HDV motion artifiacts

[Jim Giberti]

Question Douglas...I've been spending a good deal of time the last few weeks trying to make the decision on which system to use transitioning our studios to HD.

I've got XL2s now and have had the range of the XL series over the years. So I like Canon, the build and glass and form factor (especially now that they came back to their senses and returned to a logical iris wheel on the H1).
I've got a lot lenses etc., so a couple of XL-H1s would make sense.
Even an HD-100 could be a nice third camera (like to see how they cut together).

I've liked working with the Panasonic on location and in post as well, but HDV looks very nice. My one true reservation coming from my background as a music producer is the audio compression. Everything we produce goes out of FCP to MOTU in audio post and I'm used to working at 48k and 96k 24 bit.

Is the audio a compromise in your opinion?

EDITING MY OWN POST HERE.

I did a little more searching and found your detailed opinions on this so thanks.
It seems business as usual is the approach with HDV, fine for commercial and doc work, use a separate mixer and recorder for bigger narrative projects.
FWIW I really wish the "which camera, which work flow, FCP 24p, Mac Intel transition thing" would settle down quickly.
I'm spending way too much time researching and just want to get back to writing the upcoming projects ;)

[Ben De Rydt]

Well I bet you were wrong :-)

I was surprised that the high I-rate, mid P-rate and low B-rate shot was goldentree. The locked off static walnut shot had about an even I and P rate with the B-frames about half of either I or P frames. The only explanation I can give for this is that the walnut shot contains so little information that it doesn't really matter how it's being compressed.

Now, to compare these results to DVCProHD, I formulated the hypothesis that an HDV codec implementor would strive for constant quality, that is, there should be no visible difference between I, P and B frames. That is, I pretented that HDV was an I frame codec only. So I took the results of the I frames in the two different shots and caculated an I-frame only bitrate. Goldentree comes out at about 67 Mbps, the walnut shot at 37 Mbps. This is a 6.6:1 to 12:1 compression ratio, compared to DVCProHD 5:1 compression ratio.

As I said, it's too early to call my results preliminary and the results are hardly significant. It will take a while before I can put some more time in it, that's why I posted it now.

[Dan Euritt]

Originally Posted by Douglas Spotted Eagle

HDV doesn't have a delivery format? HDCAM, D5, and diskbased delivery to a media server such as MediaBase or Matrox Media server aren't delivery formats?

yeah right... i'm going to run right down to blockbuster and pick up march of the penguins on hdcam... or perhaps those copies will all be checked out, and i'll have to settle for d5, lol.

maybe i can watch an hdv movie over the 'net? no... how about seeing hdv projected in hd at the local theatre? nope.

"people are using it", and "hundreds of hours", is idle speculation by someone selling hdv products... perhaps we need a factual list of just where hdv is being used, and just where it's being rejected.

make it a sticky for this forum... i already listed the initial hdv rejection, it's the national geographic hd channel, as reported by tvtechnology on 1/11/06, page 22.

and shannon... minidv was shown at sundance in 1998, perhaps even before that... they'll take anything :-)

[Dan Euritt]

Originally Posted by Shannon Rawls

http://dvestore.com/theatre/
Watch "NAB 2005 - Panasonic AG-HVX200 (extended version)"

i really liked the part where she said that "hdv was designed as a consumer format"... the national geographic hd channel sure proved that.

did you catch her line about "bit starved"? that's exactly what i stated in this thread, when i said that the per-pixel bitrate of hdv is far less than it is for dvd... prove it for yourself, the math is pretty simple.

how about the way that she pointed out how dropouts can destroy the entire hdv gop? here is another explanation of that, from someone who understands the hdv drawbacks, but still wants to buy into the format anyway: http://www.technologyevangelist.com/...ate_it_bu.html

Jan Crittenden is very smart, i remember her posts on the 'net from way back in, heck, the compuserv forum days? 10 years ago??

