How to convert mp4 file to webm or ogv?
Whether under MAC OS or WINDOWS, FIREFOGG is a free Firefox plugin downloadable from the publisher’s site. Firefogg is a simple solution to convert your mp4, mov and avi videos to webm or ogv!
With the advent of HTML5 video formats on the web have changed from the traditional .flv. Compressing your video in webm or ogv to match the new standards can quickly be a hassle because few software offer this type of compression. Firefogg is a completely free conversion tool (plugin from MOZILLA FIREFOX) that meets this need. At bluevista, it is used daily to convert mp4 or avi files to webm or ogv.
Some precisions :
The .webm format is one of the formats supported by the native HTML5 video player (Firefox, Chrome, Android, Internet Explorer 9, Opera)
The .ogv format is one of the formats supported by the native HTML5 video player (Firefox, Safari, Chrome, Opera)
Here are some screenshots to help you:

Select
You select an mp4 video file for example.

Webm or Ogv?
You choose the format

Compression
You choose the video compression quality.

Advanced mode
There is an advanced mode to fine-tune the compression settings.

Compression in progress
You wait while the video compresses.