If you had to choose... imagine you're shooting a project ENTIRELY on greenscreen.

You've got a LIMITED budget for only two choices. (HD-SDI and Sony V1U are out) Either an excellent camera image-the Canon A1-but it's compressed HDV 8bit 4:2:0. Not so desirable for pulling keys.

Or you could go the other way and put your money into an expensive RAID and Black Magic Infinity card and pickup a more consumer oriented but less expensive camera-Sony HDR-HC3 or HDR-SR1, but both of which will spit out pure uncompressed 8bit 4:2:2. A lot more desirable for pulling keys.

From a technical hypothesis and FORGETTING about keyer software, lighting etc.-which would you choose for this greenscreen only project and why?

*I have private noncommercial server space and can host greenscreen clips taken with any of the Canon or Sony cameras for the community. PM me if you'd like to share. Thanks.

Hi Derek!

I have not tried any of the following so please use them only as a guide for further research. With that being said, here are some ideas for your problem:

1) A project entirely on green screen! Man, you would need a LOT of keying! How many minutes would that project be? If it is long, I would try to get 4:4:4 colour sampling to avoid hours of correcting the keys. How? Do you REALLY NEED a final export in HD? I have read in a lot of different occasions that HD downsampled to SD gives a full 4:4:4 colour space. Try to find out some more about this because I might be wrong. You may also check http://www.dvinfo.net/conf/showthread.php?t=80086&page=2&highlight=chromakey, the post by Matt Daviss. He seems to have experience on this issue. Also, don't forget you may uprez your final product in the end (not same as working with HD all the way of course but still a potential workaround if HD is definitely needed for delivery - in what medium, by the way?)

2) How much camera control are you willing to give up? Keep in mind that the small SONY cameras that you mentioned do not have control over shutter and gain. Lack of control on shutter makes a filmout impossible (if that's what you are after). They also do not shoot progressive. Keying progressive frames is supposed to be easier than keying interlaced. You may of' course convert interlaced signal into progressive in post (with all the subsequend loses) but it also means extra post time.

3) Why do you need an expensive RAID to capture through HDMI? You only need that if you want to capture the original HDMI signal. As far as I know, if you use the blackmagic card and capture mjpeg avi files with Premiere, you need normal hard disks. You may need more than one of them depending on the size of your project (around 40GB per hour for the mjpeg codec) but how many hours do you plan to capture? If you already have a good computer it may well be the case that the only thing you need to buy is the Intensity card for 250$. You may want to research some of the posts of Thomas Smet regarding his experiments with the card and the quality of the mjpeg codec for keying. See also his posts on http://www.dvinfo.net/conf/showthread.php?t=76873&page=3&highlight=HDMI+blackmagic+software and http://www.dvinfo.net/conf/showthread.php?t=80520&highlight=mjpeg . If you already have the pc and premiere or Apple and FCP and the only thing you will need to buy is the intensity card then maybe the FX7 may be the best (simplest) solution for your project. The only potential drawback could be that it is not progressive (how are you recording your sound by the way? No XLRs on the FX7).

4) XH-A1 may not have HDMI but it does have component out. Check out GEFEN's converter from component to HDMI. You may also feed audio to it and it embeds it to the HDMI signal. All these for only 180$. Couple it with an Intensity HDMI card and you have a possible solution. I have never heard of anyone using this setup though with an A1 (or any other camera for that matter) so you need to do some research on this as well. How is the conversion done? What is the quality of the final HDMI output? Does it work with Canon's signal? The product is made for Home theatre systems. Will it be good enough for what you need? You may also try writing an email to GEFEN and see what they say. Also, keep in mind that HDMI does not transport 24f (same goes for 24p). This means that you will have to extract the pulldown in post in case you shoot progressive. More work needed...

5) Since you are on a budget, if the Gefen solution works, you may also want to consider SONY's A1. You get XLRs and control on shutter but still no control on gain... Are you interested in 24p? If yes and you are not in pal-land, maybe a good idea would be to also consider buying a pal version of the Sony's A1, so that you can take advandage of the 25F cinema mode. Sony's 25F is supposed to be much better than 24F (is this exported from the component though? I would think yes, but don't take my word for it!). If 24p is not an issue, the NTSC version with it's 30F should do exactly the same job in terms of quality. But not the 24F, as far as I know. Of course you may capture 60i and convert to 24p or 30p in post (do you have the software?). One way or another, going progressive (either with Canon or Sony) will increase the workload in post (either extracting pulldown or converting i to p).

6) Last but not least, there are some people on this board that have extended experience in keying. Try to come in contact with Thomas Smet for example. I have found his posts to be very knowledgeable and helpful.

To summarize, there seem to be two categories of questions that need to be answered:

I) Project related questions:
a) Should the final product be delivered in HD?
b) Should the final product be delivered in progressive, interlaced or it does not matter?

II) Technical questions:
c) HD downrezed to SD gives 4.4.4 colour space, 4.2.2 or what? With what workflow?
d) Does the Gefen (or another?) product encode component to HDMI without loss? Does it work seamlesly with Canon's signal?
e) How much better is it to key progressive frames vs interlaced? Is it worth the hastle?

Hopefuly, some more experienced members will jump on this thread and help out!

Good luck and don't forget to let us know how it worked out for you!

Thanasis

or a 3rd camera that fits your budget ..

