Without the proper volume, the quality of a video can easily be lost. The free, multi-platform and open-source video editing and processing software, Avidemux, features built-in audio filters to allow you to fine-tune a video's volume. These audio filters will let you adjust the gain level of the audio of a video, providing you with the option to either increase or decrease the sound level as necessary. Increasing the gain values results in a louder volume, and as a powerful tool it requires a degree of concentration to achieve the proper volume.
Click "File" and then "Open." Locate the file that needs a volume increase and click "Open" to load it.
Click "Audio" from the menu bar and select "Filters" from the list of options.
Increase the volume in the Audio Filters window by selecting "Manual" as the Gain Mode and then adjusting the number under Gain Values. Click "OK" to increase the volume according to the new value level.