Graeme Nattress
Forum Replies Created
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I thought there was some kind of optical filter block after the lens, but before the CCD??
Graeme
– http://www.nattress.com – Film Effects for FCP
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Thanks Luis. I’m happy that I’ve not gone completely gaga yet….
Seriously Jason – help us out here to understand what you’re getting at.
Graeme
– http://www.nattress.com – Film Effects for FCP
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But under what circumstances would you repeatedly recompress DVCproHD?? Would you edit it in FCP, apply colour correction, export to AE, do more colour correction, and then export to shake to add some final colour correction before sending back to FCP for some extra final colour correction??
Unless you’re going to show that the software codec works differently from the hardware codec, necessitating capture of DVCproHD over SDI to 10bit uncompressed, any use of an intermediate codec to cut down files sizes is, I’m afraid to say, daft. I’m really at a loss to see how it fits in and works. Whenever you apply an effect, say in AE to some DVCproHD footage, AE must decompress it first. Do that in a 16bit project and AE will decompress to a 16it representation in memory, and there you are – uncompressed, in memory, ready to do your effect. Then you set an appropriate output codec. Final render and out. There’s no repeated mucking around between umpteen different applications, repeatedly decompressing and recompressing the video. This was all hammered out ages ago with DV, and you just don’t work like that. You can get equally good results without resorting to mucking around with proprietary intermediate codecs that you just don’t need.
I think you’ll have to show us a workflow where you’d have to repeatedly compress and decompress the DVCproHD back and forth and time and again. I’m really at a miss to see a) why you’d want to do that, and b) why an intermediate codec would help better than adopting a more suitable workflow that uses the benefits of native codec editing for you, rather than against you. I’m bemused….
Graeme
– http://www.nattress.com – Film Effects for FCP
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I’m sorry, but I just don’t see any kind of sensible post production workflow that repeatedly compresses the footage over and over and over. If you edit DVCproHD, send that over to AE, then AE decompresses the frame that it’s rendering into memory, and at that point, that frame is totally uncompressed. AE then does all it’s magic, and when you render, you get to pick which codec you want to render to. Say you’re going back to DVCProHD tape, then you can render back to that, or say you’re going to D5, so you render uncompressed. At what point do you need an intermediary codec, and how can an intermediate that is compressed in any way be better than going to that frame in memory totally uncompressed??? I really just don’t get what kind of workflow would warrant repeated recompressions….
Graeme
– http://www.nattress.com – Film Effects for FCP
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Well said Barry! I think your money is safe.
Graeme
– http://www.nattress.com – Film Effects for FCP
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I”ve seen such shadow problems with DVCproHD footage when played back in the FCP canvas or in Digital Cinema Desktop mode, but I cannot see the same issues on the same footage played back through the Decklink + HDlink to the very same Cinema Display.
Again, if you’re saying that the software codec is inferior to the hardware codec, it’s irrelevent to talk about using a different intermediate codec. If the hardware and software codec are equal in quality, then there is no advantage to coming in over SDI to gain access to the hardware codec, and again, with P2 you don’t capture, you edit.
Graeme
– http://www.nattress.com – Film Effects for FCP
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Jason, I’ve had discussions about this over DV over SDI and DV over Firewire, so I set up an experiment. I got a friend with some pristine 35mm footage, a digibeta deck and a DVCAM deck with SDI and firewire to help. We used the 35mm footage, telecined to Digital Betacam as our reference, dubbed it over SDI to DVCAM, and then brought it into FCP via uncompressed over SDI and natively over Firewire.
Then I compared them. The luma on the SDI and Firewire (after decoding with the Apple DV codec) was identical in every way down to a fraction of a percent. Comparing back to the uncompressed capture over SDI from the Digital Betacam, it’s impossible to say which of the lumas from DVCAM was better, just that they were ever-so-slightly different, by about 1 LSB in places.
Next I checked the chroma. As you know the Apple DV codec does not smooth chroma to improve it’s generational performance for compression back to DV. An SDI output will smooth the chroma to 4:2:2, just as the analogue outputs smooth the chroma. By applying a chroma smoothing filter to the firewire footage in an uncompressed timeline, we could compare them both as 4:2:2, and again, the difference was negligible.
The only way that DVCproHD will look any different over firewire as it does over SDI is if the software DVCproHD codec is inferior in it’s implementation compared to the hardware one. Are you saying this is the case??
Ah, Qrez, the hardware codec. Pretty useless if you want to move the footage to another machine that doesn’t have a Kona2 card in it??
Graeme
– http://www.nattress.com – Film Effects for FCP
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I’m starting to get out of my depth here with my knowledge of such things. For one, Digital Cameras use a single chip with a Bayer pattern, wo things are not as simple as they are with 3CCD video cameras, and I have no idea on the relative resolving powers of the lenses in question. If anyone here has more insight into the optical block and lens of a video camera in relation to filtering to stop aliassing on the CCD, I’d certainly appreciate some insight.
Graeme
– http://www.nattress.com – Film Effects for FCP
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The lens has to act as an anti-alias filter, so that the image sampled by the CCD doesn’t alias and create artifacts. For pixelshift to work, you need to create some aliassing so that it can be anti-aliassed as more real detail is created by the pixelshift algorithm. I’m guessing that Panasonic will make the lens just good enough for the CCD to function properly, and that to keep sensitivity of the chips up, they won’t have any more pixels than they need, and so the camera won’t generate any detail beyond what the codec is capable of, and hence capturing the image uncompressed ahead of the codec won’t add in any extra detail save reducing any artifacts from the codec. If they were to put a “better” lens on the camera, and the chips were high enough resolution for full raster, there is a point whereby the lens would be too good for the chips and produce aliassing artifacts which would be objectionable. It is the camera designers’ job to balance these factors for an intended result.
Capturing uncompressed on F900 or Varicam makes sense as the chips are more detailed than the codec allows, hence the codec can deal with super-sampled information, and the lens choice would be made so that it works with the chips and resolution detail of the camera, not limited by the codec.
Graeme
– http://www.nattress.com – Film Effects for FCP