The Mythbox HD specification
Both the Freesat HD and Freeview HD services have now launched in the UK. These services are similar to the existing Freeview service but carry high definition programmes as well as standard definition. On both platforms the HD content uses H.264 encoding, requiring hardware capable of decoding and outputting over a DVI or HDMI connection.
Another recent development is the introduction of Blu-ray content, which is also encoded in either H.264 or VC-1. Given that more and more films will be made available in this format, it would be nice to have the capability to play the format. Although currently Blu-ray decoding and viewing on Linux is a bit complicated due to the BD+ copy protection, at some point this will no doubt be circumvented so it would be good to have a system capable for the future.
At the same time as Blu-ray gains popularity, so too have HD TV's, with their high definition functionality just waiting to be utilised. Hence there are many good reasons to upgrade from a standard Mythbox to a Mythbox HD.
Below is a list of chosen components that have been used for the Mythbox HD, along with any respective links.
The motherboard and CPU needed to provide enough processing power to decode H.264 and VC-1 streams contained in the Freesat HD tranmissions, Freeview HD transmissions, and potentially Blu-ray content. At the same time, it needs to pass through any AC-3 streams and record. We didn't want the new Mythbox HD to struggle (which was sometimes the case with MPEG-4 content with the original Mythbox) so a little more power was welcomed. Additionally, in order to accomodate multiple tuners for Freesat HD and Freeview HD, the board needed to have plenty of PCI slots available. This meant that rather than a compact Mini-ITX form factor, the slightly larger but more commonplace Micro-ATX form factor was used.
To deal with content decoding, the main chipset choices available were:
Originally the popularity of Nvidia GPUs and the support given to VDPAU meant it was a chosen winner. Later once VA API support was more widespread these GPUs would also automatically have the benefit. However, Intel and Nvidia continued to battle in the courts and as a result the number of motherboards available which contained an up-to-date GPU were few and far between. Even the older boards had been discontinued. It was then discovered that the Myth TV developers were working on adding support for VA API, so an Intel Core i3 processor seemed the best choice. The final choices were:
- VDPAU (Video Decode and Presentation API for Unix) designed by Nvidia and on Geforce 8+ GPU.
- XvBA (X-Video Bitstream Acceleration) designed by AMD and used on ATI Radeon GPU.
- VA API (Video Acceleration API) put forward by Intel as a common API for Linux similar to Window's DxVA. VA API can currently utilise both VDPAU and XvBA. VA API is natively supported by Intel Core i3 processors.
- Motherboard: Gigabyte GA-H55M-UD2H H55 Socket 1156 VGA DVI HDMI Out MicroATX
- CPU: Intel Core i3 530 2.93GHz Socket 1156 with 4MB L3 cache
The TV card needed to receive Freesat transmissions and be capable of handling the HD channels as well as the SD ones.
The Hauppauge WinTv Nova-S2 HD DVB-S2 & DV Tuner, being a DVB-S2 tuner, supports the reception of both High Definition and Standard Definition services. This is an ideal choice for Freesat reception. See the full spec here and the product to purchase from dabs.com here.
Potential hard drives which are quiet when both idle and seeking, as well as being energy efficient included:
After analysing the best that each range had to offer, and based on availability, the Western Digital AV-GP WD15EVDS 1.5TB Hard Drive SATAII 32MB cache was chosen. These drives were designed to be on 24/7 and be quiet.
- Samsung F2 EcoGreen range
- WD Caviar Green range
- WD AV range
- Seagate Pipeline HD range
The were quite a few cases out there which look pretty, but finding one which matched our requirements was tricky. Most cases don't state whether they have space for an IR receiver. There were quite a few cases with built in IR receivers and LCD displays (with the iMON based IR/displays being supported by LIRC and LCDproc). Instead of a dedicated IR controller, the original Mythbox used the remote control that came with the TV card, which made it quite slow at times. Given this, it made sense to pick a case containing one of these units, circumventing the need to mod the case in order to accomodate an IR sensor.
In order to fulfill our needs, the case needed to:
After looking at what was on offer, the cases which fulfill the above requirements are either:
- accept a micro-ATX motherboard
- accept two or more standard PCI cards (i.e. not low profile)
- be quiet and cool
- be reasonably priced
- fit on an average sized TV stand (with room for your amp etc.)
- blend in with other AV kit
- contain an iMON IR receiver and display
It was decided that the compromise to be made was in size, and the Antec Fusion Remote Black case was the perfect choice. Its built well to help keep the system silent and cool, contains the iMON IR/display, and has four expansion slots. More info can be found here and you can buy it here.
- expensive case which do everything and more, and usually contain a small LCD touch panel
- slimmer cases which require the use of riser cards (which can sometimes be problematic with tv cards) and also limit future expansion
- larger cases which are extremely deep
For our power supply, we don't have a huge wattage requirement - 300W should be ample for our needs. Out of the power supplies that we investigated, the Seasonic range seemed to be one of the best brands for silence and build quality. Based on reviews we decided to go with the Seasonic S12II-330.
Hearing many mixed reviews about DVD drives, we will use one of the cheapest Sony DVD writers and use hdparm to reduce the speed of the drive if noise becomes an issue.
We don't want to under power the new system, so 4GB of DDR3-1333 was a nice amount for processing HD content.