Sound through HDMI and an nVidia GeForce 210

Continuing on from the previous post about my new HP Microserver, I was mainly interested in seeing how the CPUs did playing a HD movie. Watching the CPU load while playing back a H.264 preview and it wasn't as bad as I expected: both cores sat around 30-60% usage, which includes background system tasks. For the usage I expect of my media server this is sufficient, it's rare that it's playing any video at the same time as anything else. It's also worth mentioning that considering the vast range of formats of most of my media it would be highly unlikely if even the majority would benefit from much offloading to the GPU, however it would be nice to have, so I was still keen on a graphics card with the necessary features.

Considering the space inside the Microserver and the positioning of the PCIe slots, I've got a rather restrictive list of graphics card requirements:

• heat sink cannot be “thicker” than the width of a PCI slot
• low profile
• nVidia (Linux drivers), preferably with a GPU with good PureVideo support
• fanless/passive
• HDMI out, but would settle for DVI

After a bit of searching and lots of squinting at images of cards trying to determine how high the heat sinks were, we found a range of Zotac GeForce 210 cards that fit the bill. The GT210 is one of the first chips to have nVidia's latest PureVideo technology (although now superseded by generation 5 and the GT520). It has a low form factor face plate replacement in the box and the heat sink is the same thickness as the slot. The card also has a HDMI port so can be my sound card as well. The exact model I ended up ordering was the Zotac ZT-20309-10L GT 210 512MB DDR3 LP Silent for £34. I would have preferred a 1GB RAM model but due to availability in the region I settled on the 512MB.

Installing the card was trickier than I thought. There's some annoying bits of metal at the back of the Micro case that the top of the graphics card's face plate was hitting. Had to bend the metal out of the way with a thin screw driver to get the card to slide back properly. Aside from that, the heat sink fits snugly along the side of the case.

HD video play back performance appears unchanged. This could be for several reasons: first off I've only attempted some very basic tuning of Ubuntu and VLC, there's surely many things I haven't tried. Secondly the format of my test MPEG-4 video may not be one that nVidia's PureVideo can offload. More importantly for me at this time is sound: Ubuntu is not playing out of the HDMI audio controller.

Some research and a lot of time later (this project was shelved for a few weeks), I've got Ubuntu playing out the nVidia audio controller. The XBMC wiki and Arch Linux forums contained the necessary tips, namely the installation of the ALSA sound modules, setting the correct options for the snd-hda-intel kernel module and loading the ALSA module into PulseAudio. The probe mask has ALSA using the nVidia codec of the card:

luke@nexus-micro:~$ grep snd-hda-intel /etc/modprobe.d/alsa-base.conf options snd-hda-intel enable_msi=0 probe_mask=0xfff2

Reboot or rmmod / modprobe, then see what device ALSA detects:

luke@nexus-micro:~$ aplay -l **** List of PLAYBACK Hardware Devices **** card 0: NVidia [HDA NVidia], device 3: HDMI 0 [HDMI 0]
Subdevices: 1/1
Subdevice #0: subdevice #0

ALSA says Card 0 Device 3 so that goes into PulseAudio :

luke@nexus-micro:~$ grep alsa /etc/pulse/default.pa load-module module-alsa-sink device=hw:0,3

And done. Next I'll be looking more into video playback performance and maybe doing a disk swap from old media server to new media server.