HD or "Glorfied SD"

[Dalen Johnson]

Hello all.

The topic of HD acquisition is new to me, or rather it is only recently that I have really started to look into which HD camera would be suitable for me.

First of all, like most, I have been waiting for something from Canon in the area of HD. Seeing that they were late in the market, one would think that something like the Pansonic Hvx 200 would have been released.

This brings me to the purpose of this thread.
In all the hype surrounding the affordability of HD under 10k, it appears that even with the Canon release that the Hvx 200 is the only true HD camera.

The rest appear to be "Glorfied SD."
When material records at 25mbps we truly have SD with an HD look and feel. Hence the term HDV I suppose.

As I have read through all the threads, newsbits, etc., the fact that true HD appears to be lacking, and that everyone seems to think they are getting an HD camera from the likes of Canon for 10k is a bit disconcerting.

I will admit freely that I am not a camera expert by any means, as stated at the beginning of my post.
So when I alluded to Canons apparent lack of true HD capabilities, know that I refer to the fact that it records, in camera, directly to 25mbps tape.

Now I have seen people record DVCPRO 50mbps material to DVCPRO 25mbps tapes. And apparently its true 50mbps on the 25mbps tape, with the only difference that it eats up twice as much tape when recorded on the 25mbps.

In saying that, perhaps you could have a canon record to DV 25 tape with 50mbps (still not hd is it? dont you need minimum 100?)

The other thing is pulling a good key.
It has been stated you need minimum 50mbps to pull a good chroma key.

So if we have a 10k canon that records to 25mbps tape (though it has the "look" of HD/film) then what good is it for serious stuff when its time to key?

(Now I dont understand what benefits the SDI might have in the studio for this camera in terms of quality. It appears you can get 50mbps, but I am trying to stick with the scenerio of what it records in the camera when in the field.)

All this to say, that the closest thing to true HD that i have found was the Panasonic Hxv200. I wasnt really looking at panasonic, but discovered it throught this board, ironically, while awaiting info on Canons H1.

The fact that the Hxv200 records to a P2 card is cool. (yes expensive, etc., but this is something all these guys should have gotten into...collaberated on to get the cost down.)

But seeing that Canon is part of the HDV consortium with Sony, its no wonder they didnt try true HD like Panasonic who is not part of their group.

Well, any clarification on the issues mentioned about the 25mbps rate would be appreciated. I know a lot of you are still trying to understand what all this means yourselves, especially since no one has really had a chance to even look at one.

Gods Peace

dAlen

[Simon Wyndham]

The MiniDV tape would not be able to stand up to the increased speed needed for 50mbps recording.

HDV to me is a desperation format. The price of technology isn't really avaialble to give consumers/prosumers high def as yet, so something was built on the back of an existing format.

Tapeless formats are the way things are going, but there again the prices are still not there for the average Joe. These are all reasons why I will not jump through hoops to get buy a HD camera (aside from the fact that other than my own indie projects I haven't got any clients for HD).

[Greg Boston]

Originally Posted by Dalen Johnson

...(Now I dont understand what benefits the SDI might have in the studio for this camera in terms of quality. It appears you can get 50mbps...)

Well how about uncompressed 4:2:2 to HD-SDI at 1.485 Gbps as opposed to HDV at 4:2:0 and 25mbps using 15 frame GOP via MPEG2 compression. I believe you'll notice a difference in quality there.

HDV as glorified SD. The Sony shoots a 1440X960 image. You can put 4 SD pictures in the space of 1 HDV. Makes a difference for sure. That was demo'd at our Apple FCP meeting.

But by all means, buy the Panasonic if you feel that's the right camera for you. Just make an informed choice and try to get hands on with any camera you are considering. The Panasonic is going to put out some beautiful stuff, but it's a fixed lens non-shoulder mount camera. IOW, you hold it out in front of you like the Sony PD-170 or DVX100A. That can lead to operator fatique in fairly short order.

-gb-

[Simon Wyndham]

SDi is an okay option. But look at the kind of storage you would require! You'd be hauling a truck behind you everywhere you went! The camera is still only 1/3" too, which limits it quite severely.

No. The real HD revolution will come about once solid state media comes down in price.

Personally I think, like Ikegami, manufacturers should start using the AVID HD codec for storage on a tapeless format. Far more sensible.

[Steve Connor]

Originally Posted by Simon Wyndham

SDi is an okay option. But look at the kind of

Personally I think, like Ikegami, manufacturers should start using the AVID HD codec for storage on a tapeless format. Far more sensible.

