Uncompressed capture using S-Video

N

novelt

Well-known member
Okay I decided to start a new thread because this explanation might get lengthy. First this came about because during a shoot I was watching the field monitor and noticed that on playback the playback image didn't match the live image. So I pondered would it be possible to capture/record from the S-Video port and avoid the DV compression. Of course the answer is yes, because products by Decklink and AJA and a few others have offered uncompressed capture for awhile, but I was looking for something small and affordable. I just discovered ADS Tech - Video Xpress and it captures uncompressed AVI, compressed AVI, MPEG and WMV. It came out last summer. Here's a sample:

comparison.jpg


Now this isn't for the faint of heart :-) you need a fast CPU and a fast drive that can support a write speed of over 15MBs per second. I was using a Laptop with a Pentium 4 and dropped 7 frames a second on average. I'm still working that out. The above image came from a 49 second recording that ended up being 799MBs in size. The DV was smaller at 169MBs.

Now this is in no way a comparison of what you can get with the Andromeda. Although this whole HD thing is a bit overstated because it isn't the Andromeda giving you HD it's coming out of sculptorHD. The Andromeda wil give you more color space at 4:4:4, but you already know that. Understand I'm not knocking the Andromeda I like it, but if I had to choose between that and an HVX...it's the HVX. Plus I value my warranty :) What would be nice is if Panasonic released a DVX100C that had Component outs.

I'll admit this since it's an analog capture you can adjust the settings, something you can't do with DV. So I was able to match the capture to the LCD and get the image I was looking at on the monitor. Now in that sense that's similar to how Andromeda works because through sculptorHD you can adjust/set your output.

A few things I learned...though it's uncompressed it still needs a codec to be read and written. The default codec for YUY2 is the microsoft msyuv.dll. In my original test the microsoft codec didn't perform well, but the PC was a 1.8GHz Celeron. On the laptop with a 2.4GHZ P4 the microsoft codec performed much better. Though I did experiment and found that the microsoft codec wrote the frame rate at 30.99fps and when I changed the codec to the Intel ir41_32.ax it wrote the frame rate at 29.98fps. Now on the PC the Intel codec performed much better. Even in Premiere the microsoft codec played the files and gave them a webcam look, where the Intel played back with much better clarity. I'm now using the HuffYUV and honestly it's display is about the same as the Intel. I have yet to record/capture with it..that's next. I also learned that you can change the value of what's being used to display codecs (that's not right) but what I mean is in the Windows registry if you're tired of the microsoft DVSD if you get another DV codec then change the VIDC.DVSD value to your new DV codec, but you need to change the preferDScodec value in the prem60ini. Ah but let's not get into that. Finally I thought DV was RGB and it's not. DV is in the YUV color space at 4:1:1. YUY2 is YUV, but it's color space is 4:2:2. Oh and Premiere 6.5 and lower will capture analog with adobe certified cards, but Premiere Pro will not it's strictly DV at least that's what I saw.

Here's one main difference - good or bad - that I noticed.

blowup.jpg


In the YUY2 there's more of a bleed in this case the orange. I had another sofa shot where the red crept just a tad. On another zoom I did see that the YUY2 capture did have a faint pattern to it, but wasn't as blocky as DV. Anyway for $39 to $59 you can record uncompressed from either the S-Video or the Composite (Obviously the S-Video) and get pretty good results.

Questions, suggestions, or even corrections gladly accepted.

Just wanted to add that these pictures are untouched. Granted on capture the uncompressed footage was adjusted to match the DVX100 LCD screen, but nothing else. I even tried to alter the DV footage to match the uncompressed and did get close, but it didn't match in detail and when I did a Hue, Saturation, Lightness split. The DV hue was very noisy.
 
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i've posted this on a lot of forums and i guess it meant something because the company is pushing more of them. has anyone here checked it out or bought one?
 
jason...

if you're meaning the a/v link...i don't know...well if you had analog capture on your MAC then yes. by the way are you getting component out with it? if i go analog in and try to get component out i get nothing and using DV-in the green channel is distorted - mine might be defective. everything else works great the component-in sends to every out and the analogs send to each other. okay going off track...

you'd have to s-video from the cam into the a/v and if you had component use that over the s-video, if not use the s-video to your capture card. then you'll have uncompressed footage. if you go DV to the a/v then you're compressing down to DV and the a/v converts back to analog. worth a test though.
 
okay i'm closer to a portable working solution. i bought a WD SATA drive from newegg - $89 it's 250MB with a max transfer speed of 300MBps. i bought a SATA enclosure from CompUSA - $39, but it's rated at 150MBps and finally a SATA cardbus from amazon - $47.

