SDI ingest or P2 file transfer?

[Edwin Hernandez]

Is transfering files from P2 cards equivalent to uploading footage through SDI, or is it compared to firewire?

-EDWIN

[Chris Hurd]

I know of no digital video transfer over FireWire that happens at any speed other than realtime. P2 ingest can happen at many times realtime, and that's the whole point. P2 ingest is *not* video capture; it's simply a data transfer, exactly like downloading the contents of a flash memory card, because that's what it is. Ingest speed is a bus-side limitation.

[R Geoff Baker]

Chris, I would think the same logic applies here: You know of no Firewire transfer greater than real time because you are transferring from tape. If the media file was on a drive, or a memory card ... you could transfer via Firewire at greater than RT. I have files I keep on a Firewire drive that transfer at speeds limited by the transfer/drive speeds -- much faster than 'RT'.

So not that your post is 'wrong', just that it makes the assumption that Firewire is from tape -- that assumption becomes less likely as 'other' recording mediums become popular.

My question is what did the OP mean? What is his notion of the distinction between 'SDI transfer' and 'Firewire transfer'? Is he referring to 'speed' or something else entirely?

GB

[Edwin Hernandez]

I'm not an engineer or something similar, but as I understand, you have a better capture in terms of quality, for example to use a chroma key, when you capture it via SDI than using the firewire.
I want to know about the quality for compositing.

-EDWIN

[Scott Anderson]

Edwin, SDI and Firewire are simply file transfer protocols for getting digital information in and out of your computer - nothing more. The actual files transferred over that protocol can be anything.

The reason you have heard that SDI is better than Firewire is that higher-ended video products have used SDI to transfer, say uncompressed 10-bit video. SDI has generally been much more expensive than Firewire, whereas Firewire has been intrinsically linked with DV-format products. That is not always the case, though. Do a search for the AJA Io product, for example. It is a breakout box which offers uncompressed 10-bit video, even with an SDI input, that all connects to the computer via Firewire.

There are even pro DV decks that offer an SDI connection, but if the format of the video is DV (or DVCam, or DVCPro, which are all basically the same format), then sending it through and SDI connection will not improve the quality of the video. You could even shoot a flavor of DV, send it out of your deck through SDI, running through an Io box into your computer through Firewire (confused yet?). It still won't change the fact that the original footage was DV.

The point is that it's the signal recorded in the camera that determines video quality, not the protocol used to ingest it into your computer. DV-format video is color sampled at 4:1:1, which basically means the color information is averaged before the file is written. This means that DV footage is more difficult to composite, beacause the color in the pixels that define the edge of the matte have been averaged. It's harder to pull a clean matte when you don't have the original information in the file to tell whether a particular pixel is blue, not blue, or somewhere in between. Does that make sense?

The HVX-200 can shoot this DV Format, or can shoot DVCPro HD's 4:2:2 color sampling, which means much less averaging is being done in those all-important edge pixels. This will produce much cleaner edges for bluescreen work, and much better multi-layer compositing, much better reproduction when the video is rendered over multiple passes, etc.

The other factor in clean compositing is the original size of the video. If you have more pixels to work with in the first place, the cleaner the composite will be. Again, the HVX's 1080-line video will produce much cleaner results than DV's 480-lines.

Another factor in pulling clean composites is the quality of the optics. If the lens introduces artifacts such as color fringing or other abberations, it can also make compositing difficult. That remains to be seen with the HVX, as no one has seen a working prototype or sample footage yet.

All things considered, this camera should be fantastic for compositing work. Although the optics are small, they should be of reasonably high quality. The HD formats this camera shoots should lend themselves very well to compositing.

Let's face it - lots of people are doing very acceptable compositing on DV, despite it's limitations. Very good compositing is also being done with the 720p Varicam, which is also DVCProHD. And Star Wars EpII was shot on CineAlta in 1080p with 4:2:2 color sampling. I suspect this camera will be close to Varicam quality in 720p HD mode, and perhaps even better than Varicam in some respects when used in 1080p mode.

[Edwin Hernandez]

Scott:
Very well explained. Actually that's what I thought, but there were some people in my market with more experience that brag about their SDI decks when editing DV, and they always claim to have better results with it than using a firewire protocol. Since I'm a 1394 man, I always thought that someday I would need the SDI for my DV editing. Now I know that it's all to brag about how expensive their equipment are.
Believe me, some people even claim that using the SMOKE to edit DV material will lead much better results than using FINAL CUT.

I was wondering, because I do want to buy the HVX to do HD stuff or DVCPRO50 stuff to edit it on FCP and then send it to an edit bay as a quicktime movie and transfer it to a Beta or Digi Beta for broadcasting.
And I wanted to know the best way to maintain the best quality through the whole process
Makes sense?

[Scott Anderson]

The first time I saw the output from a Firewire-based, software-only DV NLE, I was hooked. One of the fantastic things about DV editing is that the original file the camera writes to tape is never altered unless you do a composite. Firewire capture simply writes the digital data from the tape to the hard drive. Now Panasonic takes this a step further and creates edit-ready files on removeable media, either P2 or a Firestore-type 3rd party device.

I've found the best way to retain quality through a post process is to maintain that original file as much as possible. With a cuts-only project, FCP will not recompress your original video. As soon as you introduce a transition such as a dissolve, then only those frames are re-rendered. The same holds true for DVCProHD or DVCPro50. Your game plan should be to edit in your original camera format, all the way to mastering, then take the master file and transcode it if neccessary into another format.