Yeah - let's give Avid another monoply to rip us off with

[Dalen Johnson]

Originally Posted by Simon Wyndham

SDi is an okay option. But look at the kind of storage you would require! You'd be hauling a truck behind you everywhere you went!

Yes, this is where I was trying to go with my post.
It would be nice to see more flexible & affordable HD cameras for sale under 10k.

Can you explain to me what the issue specifically is with 1/3"?
How does this affect an HD shoot?

On a side note, how is HDV marketed to a client?
You cant really tout that its HD.

I indeed am trying to learn as much as I can about this before making any purchases. It is exciting to watch as this market unfolds, and I appreciate the responces I have receieved thus far.

Gods peace

dalen

[Steven White]

In defence of HDV. HDV is deliverable 25 Mbps HD. It is higher bitrate than any HDTV broadcast you are likely to receive, and it has the resolution to qualify as HD. It certainly looks one hell of a lot better than DV, or pretty much any SD format I've seen tested (including DVCPRO-50), thanks to the ingenious compression at work. In my attempts to break the codec, I've concluded that I can't do worse than DV by shooting HDV - I can only do better.

Further to this, if the principles of compression used to make HDV what it is were applied to every acquisition system, by the time you got to the 100 Mbps of an i-frame only codec you could be recording 4:4:4 1920x1080 and seeing significant gains in image quality. HDV is a very smart solution to a problem of limited data rates. By the time you get up to HDCAM SR rates, you could be cruising at 4:4:4 4k resolutions.

As for the "solid state media" revolution - I'm not so sure. The problem with solid state memory isn't exactly price - it's capacity. Even though Moore's Law probably still applies... other technologies are already faster, have an order of magnitude more capacity, and are obeying the same laws. If we're getting into the business of uncompressed or at least neglibly compressed video we will need many TB of space - and I'm not sure solid-state will be up to that task.

Just imagine for example if Apple got on the bandwagon, and started pumping out RAID iPods. Take 4 60 GB iPods and put them in a super-speedy RAID array, and you've got yourself 240 GB of capacity (config depended obviously) on the go. The current price of 4 iPods is less than that of a 4 GB P2 card... (or is it 8 GB? Does it even matter?) You've got a factor of 30 difference.

-Steve

[Dalen Johnson]

Originally Posted by Greg Boston

Well how about uncompressed 4:2:2 to HD-SDI at 1.485 Gbps as opposed to HDV at 4:2:0 and 25mbps using 15 frame GOP via MPEG2 compression. I believe you'll notice a difference in quality there.
-gb-

From what I am gathering it sounds like Canon made a good quality studio camera. Which is probably going to reach their intended market initially.

Maybe later they will have a good field camera. (once solid state media comes down in price.)

Gods Peace

dalen

[Dalen Johnson]

Originally Posted by Steven White

In defence of HDV. HDV is deliverable 25 Mbps HD. It is higher bitrate than any HDTV broadcast you are likely to receive, and it has the resolution to qualify as HD. It certainly looks one hell of a lot better than DV, or pretty much any SD format I've seen tested (including DVCPRO-50), thanks to the ingenious compression at work.
-Steve

I did not realize that there was 25Mbps HD. So when you record HDV on a regular 25mbps minidv tape you get a higher bitrate? Or do you have to buy a specific 25mbps HD mini dv tape? (never heard of the latter.)

According to your post, recording HDV onto minidv 25mbps tape is better than DVCPRO 50. (I dont remember the exact source, but I seem to recall someone saying that their issue with the new canon was that unlike DVCPRO 50 they could not get a clean key with the 25mbps...which I have known in theory to be true.)

Thanks

Gods Peace

dalen

[Mike Marriage]

Originally Posted by Dalen Johnson

I did not realize that there was 25Mbps HD. So when you record HDV on a regular 25mbps minidv tape you get a higher bitrate? Or do you have to buy a specific 25mbps HD mini dv tape? (never heard of the latter.)

According to your post, recording HDV onto minidv 25mbps tape is better than DVCPRO 50. (I dont remember the exact source, but I seem to recall someone saying that their issue with the new canon was that unlike DVCPRO 50 they could not get a clean key with the 25mbps...which I have known in theory to be true.)

Thanks

Gods Peace

dalen

Dalen, DV and HDV both record at the same data rate (25Mbps) onto standard MiniDV tape. HDV tape has been released that is claimed to be higher quality. This does not improve picture quality, it only reduces the likelyhood of dropout and digital breakup on the recording.

DVCPRO50 is good for keying because it records in 4:2:2 colour rather than HDV's 4:2:0. This means the colour is recorded at half the luma resolution on DVCPRO50 and only 1/4 on HDV. You need good colour resolution to be able to pull an accurate colour key, for obvious reasons.

