Capture using a USB TV receiver file sizes WMC

[Cole]

Being someone who archives from off-air I have several different ways of capturing, Cable-box, DVD recorder, and PC via a TV USB receiver.

The software that came with the USB receiver records directly to .mpeg and the quality can be changed between HQ, SQ, etc. All of my captures are at SQ (across all devices so that I have the standard 2 hours on one DVDR) and the captures from my PC were of a comparable size to what I may capture on my DVD recorder. The only drawback is there are the occasional jumps in the captured .mpeg and the software is prone to freezing-up (PC is XP 3ghz Pentium 4, 3gb 333 ram).

I recently upgraded my Vista laptop (Intel dual core T2130 1.86 4gb 533 ram) to Windows 7 and tried the USB receiver with Windows Media Center which worked really well; flawless playback and recording. Then it came to converting the recording to DVDR. No problems there: convert to .dvr-ms format and edit/save as .mpeg in VideoReDo TV Suite.

At this point I noticed that the captured file size was aprox. two thirds the size of an .mpeg capture from a DVD recorder. So I looked at the settings, in WMC, to see if I could improve on the capture quality (HQ, SQ etc) but they're not there (apparently it's there for analogue tuners only). I did an on-line search to find out why and it appears to be that the file is copied bit for bit from the received digital signal. The USB receiver I have is unbranded and is at the bottom end of the price scale.

I can only surmise that the quality of capture on WMC is down to the quality of the signal (the attached aerial could be better) and the receiver itself or is this file size completely standard? Logic says that it is standard, but the original software did record at the SQ rate, or am I missing something? Can anyone clarify this please? Thanks.

[yoda313]

I am assuming you are talking about off air digital stream recording. You get what you get. There aren't quality settings if you are capturing the hdtv stream (usually in a .tp or .ts format). Its digital so its all or nothing. You either get the signal or you don't. A stronger antenna will get a higher signal strength for smoother reception. But the file size won't change.

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EDIT - the pinnacle usb hdtv turners were able to record off air hdtv to dvd format and in widescreen format. I had forgotten this while posting. I don't know if pinnacle still makes the hardware. I think it might be done by happauge now. They are usb sticks that have a coax jack for hooking up to a normal aerial antenna (or cable for sd transmissions).

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For that you will need to do that in conversion. You'll have to fiddle with bitrates in your converstion to mpeg2 for dvd authoring or whatever your intended format and destination are. But you are stuck with the capture stream from off air.

The only alternative is to use a cable or fios or sat box for getting hdtv (fees obviously involved with this route). From there get a happauge hdpvr or blackmagic intensity capture unit so you can record from component or hdmi. Than you can adjust your capture formats but that involves recording off the box and you can't set up a tuner on your computer like you can with off the air. You will be recording from an external source and anything it displays (like on screen graphics if your not careful).

[Cole]

I am assuming you are talking about off air digital stream recording. You get what you get. There aren't quality settings if you are capturing the hdtv stream (usually in a .tp or .ts format). Its digital so its all or nothing. You either get the signal or you don't. A stronger antenna will get a higher signal strength for smoother reception. But the file size won't change.

---------------------------------
EDIT - the pinnacle usb hdtv turners were able to record off air hdtv to dvd format and in widescreen format. I had forgotten this while posting. I don't know if pinnacle still makes the hardware. I think it might be done by happauge now. They are usb sticks that have a coax jack for hooking up to a normal aerial antenna (or cable for sd transmissions).
...

The hardware I have is one of these:



It sounds the same as the Pinnacle where the aerial cable plugs into the end.

The software that came with it, Arcsoft Total Media 3, records off-air to a DVD format and also in widescreen. It sounds as if programs like Pinnacle and Total Media apply some processing to the signal but Windows Media Center doesn't. WMC records to a .wtv file which, as I understand it is a wrapping around an .mpeg.

What I was concerned about was loss of detail as a lot more video can be stored onto a DVDR, from a WMC capture, than at normal SQ setting from a Total Media 3 capture or from a DVD recorder; but if the detail isn't there in the first place then the picture quality should be the same in both instances. But that doesn't make sense as less bitrate usually means a sacrifice of quality.