Contributing to global climate change since 1965, Allen believes that you have a Constitutional right to his opinion. 
HDTVPVR: Storage
High definition video files are large. Not only are they large but they must be processed at with a great deal of speed. An hour of broadcast HD video comes in at about 8.5 GB. Remember when 8.5 Megabytes was a lot of data?
Needless to say my HDTV box will need a large storage space with low latency and high bandwidth. To this end I selected a pair of Seagate 250GB SATA II drives. SATA II allows for a theoretical maximum bandwidth of 3.0 Gbit/s but that’s just the specification. I placed the two drives into a RAID 0 stripe set.
Essentially this means that the capacity of the drives are combined for a total of … er, 465GB (rounding). The RAID striping causes contiguous data to be written in alternating 64k “stripes” — first on one drive and then on the other — increasing throughput by leveraging each drive’s data buffer. I selected a motherboard with a built-in RAID controller so that the CPU would not be burdened with managing the stripe.
The Seagate drives fit snugly into one of the structural arms of the Thermaltake media case with just enough space between them to allow for ventilation.
The operating system will reside on a much less exotic Western Digital 160 GB drive on the primary PATA controller. I partitioned it so that I would have the option of adding multiple operating systems in the future if such a thing should become desirable. A DVD-RW DL drive will be attached to the secondary PATA controller. Like the most inefficient mass transit system in the world, every passenger gets his or her own bus.
Just curious, does Snapstream encrypt the stored programs?
July 21st, 2006 at 8:50 amChris,
As far as I can tell, no. Neither is there any “broadcast flag” (easily ignored) to indicate that the program should stay put. The stored file is a raw MPEG-2 transport stream so it should be possible to re-assemble it in a more compact form… say, avi or MPEG-4. Exploring that possibility is on my list.
Snapstream will convert standard def to MPEG-4 but not the HD streams. I bet such a tool does exist. Or will soon.
I’ll write a post to cover the software I’m using in a few days.
July 21st, 2006 at 5:38 pmIt’s amazing what will happen when you read the documentation. At least, that’s what I’ve heard people say. Turns out that compressing HDTV streams to Divx format AVI is possible with BeyondTV, it just can’t be set up to run automatically as it can with SD material. Compressing an hour-long show takes a few hours, but it can be done “manually” on a per-show basis.
An hour-long 8GB file becomes about 780MB and it still looks pretty good.
You can cut the commercials out too. SmartSkip makes a pass at the program after it has been recorded to mark commercial boundaries. Another tool trims out the commercials and a final tool, SmartSqueeze, compresses the result down to “reasonable” size.
August 12th, 2006 at 9:36 pm