[Douglas Spotted Eagle]

Originally Posted by Dan Euritt

yeah right... i'm going to run right down to blockbuster and pick up march of the penguins on hdcam... or perhaps those copies will all be checked out, and i'll have to settle for d5, lol.
:-)

If that's your argument, then it's an argument for ALL forms of HD, period. There is no distribution to the end consumer at this very second for your beloved Panny cam, either. Look Dan, it's pretty clear you have an agenda against HDV. You're welcome to your opinion, but frankly, it's a little old at this point.

BTW, I DO have the ability right now, this second, to watch HD media on a DVD player, I spent about 4 hours today doing exactly that. From a shiny disk, not from a computer, not connected to a computer.

Curious, if Sundance will take "anything" when will we see one of your projects there? Having been a participant in the selection process, I'm wondering where that silly notion comes from?

Finally, whilst you suggest National Geo will not accept anything in HDV....they already have. (4 bull elk battling simultaneously) It was converted to 4:2:2 YUV, and delivered on HDCAM.
As far as a list, I think I've pointed out enough shows using HDV over the various fora.

What is your point? That you don't like HDV? I think the point has been well-taken. Probably a good time to move on.

[Ken Hodson]

Dan I think you arwe simplifying things in your head just a little too much.
What is the bit rate of you beloved Panny codec at 720p24?
Whats the HDV equivalent at 720p24?
How much more efficient is HDV's mpeg2 over DVCproHD?
So whats the mathematical differance that is so huge you are willing to stand up like a cock in a chicken coop and crow your head off?

[Alister Chapman]

I can confirm that National Geographic will accept HDV in HD programmes. Much of my footage was used in the recent programme "Tornado Chasers", don't believe me, then check the end credits. I will also bet that you can't pick out what's HDV and whats DVCPRO HD. The programme was shot on a mix of DVCPRO HD and HDV and delivered on HDCAM.

[Wayne Morellini]

Originally Posted by Alister Chapman

As HDV hardware and software codecs improve users will squeeze more and more quality from HDV in the same way as happened with DV. If you compare the quality of first generation DV codecs to todays DV codecs you will see that there has been a significant improvement in quality even though the "standard" itself hasn't changed.

The problem is that HDV is a mature technology, most of the improvements in mpeg2 performance have already happened in the last ten years and things have moved on, to improving h264, which has seen significant performance improvements in compression in the last year.

JVC has said they are moving to hard disk, I suspect they might even go to h264 as well (conjecture, they showed a HDV hard disk consumer camera last year).

Originally Posted by Ken Hodson

Dan I think you arwe simplifying things in your head just a little too much.
What is the bit rate of you beloved Panny codec at 720p24?
Whats the HDV equivalent at 720p24?
How much more efficient is HDV's mpeg2 over DVCproHD?
So whats the mathematical differance that is so huge you are willing to stand up like a cock in a chicken coop and crow your head off?

I see what you mean Ken, but I have to say something in Dan's defence. There is an interesting thing I have determined about codecs, that (and I'm guessing this does not apply to inter-frame compression techniques) efficiency matters less the closer you get to lossless, and bandwidth wins when dealing with high movement/image change. So in the extremes, bandwidth matters. The solution has always been to put the bandwidth up of HDV (well without changing it to another) even that extra 20%+ is probably going to make a great difference to the number of places that HDV falls over. Codecs like h264, hopefully, has increased efficiency in dealing with movement that might also help.

Here is an interesting thread that shows some of the deficiencies on HDV.

http://www.dvinfo.net/conf/showthread.php?t=58485

[Kevin Shaw]

Originally Posted by Dan Euritt

did you catch her line about "bit starved"? that's exactly what i stated in this thread, when i said that the per-pixel bitrate of hdv is far less than it is for dvd... prove it for yourself, the math is pretty simple.

Okay, let's do that math just to get it over with.

