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BBC (UK) View on Z1 and HDV
Hello,
Thought you might be interested in the BBC's view of the Z1 for broadcast use. Long , but interesting. HDV and the Sony HVR-Z1E - an introduction This year is set to be a momentous one for small DV cameras. For the first time we should be able to shoot broadcast quality "true" widescreen pictures on a new range of small DV cameras. We will no longer have to aspect ratio convert (ARC) DV material for widescreen delivery, which will have a significant impact on picture quality. As well as recording DV and DVCam, these cameras are capable of shooting true high definition (HDV). At present however the HDV format is not compatible with most popular editing systems like Avid. The potential quality improvement to be gained from shooting in HDV mode is largely cancelled out by having to down-convert all material to standard definition (SD) prior to editing. Until Avid can accept HDV material directly, (anticipated to be some time in the summer), we expect these cameras to be used primarily to shoot standard definition in DV/DVCam mode, as alternatives to the current workhorse DV cameras like the PD170 and DSR570 (or PD150 and DSR500). The Sony HVR-Z1E (everyone's calling it the "Z1") is the first of these 'professional' HDV cameras, due for launch in February 2005. Interest has been high, and this is an introduction to its potential uses, attributes and drawbacks. All guidance herein is based on our evaluation of the Z1 and the consumer version the FX1, which was launched before Christmas. DVSolutions does not recommend the FX1 for production use as it requires modification for XLR audio inputs and lacks other features available on the Z1. Z1 picture quality comparison tests We've compared material shot on the Z1 in DV/DVCam mode with material shot in HDV mode then down-converted to DV/DVCam. We've also compared Z1 DV/DVCam material with material shot on a PD170 and ARCed. Shooting in DV/DVCam mode. Using the Z1 in DV/DVCam mode produces considerably better quality pictures than offered by the PD170 in most circumstances. Shooting in HDV mode, with down-conversion to DV/DVCam through the camera or Sony HVR-M10E deck (through firewire) does not produce noticeably better quality pictures than shooting in DV/DVCam mode. Shooting in HDV mode, with down-conversion through a Snell & Wilcox Ukon or Sony HDW-A500 deck: The better quality offered by HDV is realised by down-converting with one of these more expensive post-production down-converters. Page 2 10/02/2005 Using the Z1 in DV or DVCam modes We anticipate this will be the primary use for the Z1. Of course recording in DV/DVCam mode means that no further investment or upgrade of existing DV kit is needed - the cameras simply replace your existing DV cameras. Our test results show that the improved lens, image sensor and its 16:9 capability mean better quality pictures than the PD170 and PD150 in most circumstances. The 16:9 capability should also make it a viable 'small camera' alternative to the DSR570 in some circumstances. For PD170 users - pros and cons: Improved picture quality due to new image sensor and better lens. The Z1 shoots true 16:9 pictures - this means an end to the need for high quality aspect ratio conversion ('arcing'), or use of the alternative poor quality in-camera widescreen setting. Size and weight slightly greater than the PD170, but the camera is better balanced and... Angle of view is wider than the PD170 - so no need for a wide angle adaptor and extra weight on the front of the Z1, and... LCD screen nearer the front of the camera - makes operation less tiring as the camera can be held closer to the body alleviating manual handling issues. Assignable buttons for personal preferred camera settings/operations which should mean less need to access the camera's menu systems. Audio operation good - separate built in limiters for each channel, and easy manual adjustment of levels. Full auto also available. If you're shooting a lot in low light, then the Z1 may not be ideal as it doesn't perform as well as the PD170 in poor light. Battery life slightly shorter - about 4 hours not 5. A shallow depth of field is still difficult to achieve due to the camera's small image sensor size, as with the PD170. More expensive than the PD170 - Rates will vary nationally, but as a guide, the Z1 is nearly 50% more expensive than the PD170. DVSolutions will hire out a Z1 kit with sound and tripod for £65/day, compared to £45/day for a PD170 kit. For DSR570 users - pros and cons: True 16:9 widescreen - like the