You don't need to be an 'investor' to invest in Singletrack: 6 days left: 95% of target - Find out more
We have been trying to record to an external Hard drive using our smart TV.
Because of problems with programs getting clipped it's being checked over .One engineer said you should be able to record to the drive and watch a previous recording at the same time ( which my missus claims to have done) but the workshop says it's impossible.
Can anyone clarify and also if you can't read and write from a HD at the same time how do PVR's do it ...do they have a special type of storage drive ?
thanks in advance
Depends on the device I expect. My Sky+ box can record two channels whilst playing back a recorded show. Whether yours can is anyone's guess. Why not try it and see?
They do use special AV drives optimised for the purpose yes, in the same way you can get drives optimised for a NAS and suchlike. How big a difference it really makes beyond marketing is open to debate though.
As Cougar says yes it’s possible but depends on your TV.
No special drive, they'll be pretty standard. I've used off-the-shelf USB drives.
What you can record depends on a few things. Firstly if it's a satellite system you need at least a dual LNB, this is the small box in front of the actual sat dish.
Next your TV needs to have multiple tuners. There is a case where only one tuner is sufficient but it is limited. Digital TV channels aren't broadcast on separate frequencies like the old analogue, they are mixed together in what is known as a multiplex or mux with each channel having an ID number, the TV or decoder box then filters out the channel you want to watch or record. So if the channel you want to watch and the one you want to record are on the same Mux then the TV sets a filter for its channel and the recorder sets a filter for the one it wants and all is good. If the channels are on different muxes then you need a tuner for each mux that you want to access at the same time. So if you want to record three programmes on three different muxes you will need three tuners (and 3 LNBs).
PVRs always write, and then immediately read, the data for the channel you are watching. This is so that they can do the trick modes like pausing TV while you go and make a cup of tea, tell the salesman at the door to eff off, etc.
Disk drives have a lot of read/write capacity, it's doubtful that you've enough oomph in your TV to overload it. The biggest bottleneck might be the connection, say USB.
No special drive, they'll be pretty standard. I've used off-the-shelf USB drives.
Yeah, I've just realised I worded that badly. The drives in STBs like the Sky box are "special" for some value of, but an external HDD will be just a regular drive.
"Special" in the sense that Sky use up half the capacity for their purposes. 😥 They are just standard HDD units, you can replace them with a bigger drive if you wish but you'll need to go through the installation process again which will put some user information on there so that the system knows what it's dealing with.
Edit: SD TV requires a bitrate of around 3MBs, HD around 8MBs. A typical HDD can read/write at speeds of close to 130MBs. In theory, if everything else was up to it, you could record 8 HD programmes and play back 8 HD programmes at the same time before you reached the limit of the drive. In practice I doubt you'd get those figures (but have never tried!)
Yeah as above, the Sky HDDs are just regular drives, I believe they are formatted in a non-standard way though.
The drives aren't special ... its the box / TV that does the 'magic'.
Most boxes will have 2 tuners allowing you to record 2 channels (or more in some cases) and / or watch a prerecorded programme. The drive can only do one thing at a time so the box will queue things up for the drive ... making it appear like you can do more than one thing at a time.
I don't think most TVs have this facility though.
My Humax box can record two channels and watch a third or watch something else prerecorded.
They’ve been able to do that for more than a decade by my reckoning.
And the drive isn’t special. I replaced the one in my old box and it was just an off the shelf IDE hard drive. From memory the Hummy forums recommended a specific brand but it wasn’t anything magical.
Sounds like it is your TV that is the limiting factor.
thanks to all for the replies . Despite all the extra info offered I'm still not clear whether a single standard external HD is physically able to record a program whilst at the same time allow the playing of a previously recorded/stored program .The engineer tells me not because of the way the drive works but my missus insists it does.(I have little interest in TV so she's the one who uses all the functions etc. I can't test as the tv's at the workshop but if the engineer is wrong then I want to tell him so one of the problems can be sorted.
well, no, obviously the drive can't both read and write at the same time. But it doesn't need to because the data can be buffered.I'm still not clear whether a single standard external HD is physically able to record a program whilst at the same time allow the playing of a previously recorded/stored program .The engineer tells me not because of the way the drive works
To massively over simplify it, say for example the box reads the next 10s of the recording A into memory (as in RAM, not hard disk) in advance. Whilst doing that it saves 10s of a program B being broadcast into memory. Then B can be written to the disk whilst A is played from memory. And just repeat.
Whether YOUR exact box has this function, or has ever actually done it in the past, is another matter! 🙂
Yes they can, or at least as far as anything on the outside looking in is concerned they can. It's not a restriction of the HD, that will be near identical to one in a full blown PVR, but the device controller for the connection (probably USB) in the TV could scupper things.
I've used USB drives with no problem as extenders to non-PVR STBs to turn them in to a PVR. I have one such decoder box in front of me on my desk at this very moment.