File size for uncompressed HDTV - AVS Forum
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post #1 of 22 Old 01-09-2007, 03:15 PM - Thread Starter
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The idea behind using HDMI cables for direct digital connection is that it is secure from copying, due to the large file size.

What would be the file size of say 1 hr of HDTV uncompressed? The reason I ask is that computers are getting faster and storage media are getting larger every year.

Will there be a point in the not too distant future where a computer could store an entire uncompressed movie? There goes the security.
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post #2 of 22 Old 01-09-2007, 03:19 PM
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1 hr of HDTV on my DVR takes up about 6 percent of a 120GB hard disk. That's about 7.2 GB, which is about the size of .TS file when recording one hour of HD on the PC over the firewire connection.
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post #3 of 22 Old 01-09-2007, 03:22 PM
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Quote:
Originally Posted by maltesefalcon View Post

What would be the file size of say 1 hr of HDTV uncompressed?

About 675 GB. Could someone check my math?

The real threat is that HD compressor chips are starting to get reasonably priced. 1080i camcorders that output HDV and AVC are about a thousand bucks now.

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post #4 of 22 Old 01-09-2007, 03:23 PM
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Quote:
Originally Posted by Al Shing View Post

1 hr of HDTV on my DVR takes up about 6 percent of a 120GB hard disk. That's about 7.2 GB, which is about the size of .TS file when recording one hour of HD on the PC over the firewire connection.

That's compressed. He asked for the size of uncompressed HD.

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post #5 of 22 Old 01-09-2007, 03:27 PM
 
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Quote:
Originally Posted by maltesefalcon View Post

The idea behind using HDMI cables for direct digital connection is that it is secure from copying, due to the large file size.

What would be the file size of say 1 hr of HDTV uncompressed? The reason I ask is that computers are getting faster and storage media are getting larger every year.

Will there be a point in the not too distant future where a computer could store an entire uncompressed movie? There goes the security.

Well, first, if you consider ATSC 19.3 Mbps is roughly 8.8 Gig per hour of MPEG2 - and the D5 Recorder/Players are still compressed (though not as much) and about 300 Mbps or 15x - that's 130 Gig per hour and you are still compressed. Multiple it by roughly 3x to get a good estimate of uncompressed - or about 400 Gig an Hour - though it could be as high as 675GB as scowl said.

Furthermore, though a computer can handle it (well maybe a PCI Express Bus), a single hard drive or two cannot begin to handle that much data in real time.

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post #6 of 22 Old 01-09-2007, 03:50 PM
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Since HDTV OTA is transmitted as mpeg2 (19+ Mbps if not degraded), I consider that uncompressed, as in that's the ultimate the consumer can get. Compressed would be further compression such as mpeg4 or rate shaping or multicasting.

And I don't think the reason for HDMI has anything to do with file sizes.
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post #7 of 22 Old 01-09-2007, 03:55 PM
 
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Quote:
Originally Posted by grittree View Post

Since HDTV OTA is transmitted as mpeg2 (19+ Mbps if not degraded), I consider that uncompressed, as in that's the ultimate the consumer can get.


That's totally untrue. No matter how you try to spin it, MPEG2 is already highly compressed - and the OP original question acknowledged that. If 19.3Mbps is an uncompressed movie - then I believe we have already come to the point where a Hard Drive will hold an "uncompressed" movie by your standards - all 15 GB of it, lol.

Even D-Theater is around 25 or Mbps and that has been available for years.

I can watch Network Backhauls of Sporting Events via Satellite that approach upwards of 40 Mbps.

So saying 19 Mbps is the uncompressed and the ultimate is very naive.
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post #8 of 22 Old 01-09-2007, 04:05 PM
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Quote:
Originally Posted by grittree View Post

Since HDTV OTA is transmitted as mpeg2 (19+ Mbps if not degraded), I consider that uncompressed, as in that's the ultimate the consumer can get.

Heavens, even HD-DVD and BluRay players can go way past that bitrate and they're still extremely compressed formats.

Doesn't D5 use lossless compression of something like 4:1 in a 4:2:2 color space? I was thinking we might as well keep the whole 4:4:4 color space since I'm not paying for it.

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post #9 of 22 Old 01-09-2007, 04:34 PM
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I thought the subject was HDTV, which in normal speak means what TV stations broadcast.

I don't consider attaching devices with higher bit rates germane to the question. But that's just my opinion.
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post #10 of 22 Old 01-09-2007, 05:00 PM
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Quote:
Originally Posted by scowl View Post

Heavens, even HD-DVD and BluRay players can go way past that bitrate and they're still extremely compressed formats.