DSR570. Considerably smaller & lighter than the DSR570 - fewer manual handling issues. Battery life is longer - about 4 hours instead of 2. Considerably cheaper than the DSR570. Z1 kit from DVSolutions £65/day, compared to £85 for the 500/570. Low light performance is not as good as the DSR570. A shallow depth of field is difficult to achieve due to the camera's small image sensor, compared to the DSR570. Lens construction and focussing system not comparable to the professional, detachable lens on the DSR570. Page 3 10/02/2005 Using the Z1 in HDV mode for standard definition delivery As revealed by our tests, shooting in HDV mode and down converting for SD delivery can produce higher quality pictures, but only if the down-conversion is achieved with more expensive downconversion devices. DVSolutions can advise on the use of the Z1 in HDV mode, which must be carefully considered for a number of reasons: Higher post-production costs - To edit in standard definition, all HDV material will need to be down-converted before editing - meaning additional costs and processes. For high-end productions good quality results can be achieved by using a Sony HDW-A500 high definition deck or Ukon down converter - both of which need correct set-up. Availability and cost of these high-end down conversion tools will vary, and it's not safe to assume that they will be widely available in your area - you'll need to check. The camera or a Sony HVR-M10E HDV deck can also be used to down-convert, and will output DV/DVCam standard definition over firewire. As our tests have shown, using these more economical down-conversion tools produces no discernible quality improvements over shooting in DV/DVCam mode, but it's the most cost-effective way of down-converting material inadvertently shot in HD mode. DVSolutions will publish down conversion guidelines. Higher compression - In order to record the increased picture information when shooting in HDV mode, HDV has to be compressed to a greater extent than equivalent DV. The effect of this higher level of compression is unclear at this early stage, and further tests will follow to assess any impact on picture quality. Higher logging costs - Viewing and logging HDV rushes will require an HDV deck (or camera). Drop out in HDV mode - Rather than the distinctive pixellated picture break-up suffered with DV and DVCam (audio is often preserved), drop out in HDV mode will probably mean total loss of picture and sound, and will last for up to half a second - 50% longer than most DV/DVCam dropouts. Higher stock costs - New HDV stock is available, which is intended to minimise drop-out, but HDV can also be recorded onto mini-DV and DVCam stock. The HDV stock will be at least 100% more expensive than normal mini-DV stock initially, and as yet it's unclear how much more robust it will be. ...for high definition delivery Current BBC Worldwide delivery guidelines state that "For HD delivery, the use of Standard Definition broadcast and non-broadcast video formats, and certain non-broadcast HD domestic formats is not permissible." So any proposed use of HDV material for HD delivery must be referred to the High Definition support group. These guidelines will probably change now the Z1 is available, so refer to the BBC Worldwide delivery guidelines for updates. |
good info & thanks for sharing Jonathan....
One interesting point they made is "the FX1 is not recommended" due to not having XLR audio unless you adapt it. When you use a beachtek adaptor or similar does the FX1 give you just as good audio as the Z1? |
Hi
I'm quite happy with my FX1 and adapter.. i guess side by side tests would be needed to see if there is a noticeable difference.. Robin .. who posts on here also seems pretty pleased with his FX and Beachtek... For me that is really the only important difference with the Z1 and i can't justify the large price difference.. cheers Gareth |
Isn't autogain always on with the FX/1? not so with the Z1
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Jonathan,
Can you tell me which is the original URL for that BBC article? Thanks! Carlos |
Carlos,
Unfortunately it is an internal article for BBC employees, only available on the BBC's intranet site called Gateway, which is not accessible externally. I got it from a colleague with access. Jonathan |
I can't say I was very impressed with this report, if it is supposed to be the result of intensive testing. There is too much conjecture and indecisiveness for my liking. If they can't come down firmly in favour or against it, they have not brought anything to the table apart from maybe and perhaps.
