Format Factory is a  multifunctional converter software that's able to convert all types of video, audio and image files. Complete, powerful and free, it's a must-have conversion tool.

Link download: http://www.pcfreetime.com/formatfactory/

Use FormatFactory 2.70 (or newer version):

Remove sound (disable audio) in video (Xóa âm thanh trong Video)

- Disable Audio: Yes

Volume up (Tăng âm lượng)

- Volume Control (+dB): 3 dB, 6 dB, 10 dB, 12 dB

Volume down (Giảm âm lượng)

- Volume Control (+dB): -3 dB, -6 dB, -10 dB

Not change (Không thay đổi)

- Volume Control (+dB): 0 dB