HDV may outperform DVCPRO50 when viewed in HD, but it is very unlikely to do so if you are downconverting it to SD.

It isn't all about datarates, the efficiency of the codec is very important too. HDV is a pretty efficient codec, being able to record a "reasonable" HD (1440x1080) picture into just 25Mbps. There are newer codecs that are even better, like H.264, but are not being used in cameras quite yet. There are some cameras being released soon that use MPEG4 compression.

[Steven White]

DVCPRO50 is good for keying because it records in 4:2:2 colour rather than HDV's 4:2:0. This means the colour is recorded at half the luma resolution on DVCPRO50 and only 1/4 on HDV.

All true. The only thing that needs to be clarified is that DVCPRO50 records SD 720x480 4:2:2, and HDV records HD 1440x1080 4:2:0. There is more than enough information in an HDV stream to render out 720x480 4:4:4.

However, because HDV doesn't actually have 50 Mbps of real data, it is likely not going to perform as well on a mathematically intensive application such as keying. In SD resolutions though, it may very well be perceptually comparible or superior to DVCPRO50.

HDV may outperform DVCPRO50 when viewed in HD, but it is very unlikely to do so if you are downconverting it to SD.

I disagree. At SD resolutions they should be very comparible. At HD resolutions, the softness of upsampled DVCPRO50 ought to be equally offensive as compression artefacts in the HDV signal. The efficiency of the MPEG-2 GOP structure is rated somewhere between 2x and 4.5x, which places the effective data rate of HDV well near the 50 Mbps (or higher) of DVCPRO-50. The same can be said for a comparison between DVCPRO-HD 720p and the HDV1 720p standard.

I highlighted "perceptually" a little earlier - which is an important point to make. The objective of a compression algorithm is to lower the data rate without affecting the perception of the image quality. It is most definitely a fine art.

-Steve

[Simon Wyndham]

Originally Posted by Steve Connor

Yeah - let's give Avid another monoply to rip us off with

Why a monopoly? The Ikegami cameras can already record to the Avid codec. On top of this you can download the Avid codec reader for free meaning that you can get any NLE software from Premiere to Vegas to read the files. On top of which it is a damn good codec that allows editing of full resolution HD files without needing a computer the size of a warehouse to process it.

[Kurt Madel]

Dalen, if you do, I just wanted to point out that all of the HD that you watch over cable or from a sattelite provider is usually 12Mbps or lower, and never higher than 18Mbps. So you are saying that this is SD?

HD has nothing to do with bit rate, that is a codec thing, it is only about resolution. Anything that is 1280x720 or larger is HD even if the data rate is 1Kbps. Of course I wouldn't want to key 1Kbps HD and not even 1080i HDV.

[Simon Wyndham]

[QUOTE=Dalen Johnson]
Can you explain to me what the issue specifically is with 1/3"?
How does this affect an HD shoot?
[QUOTE]

The issue, as I have mentioned many times before is that a 1/3" camera at HD resolutions cannot give anywhere near HD detail above around f5. Apparently the Sony Z1 etc have an option to stop you going above this f-stop for this very reason. Here is the technical explanation why http://forums.dvdoctor.net/showthrea...4&page=1&pp=10

On a side note, how is HDV marketed to a client?
You cant really tout that its HD.

I'm not sure where this idea comes from? HDV is 1440x1080. That is high def by anyones standards. If you shoot HDV you *are* shooting high def. Its just that you are not shooting very high end high def. I feel that HDV was developed as a rush to market as a way for the manufacturers to help justify making us purchase new televisions capable of high resolutions. The technology isn't really here yet for efficient HD production at the lower level. But the electronics manufacturers want to sell more new televisions and they need a new selling point.

HDV is a limiting factor. Any camera worth its salt should record and compress individual frames. If P2 comes down in price soon enough and Panasonic introduce much lower end HD cameras that use it, I cannot foresee HDV lasting much longer. I can't see anyone choosing 25Mbps HDV over 100Mbps DVCproHD.

I believe HDV is an interim format. The development of solid state and optical recording is such that there will be a lot more flexibility.

[A. J. deLange]

This brings to mind the question "How good is the implementation of MPEG 2 on this camera?" As we all know codecs range from pretty decent to abysmal. In software we have the option of changing encoding parameters or of buying another software package. With a camera the algorithm is cast in concrete (well, silicon actually) so a good implementation is most important for anyone planning to use the camera untethered to a device which can take the SDI output. So, guys on the floor - please try to check this out for us!