IMO shooting a whole project green screen = you get the BEST image for green screening and that would be a image that has 4:4:4 color space ...
based on your budget the camera would be a modified DVX = outputs 1540x990 images plus i think you can go 10bit images

http://www.reel-stream.com/andromeda.php

I know you've said "forgetting keying software", but there is one piece of keying software that can change your workflow. If you're on a Mac you can get very good keys from DV and HDV (in real time) using dvMatteBlast (for Apple Motion) from dvGarage for $99.

It uses a combination of the chroma and luma channels to pull very nice keys out of 4:1:1, 4:2:0, or 4:2:2 footage.

I've used it with HDV from a Sony FX1 in cineframe30 (faux progressive) and a Canon A1 in 25F to pull a exceptionally clean keys.

I'm very pleased with the way they look - although I have to add that I've only been using them on SD products (we film HD for SD output).

Hi everyone, thanks for taking the time to respond, I really enjoyed the different perspectives you have shared.

Thanasis Grigoropoulos wrote:
"Do you REALLY NEED a final export in HD?"

Yes, it needs to be HD for release in HD DVD/Blu Ray and to be future proofed as much as possible, but thanks for the link. It would be an interesting possibility to shoot HDV and downscale if only releasing in SD.

"How much camera control are you willing to give up?"

Obviously, as little as possible... but as long as I have a clean
image of the talent that's all that really matters since the backdrops will be either cgi or high quality stills. The thing that bothers me about the little single chip cameras is they don't handle highlights that well from what I've seen.

"Why do you need an expensive RAID to capture through HDMI?"

If you're capturing uncompressed you would need at least a 5 disk raid from what I've read. I'll admit, I have zero experience with raids so I could be mistaken about this. I would be using a PC, not a mac and I haven't tried the mjpeg codec yet. If I was happy with it's quality perhaps that could be an option.

"how are you recording your sound by the way?"

Depends what camera I end up with. Main ingest is through a Creative Audigy4 since it has balance inputs and captures at 24-bit/96khz which leads to a terrific sound.

"Check out GEFEN's converter from component to HDMI"

It would be interesting to see what kind of image degradation there was.

"This means that you will have to extract the pulldown in post in case you shoot progressive"

I do this already for SD DV and am OK with it.

"you may also want to consider SONY's A1."

I considered the A1 but the for the $, you don't get any better image then the HC3 IMO. I'm all about image over features. 24p is OK, but not a must.

Thank you for all your suggestions Thanasis!

Don Donatello wrote:
"based on your budget the camera would be a modified DVX"

I seen that reel-stream a long time ago and it is an interesting idea. Overall I didn't think the samples looked anything like HD but if you could get 4:4:4 10bit out of it...it would be a great solution for keying, especially if you only need to frame talent. Hmmmm...I will have to search for a greenscreen sample. Thanks for the suggestion Don.

Alex Leith wrote:
"I know you've said "forgetting keying software""

Well, the project is scheduled to be keyed on a PC based studio setup which has Keylight or Primatte. Both are pretty sweet on SD DV footage. But 4:1:1, no matter how great it looks keyed, always, in my eyes, has that amatuer look I would like to avoid.

Derek,

I understand your desire to get as clean a key as possible. You have to take into consideration the following factors:

Internal processing in the camera takes place at full resolution in a 4:2:2 color space, which through HD-SDI or HDMI can be captured live @ 1.485 Gbps, if the camera allows that. After the internal processing, the signal is compressed and stored on tape (or external HD) in a 4:2:0 colorspace @ 25 Mbps. So heavily compressed.

AFAIK the HDMI connectors on the Sony cameras allow for digital transfer of the recorded data from tape, not live, so in essence they only allow 4:2:0 @ 25 Mbps streams and not a 4:2:2 stream @ 1.485 Gbps. The HD-SDI version from Canon, the H1 or G1, do allow live capturing at that level.

To capture a stream @ 1.485 Gbps you need a sustained write speed on your disk system of close to 200 MB/s, hence the large disk array.

With the indicated budget restraints, I think you just have to accept you can only work with HDV recorded material, 4:2:0 @ 25 Mbps.

AFAIK the HDMI connectors on the Sony cameras allow for digital transfer of the recorded data from tape, not live, so in essence they only allow 4:2:0 @ 25 Mbps streams and not a 4:2:2 stream @ 1.485 Gbps. The HD-SDI version from Canon, the H1 or G1, do allow live capturing at that level.

Hi Harm!

This is definitely some news for me! So, all Sony cameras output HDMI signal AFTER HDV (or AVCHD) compression and NOT live uncompressed? The blackmagic site claims the opposite (although indirectly: There is a picture of HC3 but no mention in the text - http://www.blackmagic-design.com/products/intensity/). Is this also the case for the component of the XH A1? Or the component of HC1 or Sony's A1?

I have read a lot of other posts claiming that HDMI and component can be captured live before compression, at full 4.2.2. AFAIK, this is the consensus at DVinfo at the moment. But it's true that I never came across any sample footage captured live from HDMI or XHA1 component...

Is there someone who tried this already and can enlighten us?

Happy new year to everybody!

Thanasis

This is definitely some news for me!

I have read a lot of other posts claiming that HDMI and component can be captured live before compression, at full 4.2.2. AFAIK, this is the consensus at DVinfo at the moment. But it's true that I never came across any sample footage captured live from HDMI or XHA1 component...



This would be news to me too. It simply can't be true. The whole point of a HDMI output is to have an uncompressed signal for monitoring...there would just be no point if it was compressed and you couldn't see the true shot you were getting...



