What's video converters are available for Ubuntu?

There are at least four video converters you can try:

1. arista | [Install arista]
2. transmageddon | [Install transmageddon]
3. ConvertMe!
4. Handbrake

Arista is a basic converter which you can add new conversion types to through there web site which will give you a new script which you can install adding the new conversion type.

Transmageddon is the development version of arista which gives you the option to choose your specific encoding preferences in the program interface.

ConvertMe! is a very user friendly new frontend for FFmpeg. It comes with widly used presets and gives you a preview of the conversation progress. ConvertMe, intergrates with your Nautilus file manager allowing you to rightclick on an any video file and convert it instantly. View screenshot

Handbrake has a limited number of output formats including mp4 and mkv but there are many more options available and a good description of what these options will do however handbrake is not in the software centre and you will need to add it by adding a PPA* which can be found at launchpad.

The ppa can be added through the software sources dialogue described here

ppa:stebbins/handbrake-snapshots

Transmageddon

Transmageddon supports almost any format as its input and can generate a very large host of output files. The goal of the application was to help people to create the files they need to be able to play on their mobile devices and for people not hugely experienced with multimedia to generate a multimedia file without having to resort to command line tools with ungainly syntaxes.

The currently supported codecs are:

Containers:

• Ogg

• Matroska

• AVI

• MPEG TS

• flv

• QuickTime

• MPEG4

• 3GPP

• MXT

Audio encoders:

• Vorbis

• FLAC

• MP3

• AAC

• AC3

• Speex

• Celt

Video encoders:

• Theora

• Dirac

• H264

• MPEG2

• MPEG4/DivX5

• xvid

• DNxHD

It also provide the support for the GStreamer's plugins auto-search.

Winff

WinFF is a graphical user interface for FFmpeg. It will convert almost any video file that FFmpeg will convert. WinFF does multiple files in multiple formats at one time. You can, for example, convert mpeg's, flv's, and mov's into avi's (or DVD/VCD format or MPEG or 3gp etc.) all at once.

This package provides a variety of preset conversion settings for common formats and devices. These presets are intended to hit the "sweet spot" for each individual codec. They have been written with a tip of the balance to quality.

Arista

Arista is a simple multimedia transcoder, it focuses on being easy to use by making complex task of encoding for various devices simple.

Users should pick an input and a target device, choose a file to save to and go. Features:

Presets for iPod, computer, DVD player, PSP, Playstation 3, and more.
Live preview to see encoded quality.
Automatically discover available DVD media and Video 4 Linux (v4l) devices.
Rip straight from DVD media easily (requires libdvdcss).
Rip straight from v4l devices.
Simple terminal client for scripting.
Automatic preset updating.

I suggest you to give a try to both FFmpeg and/or Mencoder.

They are very powerful in the sense that you may be able to convert any format in any other format. You can also very extensively fine tune the settings for your codec.

They seem to be mostly suited to run through command-line, but :

1) Ready-to-use scripts can easily be found on the web

2) Some GUI exists to make their use easier. (I know WINFF for FFmpeg and Handbrake, as mentionned by Allan, is also a GUI for FFmpeg)

3) You may find interesting and funny to learn their specific languages and moreover, if you encounter troubles in adjusting some settings with the more user-friendly one, they might be the one which will work for you due the huge variety of their settings.