Doesn't D5 use lossless compression of something like 4:1 in a 4:2:2 color space? I was thinking we might as well keep the whole 4:4:4 color space since I'm not paying for it.

D5 is not loss-less for HD material, as you say it uses around 4:1 compression of a 4:2:2 uncompressed source, and this isn't lossless, though it is very high quality.

D5 IS lossless for SD material (13.5MHz 10bit 270Mbs or 18MHz 8bit 270Mbs uncompressed 4:2:2) - and the HD-D5 format was effectively created by tacking on an external compression unit that 4:1 compressed a 4:2:2 HD-SDI 1080i or 720p source down to 270Mbs, allowing this to be recorded on tape. (A similar system was also developed for the earlier D1 uncompressed SD VTRs but D1 was already an aging, expensive and less practical tape format by this time)

The only uncompressed VTR for HD that I know of is the BTS/Philips and Toshiba D6 (aka Digital Voodoo) HD VTR - and this is also pretty obsolete these days.

Back of envelope calculation, assuming you only store the active picture content of a 1080p or 1080i frame :

1080x1920 pixels at 4:2:2 colour space with 8 bit depth would be :

1080x1920x16 bits, or 1080x1920x2 bytes per frame

This is approx 3.96 Megabytes per frame

So for 24fps (24p) that would be 95 Megabytes per second, for 25fps (25p or 50i) 99 Megabytes per second, and for 30fps (30p or 60i) 119 Megabytes per second.

Let's take 1080/60i, as that is probably the format whizzing down your HDMI link to your TV.

In 60 seconds that would be 6.95 Gigabytes (assuming 1024 Megabytes to the gigabyte - which hard drive manufacturers don't usually, and instead use 1000...), which would mean in an hour it would be around 417 Gigabytes?

So for a 4:2:2 YCrCb 1080/60i or 1080/30p video feed - assuming you only record the active 1920x1080 frame - you end up with around 420Gb per hour? This isn't quite the same as losslessly recording the HDMI or HD-SDI digital video stream - as you aren't recording any data that might be carried in vertical or horizontal blanking.
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post #11 of 22 Old 01-09-2007, 05:01 PM
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Quote:
Originally Posted by maltesefalcon View Post

The idea behind using HDMI cables for direct digital connection is that it is secure from copying, due to the large file size.

What would be the file size of say 1 hr of HDTV uncompressed? The reason I ask is that computers are getting faster and storage media are getting larger every year.

Will there be a point in the not too distant future where a computer could store an entire uncompressed movie? There goes the security.

Except that HDMI is usually, these days, accompanied by HDCP as well, which adds an extra layer of security.
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post #12 of 22 Old 01-09-2007, 05:08 PM
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Quote:
Originally Posted by grittree View Post

Since HDTV OTA is transmitted as mpeg2 (19+ Mbps if not degraded), I consider that uncompressed, as in that's the ultimate the consumer can get.

I don't agree with that. Compression is compression. Just because the consumer can't receive uncompressed broadcast TV doesn't mean it ceases to be compressed.

Also - the consumer DOES have sources of uncompressed HD. At least one Sony HDV camcorder now offers an HDMI live video output generate prior to the HDV compression - which is a source of uncompressed HD. (This is one of the main reasons that PCI cards with HDMI inputs are now being produced, to allow PCs to accept the uncompressed outputs from these camcorders)

Similarly PCs and Macs are available with HDMI or DVI digital outputs, both of which are uncompressed and HD.

Quote:


Compressed would be further compression such as mpeg4 or rate shaping or multicasting.

Sorry - again I don't agree. That is further compression, re-compression etc. it doesn't make the source suddenly uncompressed.

If you describe an 19Mbs ATSC stream as "uncompressed" does that make the picture quality faults "uncompression artefacts" caused by the lack of compression?

Quote:


And I don't think the reason for HDMI has anything to do with file sizes.

HDMI exists for lots of reasons.

1. An inherently digital interconnect between digital sources and fixed pixel displays based around digital signal processing makes a lot of sense, as it gets rid of D/A and A/D processes that degrade picture quality.
2. HDMI also allows for a greater degree of source/display communication, allowing for both content protection using HDCP, and also easier configuration of source resolutions for optimal use with displays.
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post #13 of 22 Old 01-09-2007, 05:11 PM
 
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Quote:
Originally Posted by sneals2000 View Post

I don't agree with that. Compression is compression. Just because the consumer can't receive uncompressed broadcast TV doesn't mean it ceases to be compressed.

.....


Sorry - again I don't agree. That is further compression, re-compression etc. it doesn't make the source suddenly uncompressed.