I seriously reduced the amount of dropped frames to about 1 every 4 seconds. still not totally acceptable, but better than what it was. i think i may need o increase the RAM because ADS Tech does recommend 512MB and the laptop i'm using is 256MB.

anyway here's a shot/still from earlier this evening...

flowers.jpg


oh and i think the capture utility i'm using is deinterlacing the footage, but there's no settings for me to change. so i'm guessing that deinterlacing is just one more thing the CPU is doing so that may be affecting the speed. by the way the data transfer of the video went from 15MBps to 19MBps...how did that happen?
 
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So what are the size of the .AVI files you are capturing?

I must have misunderstood your original post. Were you saying that the footage was 800 meg a second?
 
the footage is averaging 15MBs per second, but strange last night as i said above it was 19MBs per second. i'll be doing more tests tomorrow after getting some more RAM. i'm looking for a different capture utility because the ULead VideoStudio is deinterlacing the footage and i can't change it...i have the SE version so i don't have the full features. anyway will be trying the microsoft capture 9 utility and then mess around with some others and see which provides the best results.

as for file size the cap above was from a little over a minute and was 1.1GBs in size...which is a good "byte" of space :grin:, but i've got plenty of room on my SATA drive :thumbsup:

and this is strange, the uncompressed data was going at 19MBps and not the previously mentioned 15MBps.
Click to expand...

:) i was searching for another capture utility when i came across this other forum and this guy jukka posted an explanation of how fast uncompressed video is and it made complete sense here's the short version...

1) 720x480 = 345600 pixels
2) with 8-bit 4:2:2 chroma subsampling each frame will take 345600 for the "Y" channel, 172800 for the "Cr" channel and another 172800 for the "Cb" channel. total 691200 bytes.
3) at 30fps that would be 691200 x 30 = 20736000 bytes per second, which is 20250 kilobytes per second, which is 19.77 megabytes per second.
Click to expand...

so now i think that maybe the frames i was losing affected the transfer rate the first time around. either way now i know.

EDIT:

found the setting for the deinterlacing. so now i fixed that.
 
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I completely forgot I was a part of this thread. Ha! I'll have to take a look at my Pyro and see what I can do with it.
 
Interesting.... I didn't think the analogue outputs bypassed the color decimation....

Very interesting..

Any chance you could shoot a simple green screen shot in DV and captured analogue (and post some grabs of course for us to experiment with!)? Keying would be a really useful test of what is really going on.
 
ahhh shaw...that is exactly what led to all this. the original shoot we were doing a green screen and i was watching the monitor during the shoot and thinking this is going to be nice, but when i played the tape back there was some serious green bleed. so that will be my next step once i clear up this dropped frames issue...i fixed the deinterlacing and now it looks even better because it's full resolution.
 
okay whew i did some shots today...ah wait first things first. figured out how to stop the deinterlacing that was going on. granted it's still doing it in a sense because the setting is "deinterlace method:weave"...anyway...this grab (nothing special) is from the day before yesterday. full resolution. the before i had captured using the default settings so there's little color and the picture is less sharp and darker. on the CC i didn't do much except saturation, color balance, and levels.
bna-post.jpg

then today...whew 5 shots, but guess what on one of them i only dropped 6 frames. that's really good because the area the frames were dropped were at the beginning of the capture. kinda like when the dvx first starts to record the button flashes then goes steady. well the capture program the screen blanks out and then comes to life that's were my loss is because after that pure uncompressed full resolution video with every frame intact. i'll go more in depth later...this shot i boosted the saturation and raised the brightness and sharpness just a tad. on the CC didn't need the saturation so just color balance and levels.
soclose.jpg

now this i'm posting just because the above is a bit soft. the camera was moving so there's a slight blur.
livingroom.jpg


okay explanation. i first thought that with the capture settings adjusted maybe i was asking too much of the CPU so i dropped it to default. yes it did alter the transfer rate a tad, but i was still dropping frames. i really don't know what my settings were (overall) i know what the saturation, brightness, and sharpness were, but i had changed some things on the laptop...those i don't remember. so my presumption is maybe dropping it to default was causing the CPU to rewrite the image data because on the DVX screen it is more colorful and brighter. so i changed those settings to match the screen and that's the capture that worked out...more tests tomorrow will confirm that and if that's right then the green screen will be here shortly :) if there was a way to set it for "as-is" coming through the pipeline then there'd be less processing for the CPU.

