BBC (UK) View on Z1 and HDV

[Richard Lubash]

Hi Graeme,

I just picked up a Z1 this weekend and wonder what filter you are using? I would like to import 1080i from the Z1 into FCP5 and then output to DV as full picture, pan and scan or zoom to create multiple streams from one shot.

Thanks,

Richard
2K-plus
Atlanta

Originally Posted by Graeme Nattress

Michael, I'm getting pretty darn good results here. Why not try the demo and see? I'm now testing software to vastly improve 4:2:0 as well as the 4:1:1 that I do now.

Graeme

[Graeme Nattress]

The new filter is for improving the quality of the 4:2:0 from HDV (or PAL DV or DVD for that matter). It's not ready yet, as I'm still testing it. When it's ready for sale it will be part of Film Effects.

Graeme

[Richard Lubash]

Thanks Graeme. being a happy Film Effects user I'll check for the update

Richard

[Graeme Nattress]

Richard,

send me an email if you're interested in beta testing then..

Graeme

[Ruslan Odintsov]

I guess the lack of replies to my challenge about the inferior quality of software downconversion of interlaced HDV to SD means that most of you agree with my statements that Z1's downconversion is actually better. Well, that's fine by me...

P.S.: I thought this was a discussion board and not a forum where all you get is one-liners that you're doing something wrong (where there's obviously nothing wrong with my software export to SD), instead of exploring the issue. Oh well...

P.P.S.: Thanks to Thomas Smet for his opinion though.

[Douglas Spotted Eagle]

Yes, Ruslan, it is a discussion board, one where when people have time to have discussions, they do so. At the moment, I'm in the middle of an HDV Solutions training tour that encompasses travel from the Pacific Rim to New York, to Taipei, to Singapore, and 18 points in between.
So, in order to intelligently demonstrate why both Graeme and myself believe that software can provide a better solution, I'll need to take a fair amount of time to write the article, provide images, and comparisons. I don't have time to do so right now.

Bottom line from my opinion, without taking the time to write up an article, is that if you feel the camera can do a better conversion than Sony Vegas or Adobe Premiere, you're clearly doing something incorrectly. Search these boards, you'll find *several* discussions backing up my opinion, from a wide variety of users. If that doesn't satisfy you, then when this tour ends in July I'll try to find the time.
Please remember that participation in these boards is voluntary, and no one is paid for the information you are provided.

[Steve Crisdale]

Originally Posted by Ruslan Odintsov

I guess the lack of replies to my challenge about the inferior quality of software downconversion of interlaced HDV to SD means that most of you agree with my statements that Z1's downconversion is actually better. Well, that's fine by me...

P.S.: I thought this was a discussion board and not a forum where all you get is one-liners that you're doing something wrong (where there's obviously nothing wrong with my software export to SD), instead of exploring the issue. Oh well...

P.P.S.: Thanks to Thomas Smet for his opinion though.

Boy... If only I had known, I'd have replied straight away... But then I have the FX-1e and not the Z1. Many FX users would have - like myself - not responded because we don't know for certain whether the processor works identically on both models.
And, as Douglas has pointed out... writing anything beyond mere opinion involves the sort of time that just isn't always available.

Now for my 2c worth...

The logic behind downconversion through software; and more specifically using a 'lossless' intermediate codec, revolves around the quality of the 'real-time' downconversion of the already compressed MPEG2 stream that must be carried out by the camera's internal chip. I'm not aware of any specifications released by Sony on how the chip performs the downconversion. Perhaps you are.
Regardless; the number of times the video must be re-sampled to achieve the final SD product via the internal chip is greater than if you use the HDV original and good quality software algorithms, which don't have to re-sample in 'real-time'.
i.e. subject>lens>chip>processor>tape>processor dv>capture>re-encode.
or subject>lens>chip>processor>tape>capture>re-encode.
or subject>lens>chip>component capture>re-encode (requires capture hardware)

The idea is to reduce the number of pathways that the image has to pass through until it reaches the final product: and barring that, to use some means of maintaining the highest quality of image until the final step. Digital isn't that different to analogue in that regard.

As an FX-1e (and HD-10u) user, I can honestly say that Cineform's CFHD codec has provided my 720x576 progressive DVD renders with the sort of quality that I just couldn't get close too by using the raw m2t's, let alone from the cams DV downconversion. I managed a DV capture by mistake once... and that was enough.

It may be different for the Z1... I don't have one to test. If you have one, you've already got the best HDV camera available, so you are streets ahead of the vast majority of SD/DV camera users. I'm sure that's not such a bad feeling.

[Sergio Perez]

Just a tought: can you actually edit the footage in HDV in FCP5, export to tape as HDV, and then let the camera do the downconversion to sd?

[Steve Crisdale]

Originally Posted by Sergio Perez

Just a tought: can you actually edit the footage in HDV in FCP5, export to tape as HDV, and then let the camera do the downconversion to sd?

Not that I'm a Mac owner, but the process would be do-able....it certainly is on PC: but why would one bother to follow such a pathway? The quality of the result wouldn't justify the extra steps as far as I can see...

Going back to the camera with a 'finished project' is great for quality evaluation (via-component) and archiving at 1080i, but I wouldn't downconvert such a project from the tape to achieve a DV end product.

[John Poore]

This is a very interesting discussion. But I am getting a bit lost here with the various claims.

