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  • Compression Techniques

    FFMPEG: I need to remove 14 out of 16 audio channels from a mov file

    Posted by Andreas Wojtaschek on September 3, 2019 at 8:05 am

    Hi,

    first of all: I’m new to FFMPEG so I need some help from some professional users.

    I have a relative simple task:

    I have some MOV files with a single audio track that contains 16 channels.
    I want to remove the last 14 tracks and create a file with copied video (no reencoding) and just the first two audio channels. The 14 last tracks should be discarded.

    I found a lot of tutorials for creating 5.1 files etc. but not what I need. Could someone please point me to the right direction or even post the command to accomplish this task?

    Thanks so much for all your help!

    Robert

    Lou Logan replied 6 years, 7 months ago 2 Members · 1 Reply
  • 1 Reply

  • Lou Logan

    October 9, 2019 at 7:05 pm

    It is not possible to split channels or use filters without re-encoding, but in this case you can stream copy (re-mux) the video without re-encoding because you are not filtering it.

    Use the channelmap filter:

    ffmpeg -i input -af "channelmap=map=0|1:channel_layout=stereo" -c:v copy output

    or

    ffmpeg -i input -af "channelmap=map=FL|FR:channel_layout=stereo" -c:v copy output

    See “ffmpeg -layouts” for channel layout names and descriptions.

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