Quote from nullstring on October 14, 2011, 18:13
I am worried about the same thing.
I'm wondering if there is a way to connect a real hard drive to the SD slot. AFAIK the SD card slot uses MMC directly to the chip. I am not sure what the bitrate of this is.. but it'd be nice if we could use this rather than usb for the disk.
I doubt that's possible, but thinking about things more, USB bandwidth might not be too much of a problem.
Again, all countries use different systems and bitrates. I can't detail them all here (and can't be arsed to either) so am basing this on the UK freeview transmissions.
So, first off, USB high speed has a theoretical maximum throughput of 480mbps though real world is more like 240mbps (a little higher actually but better to go lower than higher for these purposes as then we don't have to worry about overhead which on USB is quite high).
The highest bitrate freeview SD channel in the UK is BBC1 which uses a bitrate of 4mbps (all the others use much lower bitrates), freeview HD uses max 10mbps. So if you want to record an SD stream it should only take roughly 8mbps of total USB throughput, HD about 20mbps.
So the USB bus should be able to use and record from multiple tuners. However, USB transfers can be quite CPU intensive when using multiple devices so that might be a restricting factor.
So, on to tuners that can be used in linux. A list can be found here: http://www.linuxtv.org/wiki/in.....SB_Devices
It seems that DVB-T2, which the UK uses for HD, is only supported by one dongle at the moment and requires a 3.0 kernel. I'm not sure when/if the rPi will get 3.0.
As for drivers, it may be necessary to build a kernel with the drivers from scratch according to this page: http://www.plugcomputer.org/pl......php/DVB-T
. (not sure if it all applies as it's for the sheevaplug which uses ubuntu, but the modules needed should be the same)
All of this is blue sky thinking until we can actually get our hands on some rPis' and have a play.
I really hope it can be done, the thought of an uber cheap, low power, networked, customisable and expandable HD PVR really appeals to me.