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Colvin,
I thought the report was quite good! Typical advisory style, but lots of guidance given for anyone considering the Z1 for DVCAM. Answered my queries Ok. The later reports of some BBC crews changing their old PD150's for Z1 DVCAM use tells us a great deal too. Jonathan... any updates from your source? I am wanting DV widescreen and was pleased to see the BBC calling the PD150 in-camera WS 'poor quality'. Earlier BBC guidelines suggested it was 'just acceptable'. Technology moves on and so does the quality bar. I was hoping to use my PD150 but that is a no-no for sure. Now it looks like a Z1 (or FX1) or XL2. Richard Hong Kong |
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-Steve |
You can always use a picture profile that does not allow the gain to kick in, or you can limit it in steps.
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Confirms my tests that the down-conversion is not the way to go.... shoot in SD until your NLE can support HDV. I did not share these results because my tests varied widely depending on the subject matter.
George |
I completely disagree with George. I shoot HDV, and if necessary, downconvert. But shooting SD on the FX1/Z1 is just a waste of time for me. Even if I know I will downconvert, I still want to have the HDV for the future. The BBC folks are a couple of months behind the times. And probably because the thread was started back then.
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All of my tests downsampling 1080i HDV to 480i or 480p60 (uncompressed, using After Effects 6.0 Std) have resulted in absolutely beautiful images - and any macro-blocking artifacts in the original source are on the scale of DV compression artifacts or smaller in SD resolution, with increased sharpness (not-meaning "sharpening artifacts" but rather, higher effective resolution) and colour information. My test subject was a hyperactive kitten. |
Steven Gotz, let me try to clarify: what I was saying is that I thought the internal down-conversion does not look good to me.
There are external ways to do a conversion as mentioned in the BBC article and they can look good. I not sure what the "behind the times" has to do with the quality of the internal down-conversion--- it is what it is and I don't care for it. Individual preferences vary, and if you have a method that you are happy with-- go for it. Thank you, George |
So what exactly is 'wrong' or lacking with the in-camera down conversion?
Is it a silly 'clutching at straws, no one can tell the difference at the end of the day' issue, or is converting HDV in post to DV using whatever program going to be immeasurably better images? Just want to know if it's worth the hassle... |
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Also, the editing system probably has far more power than the chip that's downconverting to DV in real-time in the camera, so it should be able to produce a better result. I'm not convinced that there's a huge difference, but editing HDV and then downconverting to DVD does look a bit better to me than editing downconverted DV and then compressing to DVD. |
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But then again, I had no complaints the one time I downconverted in camera. But since I only did it once, and that was before I had Aspect HD or even Premiere Pro 1.5.1, I don't particularly care about the in camera solution. Your response indicated that you agreed with the BBC and I can not say that I do. But I would never shoot DV with my HDV camera for any reason that I can think of at this time except for one. Perhaps if I was a second shooter for someone with a DV camera and I needed to turn my tape over to them. Other than that? |
When the camera does the down convert to SD I'm sure there is no pixel sampling filtering going on. This might give you not as good results. I actually wrote a filter that gives me almost perfect 4:4:4 RGB SD images from the camera. So far I have been only able to test it on still images from the internet but it works great. I don't think we will ever see a better option for SD work. I can do the same thing with 1280 x 720 but it just isn't as good.
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Yeah Thomas, similar experiences here, though I did it all with After Effects, rendering the 1080i to 480p60. The results were astonishing! I've since compressed it to DV, and it looks awful in comparison, likewise to DVD... But gosh - the uncompressed 480p (even 480i) from HDV is gorgeous stuff.