With the indicated budget restraints, I think you just have to accept you can only work with HDV recorded material, 4:2:0 @ 25 Mbps.

That would be true if I was restricted to HD-SDI. But a raid $3000, and an HC3 $1500 is about the same cost as a Canon A1 so it's completely within reason.

It's really going to come down to one of those 2 choices for me. My main point in starting this thread was to solicit opinions on which would provide a better key for greenscreen:
Canon A1 or HC3 using HDMI out.

Keep in mind that HDMI is just one part of the entire pipeline.
Consider that a DV image from a palm-sized ZR10 doesn't look the same as a DV image from a new XL2. DV and HDMI are delivery technologies, but the lens, imager, internal processors, user configurable settings, etc. that the image passes through in the camera BEFORE the signal gets to them are every bit as important.

You have a great question, there are many great opinions here in reply.

Ultimately, shooting tests using both tools, with a lighting setup comparable to your production situation to compare the results of the pipelines is the best way to compare the options. Looking primarily at the theoretical specs of HDMI capture vs HDV is a very limited (and perhaps meaningless) scope.

My personal impression (I have no experience with any of these cameras) is that a G1 or H1 with SDI capture would be your best bet. A1 next, due to my instinct (could be wrong) that 3CCDs fed by the A1 lens would perform better than a hand-cam using a single CMOS.

A soft, over sharpened image through HDMI is generally not going to be as useful for keying as a sharp clean image compressed to 4:2:0.

Also, if you control your subject and screen selection to use either a dark subject (Dark hair, dark clothes, dark skin) in front of a green screen ... or use a bright subject (blond hair, fair skin, white clothing) in front of a blue screen .... you can basically avoid color compression based artifacts in your composits altogether and the 4:2:2 vs 4:2:0 concern becomes a non-issue.

In my earlier post I said:

"Internal processing in the camera takes place at full resolution in a 4:2:2 color space, which through HD-SDI or HDMI can be captured live @ 1.485 Gbps, if the camera allows that."

The reason I made the second remark:

"AFAIK the HDMI connectors on the Sony cameras allow for digital transfer of the recorded data from tape, not live, so in essence they only allow 4:2:0 @ 25 Mbps streams and not a 4:2:2 stream @ 1.485 Gbps."

is based on one fact and one supposition. The fact is that the Sony Operating guide does not mention the capability of live HDMI output @ 1.485 Gbps and let's be realistic, this would be a HUGE selling point. See for instance pages 58 and 61 of the V1 operating guide. The HDMI connector is shown as an alternative to fire wire, because there are few TV's with fire wire connectors, but rather a lot with HDMI.

Secondly, and this is the assumption I made, is the HUGE price difference between cameras with or without HD-SDI. Example Canon A1 vs. G1, around $ 3K. Given the pricing structure of Sony, example the XDCAM-HD 330 vs. the 350, is seems utterly inconceivable to add a live HDMI capability on a less than $ 2K camera and even on the V1 it is unrealistic.

It would be nice if Chris Hurd, DSE or other experts could confirm or deny my statements.

HDMI lacks timecode and the means to make it work with pro equipment. It's original intent is for HDCP and protecting copyright. I don't think Sony is worried about 4:2:2 HDMI hurting their upper end. There are other factors that effect the signal, such as the lens as already mentioned, and how well you light your scene.

I can understand the difference in cost between a G1 (or used H1) and a Sony HC3. Including a system capable of working with 4:2:2 10bit. But after all that work of setting up your scene and the human effort involved, why make the most important tool in your pipeline the weakest link? Can't you just rent what you need?

Interesting discussion! For clarification, as a manufacturer of an HDMI to HD-SDI converter (HD-Connect MI), I can absolutely assure you that the "live" output from the Sony camcorders has never seen any compression whatsoever. The uncompressed video is 1920x1080i 4:2:2, while the audio is 48Khz stereo, 16-bit uncompressed. Additionally, it is possible, using our converter box to get 720p or 480i out of the Sony camcorder (or M25U deck) in either live mode or while playing back from a tape.

The HD-Connect MI also supports deck control via RS422 to 1394 command translation. You can find more info on our web site as well as a recent technical paper on HDMI technology ("HDMI in HDV and AVCHD camcorders").

Mike Schell
Convergent Design

HDMI works just as component output in terms of it being uncompressed. That is the whole point to it.

HDMI is first just a connection to your TV so you only need a single cable to view your material in high quality with very little effort. It is only Blackmagic design who came up with a way to treat this port as a capturing device and I'm sure other people will follow as well.


With that said if live capturing is not an option true progressive 4:2:0 actually isn't all that bad. The Canon F modes and any video from the JVC HDV cameras uses true progressive 4:2:0 encoding which means clean 2x2 blocks of chroma. It may not be as detailed as 4:2:2 but it is clean. If you have decent software that can upconvert or smooth the chroma channels you will get very good results.

The SONY cameras only use interlaced HDV encoding which alternates chroma samples every other line so you really kind of end up with 2x4 blocks of chroma samples which is not very clean. This only happens this way if you deinterlace the video. If you have a progressive frame sitting inside of a 1080i stream then you end up with chroma jaggies because the chroma samples may not line up exactly with the luma samples because they alternate every other line. If you need to shoot interlaced then this isn't an issue because thats the way interlaced 4:2:0 has to be. If you plan on shooting progressive however and need to shoot to tape first then the Canon and JVC cameras will give you a cleaner image with less artifacts. If you will be able to capture the live output from the camera then I'm not yet sure which camera will be better. While HDMI sounds very nice it still has not been used by anybody on this forum that I know of so we do not yet know exactly what it will look like. In theory it should look as good as 8 bit over SDI but I have not seen anything to show this as of yet. The Intensity cards are now starting to ship so perhaps we will see some examples soon.