If you describe an 19Mbs ATSC stream as "uncompressed" does that make the picture quality faults "uncompression artefacts" caused by the lack of compression?

Don't worry about it...he's only trying to spin it to save face - as the original post set up the parameters of which he ignored.


Quote:
Originally Posted by sneals2000 View Post

.... you end up with around 420Gb per hour? This isn't quite the same as losslessly recording the HDMI or HD-SDI digital video stream - as you aren't recording any data that might be carried in vertical or horizontal blanking.

So my non-back of envelope estimate of 400Gb per hour was pretty good for not putting a paper and pencil to it
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post #14 of 22 Old 01-09-2007, 05:22 PM
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Quote:
Originally Posted by grittree View Post

Since HDTV OTA is transmitted as mpeg2 (19+ Mbps if not degraded), I consider that uncompressed.....

That is compressed.

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post #15 of 22 Old 01-09-2007, 07:07 PM
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Quote:
Originally Posted by HDTVFanAtic View Post

So my non-back of envelope estimate of 400Gb per hour was pretty good for not putting a paper and pencil to it

But still, isn't this 400GB an hour for a 4:2:2 color space? Darn it you're throwing away half my color! When I say uncompressed, I demand 4:4:4 color space! I don't want any weird lines around my actors when I do all that fancy green screen CGI stuff! It can't be more than another 200GB or so an hour.

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post #16 of 22 Old 01-10-2007, 03:47 AM - Thread Starter
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Thanks for the info. Looks like we are several years from storing uncompressed files.

Here's an interesting point. If we use a PVR like me, does it uncompress the stored program material then send to to the tv as raw data which is then recompressed in the tv as MPEG 2 or 4 again? (Using HDMI cable)
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post #17 of 22 Old 01-10-2007, 05:06 AM
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hdmi is uncompressed , YUV (i think) bitstream.
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post #18 of 22 Old 01-10-2007, 09:47 PM
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Quote:
Originally Posted by maltesefalcon View Post

The idea behind using HDMI cables for direct digital connection is that it is secure from copying, due to the large file size.

What would be the file size of say 1 hr of HDTV uncompressed? The reason I ask is that computers are getting faster and storage media are getting larger every year.

Will there be a point in the not too distant future where a computer could store an entire uncompressed movie? There goes the security.

Well you can store it now. I happen to have 4 tb of storage on one of my machines, mostly in external SATA raids. That's not really the point though....Why would you want to store it uncompressed? There's a lot of redundant data anyway, which is why video compresses well. Not to mention that the stream was compressed in the first place by the broadcaster.


So a better question might be "when can I capture and compress the video in realtime". Well.....right now, and for the forseable future, it'll take a lot of computing power to do that. Plus, a PCI bus would flood with the data from uncompressed HDTV. So figure: A really fast machine (possibly something like 4 really fast cores may be enough) and a big pci express bus...

Actually though, you can probably do better with a dedicated hardware capture/compression card. Now that'll set you back...well...at least a few grand, and probably more when all is said and done.

That brings up another issue: Eventhough HDMI is digital, it is uncompressed, so the video is decompressed and then you need to capture and recompress it. This means there will be some loss due to recompression. This is another reason why capturing the transport stream is preferred.

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post #19 of 22 Old 01-11-2007, 01:48 AM
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Quote:
Originally Posted by maltesefalcon View Post

Here's an interesting point. If we use a PVR like me, does it uncompress the stored program material then send to to the tv as raw data which is then recompressed in the tv as MPEG 2 or 4 again? (Using HDMI cable)

No, there's no reason to do that. You'd simply be adding cost to the TV (since they don't have MPEG encoders in them) and reducing picture quality.
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post #20 of 22 Old 01-11-2007, 03:53 AM - Thread Starter
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OK I am getting really confused. If HDMI sends uncompressed data to the display in a file so large it is impractical to record, does it not make sense that the display has to have some kind of MPEG encoder?

Otherwise the files are already encoded therfore compressed and the whole point is moot.
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post #21 of 22 Old 01-11-2007, 04:22 AM
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? display displays this uncompressed data. does your TV record shows you watch? mine doesn't.
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post #22 of 22 Old 01-11-2007, 12:43 PM
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Quote:
Originally Posted by maltesefalcon View Post

OK I am getting really confused. If HDMI sends uncompressed data to the display in a file so large it is impractical to record, does it not make sense that the display has to have some kind of MPEG encoder?

Just think of HDMI as nothing more than a fancy digital wire. The data sent across it never exists as a file in uncompressed form. The data is displayed and it's gone forever.

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