Digital Spy

Search Digital Spy
 

DS Forums

 
 

TV with PVR to USB - can I record from HDMI


Reply
Thread Tools Search this Thread
Old 01-12-2012, 17:15
bazellis
Inactive Member
 
Join Date: Oct 2007
Posts: 5,263

I have a TV with built in PVR functionali that records to a USB stick. I can record channels from the digital channels on the TV but it will not let me record channels when I connect my sky hd box via HDMI.
Can you not use the PVR functionality for other input sources?
bazellis is offline   Reply With Quote
Please sign in or register to remove this advertisement.
Old 01-12-2012, 18:20
cp2
Forum Member
 
Join Date: Oct 2002
Location: Standish, near Wigan
Posts: 411
No. PVRs only record from their internal tuners. Recording from an external source requires much more than a PVR has.
cp2 is offline   Reply With Quote
Old 01-12-2012, 18:37
chrisjr
Forum Member
 
Join Date: May 2004
Location: Reading
Posts: 22,038
I have a TV with built in PVR functionali that records to a USB stick. I can record channels from the digital channels on the TV but it will not let me record channels when I connect my sky hd box via HDMI.
Can you not use the PVR functionality for other input sources?
There is no technical reason why the TV could not record from an external source to USB. It simply requires the necessary electronics.

If the TV allows you to set up timers manually as well as select a programme from the EPG then that would be the place where you would select an external source. If there is no manual timer option and you can only record from the EPG then you will not be able to record from Sky.

The other thing to consider is HDCP copy protection which could stop you recording anything over HDMI anyway.
chrisjr is offline   Reply With Quote
Old 01-12-2012, 20:44
Nigel Goodwin
Forum Member
 
Join Date: Apr 2006
Location: North Derbyshire
Posts: 38,233
There is no technical reason why the TV could not record from an external source to USB. It simply requires the necessary electronics.
I would disagree - while it's true it 'just requires the necessary electronics', that's a VERY misleading statement.

It would require a substantial amount of extra electronics (and money) to do so, and it wouldn't really be a 'PVR' any more then, more like a DVD recorder (without a DVD ).

It's the PVR capability that makes it relatively easy and cheap to add - it requires little extra electronics, as most of it was there already, mostly just software to make it happen.

Incidentally, does anyone know which was the first TV to add the simple PVR capability that many sets now provide?.
Nigel Goodwin is offline   Reply With Quote
Old 01-12-2012, 21:30
chrisjr
Forum Member
 
Join Date: May 2004
Location: Reading
Posts: 22,038
I would disagree - while it's true it 'just requires the necessary electronics', that's a VERY misleading statement.

It would require a substantial amount of extra electronics (and money) to do so, and it wouldn't really be a 'PVR' any more then, more like a DVD recorder (without a DVD ).

It's the PVR capability that makes it relatively easy and cheap to add - it requires little extra electronics, as most of it was there already, mostly just software to make it happen.

Incidentally, does anyone know which was the first TV to add the simple PVR capability that many sets now provide?.
To record off the HDMI would simply require a path for the digital data stream to get to the USB socket at it's most simple. Mind you probably wouldn't give you much recording duration.

Bear in mind you can buy video capture devices for PCs that take analogue audio and video and convert to MPEG digital for as little as £20 or even less I would dispute that it would cost a lot of money to add such functions.And some of these devices are barely any bigger than a USB memory stick so hardly loads of electronics to squeeze in.
chrisjr is offline   Reply With Quote
Old 02-12-2012, 02:32
jjne
Forum Member
 
Join Date: Mar 2011
Posts: 5,252
To record off the HDMI would simply require a path for the digital data stream to get to the USB socket at it's most simple. Mind you probably wouldn't give you much recording duration.
An HDMI signal could not be copied onto USB -- the data rate is far too high.

Bear in mind you can buy video capture devices for PCs that take analogue audio and video and convert to MPEG digital for as little as £20 or even less I would dispute that it would cost a lot of money to add such functions.And some of these devices are barely any bigger than a USB memory stick so hardly loads of electronics to squeeze in.
Recording in SD would not be massively expensive (SD MPEG2 encoding chips are available for a few dollars). HDMI would be a different story -- capable chipsets are around 10x the price currently.

Also HDMI has copy-protection built-in -- this would be problematic both legally and technically.