Hi Thomas-
The HDMI ouput will be exactly the same image as the 8-bit over SDI. The The same data stream would be used to drive either type of output as well as the analog component encoder.

Mike Schell

Interesting discussion! For clarification, as a manufacturer of an HDMI to HD-SDI converter (HD-Connect MI), I can absolutely assure you that the "live" output from the Sony camcorders has never seen any compression whatsoever. The uncompressed video is 1920x1080i 4:2:2, while the audio is 48Khz stereo, 16-bit uncompressed. Additionally, it is possible, using our converter box to get 720p or 480i out of the Sony camcorder (or M25U deck) in either live mode or while playing back from a tape.

The HD-Connect MI also supports deck control via RS422 to 1394 command translation. You can find more info on our web site as well as a recent technical paper on HDMI technology ("HDMI in HDV and AVCHD camcorders").

Mike Schell
Convergent Design

Mike,

It is interesting indeed, since if your statements are indeed accurate, Sony would have an incredibly attractive deal with all HDMI cameras, blowing all competition to h*ll. Strange however that Sony, who is very, very marketing oriented and always the first to show their strength's in comparison to the competition, would play this MAJOR advantage so low key, no even FORGET about mentioning it.

I posed this question to Sony, asking whether the signal out of the V1 through HDMI was a compressed 25 Mbps signal or a 1.485 Gbps signal and they will investigate further, but the initial reaction was, since it is a TV compatible signal, that it is only 25 Mbps and thus compressed.

There is no possibility to change the signal in the menus from one to another and it definitely is compatible with TV's, this leads me to the conclusion you are possibly wrong in your statement. Once I have heard from Sony, I'll keep you posted.

I can absolutly assure you that the HDMI output from a "live camera" has never been compressed. MPEG2 compression adds anywhere from 15 to 30 frames of additional latency to the signal. We see this latency when an HDV camera is connected to our HD-Connect SI box, which does HDV -> HD-SDI conversion. There is an undeniable delay of the video and audio signal (about 1 second). However, when we use our HD-Connect MI (HDMI -> HD-SDI) converter there is no perceptible delay in the audio and video.

Furthermore, if the HDMI output from a "live camera" was indeed compressed, then the camcorder would need to perform both a compression and decompression process simultaneously. This would add even more latency and further increase the power consumption (always a concern for battery powered devices).

So, the HDMI output from a live camera has indeed never seen a compression, just like the HD-SDI ouput from the Canon (in live mode). Sony likely has a number of marketing reasons to not advertize or promote this capability.

Mike Schell

So, the HDMI output from a live camera has indeed never seen a compression, just like the HD-SDI ouput from the Canon (in live mode). Sony likely has a number of marketing reasons to not advertize or promote this capability.

Mike Schell

If you are correct (I'm still waiting for confirmation by Sony) then the marketing reasons of Sony seem like BMW introducing a new 2.0 liter 4 cylinder car, which underneath has a 4.2 liter V8 but does not want the public to know. Does not make a lot of sense, does it?

From another perspective, how do you explain that Sony confirmed that their single chip range of cameras, the HC3, UX1 and SR1 output compressed HDMI signals @ 25 Mbps? That there is no way to switch from a 1.485 Gbps stream to a 25 Mbps stream? This means that you can only use HDMI live and not afterwards. How do you explain the fact that the HDMI connection is TV compatible, but the TV HDMI input is limited to 25 Mbps and the camera has no way of switching between the two different signal streams?

How do you explain, from Sony's perspective, the price difference between the XDCAM-HD 330 and 350 due to HD-SDI (and some other differences), the relatively high price of the Canon H1 with HD-SDI, the price differential between the Canon A1 and G1 with HD-SDI and a long list of possible other examples?

If you are correct, Sony is definitely embarked on a route that can be designated as a price fighter. That is a new one for me. Also, for the first time in their existence, they act mute in promotional terms.

Sorry, I just don't buy it without confirmation from Sony.

Mike, please do not consider this a (personal) attack. Just expressing my doubts.

It might be worthwhile to check whether a HD-SDI signal from a camera (H1, G1, 350 or similar) converted to HDMI can be directly displayed on TV during live recording, and repeat that for HDMI. I assume (hopefully I'm wrong) HDMI is no problem, but the HD-SDI data rate is just too much for the TV and chokes on it.

Just in the lucky case that I find a 4.2 liter V8 under the hood of the car sold as a 2.0 liter 4 cylinder, that nobody told me about, I consider the start of 2007 very, very good.

Not sure why you think this is so breakthrough of a feature -- every HD camera on the market outputs uncompressed high-def through at least analog component outputs; the XHG1 and XLH1 do so through genuine HD-SDI, and the tiny little Sony HC3 and the AVC-HD cameras from Sony and Panasonic all output uncompressed digital HD through their HDMI ports.

It's a great feature, sure, but it's not like it's a) hidden, or b) unique to the V1U. The HC3 brought uncompressed HDMI output to the market almost a year ago.

From another perspective, how do you explain that Sony confirmed that their single chip range of cameras, the HC3, UX1 and SR1 output compressed HDMI signals @ 25 Mbps?
I would chalk that up to a misinformed individual giving you erroneous information. HDMI is always uncompressed.

