The usage of PCs in home entertainment environments is constantly growing. A so called home theater PC (HTPC) can replace most of the traditional home entertainment components, like TV tuner, video recorder and DVD/CD player and integrate them into one device. Controlled with a normal remote control a HTPC can become the central component of your home entertainment environment that interconnects the remaining components and stores your private audio/video collection. In addition it enables the user to execute several tasks concurrently, like watching TV, transcoding a video and programming the digital VCR. If the PC is connected to a local network or the internet audio and video data can be received from other systems as well.

The main requirements for such a HTPC is that it should be seamless integrated in the existing home entertainments environment, which requires a small and pleasing case. But the problem with small cases is, that special motherboards must be used and only a few extension cards can be installed. Therefore barebone PCs, like the barebone series from MSI,  are especially suited to build up such a home theater PC, because they come in a small case and the installed mainboard already provides the most important PC components, such as audio-, video card with TV output and a network adapter. To build up a running system only a CPU, a memory module and a hard drive is required. Together with our developed Multimedia-Box application, which is based on NMM and runs under Linux,  all requirements to build a home theater PC can be fulfilled. NMM and the Multimedia-Box were featured in the german journal c't, issue 22, on pages 232-237: "Ein Knoten für alle Fälle, NMM - Vernetztes Multimedia Home Entertainment mit Linux"  

On this web page we present our experiences in building such a home theater PC, based on the Hermes Barebone PC 651-P which was kindly provided by MSI and our Multimedia-Box application, developed with NMM. This page can be used as guidelines to make the correct decision which additional hardware components should be used and how to install and setup the system. We assume that the reader has experiences in building a PC, installing Linux and compiling source code under Linux.

   As mentioned in the introduction we will use a barebone PC as a basis for our home theater PC. Because most of the components are on board, like VGA and sound card, we must ensure that they are supported under Linux. Therefore we use the Hermes Barebone PC 651-P, which was kindly provided by MSI. This PC provides an integrate solution where the most important components, such as audio, video card and a TV output, are provided on board and are supported under Linux as well. Furthermore it provides the most important connectors as seen in picture 1 and picture 2. The nice design and small dimension of the chassis allows an unobtrusive integration in the existing home entertainment environment. A full specification for this barebone PC, can be found here.

Picture 1: Front of the Hermes PC with all its connectors	Picture 2: Back of the Hermes PC with all its connectors

                  

   The CPU that can be used depends on the mainboard. The Hermes PC supports socket 478 processors, so that only a Pentium 4 CPU can be installed. The required CPU speed strongly depends on the usage environment. For most multimedia playback applications, such as watching a TV or DVD, a cup with 1.4Ghz~2.0 Ghz is sufficient. But if several applications should run concurrently, such as watching DVD and transcoding some mpeg files, a CPU with more than 2.0 Ghz should be used. The lack of faster CPUs is that they normally produce more fan noise, which is often unacceptable if the PC is located in a living room. So again: It strongly depends on the user requirements to determine the 'best' CPU speed for the PC. Because the CPU noise is not so important in our environment, we use a 2.6 Ghz Pentium4.

Memory:

Hard disk:
    The used hard disk must provide sufficient space to store the user's multimedia archive, such as mp3 files and TV recordings. Therefore we propose a large hard disk with 80~120 Gb space. To reduce hard disk noise a hard disk with 5400 rpm can be used.

DVD Drive:

TV-Card:
    To watch and record analog TV on the PC, a TV card is required. This card should offer an on board MPEG2 encoder to enable video compression in real time without using CPU speed. This is especially required if a slower CPU is used. The Hauppauge WinTV PVR 250/350 cards offer these feature and are supported under Linux and by the Multimedia Box. Furthermore a remote control, that is supported under Linux as well, is included in delivery. If digital TV is available over DVB, a DVB card is required. A list of supported DVB cards under Linux can be found here.

After discussing the hardware requirements, we propose two different hardware configuration that can be used to build your own home theater PC. The first hardware list uses components that provides more capabilities, such as faster CPU and a DVD burner instead of a simple DVD player, whereas the second hardware list focus more on cheaper components. For our HTPC we use the components from the first hardware list. We get the prices mentioned in the hardware list from the internet shop Alternate at the 17.01.2004.