USB PVR technology literally copies the data stream from the broadcast multiplex (you knew that of course) -- that does rather simplify things.
jjne is offline   Reply With Quote
Old 02-12-2012, 09:59
grahamlthompson
Forum Member
 
Join Date: May 2005
Location: Redditch Worcs
Posts: 15,751
It is possible to record from a HDMI output in full HD quality using a roundabout route.

You need a hdcp capable hdmi to component converter like the HDfury2 and a Hauppage HD pvr which will record component output. USB 2.0 is easily fast enough for HD recording. A ripped blu-ray at it's original 35Mbps data rate plays back just fine on a usb powered 500GB pocket sized drive both on my laptop and on an Asus Tablet PC.
grahamlthompson is offline   Reply With Quote
Old 02-12-2012, 10:55
jjne
Forum Member
 
Join Date: Mar 2011
Posts: 5,252
It is possible to record from a HDMI output in full HD quality using a roundabout route.

You need a hdcp capable hdmi to component converter like the HDfury2 and a Hauppage HD pvr which will record component output. USB 2.0 is easily fast enough for HD recording. A ripped blu-ray at it's original 35Mbps data rate plays back just fine on a usb powered 500GB pocket sized drive both on my laptop and on an Asus Tablet PC.
You'll note that the only way of doing it is to convert to analogue first.

USB2 is *not* capable of recording direct from an HDMI stream, and your comparison is absurd. HDMI at even 720p has a data rate of over 1Gbps. this is more than twice what USB2 can even theoretically handle.

Yes, of course it's possible to get around HDCP, and of course it's possible to compress an HD stream such that it'll fit into the parameters of the USB standard.

But all this requires significant extra hardware, and the political will on the part of the manufacturer to bypass copy protection mechanisms (a legally dubious process).

Can't see Panasonic implementing any of that soon.
jjne is offline   Reply With Quote
Old 02-12-2012, 11:30
grahamlthompson
Forum Member
 
Join Date: May 2005
Location: Redditch Worcs
Posts: 15,751
USB2 is *not* capable of recording direct from an HDMI stream, and your comparison is absurd. HDMI at even 720p has a data rate of over 1Gbps. this is more than twice what USB2 can even theoretically handle.
It's your comparison that's absurd

A Astra 1N DVB-S2 transponder carrying 3 HD channels has a datarate of 44.5 Mbps. That's a whole multiplex. Blu-ray typically delivers around 35Mbps.

The whole point of hdmi is to allow digital copy protection (hdcp) simply not possible with analogue delivery systems.

Why would you need a data transfer rate of 1Gbps to deliver a video and audio signal whose datarate is only around 4Mbps,

Your numbers are just plain daft. A 1 hour recording of BBC-HD will use about 5GB of storage, your 1Gbps 720p would need 450GB

In fact your whole post is fatally flawed USB2 HDMI recording devices already exist, they are used by games console enthusiasts to record gaming activity. This of course is hdcp free.

Example

http://blitzcast.com/gamepro1080/

Similar devices are available on slot in computer cards.
grahamlthompson is offline   Reply With Quote
Old 02-12-2012, 11:43
jjne
Forum Member
 
Join Date: Mar 2011
Posts: 5,252
It's your comparison that's absurd

A Astra 1N DVB-S2 transponder carrying 3 HD channels has a datarate of 44.5 Mbps. That's a whole multiplex. Blu-ray typically delivers around 35Mbps.

The whole point of hdmi is to allow digital copy protection (hdcp) simply not possible with analogue delivery systems.

What you are saying is ridiculous, and you are totally missing the point. The OP explicitly asked why it was not possible for a TV to record directly from HDMI.

Not a compressed datastream. HDMI.

HDMI, which is an uncompressed data stream.

Once you have uncompressed the "35mbps" stream, it isn't 35mbps any more, is it?

In order to make it fit USB, the stream needs to be recompressed once again.

http://en.wikipedia.org/wiki/Uncompressed_video

720p HDTV uncompressed

8 bit @ 1280 x 720 @ 59.94field = 105 MB per/sec, or 370 GB per/hr.
10 bit @ 1280 x 720 @ 59.94field = 140 MB per/sec, or 494 GB per/hr.
Well I never.

Why would you need a data transfer rate of 1Gbps to deliver a video and audio signal whose datarate is only around 4Mbps,
See above.

Your numbers are just plain daft. A 1 hour recording of BBC-HD will use about 5GB of storage, your 1Gbps 720p would need 450GB
Correct. BBC HD is compressed, output from HDMI is uncompressed.

