I have no sound in youtube and another videos in the Internet. The OS is Fedora 25. Browsers are Opera 42.0.2393.94 and Firefox 51.0.1 (64-bit). I using the OSS 4front driver for my Lynx L-22 audio card, and this card doesn't support another sound systems. Audio files and video I play with smplayer and everything is OK.
Which settings have I to modify?