-Steve |
Steven Gotz: Please Elaborate
Steven
I'm a little confused as to what you are recommending. Clearly, one should acquire in HDV, then-- 1) downconvert in camera, capturing SD, and edit in SD, or 2) capture the m2t to system, convert to SD using Premiere Pro (will PPro do that???) and edit in SD, or 3) capture m2t using Cineform Aspect, edit with PPro 1.51 in Cineform IC, output to SD or DVD, etc. Which workflow, in your opinion, gives the "best looking" SD final product? I haven't taken the HDV leap yet and I want to be sure it's really worth it. All of my delivery is SD DVD. I do not want to go thru all the HDV upgrade expense, workflow hassel, etc. to end up with DVDs that look like they could have been shot on my PD 170. Thanks Bob |
Robert,
4. Capture in Premiere Pro 1.5.1 (or on weaker systems, use HDLink to go to M2T and then CFHD AVI in two steps). Edit HDV all the way. Produce a HD WMV. Play it on the Linkplayer2. Enjoy it a few times, and then realize you must downcovert for old Uncle Andy. Sigh. That's OK, at least your wife and her cousin Susie saw it in the original. Sigh again. Rather than just export to MPEG2-DVD, I bring the finished CFHD AVI into a DV project and then Pan/Scan to get the best portion into the 4:3 frame that I can. Why not letterbox? Good question. It's a lot easier, but Uncle Andy has bad eyes, and the bigger the image on his 19 inch TV the better (his kids are too cheap to even get him a 27 inch). Why not just center cut like the Z1 will do for you? Because I am a lousy cinematogrpher and didn't plan that far ahead. Not all of the best stuff is in the middle of the frame. Here is one reason to work like that. I shot a school choir. Little kids. I got three takes and there was no way to use additional cameras because I was not told far enough in advance. I needed to downconvert for their televisions at school. So I used the 16:9 wide shot for the entire song, moving it up to the top of the frame to make room for the lyrics at the bottom. I put a black matte behind the text for reasons that will become clear if you try this. I made the first version of the video just that way. Then I made a second version. This time, I zoomed in and moved around to show closups of each kid in each row. The next video I did the same thing, but panned from the other direction. There were a few weeks left of school, they play it on Fridays, and each one for the rest of the year was slightly different. It completely confused the kids as to how I did that. If you haven't tried it, messing with the heads of elementary school kids is great sport if you do it carefully. The point is that if you edit a very large frame in a small framed project, you have many, many choices that you would not have if you downconverted in camera. How many times have you wanted to zoom in on a shot and couldn't without pixelization. Well now you can. Over 200% zoom and you are just getting back to the original frame resolution. |
Z1 vs PD 170 to DVD:Better/Worse/Nada?
Steven
Doing the pan n scan while still in the large format sounds like a great technique to get more miles out of your footage. Definately an advantage of the HDV workflow. The entire subject of {Z1 HDV>SD DVD out vs. PD 170>SD DVD out: is there really a difference?!?} seems to be very controversial. I have read so many conflicting opinions on the 4 different HDV forums I follow. The BBC paper in this thread seemed to conclude that Z1 SD looks better than PD 170 SD in 16:9. I can buy that- Z1 chips are a little bigger. But BBC doesn't address this other issue at all. People seem to have many technical reasons for concluding that one is better/ worse/no difference. i.e. Z1 HDV>CFHD >DVD is 4:2:0> 4:2:2>4:2:0= gotta be better; and other arguments are to the contrary conclusion. I'm really interested it the basic eyeball test. Since it all ends up as 720 x 480, the question is: does the Z1 HDV workflow result in SD DVD that has noticably more color depth, dynamic range, or some other intangable benefit that causes the audience to look at that 42" plasma screen and scream "Whoa...this is great!!! This is MUCH better than your last one... we want more, more, MORE like this!!!" , or not? I would really welcome any first hand eyeball opinions. Thanx Bob |
If you convert, in camera, down to DV from an HDV shoot, then that could look slightly worse than shooting DV as the video has gone through two compressions. However, from what I'm told, if there is a difference, you can't see it.
