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Codec/format question. Please Help!


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#1 Jonathan Burton

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Posted 20 May 2009 - 05:11 AM

Hello. I have been shooting some tests with a Sony Z1P and overall i am liking the results, however there is an annoying problem I have noticed. In the grey or darker areas of a shot there seems to be a weird digital blocky noise which flickers and moves distractingly. This occurs straight out of the camera when importing footage in HDV1080i50 (its native record format). It can be improved by converting the footage using another codec, but it is still there. I have tried an in-camera feature called Cinematone which adds detail in the grey areas and this seems to make the rushes better. However, if there is a codec or program or filter that can be applied in post, or even if someone can just tell me what the blocky noise is I would be very grateful. (look at the left side of the mirror, in the cabinet behind for best example)

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Edited by Jonathan Burton, 20 May 2009 - 05:14 AM.

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#2 Phil Rhodes

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Posted 20 May 2009 - 05:34 AM

If you're talking about (for example) what's going on in the back of his head, where the hair is darkest, then I'd accept that as fairly normal HDV compression artifacts. This is why HDV isn't widely used in the high end.

Only solution: use a better tape format, or record the camera to something with less compression.

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#3 Jonathan Burton

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Posted 20 May 2009 - 06:11 AM

If you're talking about (for example) what's going on in the back of his head, where the hair is darkest, then I'd accept that as fairly normal HDV compression artifacts. This is why HDV isn't widely used in the high end.

Only solution: use a better tape format, or record the camera to something with less compression.

P


Sorry for the dumb questions, but like what? It records on MiniDV tapes. Would the HD MiniDV tapes be better? I hear they are a higher quality tape, still MiniDV though. Also when you say record the camera to something with less compression, what do you mean? are you talking about an external deck or hard drive? Wouldn't the compression be the same as it will still be HDV coming from the camera?

Thanks for the help.

Edited by Jonathan Burton, 20 May 2009 - 06:11 AM.

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#4 Phil Rhodes

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Posted 20 May 2009 - 08:56 AM

> It records on MiniDV tapes. Would the HD MiniDV tapes be better?

Common sense along with all anecdotal evidence indicates that the tape stock itself is exactly the same; either way, it's recording the same signal regardless of what you put in it.

When I say "use a better format", I mean - use a completely different system, such as HDCAM, which uses vastly less compression. And costs vastly, vastly more money, of course.

> Also when you say record the camera to something with less compression, what do you mean?

Well, since it's a Z1, it doesn't have SDI output. If it did, you could record that via a Blackmagic card to a disk array, which would very definitely get you better images. As it is, the only uncompressed output you have access to is the analogue component, which is very much a second best option; it might be fractionally softer, but it wouldn't have the compression artifacts. You're right in thinking that if you record the firewire output, it'll be exactly the same compression as what goes on tape.

All that's happened here is that you've noticed the problem with HDV - it looks superficially OK, but it's very heavily compressed. The only practical way out of this is to upgrade, though your options are somewhat limited. You can get an HVX-200, but that's fairly soft and noisy anyway and the codec is, while better, still not the world's nicest. You can get any HDV camera that has SDI outputs and record that, but then you're tethered to a PC.

Or you can go and buy an HDW-F900, at which point the lens alone will cost three times what your whole camera does. Unfortunately, budgets are a bitch.

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#5 Peter Moretti

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Posted 21 May 2009 - 05:31 AM

First, have you tried capturing the footage with another NLE or capture program? There is a chance the problem is being caused by your NLE barfing during ingest and has nothing to do w/ HDV.

Second, most NLE's have effects that can blur and be tracked for motion, if need be. So it shouldn't be too much of a PITA to fix it in post if it's not a common occurrence.

