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Do capture cards give better quality input source than firewire?
I am about to bring in HDV footage from a Sony Z1U. I still get jagged edges that look like DV artifacts when capturing with firewire. I know that my text will look better upon export with a nice card, along with other benefits. But the big question is: will HDV source footage look better captured via a (Kona), or other) card than with firewire.
Television broadcast, output to High def tape stock.
Thanks,
Brian -
12 Replies
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Well, the rule of thumb is that you cannot judge the quality of ANYTHING on the computer monitors, you need to view them on an external monitor. Since HDV is not viewable on an external monitor without a capture card, or Matrox MXO, then you need one to see what you are doing.
Shane
Littlefrog Post
http://www.lfhd.net -
[motionfx] ” I still get jagged edges that look like DV artifacts when capturing with firewire. I know that my text will look better upon export with a nice card, along with other benefits. But the big question is: will HDV source footage look better captured via a (Kona), or other) card than with firewire.”
YES ( thats a big yes)
thats why kona cards are used in live sports, motion graphics, movie production.
not to mention you cannot monitor HDV without some 3rd party support.it also requires faster storage, HD monitors and any number of additional things, but if you are doing a show for HD delivery it is hard to deliver to HDcam or D-5 over FW.
gary adcock
Studio37
HD & Film Consultation
Post and Production Workflows -
great answer! Can you explain why the two captures would provide different quality levels? Is it because going in firewire is in itself, a bandwidth limiter? I am sure it is an easy answer.LOL
by the way, this post makes it clear that on important jobs, it it smart to hire a pro, with a REAL system.
Brian
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“on important jobs, it it smart to hire a pro, with a REAL system.”
Amen to that!
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[motionfx] “Can you explain why the two captures would provide different quality levels? Is it because going in firewire is in itself, a bandwidth limiter?”
It’s not a bandwidth issue. FW is plenty fast for transferring HDV material (FW400 is 400Mb/sec). Sony’s HDV is ony 25Mb/sec which is the same as regular old DV. That’s why you can get an hour’s worth of HDV material on the same cassette that records an hour’s worth of DV material. It’s the same amount of data whether it’s HDV or DV. So.. capturing HDV over FW takes no more disk space or i/o bandwidth than does DV. The price you pay, however, is that you need a much more powerful cpu to process (that is, edit) HDV data because it is uses a very processor-intensive codec (mpeg2) to compress the HD signal all the way down to where it can fit on that tiny, cheap cassette.
There’s another big problem with HDV asside from its hardware requirements: everytime you ‘touch’ your HDV material (i.e. color correct, add a dissolve, add graphics, etc), you lose information and basically take a generational loss. That again is due to the mpeg2 long-GOP encoding that is used for storing HDV. In fact, unlike DV, even when you do cuts-only editing with HDV, you lose quality because FCP has to re-encode every frame of the entire sequence in order to assign new ‘I’ frames to the video data stream. This is what happens when FCP says it is ‘conforming’ your footage as you do an export, for example.
So.. to answer your question: What most people are doing to avoid the above two problems with HDV is to re-encode the HD material and store it in a different codec. There are two ways (as far as I know) to do this with the Sony Z1U, three ways with the new Sony V1U:
1) Capture over FW into FCP using the Apple Intermediate Codec (AIC) To do this, use the ‘HDV-Apple Intermediate Codec 1080i60’ Easy Setup in FCP. When you capture, you will not be able to set in and out points. It is bascially a ‘Capture Now’ process. The footage will take up roughly 70GB per hour of video, and you will need a fast RAID array to keep up with the increased data rate. Your footage is no longer HDV. It is now AIC footage, and thus, you will need to edit in an AIC timeline. Although it is taking a bit more than five-times the disk space, FCP will actually have an easier time editing and working with this footage than it would with the much more compact HDV data. This is because FCP doesn’t have to do as much processing to load a frame.
2) Capture using a Kona or Blackmagic card This is probably what most pros are doing with HDV footage right now to make it useful. When you capture with one of these cards, you basically re-capture the HDV material from your camera or deck and re-encode that material in a different codec — most commonly DVCProHD. To do this with the Z1U, you go from the component video output of the camera (using the supplied cable) into the Kona/Blackmagic card and capture using something like the ‘DVCPro HD 1080i60’ preset. This seems counter intuitive because the component video out is ANALOG!! But it is still HD. So.. you are taking the HDV data stored on tape and letting the Sony decompressor (built-in to your camera) decode that data into an component analog HD signal. You then send that data over the analog component cable to the Kona/Blackmagic card, and then re-encoding the analog HD signal using a different codec — thus shedding your attachment to HDV. One of the advantages to capturing in this manner is that you can choose which codec you want to edit in. You could, for example, recapture your 1080iHD footage as 720p if you wished. Or.. Standard Def. Whatever codec you use for capture will, of course, have to be the codec you use to edit with (i.e. if you capture in DVCProHD 1080i60 then your timeline in FCP must also be set to DVCProHD 1080i60). The big downside in all of this is the same as with the AIC FireWire capture mentioned above: you will need really fast hard drives and lots of space. BTW.. one other nice advantage of using a Kona/Blackmagic card is that you can hook up a second flat-panel LCD to use for monitoring the HD material. If you use a monitor that displays 1920×1080 pixels, then you can see every pixel of your HD as you edit.