The only way they could be outputting the 25mbps signal would be if they uncompressed it to full uncompressed before transmitting, and you'd know that real quickly on an HDV camcorder because you'd see a 1/2-second lag between action in front of the lens and when that action shows up on the monitor. HDV has to buffer 1/2 second of footage before it can compress a GOP, so HDV output is always delayed by a minimum of 1/2 second (shorter GOPs can reduce that time, but Sony always uses 1/2-second GOPs).

So -- if someone were to report that the HDMI monitoring on their Sony camcorder was lagging 1/2 second behind reality, then yes that would be an indication that the HDMI output was perhaps being compressed to HDV, and then uncompressed and output over HDMI. But AFAIK there is no lag, which would in and of itself be proof positive that the HDMI output has not undergone 25mbps HDV compression.

Not sure why you think this is so breakthrough of a feature -- every HD camera on the market outputs uncompressed high-def through at least analog component outputs; the XHG1 and XLH1 do so through genuine HD-SDI, and the tiny little Sony HC3 and the AVC-HD cameras from Sony and Panasonic all output uncompressed digital HD through their HDMI ports.

It's a great feature, sure, but it's not like it's a) hidden, or b) unique to the V1U. The HC3 brought uncompressed HDMI output to the market almost a year ago.

and this is exactly what Sony denied. According to them it is a compressed signal being output for their single chip camera line.

Hi Harm-
This is also not a personal attack, but I don't think you have a clear understanding of HDMI. May I suggest that you visit hdmi.org and also download a copy of our white paper: "HDMI in HDV and AVCHD camcorders".

Firstoff, HDMI only supports uncompressed video, not 25 Mbps compressed video. Camcorders and decks use an MPEG2 decoder chip to decompress the (25 Mbps) HDV or AVCHD video/audio before it is output on the HDMI port (this assumes playback from a tape, DVD or hard drive). In the case of live capture, the video stream out the HDMI port has never been compressed.

Our HDMI white paper, available from the Convergent Design web site, shows the video/audio dataflow through the camcorder/deck. This diagram should help everyone better understand how the video and audio are processed.

I can't comment on the marketing reasons behind adding HDMI output to camcorders and decks. I do know it works and produces excellent quality video/audio.

Yes, 2007 will indeed be a very very good year.

Mike Schell
Convergent Design

lots of good responses to the initial line of questions. i'll just add this...


I can't comment on the marketing reasons behind adding HDMI output to camcorders and decks. I do know it works and produces excellent quality video/audio.


probably a good guess that the hdmi connectors are so that people can conveniently connect their cameras to their hdtv's to playback footage, not so that people can connect their cameras to raw video acquisition systems. that would be a nice side-effect which has only recently become cost-effective (cineform, blackmagic, fast laptops, harddrives, etc.).

and this is exactly what Sony denied. According to them it is a compressed signal being output for their single chip camera line.
I would suggest asking someone else then, as apparently the person who answered your question was misinformed.

As usual, a thread full of useful replies!

Some more questions though that I am really hoping for an answer to:

1) If you want to capture live using the HDMI but without using RAID, which is the best way to go, for bluescreen work? Is there a way to keep full 4.2.2 without using DVCPROHD and thus scaling down the image? And if there is such a way, what are it's potential drawbacks?

2) How about this Gefen adaptor? Feed component and sound, export HDMI. Does it work? What are the loses? Or what could be the loses? (I mean, technically, is there a lot of ways to convert component to HDMI?)

3) Thomas: You mention in your post that "if you have a progressive frame sitting inside of a 1080i stream then you end up with chroma jaggies because the chroma samples may not line up exactly with the luma samples because they alternate every other line." From what I gathered you are discussing the V1's recording of progressive signal on tape. How about the signal of say A1's 24f from component? From what I understand, A1's component signal is always interlaced - therefore another "progressive frame sitting inside of a 1080i stream." Would that mean that this signal would suffer from the same problems (in reference always to bluescreen work). Given Mike's point that component's signal is exactly the same as SDI, I guess bluescreening with H1 -> 24F -> SDI would give the same results (and problems, IF any).

4) Finaly, one thing I really don't understand: How come the sensors of these cameras capture 4.2.2 and not 4.4.4? I really cannot understand what these sensors "see"! I thought sensors "see" all the colour spectrum and AFTER they capture that, then their signal is processed and encoded to whatever codec is to be used. Andromeda plug in for the DVX claims a full 4.4.4 capture out of the sensor. How come these HD sensors, made so many years after DVX, capture only 4.2.2? Please excuse my ignorance! I just cannot understand how this works!

Thanks a lot,

Thanasis

3) Thomas: You mention in your post that "if you have a progressive frame sitting inside of a 1080i stream then you end up with chroma jaggies because the chroma samples may not line up exactly with the luma samples because they alternate every other line." From what I gathered you are discussing the V1's recording of progressive signal on tape. How about the signal of say A1's 24f from component? From what I understand, A1's component signal is always interlaced - therefore another "progressive frame sitting inside of a 1080i stream." Would that mean that this signal would suffer from the same problems (in reference always to bluescreen work). Given Mike's point that component's signal is exactly the same as SDI, I guess bluescreening with H1 -> 24F -> SDI would give the same results (and problems, IF any).