CC - when i started to color correct the footage i don't know, but it looked different. it just was a bit more vibrant and i'd have to attribute that to the fact the color space is 4:2:2 instead of 4:1:1. it's not 4:4:4 but i'm happy with it. what's even more impresive to me was i took the "saturated" capture and added the quicktime HSL saturation and geez got even more color without muddying up the picture. it was too colorful though, but to know it can be done...wow.

just a quick aside the bottom two don't match in color. i did them at separate times. oh and my big mistake white balancing the window and then making a 180 and shooting the sofa which is being lit by the yellow halogen...my bad.

hopefully all shots tomorrow are either no dropped frames or 10 or less at the beginning. if it is then i'm in business...and for those that care you could do this with a desktop and more than likely get no dropped frames. i'd test that, but my desktop CPU isn't as fast as the laptop so that test would be tainted and i don't have a SATA port on my desktop. however on a desktop using a PCI USB port you'd get better results...at least that's what i've read on the 'net.

so tomorrow will be the judge.
 
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okay i forgot to do something...change the process priority of the capture program...but one of the five i lost 10. the others were about the same i lost 1 every second or so. tomorrow i'll do the process change and see if that does anything. i just wish i could turn off the audio/video preview. so tomorrow and then in a few i'll find something to do a greenscreen on...oh wait i have an idea. for now today's grabs...
egg.jpg

cat.jpg

i know, i know...get out of the living room.
 
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This is really awesome, thanks for doing all this testing. On your potential recommendation I've ordered one of those devices as well (I have other uses for it even if it doesn't turn out for some of the DVX work).

I'm shooting a series of shorts coming up done entirely in front of greenscreen, so I'm really hoping this works out well for that. I can record straight on to my desktop, which should give me the power I need to avoid dropping frames, if that's the problem. I'll be happy to add the information on my own tests once I get them done, although that may not be for another few weeks at least. Please keep us updated, and thanks for all this!
 
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by all means let me know about your desktop setup/capture. i think if you use a pci card with usb that will be better than my setup, but i'm sticking with the laptop for portablility.

i'll be doing some greenscreen shortly...i haven't solved my dropped frames issue, but i think i can work something out. do you know of any other software that captures analog using i think it's WDM or the directshow capture utility. the VFM doesn't work...well i need to be sure of that...i tried capturing with premiere it did recognize the device and even showed playback during capture, but nothing recorded - though the progress was working as if it was.
 
Even if you get rid of the DV artifacts, the chromares gets so low with S-video I dont think its a good idea to capture this way.
 
the color space is 4:2:2 how is that lower than 4:1:1??? it wasn't all about artifacts it's about having more color space to work with. which improves color correction, which makes for a better image.
 
I'm not sure exactly what you mean by chromares... As I understood it, the Color would -in some ways- be better through S-Video because of the 4:1:1 "chroma subsampling" of mini-dv, while kicking it out via the s-video would leave it 4:2:2. I'm not that knowlegable about this though, so you may well know about something I don't. I know the overall quality will be a little worse, but for my all-greenscreen purposes, I think an improved chromakey situation is more important than the higher quality of the elements being kept.

Novelt - To answe you question about my system, I'm going to be saving it on a Pentium D 930 (the 3 gighz dual core) with 2 gigs of ram, on a SATA HD, with the capture card you started out the thread speaking about. I'm not sure if it's going to able to prevent the frame dropping issue, but we'll find out.

I'm not sure if I'm going to be able to do any of my testing until Next weekend though, so let me know if you get anything else figured out, and I'll let you know what I come up with as well.
 
I've gotten my own little VideoXpress box, and it sounds as though I'm having many or most of the same issues you have so far.

I installed the HuffyUV codec which Ulead is able to find to use, but if there's a wqay in windows to make it the "absolute YUY2 codec for viewing purposes, I don't know/understand how that works.

a) The included software, Ulead Videostudio 9 or such, captures it at 31.something fps, despite my setting it for 29.97.

b) If I try to capture through Premiere 6.5 it will display the video preview, but doesn't actually capture anything, as you described. Haven't been able to solve that problem.

c) All the footage looks very dark, and if I raise the brightness in the capture through Ulead it looks brighter but very... "faded", I guess, as video tends to do.

d) I'm dropping about one frame per second, so I don't think it has anything to do with my hardware specs, although it Could in theory have to do with USB bandwidth.

I'm still messing around with it... Have you discovered a way to deal with any of these issues yet?
 
on average i've captured around 30fps, but once i did actually get 29.97...that i don't understand.

as for dropped frames...i was thinking a hardware encoder would help, but you're using a desktop right? are you using a pci card or a port on the motherboard? one thing i also considered since the preview window is being updated by the CPU i thought closing it would help, but you can't close it. however i used MS media capture 9 and with it you can turn off the audio/video preview, but i still dropped frames.

the thing i like (if i can get it to work perfectly) is that once you set it...the recorded footage is as-is and you don't have to color correct later. that i like plus the added benefit of the color space. i've contacted ADS Tech about it and oddly haven't heard from them...well i got the "someone will get to you shortly" email...in the past i've gotten quick responses. so in my optimistic view i'm going to presume they're working on it. :)
 
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