Third, you don't need an F900 to get better results, nor would you want to as the camera weighs a ton and you'd need an HDCAM deck to capture the footage. I've never seen this type of HDV error with Canon or JVC. They do HDV the best IMHO, esp. Canon. So I doubt an XH-A1s would exhibit such macro blocking, posterizing, artifacting (whatever you want to call it). And Sony's EX-1 is an amazing camera that will not have this problem and gives you better DOF control b/c it has 1/2" chips.

HTH.
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#6 Chris Burke

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Posted 21 May 2009 - 05:37 PM

Hello. I have been shooting some tests with a Sony Z1P and overall i am liking the results, however there is an annoying problem I have noticed. In the grey or darker areas of a shot there seems to be a weird digital blocky noise which flickers and moves distractingly. This occurs straight out of the camera when importing footage in HDV1080i50 (its native record format). It can be improved by converting the footage using another codec, but it is still there. I have tried an in-camera feature called Cinematone which adds detail in the grey areas and this seems to make the rushes better. However, if there is a codec or program or filter that can be applied in post, or even if someone can just tell me what the blocky noise is I would be very grateful. (look at the left side of the mirror, in the cabinet behind for best example)

pic_two.jpg



you can also play around with the gamma during post color correction. This could push the darker areas towards black and therefore get rid of some of the artifacts. I just shot a short on a Canon HDV camera, XHA1 I think, and I rather liked the look. I have found Canons to have a very smooth tonality to them. Where as Sonys are much more sensitive to light it seems, as if shooting with a very grainy fast film stock. Looking at your footage on the best monitor you can will tell you the real story. Switching up the NLE is a good idea as previously stated.
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#7 Phil Rhodes

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Posted 21 May 2009 - 06:33 PM

First, have you tried capturing the footage with another NLE or capture program? There is a chance the problem is being caused by your NLE barfing during ingest and has nothing to do w/ HDV.


More information on where that still has come from, and how it was produced, would of course be of interest. That said I can't even begin to construct circumstances whereby an NLE would hypothetically choose to recompress something on ingest; with firewire ingests, for both DV and HDV, you're getting a literal bit copy of the tape data and there is very little room for this sort of issue.

Second, most NLE's have effects that can blur and be tracked for motion, if need be. So it shouldn't be too much of a PITA to fix it in post if it's not a common occurrence.


1% gaussian noise, rolled off above about code value 64, seems to fix it.

I've never seen this type of HDV error with Canon or JVC. They do HDV the best IMHO, esp. Canon. So I doubt an XH-A1s would exhibit such macro blocking, posterizing, artifacting (whatever you want to call it).


Then you haven't looked very hard, assuming we're looking at the same problem - macroblocking visible in shadows, especially the back of the actor's head in his dark hair. I would interpret this as completely normal for more or less any HDV camera, though some of them will, theoretically, do slightly better based on frame rate and resolution.

HDV is very heavily compressed; until I'm given further information, my assumption has to be that this is just an example of that.

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#8 Keith Walters

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Posted 21 May 2009 - 09:21 PM

Sorry for the dumb questions, but like what? It records on MiniDV tapes. Would the HD MiniDV tapes be better? I hear they are a higher quality tape, still MiniDV though. Also when you say record the camera to something with less compression, what do you mean? are you talking about an external deck or hard drive? Wouldn't the compression be the same as it will still be HDV coming from the camera?

Thanks for the help.

A couple of points that might bear mentioning

Standard Definition Mini DV is more or less a cut-down version of professional DV (ie Digital Betacam). In both formats the images are stored as a series of JPEG-like stills with fairly mild compression, which gives exceptionally high image quality. Despite the small tape size, SD Mini DV is still an extremely capable format, nearly always exceeding the capabilities of the camera it is attached to.

There is no physical difference between an SD Mini DV tape and an HD Mini DV tape, it's just that they have to resort to MPEG-like compression to allow HD recording with the available bit rate. So as far as recording artifacts go, SD Mini DV is always going to look better than HD Mini DV.

As always, the bottom line is, you get what you pay for.
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