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Slightly OT- reel-stream for HVX-200?
Obviously it would be awesome if the reel stream folks could do the same thing to the HVX as they are doing with the DVX. My question is, how does reel-stream get a 4:4:4 signal to run through USB 2.0? That is how they get it to the laptop for processing, and I was always confused about how that was possible. The second part of the question is, could the same technique they use for the DVX be accomplished with the HVX?
-Emery
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28 Replies
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But they seem to be runnin up against the limits of the lens on the DVX, and as the lens requirements for HD are very high, I doubt there’s going to be any extra resolution in the lens of the HVX to warrant pulling any higher rez from the CCDs, and we all seem to be guessing Panasonic will be using Pixelshift to it’s max to keep the noise levels off the CCDs low, so there’s no room to come and get any extra rez off them anyway. All you could hope for is a hack to record the output as totally uncompressed, avoiding the DVCProHD format.
Graeme
– http://www.nattress.com – Film Effects for FCP
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Right Graeme, that was my question…
Im sure there wouldnt be much resolution to gain, more interested in avoiding the DVCPRO HD codec. But how do they “fit” a 4:4:4 signal through USB 2.0, its not fast enough… right? But that seems to be what they are doing.
And would they be able to run a 4:4:4 HD signal using the same technique? Is there enough bandwidth?
Emery
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But FW400 which is similar in speed to USB2.0 can transmit uncompressed 4:2:2 SD with room to spare. I think there’s no issue with the camera transmitting raw CCD data at a fast enough speed – but, they’ll do their interpolation up to HD when it gets onto the host computer, and that’s the other piece of the puzzle.
Graeme
– http://www.nattress.com – Film Effects for FCP
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That’s right: A proper implementation of USB-2 or Firewire 400 can handle uncompressed SD video, which is what the ReelStream folks are apparently doing with their project for the DVX100.
Their modification for the DVX100 enables them to acquire uncompressed SD video data (actually a few pixels higher res than SD) directly off the cam’s CCDs and stream it out to a fast portable USB-2 hard drive or computer. Once the data is on the computer, their software app can uprez it to HD or convert it to a variety of SD formats.
Doing something similar with the HVX200 would require a _much_ faster hardware interface between the modified cam and the external storage/computer. I believe uncompressed 10-bit 720p 24 fps video is around 150 megabytes/sec (that’s megaBYTES/sec); and 10-bit 1080 resolution requires closer to 200 megabytes/sec, and 1080 4:4:4 is more than that. Needless to say, USB-2, FW-400 and FW-800 interfaces can’t handle these rates.
I believe an interfaces such as gigabit Ethernet and HD-SDI can handle 10-bit 4:2:2 HD, but 10-bit 4:4:4 HD requires dual-HD-SDI.
Further, to the best of knowledge AJA & BlackMagic/Decklink specify that a computer intended to handle any form of uncompressed HD video must have PCI-X as the minimum system bus. So laptops and many desktops are out of the question for uncompressed HD aquisition, capture and so forth.
There’s a good reason why acquisition codecs like DCVPRO-HD and HDCAM were invented: They do a surprisingly good job, and can run on relatively portable, inexpensive, battery-operable hardware.
Once an “inexpensive” version of an all-solidstate recording device like the CineRAM becomes available, then things may start to get interesting indeed. But I suspect it’ll be awhile — until prices come w-a-y down — before most shooters will consider owning such a device for recording uncompressed HD.
All the best,
– Peter
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[Emery] “more interested in avoiding the DVCPRO HD codec”
No need for a hack/modification then. The HVX will output uncompressed video on its component outputs. If you have an uncompressed HD capture system, with the attendant RAID of hard disks and capture card etc., you could capture directly to computer and avoid the codec.
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Get the most from your DVX camera. The DVX Book and DVX DVD are now available at https://www.dvxuser.com/articles/dvxbook/ and at Amazon (https://tinyurl.com/54u4a) -
I don’t see how component video can be described as uncompressed when it’s going to be noise and bandwidth limited to some extent, and has to be converted to digital video to be of any use. If the camera has an HD-SDI connector sending out pre-compression video, then I’d say that’s a fully legitimate uncompressed output, but component is neither uncompressed, nor digitally codec compressed but somewhere inbetween. I don’t doubt it’s usefullness in certain situations and workflows, but I dislike the naming of such outputs. Ok G, rant off – I guess I just want SDI connectors on everything, and that’s probably got to do with me recently buying an HD-SDI capture card….
Graeme
– http://www.nattress.com – Film Effects for FCP
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But Barry.. The DVX100 also has “uncompressed output” as well.
It’s done over the S-Video connector.
Analog HD Component isn’t any different in that regard.Expect these guys to macgyver a HVX the same way they did the DVX.
How they intend to handle that much data is unknown at this time,
as the bandwidth exceeds that of USB2.0, FireWire400, FireWire800. -
Is that right? The S-video output of the DVX-100 is not compressed by the DV codec? Really? What about Sony cameras like the VX-2000/2100 or the PD-150/170?
If that is so, then great. I would love to have that in my mental toolkit. But can I get some kind of unanimous “yes” here? I’ve just never heard this before. Can I reliably tell a producer this tomorrow, even about the Sony cams?
-Christopher
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short answer, you dont want to use the s-video out of your dvx for anything.
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Emery said he wanted to avoid the DVCPRO-HD codec. Using the analog component outputs would do that.
Whether that qualifies as full “uncompressed” or not, well… it’s not HD-SDI taken straight from the DSP, no. And we don’t know if it’ll have been through chroma decimation yet (a question I couldn’t get an answer to from the JVC guys either about their camera). But it would at least avoid the digital compression…
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Get the most from your DVX camera. The DVX Book and DVX DVD are now available at https://www.dvxuser.com/articles/dvxbook/ and at Amazon (https://tinyurl.com/54u4a)
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