I have multiple .webm files in one location, say as inside video folder. I'm using Ubuntu 13.10 32bit system. I want to merge all my webm files in one output.webm file.

I have read about ffmpeg, but when I tried ffmpeg with concat function I got:

Unknown input format: 'concat'; And ffmpeg is deprecated and use avconv instead.

Please suggest how to use avconv for merging multiple webm files to one.

  • 1
    The fake ffmpeg from Libav is what was deprecated for avconv; not ffmpeg from FFmpeg. Unfortunately the maintainer refused to clarify that in the message resulting in confused users (and some think it was the intended effect).
    – llogan
    Commented Jan 30, 2015 at 20:21
  • Please download a recent ffmpeg build and then show some info about your inputs. It will help me provide an answer, and avconv doesn't have the functionality of what I'm going to suggest. Include the full output of: ffmpeg -i input0.webm -i input1.webm -i input2.webm, etc.
    – llogan
    Commented Jan 30, 2015 at 20:27
  • 1
    2 questions: 1. Which version of Ubuntu are you using? 2. What are the file names of your webm files?
    – andrew.46
    Commented Jun 18, 2016 at 4:49
  • 1
    Ubuntu is 13.10 32bit. No specific file names yet, you can just take file names as one.webm, two.webm, three.webm etc. and merge them into merged.webm. Commented Jun 18, 2016 at 6:20
  • @MandarPandit Support for Ubuntu 13.10 ended on 17 July 2014. You should upgrade to a supported version.
    – llogan
    Commented Jun 18, 2016 at 18:23

1 Answer 1



The first step is to download ffmpeg. It's a standalone binary so you don't need to install it. Just execute it directly.

Your (expired) Ubuntu version offers avconv which is missing many features including several concatenation functions.


Use the concat demuxer if you want to attempt to join them with no re-encoding. All videos must have the same parameters.

Use the concat filter if the videos vary in width, height, frame rate, etc. The filter will require re-encoding.

Note: You never did provide the info I requested a year and a half ago in my comments to your question, so I can't suggest which one you specifically need to use. Also, I can't provide examples specific to your inputs without this info, so the following examples are generic and may not work without additional options.

concat demuxer

Make a text file listing your inputs:

file 'input0.webm'
file 'input1.webm'
file 'input2.webm'

Now run ffmpeg:

ffmpeg -f concat -i input.txt -c copy output.webm

concat filter

In this example input1.webm has a bigger width x height than the others. This example command will scale input1.webm so it matches the other videos:

ffmpeg -i input0.webm -i input1.webm -i input2.webm -filter_complex \
"[1:v]scale=640:-1[v1]; \
 [0:v][0:a][v1][1:a][2:v][2:a]concat=n=3:v=1:a=1[v][a]" \
-map "[v]" -map "[a]" output.webm

Also see

  • 1
    Nice to know about the static build availability , :) that's really helpful.
    – user.dz
    Commented Jun 19, 2016 at 3:42
  • 2
    @Sneetsher If only someone will provide a variety of ARM builds for all of those Android users on Stack Overflow...we would see far fewer outdated 2.4.2 builds (not sure where they're all getting it from).
    – llogan
    Commented Jun 19, 2016 at 3:45
  • @LordNeckbeard: Your neck beard is indeed long :)
    – andrew.46
    Commented Jun 19, 2016 at 9:17

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