SD DVD standard maximum video bit rate = 8 Mbps at a resolution of 720x480 = 345,600 pixels, which works out to 23 bits per pixel per second at 30 fps. Many DVDs are delivered at lower bit rates of 5-6 Mbps, or 14-17 bits per pixel per second, and generally look pretty good at that setting.

HDV 720p uses 19 Mbps at 1280x720 pixels for a rate of 20 bits per pixel per second. Hmmm, that's not bad compared to maximum DVD bit rates, let alone typical Hollywood DVDs. It's definitely not "far less than it is for DVD."

HDV 1080i uses 25 Mbps at 1440x1080 pixels for a rate of 16 bits per pixel per second. That would be considered a bit sparse for SD DVDs, but still within the range that commercial movies are delivered.

So yes, HDV is stretching the limits of technology, but as Wayne points out MPEG2 is a mature technology which we've learned a lot about how to get the most out of over the last ten years. It's considered good enough for HD television broadcasts and upcoming Blu-ray HD movies at HDV bit rates, so it can't be all that bad. As far as dropouts are concerned, I've had less trouble with them in HDV than I did in DV, so that no longer concerns me unless that situation deteriorates as the cameras get older.

If you shoot a lot of demanding high-motion scenes like Dan then maybe HDV recording isn't for you, so buy a Panasonic HVX200 and a stack of Firestore DTE drives and get on with your life. (Say, I wonder how well those Firestore drives will hold up in a race car or on a surfboard?) For some of us HDV is a technological marvel which allows beautiful high-definition recording at a bargain price which our customers enjoy, and it will continue to serve that role until something better comes along at a similar price. That could happen in as little as five years or so, but until then...

[Ken Hodson]

Originally Posted by Wayne Morellini

JVC has said they are moving to hard disk, I suspect they might even go to h264 as well (conjecture, they showed a HDV hard disk consumer camera last year).

A move to h264 would result in a whole new format. What gives you the impression JVC is going to break away from HDV to go it alone?

"they showed a HDV hard disk consumer camera last year"

No they didn't.
There is a HDD available for the HD100 that will record its HDV stream. But that is it.

[Ken Hodson]

Originally Posted by Wayne Morellini

Here is an interesting thread that shows some of the deficiencies on HDV.
http://www.dvinfo.net/conf/showthread.php?t=58485

That thread shows the deficiencies of a compressed stream vs. a live uncompressed feed, which also happens to be at a higher resolution. Did you really think compressed HDV was going to look as good as uncompressed?

[Wayne Morellini]

I have already addressed it over there, I am not surprised it is worse than uncompressed, but how much worse it is on the simple scene where the codec can render near it's fullest quality, it is a matter of context. I have followed up with an explanation over there.

I thought it might be interesting to examine the action and deficiencies of HDV on the scene which is what you guys are discussing (though, the chock scene is better place to check for motion artifacts which is what the thread, and Dan, was about). The best way to compare this is with an untouched/uncompressed frame. The frames were both recorded at 1440 resolution, and upscaled to 1920.

Originally Posted by Ken Hodson

A move to h264 would result in a whole new format. What gives you the impression JVC is going to break away from HDV to go it alone?

"they showed a HDV hard disk consumer camera last year"

No they didn't.

http://www.dvinfo.net/conf/showthread.php?t=52319


Here is talk about a bunch of h264 cameras coming out, Samsung's one has a bit rate of around 17-19Mb/s:

http://www.dvinfo.net/conf/showthread.php?t=58391


Kevin,

I've heard that TV/DVD movie companies have very expensive sophisticated compression setups and DVD movie companies can guide/vary the compression process through the dvd to maximise the look. So while a DVD might often still lack, because of the choices made they look good. On a camera though, it is good to have double that bandwidth of the consumer spec to star with. The extra bandwidth of XDCAM (often nicknamed HDV2 around the place) goes a long way to double HDTV bandwidth, and probably worked out to give just enough to give good results in most of the cases where HDV wouldn't, I would not be surprised if it has a broadcast quality Mpeg2 compression engine on board. But the problem with HDTV, I've looked at the channels and have never seen footage with that sheer volume of compression artifacts on Mini-DV/DVD, and I live in a 25p country. I think it is set to low to start with, and for a 19Mb/s stream I would much rather trust a h264 camera codec than a HDV camera codec. But then again most peoples TV's resolution is below the standard and hide artifacts through pixel combining.