In fact your whole post is fatally flawed USB2 HDMI recording devices already exist, they are used by games console enthusiasts to record gaming activity. This of course is hdcp free.

Example

http://blitzcast.com/gamepro1080/

Similar devices are available on slot in computer cards.
lmao.

You've just demonstrated my point.

The BlitzBox GamePro•1080 is a HD USB video game capture card. Direct-stream live and record XBox 360, PS3, Wii (HD), or PC videofrom your PC or Laptop †(USB 2.0 / USB 3.0)! It records games at video resolutions up to 1080p (1920×1080 / 16:9) via HDMI or component RCA, in real time using a high performance built-in hardware H.264 encoder – for higher quality and less required PC horsepower.
So, as I stated, you require a hardware encoder. Which costs money.
jjne is offline   Reply With Quote
Old 02-12-2012, 11:51
bazellis
Inactive Member
 
Join Date: Oct 2007
Posts: 5,263
Thank you guys, in simple terms it's a no then.
Now stop arguing, it's nearly christmas
bazellis is offline   Reply With Quote
Old 02-12-2012, 11:54
jjne
Forum Member
 
Join Date: Mar 2011
Posts: 5,252
Thank you guys, in simple terms it's a no then.
Now stop arguing, it's nearly christmas


Answer is -- not yet.

It's likely that something will happen, eventually. Technology moves on. In 10 years time they'll be giving x264 encoders away with packets of cereal, and of course USB7 50TB USB flash-drives running at 100Gbps will cost £20 from amazon.com, and at that point it'll probably be viable.
jjne is offline   Reply With Quote
Old 02-12-2012, 12:15
grahamlthompson
Forum Member
 
Join Date: May 2005
Location: Redditch Worcs
Posts: 15,751

So, as I stated, you require a hardware encoder. Which costs money.
Every HD camcorder has one. You can buy the whole camera for as little as £100.00, how much did the actual hardware cost, certainly not a lot of money. Despite what you say it is possible to record from a hdmi cable, it would of course be illegal to defeat hdcp but entirely possible.
grahamlthompson is offline   Reply With Quote
Old 02-12-2012, 12:33
jjne
Forum Member
 
Join Date: Mar 2011
Posts: 5,252
Every HD camcorder has one. You can buy the whole camera for as little as £100.00, how much did the actual hardware cost, certainly not a lot of money. Despite what you say it is possible to record from a hdmi cable, it would of course be illegal to defeat hdcp but entirely possible.
So you acknowledge that extra hardware is required to record from HDMI to USB, and that the bandwidth required is not the same as for a compressed signal.

We're getting somewhere, at least.

From my first post, I laid out the costs required. An SD MPEG2 encoder costs in the order of $3-4. An HD encoder chipset of sufficient quality to do 720p material justice costs around ten times that.

If manufacturers aren't going to release twin-tuner USB-based PVRs within TVs due to the costs of a bit of extra software and a second tuner (which costs around the same as the SD encoder), they certainly aren't going to release a TV with legally-dubious functionality that could add as much as 20% onto the manufacturing costs, for a feature that is very unlikely to be used, and even less capable of being successfully touted as a feature.
jjne is offline   Reply With Quote
Old 02-12-2012, 13:06
grahamlthompson
Forum Member
 
Join Date: May 2005
Location: Redditch Worcs
Posts: 15,751
So you acknowledge that extra hardware is required to record from HDMI to USB, and that the bandwidth required is not the same as for a compressed signal.
.
I never said it wasn't hence the post about the HDfury2.

Basically you said it was impossible to record from hdmi to a usb drive. That is false it's not impossible

The h264 encoder is simply required to re-compress the data back to where it was before the decoder expanded it. The same process used by DVD recorders for mpeg2 and the few that now offer AVCHD HD recording to DVD blanks.

I think you need to update your prices. You can buy 720P digital recording devices in the US or from China for less than the price you quote for the chip alone.

Even in the UK you can buy one for less than £100.00

eg

http://www.amazon.co.uk/Aiptek-3D-HD.../dp/B003VI27AY .
grahamlthompson is offline   Reply With Quote
Old 04-12-2012, 12:43
bazellis
Inactive Member
 
Join Date: Oct 2007
Posts: 5,263
I was just thinking, could I connect my sky box via an RF lead and tape it that way?
bazellis is offline   Reply With Quote
Old 04-12-2012, 12:51
chrisjr
Forum Member
 
Join Date: May 2004
Location: Reading
Posts: 22,038
I was just thinking, could I connect my sky box via an RF lead and tape it that way?
No. For pretty much the same reasons why you can't record from anything other than the built in Freeview. The TV does not possess the necessary electronics to make this possible.