Thanks a lot,

Thanasis

This is a good question. One thing to remember however is that video coming out of the component, SDI, and HDMI ports assumes uncompressed video. If 24F is on the tape it will come out the ports upconverted directly to 4:2:2. It may not look any better but the chroma samples will not have to alternate because the output isn't 4:2:0 but 4:2:2. It's like how DVCPRO HD will be fine as interlaced footage because it is 4:2:2 by nature. A progressive 4:2:0 should decode to 4:2:2 better then a Interlaced 4:2:0 would. Not to mention progressive 4:2:0 will always have less artifacts and give an overall cleaner compression. My opinion to your question is that the camera would have to decode the tape signal first to an uncompressed siganl and then send it out as an uncompressed 4:2:2 stream even if those 4:2:2 pixels only have 4:2:0 chroma samples the fields will still show proper samples per field. At least this is the way I hope it works. I know with component the chroma usually gets smoothed so you kind of now end up with a blurred 4:2:2 anyways. I'm not sure if the same upsampling works with SDI and HDMI however.

Hey everyone thanks for contributing to this humble thread. Some of the points you guys have brought up raised a few questions for me.


My personal impression (I have no experience with any of these cameras) is that a G1 or H1 with SDI capture would be your best bet. A1 next, due to my instinct (could be wrong) that 3CCDs fed by the A1 lens would perform better than a hand-cam using a single CMOS.

Thanks Nick for your opinion. This is exactly what I was looking for. And I can't say I don't agree. The G1 or H1 both produce great images. Too bad they're both overpriced IMO. $3400 difference right now from the A1--just for a jackpack is crazy. But they know if you need that option, you'll pay.

A soft, over sharpened image through HDMI is generally not going to be as useful for keying as a sharp clean image compressed to 4:2:0.

Again, thanks.

Also, if you control your subject and screen selection to use either a dark subject (Dark hair, dark clothes, dark skin) in front of a green screen ... or use a bright subject (blond hair, fair skin, white clothing) in front of a blue screen .... you can basically avoid color compression based artifacts in your composits altogether and the 4:2:2 vs 4:2:0 concern becomes a non-issue.

I haven't come across this tip before. I understand what you're getting at from a generalist point of view, but I'm lost on why this would work beneficially from a technical standpoint.


I can understand the difference in cost between a G1 (or used H1) and a Sony HC3. Including a system capable of working with 4:2:2 10bit. But after all that work of setting up your scene and the human effort involved, why make the most important tool in your pipeline the weakest link? Can't you just rent what you need?

Thanks for bringing this up Peter. It's something I have thought about. Cost vs Performance vs Effort so to speak. Is the camera really the most important link though? Especially in lower budget projects. I know we're all video guys and want the best image so that is our mentality (at least mine) but when it comes to creating an artistic project there are soooooo many factors. For example, would Lord of the Rings have been as cool if the hobbits had been wearing plastic Halloween costumes and using wooden swords? Probably a good thing they spent some money in that area too. There's so many potential things that can take the audience out of the moment including, like you point out, capture quality. It really is a balancing act. I know I would want my characters dressed as authentic as possible. Yes, renting is always a possibility. I always keep all my options open until I feel I've gathered all the relevant data.


I can absolutely assure you that the "live" output from the Sony camcorders has never seen any compression whatsoever. The uncompressed video is 1920x1080i 4:2:2, while the audio is 48Khz stereo, 16-bit uncompressed. Additionally, it is possible, using our converter box to get 720p or 480i out of the Sony camcorder (or M25U deck) in either live mode or while playing back from a tape.

Thanks for chiming in with specs Mike. I love this stuff. Ok, in regards to what you said about the 1920x1080i out through HDMI, can you clarify if you are talking about the V1U or all Sony HDMI enabled cams? Because it's early stages for HDMI capture here, I've been reading a lot of misinformation from blogs/filmaker/videosites across the net and maybe we can cement this right here, right now. Now, from what I've gathered, you could only get 1920x1080 HDMI output from the new HDR-SR1 and HDR-UX1 because their imaging processing chips are newly designed for AVHCD and they are different from the HDV image processing chips from the V1U and HC3. The reason for this new design is because the AVHCD standard supports up to full 1920x1080 where as the HDV standard only supports up to 1440x1080. Even though all 4 cameras have the same kind of CMOS that captures 1920x1080 at the start both the V1U and HC3 have image processors that, by design, limit HDMI out to 1440x1080 because the resolution is being converted before it hits the HDMI. Hence the reason you see Sony's flashy new black & gold FULL HD1080 banner plastered all over the SR1/UX1 but not on the HC3/V1U.

The HDMI ouput will be exactly the same image as the 8-bit over SDI. The The same data stream would be used to drive either type of output as well as the analog component encoder.

Now I could be reading this wrong but I gather you're basically saying the HDMI image output should be the same as the SDI and component because they're being driven by the same data stream?

The diagram at the sony V1U site http://bssc.sel.sony.com/BroadcastandBusiness/minisites/HDV1080/HVR-V1U/devices.html
seems to contradict this as it shows the component out AFTER the image has been converted to 1440x1080. Wouldn't this contradict what you're saying about component data stream being the same as HDMI? Unfortunately this diagram doesn't label where HDMI out is in the chain.

The bottom line HDMI question here seems to be, as I know this is still a confusing subject for a lot of people on the net, what do the following resolution size do the following cameras output through HDMI?
Sony V1U
Sony HC3
Sony SR1
Sony UX1


If you will be able to capture the live output from the camera then I'm not yet sure which camera will be better.

Yep, hard to say for keying anyways. My guess it'll come down to personal taste.