The BBC were not downconverting to DV, but on very high end broadcast gear to Digital Betacam, and hence were not subjecting the video to lots of compression in the conversion process. If you downconvert to DV in software, then you're loosing the benefit also. What you should be doing is downconverting to uncompressed SD (or very lightly compressed SD) and that should produce visibly superior results, in terms of chroma sampling etc. Because you've downsampled, this should make the image sharper and less noisey. This can only do good things for going to DVD. Whether, on DVD you can see the benefits of higher chroma resolution though, is debateable, but you should see benefits over NTSC DV more than PAL DV due to the clash between NTSC DV 4:1:1 and DVD / PAL DV 4:2:0 Graeme |
Robert,
When you say it all ends up as 720X480 I cringe. Why would I not just shoot with a higher quality SD camera if that is all I needed? My goodness, there are certainly better tools available. I could pick up relatively inexpensive field monitors, use less expensive storage. etc. And maybe get better low light capabilities. And better DOP from bigger chips? The 42" monitor? Garbage, in most cases. I want them to look at the 60" Plasma or LCD or DLP and be shocked! To heck with SD. I am distributing HDV whenever possible. But, yes, even I must downconvert for Uncle Andy. But not for real customers, thank you. Real customers get a Linkplayer as part of the contract. There must be a dozen of them throughout the training center I produce stuff for on my "real" job. I imagine that there are tests showing that the PD170 is a superior DV camera. And there are probably tests showing downconverted HDV to be better. My guess is that it depends on a lot of factors. I, however, have made my bed with HDV, and I plan to lay in it. Graeme is a lot more qualified to discuss some of these conversion issues, as are many others. I can only say that I am happy with my choices. |
I don't think that using the camera downconvert to DV is going to produce a bad DV picture by any means, but I don't think it's extracting the maximum SD quality that the camera is capable of.
As for PD170 v FX1 / Z1. In 16:9 the HDV camera is an obvious winner as 16:9 on the PD170 is rather poor. For 4:3 SD, the difference might be more subtle, and I'd expect the only difference to be that the PD170 has a little better low light. Overall picture-wise, the more modern HDV should again look better. Graeme |
Having done conversions with the Z1 via several routes, I can easily express that the software route is by far, far, far better than any other routine.
I have: 1. Converted component out to SD/SDI resampled to DV, subsequent MPEG SD 2. Converted component out to HD/SDI downsampled in software, subsequent MPEG SD 3. Converted HDV 25Mbps to DV in software, , subsequent MPEG SD 4. Converted from cam to DV, , subsequent MPEG SD 5. Converted Component out to SD in 3rd party hardware box, brought in as DV to editing application. My conclusions: 1. Sony Vegas converts better than anything I've tried. 2. Premiere converts nearly as good 3. Final Cut can't manage the m2t, but it doesn't convert the HD/SDI ingest nearly as well as Vegas or Premiere. Interestingly enough, iMovie does a better conversion than FCP does (at this time) 4. AVID doesn't convert (at this time) as well as either Premiere or Vegas. 5. In EVERY single case with these applications, the camera down convert was superior to what the software or hardware with component in could do, excepting Vegas or Premiere. These tests are all based on naked eye viewing a variety of image types. I'm no where near as technically astute as Graeme is, my math blows. But I know what my eye sees, and frankly at the end of the day, that's all that matters. But of course, that's just my opinion. |
Douglas, have you tried doing any downconverts in software from HDV to uncompressed SD? I think that would look even better still for going to DVD.
The issue with FCP is that it's scaling engine is rather poor, being bilinear rather than the bicubic it should be. However, it's possible to decent downconversion if you add a little gaussian blur to the image before it gets scaled down, as that, in effect, is forcing the bilinear to function more like bicubic, taking sample points from beyond just the immediate pixels in question. If you don't do this, you get really nasty aliassing artifacts in FCP as there is effectively no filtering going on in the downconversion. Good filtering is necessary for good results, as this is part of the averaging process that reduces noise and aliassing. Graeme |
Oops! That's what #1 is supposed to be.
Yes, I have. Of course 4:2:2 SD is better than anything when going to MPEG from there. I've done this with 2 different encoders, Cinemacraft and the Sony implementation of the Main Concept. Both are outstanding. I did these tests not for any reason other than wanting to be "informed" when both writing one of my books, and also to be able to speak to clients. Like I say, my math sucks so I haven't written anything up on my works. BTW, I love your piece on compression, very nicely done. Even an idiot like me can read it. |
Thanks Douglas. Sounds like theory is right in line with practise, which is excellent.
Graeme |
Douglas: Premiere/Vegas SD Conversion?