And if you have a Sky+ box why on earth would you want to do this anyway? Far easier to use the built in facilities of the Sky + box surely? Or do you have a Sky + box but no sub to Sky so can't use the + features?
chrisjr is offline   Reply With Quote
Old 04-12-2012, 13:40
jjne
Forum Member
 
Join Date: Mar 2011
Posts: 5,252

Basically you said it was impossible to record from hdmi to a usb drive. That is false it's not impossible
No I did not, and stop trying to create a straw man.

My exact words were:

An HDMI signal could not be copied onto USB -- the data rate is far too high.
This is a factually correct statement, and was in direct response to your factually incorrect statement that:

To record off the HDMI would simply require a path for the digital data stream to get to the USB socket at it's most simple.
This statement is wrong, precisely because HDMI's data rate exceeds that of USB (2).

It is possible to modify any video signal and fit it into something else -- but this requires additional hardware, and in this case that hardware is not especially cheap.

That has been my contention from the start and you know it.

You can buy 720P digital recording devices in the US or from China for less than the price you quote for the chip alone.
Go on then, enlighten me. I stated a figure of ten times $3-4.

Find me a device that is capable of taking a 720p signal, and compressing it at full 720p/25fps, at something approaching broadcast quality, for £19. Over to you.
jjne is offline   Reply With Quote
Old 04-12-2012, 14:28
grahamlthompson
Forum Member
 
Join Date: May 2005
Location: Redditch Worcs
Posts: 15,751
No I did not, and stop trying to create a straw man.

My exact words were:



This is a factually correct statement, and was in direct response to your factually incorrect statement that:



This statement is wrong, precisely because HDMI's data rate exceeds that of USB (2).

It is possible to modify any video signal and fit it into something else -- but this requires additional hardware, and in this case that hardware is not especially cheap.

That has been my contention from the start and you know it.



Go on then, enlighten me. I stated a figure of ten times $3-4.

Find me a device that is capable of taking a 720p signal, and compressing it at full 720p/25fps, at something approaching broadcast quality, for £19. Over to you.
I suggest you read the thread again. you are attributing quotes to me I did not make. I take it you can read a posters name

[quote]

"This is a factually correct statement, and was in direct response to your factually incorrect statement that:


Quote:
To record off the HDMI would simply require a path for the digital data stream to get to the USB socket at it's most simple.

[/ QUOTE]

I merely correctly pointed out there are a number of ways of taking the output from a hdmi cable and recording the video. One is analogue where HDCP is involved, the others are digital.

This camera costs £54.00 in the UK has the necessary encoder.

http://www.wexphotographic.com/buy-f...fwbktaodexaazw

In the US it no doubt retails for around the same price in dollars.
grahamlthompson is offline   Reply With Quote
Old 04-12-2012, 20:37
bazellis
Inactive Member
 
Join Date: Oct 2007
Posts: 5,263
And if you have a Sky+ box why on earth would you want to do this anyway? Far easier to use the built in facilities of the Sky + box surely? Or do you have a Sky + box but no sub to Sky so can't use the + features?
It's a multiroom box with no Sky+ functionality.
bazellis is offline   Reply With Quote
Old 04-12-2012, 20:49
chrisjr
Forum Member
 
Join Date: May 2004
Location: Reading
Posts: 22,038
It's a multiroom box with no Sky+ functionality.
Even if the TV was able to record from the Sky box it is quite likely it would only record what you are watching. There is every possibility you would not be able to record something on Sky and watch a Freeview channel for example. Fairly obviously you would not be able to record one Sky channel and watch a different one.

An alternative would be a DVD recorder. But again you would not be able to record and watch two different Sky channels. Though you could record Sky and watch Freeview (or vice versa by recording off the DVD's internal tuner).

And if you were going to buy a DVD recorder it would probably be easier to upgrade to a Sky+ box anyway, may even be cheaper!

But I suspect a DVD recorder or Sky+ box is the only way you will be able to record Sky.
chrisjr is offline   Reply With Quote
 
Reply



Thread Tools Search this Thread
Search this Thread:

Advanced Search

 
Forum Jump


All times are GMT +1. The time now is 22:44.