It starts off with a report by the BBC's technical staff saying that HDV converted through an expensive box produces superior SD. Now it does not specify if this superior SD is in fact 4:2:2, as some have hinted. Just as an aside for those here, who don't live in the UK, the BBC is a public funded organisation in that every person with a tv in Britain has to pay 250 USD$ per year to them, or go jail, that's the law. The result is that the BBC recieves some 5 billion USD$ a year in funds, that's a lot. The Sony reps in London call the BBC the biggest goldmine on the planet, for example they once ordered 4000 pd150s in a single morning. What I am saying is you must be aware that all BBC technical reports can be seen as an attempt to rally funds for more expensive kit, that's the way BBC culture works, they can afford anything, they have the cash to do so.

But back to the HDV. Douglas, as I read your post about downcoverting, are you saying that putting HDV through After Affects gets you 4:2:2 DV? Correct me if I am wrong? I have seen other simliar posts to this effect. Some say FCP 5 will do the same...

Anyway, what I would like to know is, if this is the case, how does this software magic work exactly. It's one thing talking about better quality, but is it really 4:2:2.

For the the record having looked at the in camera downconvert from my own FX1, it looks no different to ordinary DV footage, only with more compression. As far as I am concerned, if it don't look any better, it aint.

[Dylan Pank]

Originally Posted by John Poore

...
What I am saying is you must be aware that all BBC technical reports can be seen as an attempt to rally funds for more expensive kit, that's the way BBC culture works, they can afford anything, they have the cash to do so.

That makes no sense. Why then make statements that HDV is an acceptable format for SD production? Why not insist everything be shot on Varicam or HDCAM units. I think you misunderstood the statement. I meant that on HDV cams, HDV downconverted is better than basic DV in that particular camera, but only when using a superior downconverter rather than in camera. It's not claiming that HDV downconverted is superior to (for example) Digibeta cameras, MUCH more expensive kit that the BBC already has.

These technical reports may serve as campaigns for more expensive kit, but they are primarily guidelines for independent producers (who make something in the region 75% of the BBC's output) and regional production offices who may be intending to use HDV, and want to know what the best practice is for optimising image quality in SD.

As for outputting to 4:2:2. well, it depends, if you output to a codec that supports 4:2:2 (DVCpro50 for example) then it will be 4:2:2. If you output it to DV then it will be SD 4:1:1. (4:2:0 in PAL countries). There is no such thing as 4:2:2 DV

[Douglas Spotted Eagle]

Originally Posted by John Poore

This is a very interesting discussion. But I am getting a bit lost here with the various claims.


But back to the HDV. Douglas, as I read your post about downcoverting, are you saying that putting HDV through After Affects gets you 4:2:2 DV? Correct me if I am wrong? I have seen other simliar posts to this effect.
.

You definitely missed something in there, there is no such animal as 4:2:2 DV. There is DV, which is 4:1:1 in NTSC and there is DV, which is 4:2:0 in PAL. Then there is 4:2:2 uncompressed, which is not DV. I'm converting to Sony 4:2:2 YUV through a variety of means such as the Decklink or on direct conversion. In other words, hardware vs software.

[John Poore]

Ok I'm getting the picture here, but as I understand it DVCPRO 50 is 4:2:2. I know I am probably missing a few steps here though?? It take this is simpy uncomressed DV then?
Does the colour information in downcompressed HDV then match the amount of colour info in DVPRO 50? Or am i going in circles?

Thanks for replys. Is there then a simple way to get this DVPro 50 quality from converting HDV via software, I mean is it on the horizon yet? Can I buy it for under 1000$ Is it do-able.

Dylan,
The BBC have actually discussed doing news in HDCAM etc. So have some larger US and Japanese networks. The problem is this. It's more diffcult to edit in the field on a laptop. This is why DV25 is so popular in the news business. Also most news bulletins use lots of agency and overseas footage in their reports which all comes in DV25/Betcam/DV50 standard. So this would look out of place in HD news.

But HD news will come one day...

ps. I think independent producers do 25% percent of BBC output, not the other way around as you mentioned.

[Robert Young]

My feeble understanding of the issue/challenge of HDV to DV conversion so far is :
HDV is a Hi Rez image with 4:2:0 color sampling. To get a better SD image than native DV the goal is to retain as much color information as possible, even while reducing the resolution to 720x480.
For NTSC, direct conversion of HDV to DV (in camera, for example) will drop the color from 4:2:0 to 4:1:1. If you then output to DVD, the color is resampled again, now from 4:1:1 back to 4:2:0. This is represents a quality hit from the original.
If you convert HDV to an intermediate, or uncompressed codec, color sampling goes from 4:2:0 to 4:2:2. This doesn't add any chroma that wasn't there already, but you aren't losing any due to the conversion. Likewise, resampling to DVD 4:2:0 should be realitively lossless.
However, for PAL, HDV is 4:2:0, DV is 4:2:0, and DVD is 4:2:0. To me, this implies that in camera conversion to PAL DV may be less lossy than its NTSC counterpart possibly simplifying the workflow.
Do I have any of this right??
Are there any Luma issues with conversion workflows as well: HDV>DV/DVD vs. HDV>IC/uncompressed>DV/DVD?
Bob

[Graeme Nattress]

Robert, that's pretty much the case.

Graeme