virtualbox.org

My host is Ubuntu 14.04 LTS installed in a machine with 5,7 GB of memory and hard disk of 485,4 GB and 25 GB of used space before allocation to virtual machine.
I installed Virtualbox 5.1.4 and created a new virtual machine for Ubuntu 16.04.1 LTS with 2 GB of memory and 50 GB fixed-size file as virtual hard disk.
Installation was successful and I started to use and test Ubuntu 16.04.1 LTS inside Virtualbox.

I installed ubuntu-restricted-extras and reinstalled ttf-mscorefonts-installer following instruction in a ubuntuforum post with:
I am still unable to play any kind of media.
I tried to watch videos at youtube and to play mp3 with Audacious and Rhythmbox but the cursors stay stuck at 0:00

The tab 'additional drivers' in Software ad Updates says that 1 proprietary driver is in use:

InnoTek Systemberatung Gmbh: VirtualBox Graphic Adapter
this device is not working
Do not use the device

InnoTek Systemberatung Gmbh: VirtualBox Guest Service
this device is not working
Do not use the device

Unknown: Unknown
This device is using an alternative driver
Using processor microcode firmware for Intel CPUs from Intel-microcode (proprietary)

I followed your instructions.
I started the VM and launched first Audacious then Rhythmbox to reproduce an mp3 file (attempt failed).
Then I launched Firefox to navigate to youtube and tried to reproduce a video (attempt failed).
I closed all the three applications and closed the VM.
Saved and zipped the log file which is attached below.

Switch the guest to the Intel HD audio install of the ac97 one and see if it helps.

It works!!!
Thank you very much

NP.

I will say that the video and audio seem to be out of sync for me, but it may be just me since I usually use a pre-release and self compiled version. I don't use a guest to play video so it does not rise to the top of my todo list to find out why.

You are right, they are out of sync.
Would you suggest to fix also this issue? I would be interested to do it only for the sake of fixing it.
On the other hand, I am testing Ubuntu 16.04.1 LTS to see if I can make an upgrade from Ubuntu 14.04 LTS.
So, in the end, if this is only an issue with VirtualBox I may be tempted to ignore it

You could raise a ticket at bugtracker and report this to the DEVs but I know they are working on the audio section ( or have been ) and it probably is in a state of flux.

I surely will do it.
Thanks for the suggestion (and for the help)