HTPC FALL 2008 UPDATE

Introduction

Last year, our HTPC was a burly full-tower system running dual Opterons, dual Autumnwave OnAir GT units, an MSI 7900GT, watercooling, and 8x Seagate Barracuda ES 750GB.  This year, technology has advanced, HD-DVD has fallen to BluRay, our cable provider's Moxi DVR has been replaced with Motorola DCH3416 boxes, many more HDDs are no longer being used, and electricity to both power and cool this thing is far more expensive now. 

Perhaps the single most exciting aspect of this year's upgrade is the new Motorola DCH3416 STB.  This new DVR features 1394, USB and Ethernet ports, and a far larger HDD than the old Moxi unit.  Although its hardware is superior, the Moxi GUI is still far more advanced than Motorola's. 

Anyhow, its USB and Ethernet ports were disabled, eliminating possibilities of networking or moving recordings using a USB mass storage device.  However, the 1394 ports were found to be working.  When plugged into a Windows XP PC, the system recognizes the STB and asked for drivers.  See HERE for more info on capturing form a STB.  After installing the drivers, CapDVHS worked beautifully and recorded the stream from the STB. 

After testing on a few systems, it was determined that the IO subsystem was the bottleneck in controlling dropped frames during capturing.  As far as quality is concerned, we are at the mercy of the cable provider's compression method and amount.  Some stations are more compressed than others (TV Guide channel vs PBS-HD).  A little more research revealed that some PVR programs can utilize the STB as a tuner device, record from it unattended, and even change channels using the same 1394 interface. 

One DCH3416 was deployed in the living room, connected to the main TV for general recording and viewing.  But having only one STB which can tune into encrypted QAM channels was not good enough for a family with two small children - it was imperative that a second STB be set up elsewhere so that they can watch Noggin while the grown-ups watch Survivor.  That second STB was located in the office, connected to an old, repaired big-screen TV.  Since kids are in school during the day and asleep after 9:30pm, the STB can be used as a tuner source for the HTPC. 

The Motorola STB is great for tuning into any channel coming in from the cable company, but that's only one available tuner source for the HTPC.  When programming is available on clear QAM channels or better yet, ATSC, PC tuner devices are still the way to go.  Last year, we learned about Silicondust's HDHomerun product, but it was still in its infancy and support was limited at best.  That's why we went with the dual OnAir GT USB tuners.  But now, a quick Google search shows that BDA drivers are now available and working for the HDHomerun!  

So there we have our new recording sources - the Motorola DCH3416 STB through 1394 ports, and an HDHomeRun.  Playing back the content is another story.  Because our connection to the main living room big-screen TV is HDMI, and to the audio system is TOSLINK, distance is a major issue:  How can we connect the DCH3416 in another room about 20 feet away through a few walls, a big-screen TV with HDMI, and an audio system using TOSLINK?  I'd rather not have cables snaking between rooms, and the only in-wall connection is a CAT6 cable.  After examining dozens of possible converters, and wireless connections, the best and simplest solution ended up being this:  Split the HTPC into two separate parts - the main server which does the recording and does double duty as a general file server as well as other always-on tasks, and the playback HTPC which plays back any and all recorded content on the living-room big-screen TV.  Here is the resulting diagram:

In the Office, the main server records from the DCH3416 STB and the HDHomerun.  The STB also serves as a tuner for the TV.
In the Living Room, the HTPC plays back content recorded on the server through a CAT6 cable pre-wired in the walls.

Because the server does not playback any content, it does not require any high-end CPU or GPU.  This allows the server to be spec'd very low, and be kept on 24/7 as a file server, FTP server, and torrent client as well (for downloading linux distros, riiiight!).  Hence, the requirement for the server is super-low power consumption.  As for the playback HTPC, it needs to playback any compressed AV content for maximized enjoyment.  This means a powerful system without being too noisy, or looking too much like a PC, not AV gear.  

We shall examine the best options available for components in building the server and HTPC playback machine...