3) Capture over HDMI or HD-SDI If you get the Sony HVR-M25U deck or you have the new Sony HVR-V1U camera, you can use the HDMI signal to capture to a Kona/Blackmagic card — basically the same as option 2 above. The difference here is that you are inputting a digital signal into the capture card rather than a component analog HD signal. Whether you can tell a difference, I honestly don’t know. But if you are anal about keeping everything digital, that would do it. Another option would be to convert the component HD signal to industry-standard HD-SDI using a converter box (from AJA, Convergent Design, DataVideo?, etc). Also.. Sony has annouced a new, higher-end HDV deck (HVR-1500) that outputs HD-SDI directly. It’s going to be about $6K I believe.
There is a fourth option here that is probably worth mentioning, but one with which I have no experience. You could capture your HDV material over FireWire directly into FCP and then use some sort of software conversion tool (Compressor??) to re-encode that material to another codec such as DVCProHD. But because you are attempting to do in software what your Z1 and the AJA/Blackmagic cards would be doing in optimized hardware, I would guess that it would be very time consuming.
Well.. I hope that helps. Sorry for the long post, but I thought others who are confused (as I have been) about these HDV workflow issues might also benefit.
John
John Christensen
cdesign@airmail.net -
John,
Thanks for the detailed post. One question regarding option two. Instead of capturing to a different codec, why not capture as hdv and then just conform your final edit using a different codec, say dvcprohd or sheer? It seems like there’s no degradation on ingest, only once editing begins with cuts, dissovled, cc, etc., and that degradation doesn’t actually happen until you render anyway (or does it?), so if you have enough cpu power to edit in hdv, why use all the additional space for raw footage?
Stu
G5 Quad Core, 4.5 MB RAM, Dual Dell 1905FP’s, KRK RP-5’s, DSR-11, FC Studio 5.1.2 OSX 10.4.8
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[StuS57] “Thanks for the detailed post. One question regarding option two. Instead of capturing to a different codec, why not capture as hdv and then just conform your final edit using a different codec, say dvcprohd or sheer?”
1 – It’s MUCH slower to edit in HDV. DVCPro HD is “real” video, not the MPEG-2 Long GOP format so FCP cuts faster with it. More streams of video, more realtime effects, etc…
2 – I much prefer the hardware conversion of the AJA Kona board over doing a software conversion after the fact. Why not convert the footage to DVCPro HD in realtime during ingest instead of converting it at the end? I do not want to waste the time to convert 30 – 60 minute broadcast shows from HDV to DVCPro HD when we can do it in realtime during ingest.
Walter Biscardi, Jr.
https://www.biscardicreative.com
HD Editorial & Animation for Food Network’s “Good Eats”
HD Editorial for “Assignment Earth”“I reject your reality and substitute my own!” – Adam Savage, Mythbusters
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So the main advantages are FCP performance and loss of time, not visual quality. For me, seems like if I’m only doing a 5 min. spot, I can get the benefits of dvcprohd with the render afterwards and invest in less storage – 5 minutes worth as opposed to 5 hours worth per spot.
G5 Quad Core, 4.5 MB RAM, Dual Dell 1905FP’s, KRK RP-5’s, DSR-11, FC Studio 5.1.2 OSX 10.4.8
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Thanks soooo much for the incredible posts here guys. This info has made it clear to me the direction to take on my first broadcast assignemnt as director. Look out World!
“you can’t buy this type of info.”
Brian -
Capturing Firewire, you are capturing an exact 1:1 clone of the data on the tape. Not one iota of quality is lost. It is a flawless process, like copying a file to a disk.
The tricky thing is that some codecs like DV and HDV has a low color sample rate. Converting these codecs to a codec that uses 4:2:2 offers many advantages.
There are several ways to do this conversion. One of them is to output HD-SDI and capture with a Kona or Blackmagic card which is what this topic is about. When outputting HD-SDI from the deck, the decoder inside the deck is doing the conversion. On Sony DVCam decks, this process is known to have the added benefit of smoothing out the chroma artifacts. The same is quite possibly true for HDV decks as well using the HDMI output with an HDMI to HD-SDI converter.
Alternatively, can capture firewire and edit in HDV (which can be slow and painful to work with) and then do the conversion before or after your editing by using software like FCP or QT Pro to convert the video to a 4:2:2 format. The Apple decoder however doesn’t apply the same chroma smoothing that you get from a Sony deck. BUT… there is a filter in FCP called 4:1:1 Chroma Smoother which is known to smooth out the artifacts just like an HD-SDI capture would do.
I’m typing all this because to say that “the Kona improves the quality of HDV” is very misleading. In practice, yes, this workflow will add an improvement over capturing FW and not doing anything else to it. But the Kona isn’t actually doing anything. It’s the deck’s HDV decoder doing the smoothing, and the same thing can be achieved with the FCP filter if you want to capture using firewire instead.
All that said, I’d recommend going the HD-SDI route and not messing around with HDV capture if you can afford it. If you can’t afford it, like I said, just capture with firewire, use the chroma smoothing filter, and covert to uncompressed 8-bit. Video quality will be just as good.
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