I posed this question to Sony, asking whether the signal out of the V1 through HDMI was a compressed 25 Mbps signal or a 1.485 Gbps signal and they will investigate further, but the initial reaction was, since it is a TV compatible signal, that it is only 25 Mbps and thus compressed.

Harm, pardon my ignorance...I do all my viewing through a monitor and don't own a TV and have never heard of a TV being limited by data rate? Is this true, TVs can only handle certain data rates? I assume you're talking HD TVs only, is there an industry standard data rate?

If you are correct (I'm still waiting for confirmation by Sony) then the marketing reasons of Sony seem like BMW introducing a new 2.0 liter 4 cylinder car, which underneath has a 4.2 liter V8 but does not want the public to know. Does not make a lot of sense, does it?

Alot of the deciscions a company like Sony does doesn't make sense to the average joe like you and me. Did you see their PS3 commercials? LOL. Marketing people are not consumers, they don't get it. Companies manufacture what THEY want, and their maketing tells US why we should want it. Sometimes we do, sometimes we don't, and most of the time WE end up wishing for something that doesn't exist. Seriously, it's a mentality block most companies have. They won't promote anything they don't have total control over. They want to control then entire package inhouse (think Beta/Bluray/UMD) and make money on the entire process chain. To them it's dollars lost to some other company selling the HDMI capture cards, not money gained on selling more video cameras. Sony doesn't have a consumer HDMI capture product so it's not a focus for them that's all. Of course what they don't understand from a street level perspective is they would sell a ton more cameras if they pushed it.


1) If you want to capture live using the HDMI but without using RAID, which is the best way to go, for bluescreen work?

Shouldn't the SheerVideo Codec allow you to get away with maybe an inexpensive 2 disk RAID?

re:dark subject greenscreen/bright subject bluescreen negates 4:2:2: vs 4:2:0.
I haven't come across this tip before. I understand what you're getting at from a generalist point of view, but I'm lost on why this would work beneficially from a technical standpoint.

The answer is in the 4. Luma is sampled at full resolution with both compression schemes. Most of the luma signal is translated into the Green RGB channel, resulting in sharp detail in this channel vs blockier data in Red & Blue due to color compression. So, if you select your background and subject colors to maximize luma contrast, a sharp image is passed through to the green channel.

The Green channel should be virtually white for a green screen, so using a dark subject provides lots of high-detail contrast to work with, resulting in a better starting point even for color difference and vector based keyers like Keylight and Primatte.

If you put a bright subject in front of a green screen, though, there's little-to-no contrast in the green channel to work with. Your color keying operations end up being based on the blocky data in Red & Blue. This is why it's helpful to use a bluescreen for bright subjects. The green channel for a blue screen is almost black, so the bright subject provides lots of high-detail contrast in the green channel, again helping your keyer independant of color compression.

You'll still be battling artifacts from the lens, sensor, A->D converter noise, and post processing like in-camera sharpening (which is why my instinct favors the idea of using the A1 vs a consumer targeted hand-cam) but by setting up your scene this way, color compression itself becomes less of a factor in calculating your compositing keys.

Hey everyone thanks for contributing to this humble thread. Some of the points you guys have brought up raised a few questions for me.

Thanks for chiming in with specs Mike. I love this stuff. Ok, in regards to what you said about the 1920x1080i out through HDMI, can you clarify if you are talking about the V1U or all Sony HDMI enabled cams? Because it's early stages for HDMI capture here, I've been reading a lot of misinformation from blogs/filmaker/videosites across the net and maybe we can cement this right here, right now. Now, from what I've gathered, you could only get 1920x1080 HDMI output from the new HDR-SR1 and HDR-UX1 because their imaging processing chips are newly designed for AVHCD and they are different from the HDV image processing chips from the V1U and HC3. The reason for this new design is because the AVHCD standard supports up to full 1920x1080 where as the HDV standard only supports up to 1440x1080. Even though all 4 cameras have the same kind of CMOS that captures 1920x1080 at the start both the V1U and HC3 have image processors that, by design, limit HDMI out to 1440x1080 because the resolution is being converted before it hits the HDMI. Hence the reason you see Sony's flashy new black & gold FULL HD1080 banner plastered all over the SR1/UX1 but not on the HC3/V1U.


Now I could be reading this wrong but I gather you're basically saying the HDMI image output should be the same as the SDI and component because they're being driven by the same data stream?

The diagram at the sony V1U site http://bssc.sel.sony.com/BroadcastandBusiness/minisites/HDV1080/HVR-V1U/devices.html
seems to contradict this as it shows the component out AFTER the image has been converted to 1440x1080. Wouldn't this contradict what you're saying about component data stream being the same as HDMI? Unfortunately this diagram doesn't label where HDMI out is in the chain.

The bottom line HDMI question here seems to be, as I know this is still a confusing subject for a lot of people on the net, what do the following resolution size do the following cameras output through HDMI?
Sony V1U
Sony HC3
Sony SR1
Sony UX1


The native HDMI output from all these cameras is 1920x1080i YCbCr 4:2:2 with 8-bits of resolution (same as HD-SDI). It is possible to force the output to RGB 4:4:4 but this does not any additonal color resolution.

The compressed HDV/AVCHD video is 1440 x 1080, but is automatically resized to 1920x1080 before being output to the HDMI port or to the analog component encoder. HDMI does not support a 1440x1080 video format.

