 would be 0:a:9.

Remove all audio streams / tracks

ffmpeg -i input -map 0 -map -0:a -c copy output 

• -map 0 selects all streams from the input.
• -map -0:a then deselects all audio streams from the input.

Remove specific audio streams / tracks

Keep everything except audio streams #4 (at offset 3) and #7 (at offset 6):

ffmpeg -i input -map 0 -map -0:a:3 -map -0:a:6 -c copy output 

Remove all subtitles and data

ffmpeg -i input -map 0 -map -0:s -map -0:d -c copy output 

Only include video and audio

This example does not need to use any negative mapping.

ffmpeg -i input -map 0:v -map 0:a -c copy output 

Removing other stream / track types

If you want to remove other stream types you can use the appropriate stream specifier.

• v - video, such as -map -0:v
• a - audio, such as -map -0:a (as shown above)
• s - subtitles, such as -map -0:s
• d - data, such as -map -0:d
• t - attachments, such as -map -0:t

Extract or remove a specific audio channel

Using a stereo input and channelsplit filter. Example to get the right channel only and output a mono audio file:

ffmpeg -i stereo.wav -filter_complex "[0:a]channelsplit=channel_layout=stereo:channels=FR[right]" -map "[right]" front_right.wav 

• channel_layout is the channel layout of the input stream. The default is stereo.

• channels lists the channels to be extracted as separate output streams. The default is all which extracts each input channel as a separate, individual stream.

• See ffmpeg -layouts for a list of accepted channel layouts (for channel_layout option) and channel names (for channels option).

• See FFmpeg Wiki: Audio Channels for more examples.

More info

• -map option documentation
• FFmpeg Wiki: Map

Answer 2

You are looking for -map.

I have changed to using avconv, but it should be about the same.

Let's say you have a file called "input.vob" with one video and two audio tracks; and you want to have "output.vob" with the video and the last audio.

You would do:

avconv -i input.vob -map 0:0 -c:v copy -map 0:2 -c:a copy output.vob 

You should notice that:

1. I did not copy -map 0:1
2. I did not need to do -an, because there are audio tracks. However, if there are no audio tracks at all, you may need to use such an attribute.
3. Sometimes the streams are not numbered in the way i've described, for example audio can come before video.
4. If there are subtitle streams there, you need to figure out how to deal with them as well.

You cannot work on files "in place", you need to save into a different file.

P.S. You may want to ask such questions on video.stackexchange.com next time.