MP3 Quality Modifier is a desktop application used to change the quality of any MP3 file. This program is a free portable application and therefore doesn't have any installer or uninstaller, it can be used simply by opening the executable file.
Select the songs you'd like to add and drag and drop them to the program's list, or you can add songs by using the "Add Files" button on the main menu. Folders can also be added by using the "Add Folder" from the menu bar. Each added file will be shown on the list of the program.
The file listing shows the MP3's quality (in kbps) which ranges from 10 kbps to 310 kbps. It also shows the sample frequency, file size, and artist name, among other columns.
Before converting the files to a new quality you have to select three things: Bitrate configuration, sample frequency, and modus. Bitrate mode allows you to select average, constant or variable mode, the selected mode in conjunction with the bitrate speed configures how the final file will be encoded. Modus can be mono, stereo, or joint stereo.
Once all desired options have been selected properly you can go ahead and click on "Process" to start the conversion. A screen will be shown with the overall and individual file progress, it can be canceled at any time. When completed, the output folder will be automatically opened with the resulting files.