Douglas
When you say you've gotten the best results converting HDV to SD with Vegas/Premiere; are you importing (capturing) the m2t stream and using a Cineform type IC, or importing the component out signal thru SDI? I'm not exactly sure what you are getting out of the camera to convert to SD .avi with Premiere. It's important to me because my existing system can handle m2t/CFHD/avi bandwidth, whereas SDI/uncompressed formats/etc. is going to be the next level up hardware-wise. Also, if I am reading your post correctly, you are saying that the Z1 in-camera conversion to SD firewire out looks almost as good to you as the Vegas/Premiere in-system conversion. And that overall, all of the above "look" better than material shot in PD 170 SD. Am I getting this right??? Thanx Bob |
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Workflow to uncompressed 480p60: - Capture Premiere Pro 1.5.1 to Cineform intermediate - Edit - Render to 1440x1080i uncompressed avi (because I can't import Cineform* to AE yet) - Import 1080i uncompressed into After Effects* - 1440x1080, PA 1.333, 59.94 fps timeline, deinterlace upper field first best quality - color correct (if need be), add effects, etc. in 16-bit colour - render to 720x480, 59.94 fps, PA 1.2 uncompressed. *note: If I had AspectHD, this would be a lossless copy-paste operation into After Effects, omitting all intermediate renders and using source files directly. Since I can't do this, I am limited to using an uncompressed intermediate render. I will be rendering all DVDs I author by this method. The uncompressed 480p60 or 480i looks tremendously better than any DV go-between, as there is no additional compression or colour space reduction. Unless shot on a DV camera, I will never touch DV footage again. All my SD will come from down-conversions. -Steve |
Steven, that really should theoretically produce excellent results, and it's great to hear that it's doing it in reality too.
Graeme |
Robert,
The Camera conversion is NOT as good as the Vegas conversion, not by a long shot. The camera conversion is better than a PD 170, but not *tremendously* so. I'm capturing uncompressed from the cam by going from the cam uncompressed out, to a Decklink HD card, bringing that into Vegas and editing there. Or, I'm bringing it in via the component out into the SD Connect from Convergent and sending that in via firewire. The BEST image, is going into the Decklink, then converting in Vegas to a 4:2:2 SD stream, if that's where I'll end up. What I'm doing for *most* of my work is using our GearShift tool to convert the raw m2t files to DV proxy, editing the DV proxy, and replacing the proxy with the m2t files when I'm done, and either printing those to SD/MPEG, or back to the HDV deck, which will be then used to transfer to HDCAM at another facility. |
a ques for Graeme - will fc5 clean up these problems ? I mean , who wants to undergo these workflows- not me . thanks Kurth
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Don't know. I don't know anyone who has FCP5 yet who'd be qualified to look at the supposed new scaling in there to see if it does correct filtering or not. I'll be writing about it, no doubt, as soon as I myself know for certain what is going on.
Graeme |
See later message.
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With the software downconversion, while it looks good, but because of the horizontal lines issues, you know it was downconverted. However, with the in-camera downconversion, it looks like in was natively shot in 576i or 480i scanning mode. So, the choice should be made on whether you'd like better color reproduction or better interlaced fields downconversion. I think the only hardware that could achieve both would be one of the super expensive Snell & Wilcox converters. Sorry, but the regular software's (Sony, Adobe, Canopus, etc.) up- and downconversion of the interlaced material still leaves much to be desired. |
If you're seeing interlace twitter, then incorrect or insufficient filtering has been applied in the downconversion. There's no reason why software cannot do this correctly.
Graeme |
You're doing something wrong then. I've seen several hardware conversions, and they can't touch what Vegas is doing.
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If you'd like to check it out yourself, you can actually use the 60i clip you have on Vasst of the surfer walking on the beach. Try converting this M2T from camera and then do the same thing in Vegas or After Effects: pay attention to water waves, you'll see that the software conversion is not as smooth on those rolling waves, you see some lines (basically the very thing everybody's trying to avoid as much as possible these days). I mean it looks very good, but not as good as the in-camera conversion. And if you try it, please try to be as objective as possible, because those lines are quite visible. Also, I'm not talking about 24p downconversion (which looks good), but a normal 60i. |
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