Dan,

I'm with you in some ways. I often think about putting together a cheap low compression/no compression HD solution, but lack an engineer to do it with, and it includes parts of another confidential commercial oriented product that has to be done first, when I feel better. I've got a few things to get through before I can consider starting it though, and this Samsung camera might be good enough not to even worry about doing the HD solution.

[Chris Hurd]

Originally Posted by Douglas Spotted Eagle

What is your point? That you don't like HDV? I think the point has been well-taken. Probably a good time to move on.

An excellent suggestion. For those who have been ranting and railing against HDV ad nauseum, please find something positive to talk about. HDV is very much here to stay, and I will not allow format wars on these boards... such negativity is an utterly pointless, useless waste of cyberspace and time which serves no worthwhile purpose here at all. Please find somewhere else to vent. Thanks in advance,

[Ken Hodson]

Wayne, that link for the Hard disk cam has no mention of HDV spec. In fact HDV is a tape only format. The side of the cam has clear HDD writen on it which means it uses a hard drive. No mention of HDV or HD anything except from other posters. No new HD cam has been showen from JVC yet, and there has been no statement from them either.

As for your other thread.
"The frames were both recorded at 1440 resolution, and upscaled to 1920."

The uncompressed frames are captured at the full 1920. The HDV frame was captured at 1440. Then as you state, was upscaled. This would account for some of the softness in comparison. As well it should be noted that HDV cams are not all the same. While the Sony's have recieved deserved praise for their image/price, they offer the softest least detailed image of the HDV cams. You can't really blanket a format based on one product.

[Wayne Morellini]

Sorry, you must be looking at the wrong link on the thread. Most of the links that the posters over there are talking about do mention and show a picture of what is supposed to be the HD Everio, and even mention HDV and 720p recording, except the last link, the poster has seem to got the wrong camera (he is looking at a standard def version by mistake. There is a link there to a thread that has somebody that actually was at a JVC dealers meet were they mentioned the HD Everio version. Most of the links are from some JVC press release/meeting. The story goes, that they are not sure when they should release it and are delaying it (I think, probably until they sell most of the HD100's to early adopters).

As far as I understand, the HDSDi output of the Canon only transmits a version of the original 1440 image, we can probably ask Alister. The softness of the HDV footage is a lot wider than 1/3rd of the pixel, looks more than two pixels.

Sorry for the confusion Ken, but I don't think I'm misreading it, and I think that ends my conversation on this thread. I wish reviewers would get serious about reviewing cameras/codecs in-depth, they see and Iceberg and write about it usually, no in-depth Analysis of what is beneath what is easy to test (I have, at times, thought of even making my own test charts to test fro various things through out the whole colour/luminance scale). I think professional engineers at TV stations must have a good laugh at some of the testing that goes on some camera sites. If I had the full setup and cameras here, I would love to do very in-depth testing. As I've shown, just getting values and pointing the thing at a correctly lit test chart will only scientifically test the tip of the iceberg, you really need to get hold of footage (preferably using it yourself) to get an idea of/experience the rest. If such an opportunity comes up I would like to have an accurate knowledge of all compression schemes, their artifacts and characteristics (When and to what degree they happen where) first. So, if anybody has links to everything. technical about camera image and codec faults, please let me know, better that one man swallow the nat and strain the camera than every man have to. Sorry Chris, if I've been a bit annoying, but I think their is a need for analysis of the camera codec performance, to see how well things will come up in practice.

Thanks

Wayne.