Anybody recommend a GUI app (preferably in Ubuntu repos) to convert from .flv to .mp4 other than Transmageddon? Transmageddon now crashes in Trusty.

  • 4
    Take a look at FFmpeg.
    – Mitch
    Aug 1, 2014 at 8:02
  • I used VLC a lot to transcode. I think it uses some of the LI tools from the other answers as underlying engines. But it provides a GUI for the task.
    – Run CMD
    Aug 1, 2014 at 10:28

7 Answers 7


I don't think so there is GUI app is available in Ubuntu repository.

But you can simply convert your required formats in terminal. Try the following,

First you have to install libav-tools, Open terminal(Ctrl+Alt+T) and type the below command,

$ sudo apt-get install libav-tools

Now you can do your needs, for FLV file to MP4

$ avconv -i input.flv -codec copy output.mp4
  • On 18.04 and above you can apt-get install ffmpeg and run the exact command substituting ffmpeg for avconv, so just do: ffmpeg -i input.flv -codec copy output.mp4
    – vlz
    Sep 21, 2020 at 13:24

Have a look at winff

It is a graphical application that uses ffmpeg (like a lot of other programs) to convert videos and audio.

It is included in the official Ubuntu repositories, so you can simply install it with

sudo apt-get install winff

The official website includes a link to a wiki and a mailing list if you need specific support and documentation with this tool


Handbrake is in the official repositories since Trusty (14.04). It is a small, efficient DVD ripper and video transcoder with a clean GTK GUI.

It can convert from a number of video formats, including flv, to either MPEG-4 or Matroska.

To install:

$ sudo apt-get install handbrake
  • And Handbrake is of course available for Windows and OSX / macOS as well.
    – SPRBRN
    Sep 27, 2017 at 20:37

Abstract from the blog Transcoding an audio or a video file - http://www.frasq.org/en/transcoding-an-audio-or-a-video-file (look for mp4flv in the page):

To convert a FLV already containing a video in H264 and an audio in AAC in MP4:

ffmpeg -i file.flv -acodec copy -vcodec copy -y video.mp4    

MP4Box -raw 1 video.mp4 -out video.h264
MP4Box -raw 2 video.mp4 -out audio.aac

MP4Box -add video.h264 -add audio.aac file.mp4

rm -f video.mp4 video.h264 audio.aac

If the FLV contains an audio in MP3, extract the video while converting the MP3 in AAC:

ffmpeg -i file.flv -vcodec copy -y video.h264 -f adts -ar 44100 -f wav -ac 2 - | faac -b 128 -o audio.aac -

Assemble the MP4 with MP4Box:

MP4Box -add video.h264 -add audio.aac file.mp4

The blog explains how to install ffmpeg, faac, MP4Box, etc.

La version en français : Transcoder des fichiers audio et vidéo - http://www.frasq.org/fr/transcoder-des-fichiers-audio-et-video

avconv -i input.flv -c:a copy output.mp4

This has the effect of transcoding the video stream with the default codec and copying the audio stream.

avconv can be installed with

sudo apt-get install libav-tools
  • @DavidFoerster This answer has different flags for avconv. The flags in the top answer don't work for me, whereas these flags do
    – Zags
    Sep 27, 2017 at 18:47
  • Fair enough. Could you please explain what this command will do, e. g. which streams are copied and which are transcoded (and to which codec)? Sep 27, 2017 at 22:49

It's not in the Ubuntu repository, but I liked Format Junkie for video conversions:

Add repository:

sudo add-apt-repository ppa:noobslab/apps


sudo apt-get update

Install it:

sudo apt-get install formatjunkie



I've written a GUI (named ConvertFLVToMP4)for CLI avconv program. Its .deb can be downloaded from: https://app.box.com/s/vyr473g7q2nwkj6haq22 It requires the installation of gambas3 from: https://launchpad.net/~gambas-team/+archive/ubuntu/gambas3 before installing the app from the .deb.

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