Even though the chosen Hermes PC, seen in picture 3, has a small chassis, it's internal structure is well designed and allows a simple and fast hardware installation. The most important steps such as installing CPU are well described in the manual. Therefore we only shortly summarize the hardware installation process in this section and illustrate it with some pictures.

Picture 3: The Hermes PC from MSI.

After removing the cover, the front panel bezel and the installed riser card a good access to the mainboard is enabled and the CPU, the memory module and the hard disc can be installed easily. First the CPU must be installed and the CPU cooler must be screwed on it as seen in picture 4. The CPU cooler is included in delivery and is especially designed for this case. After this the memory module can be installed in the first memory slot which is near the CPU as seen in picture 4 as well.

Picture 4: Put the included CPU cooler on the CPU and install the memory module.

Picture 5: Installing the hard disk


Picture 6: After installing the CPU, memory module and hard disk the Hermes PC looks like this.

    To use the on board SiS video card and to enable the TV output a special driver is required, that can be found on Thomas Winischhofer's homepage. Furthermore he provides binary packages for the Debian distribution which we use for our PC. A description how to install the required driver can be found here. After installing the driver the X server must be configured in dual head mode, which means that two different video outputs are used, the VGA and the TV output. Some examples for the corresponding XF86Config (or XF86Config-4) file here. For our computer we use the following XF86Config file, that should work for most other user as well. After installing the driver and configuring X11, the display should be appear on the TV output as well as on the VGA output.

    To use the WinTV PVR 250/350 with the hardware MPEG encoder under Linux, the driver developed by the IvyTV project is required. Because the driver is still under development, you should use the latest CVS version that can be downloaded here. On our  PC we use a CVS checkout 18.09.2003 that can be downloaded here. After extracting the archive enter the ivytv/driver directory and type make and make install. Furthermore you should compile and install the utilities in ivytv/utils because the application test_ioctl can be used to configure the TV card. A detailed description how to compile this driver can be found in the IvyTV project's FAQ. Then you can load the modules ivtv and ivtv-i2c by calling 'insmod ivtv' and 'ivtv-i2c'. Now your TV card and the card's infrared remote receiver can be used under Linux.

    After installing the TV card's driver, the infrared remote control can be installed. To use the remote control from our Hauppauge's TV card the latest CVS version of LIRC is required. A description about how to access their CVS server located on Sourceforge can be found here. For our Hermes PC, we use a CVS version from the 1.12.2003, that can be downloaded here. If you not use the new dev-filesystem (devfs), that allocates required entries in the dev-directory dynamically, you must edit the file lirc_dev.c, located in the directory <lirc-sources>/drivers/lirc_dev/ and replace the code

#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,4,0)
#define LIRC_HAVE_DEVFS
#endif

with

#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,4,0)
/*#define LIRC_HAVE_DEVFS*/
#endif

Furthermore you have to (re)create the  /dev/lirc device by calling 'rm /dev/lirc' and 'mknod c 61 0 /dev/lirc' as user root.

    Finally NMM and the Multimedia box application must be installed. NMM requires the two libraries libpng and libjpeg, but normally these libraries are available after a standard installation of most Linux distributions. If not, you they must be installed. Corresponding Debian packages for the libpng can be found here and for the libjpeg here. Furthermore we use the pre-compiled binary packages of the latest NMM version (which is currently 0.4.1) that can be found on our download page. The source code of NMM is also available on this download page, so you can compile your own version of NMM as well. After downloading the NMM binary package or the source code, follow the corresponding installation instructions from this web page and finally start the application 'mmbox'. The application can now be controlled via the remote control as seen in the pictures below.
    If the Multimedia Box should start after login automatically, you have to write your own .xsession file, that must be copied in your home directory. The following .xsession file can be used as template. You must only set the NMM_DEV_DIR variable, which specifies the directory of the extracted NMM binary package. After this the Multimedia Box is started in a loop and can be stopped by pressing <ALT>-<CTRL>-<Backspace> (which kills the X-server)

Pictures from the Multimedia Box with different skins

Multimedia Box in action

Choose a video or audio file for playback.	Playback a video file.
Insert a DVD for playback.	Navigate through the DVD menu and start playback.
Watch the movie.	Start another task which will be executed during DVD playback.