Transformers

Tutorials, screencasts, or even training videos are becoming increasingly important in everyday life. Multimedia is particularly useful in the home office and for homeschooling. But not every device can handle every file format, and not every screen displays all resolutions. Conversion programs help to adjust the formats and modify the image resolutions for the best possible results. Linux offers a great variety of multimedia conversion tools. We decided to investigate a few of the top contenders. Note that we focused on active projects for this report and did not consider some of the alternatives that are still widely known but not in active development (see the box entitled "Out of the Running").

Containerized

Audiovisual content can be stored with different parameters and image resolutions. Audio files can be saved in lossless or lossy formats with different bit rates. Container formats, such as MP4, MKV, and AVI are popular for video files. A single container can hold multiple files. For instance, a movie container can store several audio files in different languages. Since the codecs vary, the container format alone does not allow any conclusions about the quality of the contents.

Linux supports most free multimedia formats and codecs out of the box. Commercial packages also make proprietary codecs available; Linux can clearly score points in direct comparison with other operating systems as a platform for converting and playing multimedia content.

Existing solutions for converting multimedia content offer some flexibility: Often you can modify the resolution or bit rate to adapt to external playback options. For this purpose, most Linux applications for converting multimedia content rely on one of the leading open source multimedia frameworks. Many of the tools use FFmpeg [1], but GStreamer [2] also forms the basis for some conversion programs.

Ciano

Ciano [3] is a multimedia conversion tool that keeps with the philosophy of providing the easiest possible user interface. The Ciano conversion utility has an easy program interface that requires no training.

Ciano uses FFmpeg as its back end. Because Ciano can also convert image files, you'll need to install ImageMagick on the system. Several Linux distributions have added Ciano to their package archives, and you will also find a deb package on the project website.

Ciano's interface (Figure 1) is divided into three parts: On the left of the window is a vertical bar with the different target formats. To the right is the large work area, where you can see a list of the files to be processed. A small settings dialog resides in the titlebar, which you can access via a gear icon.

Figure 1: Ciano requires no training thanks to a very simple structure.

To convert content, click on the desired target format in the format bar on the left. In the dialog that opens, click on the + icon and then select the desired files in the file manager. Ciano will transfer the files to the list view. Click on the Start conversion button to start the conversion.

The selection window then closes. Ciano loads the contents into the working area of the main window and starts the conversion. A bar below each file indicates the progress of the action. Ciano can convert several files simultaneously.

Curlew

Curlew [4] is a graphical user interface for converting audio and video files written in Python and based on the FFmpeg framework. The still-quite-young project is available in the repositories of many distributions. In addition, you will find the software as a tarball on SourceForge. Installing from the repositories creates a separate launcher in the menu hierarchy.

Curlew opens a clearly arranged program window with a state-of-the-art look. In the usual style for the Gnome desktop and its applications, Curlew combines the most important control elements in the titlebar (Figure 2). An initially empty table view takes up most of the window. It later fills up with a list of selectable files, which also contains information about the file size, as well as time information for the conversion.

Figure 2: Curlew impresses with a very easy-to-use interface.

At the very bottom of the window, you will find a button that covers almost the entire width of the window, which you can use to select the target format. Clicking on the button opens the list of target formats in a separate window. In addition to the conventional container formats, the list contains numerous hardware-specific formats. Double-click one of the listed formats to add it to the favorites list.

You can configure individual settings for each of the listed formats. Clicking on the gear icon in the titlebar opens a dialog in the list area of the program window with a tab structure that supports format-dependent modifications.

The settings dialog also lets you click to configure a two-pass setting, where the second conversion run is supposed to offer better image quality. Checking another box tells the application to convert only the video track but not the audio track.

Once you have configured all the settings, click the gear icon in the titlebar to go to the empty workspace. If necessary, save the configuration up front as a favorite so that you can use the settings in later conversion runs.

To convert multimedia content, drag and drop the source file from a file manager into the workspace of the program window. Curlew lists the individual files one below the other. After you click the Convert button top center in the window, the software starts to convert the source file.

Converting high-resolution video files takes a long time even on state-of-the-art computer systems. If you want to stop the conversion process, click the red Stop button. To view the contents of a file in the conversion list, right-click on the desired entry and select Play in the context menu. Curlew now opens the preset playback software and plays back the content. You can even play back a file that the program is currently converting.