Using our HD-Connect MI box we can get either 1080i, 720p or 480i/576i out of the HC3 camcorder. While we have not tested these modes on the other camcorders, we are fairly certain they all perform in a similar manner. Note that the HC3 does not list 720p as an output option, but we have found a technique to coax this output from the camcorder.

Ultimately, I think the analog connections will disappear completely and we'll move to serial digital formats like HDMI and HD/SD-SDI. They include both the video and audio and offer no degredation of the signal (no A/D and D/A conversions). They also can be less expensive to implement. Connections are also simplified (only one cable).

I am working on an update to our HDMI white paper with a compatibility chart for playback of Sony, Canon and JVC tapes in the variious camcorder and decks. Bottom line, HDMI offers far more playback options compared to 1394. The Sony M25 deck, for example, can playback JVC 720p30 tapes through HDMI, but not through 1394.

Shouldn't the SheerVideo Codec allow you to get away with maybe an inexpensive 2 disk RAID?

I have never heard of anyone doing live capture using SheerVideo codec. It would still need a fair amount of drive speed and space. ProspectHD is a proven codec for this application. It can do 10-bit although only 8-bit is needed. Its downside is high price and a fast PC for capture. I think it can capture to a single 7200rpm drive, but who wouldn't want to use a cheap big RAID 0, for overall speed.

The answer is in the 4. Luma is sampled at full resolution with both compression schemes. Most of the luma signal is translated into the Green RGB channel, resulting in sharp detail in this channel vs blockier data in Red & Blue due to color compression. So, if you select your background and subject colors to maximize luma contrast, a sharp image is passed through to the green channel.

The Green channel should be virtually white for a green screen, so using a dark subject provides lots of high-detail contrast to work with, resulting in a better starting point even for color difference and vector based keyers like Keylight and Primatte.

If you put a bright subject in front of a green screen, though, there's little-to-no contrast in the green channel to work with. Your color keying operations end up being based on the blocky data in Red & Blue. This is why it's helpful to use a bluescreen for bright subjects. The green channel for a blue screen is almost black, so the bright subject provides lots of high-detail contrast in the green channel, again helping your keyer independant of color compression.

You'll still be battling artifacts from the lens, sensor, A->D converter noise, and post processing like in-camera sharpening (which is why my instinct favors the idea of using the A1 vs a consumer targeted hand-cam) but by setting up your scene this way, color compression itself becomes less of a factor in calculating your compositing keys.

This is a great explanation Nick. Appreciate it.

The native HDMI output from all these cameras is 1920x1080i YCbCr 4:2:2 with 8-bits of resolution (same as HD-SDI).

Awesome. Thanks for answering that.

HDMI does not support a 1440x1080 video format.

Good to know.

I am working on an update to our HDMI white paper with a compatibility chart for playback of Sony, Canon and JVC tapes in the variious camcorder and decks.

That would be very handy I'm sure.

I have never heard of anyone doing live capture using SheerVideo codec. It would still need a fair amount of drive speed and space. ProspectHD is a proven codec for this application. It can do 10-bit although only 8-bit is needed. Its downside is high price and a fast PC for capture. I think it can capture to a single 7200rpm drive, but who wouldn't want to use a cheap big RAID 0, for overall speed.

I'll be honest I have zero experience with the Sheer codec. I just came across the website the other day and it claims on the homepage that you capture HD video using a two-disk SATA RAID, while encoding or decoding on the fly in real time. Do you have experience capturing with the Sheer? Did it not work for you? Seems like an inexpensive solution if it works.

Never used it for capture, only in AE for render when I was beta tester for the PC version a while back. I notice that they do now promote the codec for HD capture on a two drive array on their web site, as you say. That is exciting news given its lossless quality and price. It is hard to pin down the numbers but it seems to be a 55-60% space savings over uncompressed 4:2:2. This is still a fair sized chunk, but might now be the leading candidate for a home brew portable uncompressed capture PC. Which is what we all want isn't it?

I have never heard of anyone doing live capture using SheerVideo codec. It would still need a fair amount of drive speed and space. ProspectHD is a proven codec for this application. It can do 10-bit although only 8-bit is needed. Its downside is high price and a fast PC for capture. I think it can capture to a single 7200rpm drive, but who wouldn't want to use a cheap big RAID 0, for overall speed.

I've done live SDI (raw) capture to the Sheer codec with a single SATA drive. I can only capture to the outer sectors of the disk for maybe up to 10 min. without dropping frames, but 2 drive SATA raid can definitely do it...and the quality is truly lossless compared to uncompressed.

Edit: btw, the codec is 50% off for a limited time right now. Well worth the $!

Here's an email I got from bitjazz:

Hi Barlow Elton,

anniversary sale:
To celebrate the 4th anniversary of SheerVideo, we're offering a discount of 50% through January 14 through our online store:

http://www.bitjazz.com/en/shop/sheervideo/
new website:
We've completely redesigned our website for ease of use:

http://www.bitjazz.com/
new version: v2.4.9
The latest version of SheerVideo fixes important bugs on Windows and Mac:

Windows color-shift fix
Final Cut Pro 5.1.2 crasher fix
For details, see:

http://www.bitjazz.com/en/support/sheervideo/release_notes.php
download:
You can download the latest version through our website:

http://www.bitjazz.com/en/products/sheervideo/
Mac universal edition: soon
We plan to release a “universal binary” edition for Intel+Mac by the end of January. Customers who buy SheerVideo Pro for Mac OS X now will receive a free upgrade to the universal edition.