Linux Mint 18.3
Cinnamon 64-bit v3.6.7
Internet Browser: Firefox Quantum v58.0.2
Audio input is via HDMI cable from video card (have no other issues with audio except Youtube so far)

I'm totally new to Linux. Been on Windows for 25 years starting with Windows93. Had a problem activating a copy of Windows7 to a Motherboard it was already previously activated on and finally said screw Windows. Microsoft makes all it's customers feel like pirate scoundrels that need to be kept in line. You are owned by Microsoft. You run a computer and browse the Internet at Microsoft's behest. FU Microsoft!! Ok. Got that off my chest.

So I installed Linux Mint last week and have figured out everything I need to do so far to set up Linux for long term operation but I'm stumped on the Youtube audio issue. Got a feeling it's either some kind of setting in Firefox our some kind of audio codec issue in Linux Mint. Anyone got any idea's? The video portion of the video is smooth as can be even at HD resolution. The sound is so choppy it's totally not understandable.

As per https://www.reddit.com/r/linux/comme..._choppy_audio/, have you tried disabling "Auto Mute" in alsamixer?

Have you tried another browser?

Have you tried playing a video directly from your PC, using e.g. Xplayer?

Have you tried playing videos from an internet site that isn't YouTube?

Hello and thanks for the reply. I was getting messed up sound in everything that outputs sound from a music CD playing through Rhythmbox or VLC Media Player to Flash video on YouTube to everything. I kind of have the issue partially resolved. I got on the Linux Mint help chat on HexChat and someone helped me to figure out the problem.

In Linux Mint 18.3 if you click on the Sound Icon in the bottom right hand corner of the taskbar and click on settings/input, there I had two sound input profiles. "Built in Audio" and "HDMI Audio". I had the correct audio profile selected as being "HDMI". However, when I got on Linux Mint help on HexChat someone told me I needed to go to software manager and search for an application called "PavuControl" and install that first in order to set my "Built in Audio" to "Off". After installation of Pavucontrol go to Menu/Sound & Video/PulseAudio Volume Control and open that sound control panel. Then go to the "Configuration" tab and make sure the setting for "Built in Audio" is set to "Off".

After I followed that my sound was still messed up so I decided to reboot to see if that would work and that did finally work. All sound output from everything was fine after that. But, later that night the sound messed up again and I had not changed any settings. So a rebooted Linux and the sound was fixed again. So, I would have to say I have found a partial solution.

There may be an option in my BIOS settings to turn off onboard audio but I do not think so. I have been in my BIOS settings many times and do not recall seeing that but I am going to check for that. As it stands right now my audio is fine. If my sound messes up again I will just reboot. I hope I can find a permanent solution. I will post an update if there was an option to turn of onboard audio on my BIOS settings and if that resolved the issue for good.

By the way, I'm not sure I even have alsamixer installed on my system to see if "Auto Mute" is turned off. It's not in Menu/Sound & Video. Where would that be located at if it was installed?

Thanks. I'll have a think about your partial solution in a moment - have you followed it up on Mint's HexChat to say that it it only seems to solve the problem temporarily? alsamixer can be run by just entering that command in the Terminal.

I pulled up alsamixer and there is no "Auto Mute" function toggle in any of the preferences in the panel.

Interesting. There is on mine (at the extreme right) and I'm also running Mint 18.3, albeit the MATE flavour.

Never mind. If you would like to try something else, enter the following on the command line:

and then run Pavucontrol, select Configuration and say what the Profile is set to.

please have a look at this - it's a bit small but if you look at the far right, it's right there.
are you sure you haven't missed that?