Uncle, Uncle!!! Actually that was a good answer. I see that I need to learn more :)
So about 8-9 GB/hour.... What I have in mind is a large number of hours of HDTV being recorded to storage. I'm guessing that total number of hours, but I think the general number is over 4,000 hours (about 36,000 GB or 3.6 TB). Actually it's not that much data is it? Just a few hard drives and you've got it. Thanks! Jeff > At 08:49 AM 5/29/2007, [EMAIL PROTECTED] wrote: > >Good morning, > > > >I was doing some thinking over the weekend (while cooking ribs on > >the grill :) ). > >Does anyone know who much data 1 hr. of HDTV produces? Let's try 720 for > >now and perhaps 1080. I'm looking for the file size if you store the > >whole thing > >in a single file. > > > Are you asking about "as generated in the studio" or "as recorded" or > "as broadcast" > > the raw data rate is >1 Gbps (142.18 Mb/s for NSTC sampled at 14.318 > Ms/s up to 1.486 Gbps for SMTPE 292M sampled at 74.25 Ms/s) > > > > There's several compression/redundancy removal steps in the chain, > and different HD broadcast media (over the air in US (ATSC), over the > air in Europe (DVB-T), direct broadcast satellite (DVB-S, and others) > , cable) use different bit rates, and different compression > schemes. And, of course, the DVD (including the new BluRay and > HD-DVD) have their own encodings as well. > > In the US, HD is broadcast over the air in a 6MHz wide channel at > between 19-20 Mbps (3 bits/symbol). However, that 20 Mbps stream can > be divvied up in lots of ways: 1 really HD channel, 5 SD channels, 2 > SD channels plus a medium rate HD channel. > > Wikipedia has a lot of info on this.. > > The appearance of the decoded output depends a LOT on how good the > encoding was. You can cheap out and just do simple frame encoding, > with no frame-to-frame encoding, in which case you get high > resolution with lots of artifacts. Or, you can spend a lot more > effort on the encoding, and make use of the frame to frame > redundancy, and get a lot less artifacts. The telling difference is > if you have something like a panning shot over a complex, but fixed, > background (e.g. a forest in the distance). A good encoder will be > able to make use of the fact that big swaths of the image are > actually the same from frame to frame, just displaced. A cheap > encoder will not. > > Cable TV and direct broadcast satellite use somewhat different data > rates (since they have different heritage), and different encodings, > sometimes. > > Compressed digital video that is intended for further editing is also > compressed differently, because the "broadcast" compressions tend to > have unsuitable artifacts in the editing process. Squeezing a raw > data rate of >1 Gbps down into 20 Mbps or so always entails some > compromises, and the broadcast compressions are designed to allow > inexpensive decoders (and expensive encoders..you'll be making > millions of decoders and dozens of encoders) and for artifacts that > are visually unobjectionable to an end user. > > As you can imagine, there is much opportuntity for transcoding artifacts. > > These days, H.264/AVC is probably the leading candidate for compression > > > So.. for over the air HD broadcasts, 20 Mbps should do you, which is > well within the range of a variety of hard disks. Converting to > GB/hr, I get 8-9 GB/hr > > > James Lux, P.E. > Spacecraft Radio Frequency Subsystems Group > Flight Communications Systems Section > Jet Propulsion Laboratory, Mail Stop 161-213 > 4800 Oak Grove Drive > Pasadena CA 91109 > tel: (818)354-2075 > fax: (818)393-6875 > > _______________________________________________ Beowulf mailing list, [email protected] To change your subscription (digest mode or unsubscribe) visit http://www.beowulf.org/mailman/listinfo/beowulf