I find that even DV25 can hold up fine to 1 or 2 steps of recompression, as in compositing, and still be able to cut seamlessly with original camera video. DVCPro50 will work even better, as there is double the bitrate. Friends I know who work with the Varicam have reported the same of 100Mb/s DVCProHD, using FCP to edit DVCProHD natively.

Using the DVX in HD or DV50, using FCP to edit that footage naitively, then mastering at the end to an appropriate format will maintain the quality this camera is sure to deliver. It's like the first days of DV editing all over again, except this time it's HD.

My only wonder is that after shooting and posting all this wonderful DVCProHD material, what will be the final delivery format? DVCProHD decks are still too expensive to own, and there's no solid infrastructure for delivering raw DVCProHD files. Even though the capture and post can be tapeless, unfortunately tape is still the delivery media of choice. I hope that will change quickly with Blu-Ray DVD capacities, and increasing bandwidth both inside post houses and the outside Internet.

[John M Burkhart]

FWIW faster than real time transfer of digital video off tape is possible.

There are some Sony broadcast decks that transfer DV, SX and IMX footage faster than real time off of tape. Using the very little used SDTI protocol. The speeds are from 4x-8x real time if I recall correctly.

You connect via a BNC cable just like sdi.

I've never seen an NLE capture card capable of it, although I think the liquid series had the option, as well as the xpri. Essentially you could do 4-8x capture and layback. (no insert editing was possible for obvious reasons).

But it really kicks ass for dubbing/cloning of masters. Both from the time savings, and the advantage of being a true clone of the material (data) on the tape, rather than the data being converted from DV/SX/IMX to SDI and back.

[Stephen L. Noe]

John is correct, Edition Chrome will capture 4X or 8X through SDTI with their hardware but that is typically in place a high level organizations.

[Will Kennedy]

My apologies if this has been answered already. Not lazy, just curious:

Would a firewire to on-set laptop live transfer be possible? Instead of suffering the offerhead of rotating P2 cards from camera to laptop and back; what happens if you run a constant firewire cable from camera to laptop? Can the clips be spooled to the laptop while shooting? Or between takes? Can the "bad" clips be deleted remotely from the laptop to free up space on the P2 disks (which stay in the camera at all times in this scenario). Does the camera need to be turned into VTR mode to free up the clips for transfer?

Admittedly the firewire transfer would likely be far slower than RT, and hard drive space would still be an issue, but the working process could be far more reasonable. There is downtime between takes on feature shoots consistently. And the laptop monitor crewmember could selectively transfer the approved takes.

-- Will

[Chris Hurd]

Originally Posted by Will Kennedy

Would a firewire to on-set laptop live transfer be possible?

It's been established that the HVX sends DVCPRO HD out over FireWire, so yes a live transfer is possible.

Can the "bad" clips be deleted remotely from the laptop to free up space on the P2 disks (which stay in the camera at all times in this scenario). Does the camera need to be turned into VTR mode to free up the clips for transfer?

Hmm, those are questions for Jan...

Admittedly the firewire transfer would likely be far slower than RT,

Nope, it would be realtime. DVCPRO HD transfers at 100mbps, and plain vanilla FireWire allows for 400mbps so there's plenty of overhead through that bus.

[Will Kennedy]

Thank you for the quick reply.

That is encouraging. I'm currently doing dv camera, firewire cable, to on-set laptop live transfer for dv rack monitoring and backup and it's a very reasonable solution (except the cord running the length between trying to trip everyone). Keeping this workflow and substituting in HD would be very enticing.

Thanks
Will

[Chris Hurd]

I'm hoping the folks at Serious Magic will do a version of the DV Rack that will offer MXF support and DVCPRO HD recording to disk. Maybe they support MXF already, I'm not sure. DV Rack is an excellent, must-have application.

[Scott Anderson]

I really hope the HVX is the first step towards the wave of the future: tapeless, tapeless, tapeless... Panasonic has a rough road in explaining this - getting people's heads wrapped around the idea of an I.T. centric workflow.

It's unfortunate that the storage and archiving methods are still slightly behind the bandwidth needed for HD. I don't think there would be so much F.U.D. over this camera if P2 cards were 80 gigs at $100 a pop, or if Blu-Ray discs and drives were readily available at comparable costs to DVD-R. One of the exciting things for me is that file-copy speeds are many, many times realtime. Now that all video (and film) is quickly becoming just data, there's really no excuse (besides the early-adopter prices) not to treat it like data.

Ah, well... By the time the HVX-200's product cycle is through, the storage and archiving issues will be completely moot, and we can all start freaking out and spitting F.U.D. over UHDTV, or 2K or 4K Digital Cinema standards. Gee, this is starting to feel so much like 1996, when DV was too much for most computers to handle. Now it's positively trival.

(note: this post wasn't diected at anyone in this thread. No one's "freaking out" here, but there's lots of unnecessary Fear, Uncertainty and Doubt going around. It just got me thinking.)

[Jaime Valles]

Originally Posted by Will Kennedy

Thank you for the quick reply.

That is encouraging. I'm currently doing dv camera, firewire cable, to on-set laptop live transfer for dv rack monitoring and backup and it's a very reasonable solution (except the cord running the length between trying to trip everyone). Keeping this workflow and substituting in HD would be very enticing.

Thanks
Will

Yep, you'll be able to do the exact same thing with the HVX. You don't even need P2 cards to do this. Just get the $6000 model, plug in the camera to the laptop via Firewire, and you're set to record 1080/24p direct to laptop.

For complex camera movements where you CAN'T have a firewire cable hookup to laptop, then you'd either need P2 cards or Firestore.