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Old March 22nd, 2006, 04:37 PM   #1
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Uncompressed vs. DV

I am currently using DV video - going out from a DVD player with Component video into my ADS pyro a/v link converter and into FW into my computer. (I know DVD isn't the best video source, but it's what I have to work with).

This signal brings in a video that is somewhat faded and a little bit off center. I'm not actually sure if this is because of the analogue to DV converter or the mini DV codec or the DVD player.

What I have to do right now is, before rendering my finished edited video to MPG I must put a brightness/contrast and HSL color filter on the video to make it the correct colors, as well as a crop effect with a 16% grey underneath (thanks Jimmerson and Eagle) to get rid of the jagged frame edges. This produces a great quality finished product, but takes about 4 hours per 1 hour of video to render (ouch).

I talked with a resailer about buying a decklink card and a very expensive SCSI array to use uncompressed video. He was very honest and told me that the SCSI was not my bottleneck in the rendering process....it is my processor. I have a P4 3.4ghz...so the only thing significantly faster would be a 64 bit processor. Does anyone know how much faster this is?

Even if the SCSI and uncompressed really won't increase render time that much per say...I am wondering if they would eliminate the need for certain filters and therefore decrease them by default. Could anyone who has experience with both of these types of input tell me if uncompressed handles colors better? Does it get the frame alignment more accurate?

Or does the DVD player you are using have anything to do with it? If there is a DVD player out there that lets you adjust the color settings or align the frame to the screen, or either one of the two, could someone please let me know? I would buy that right away, because they are not that expensive...also someone mentioned that 12-14 bit was the highest quality DVD player...I have no idea how much mine is or where in the owner manual to find it.

Thank you in advance for any info you can give me.
I'm not going to edit mpgs in womble.
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Old March 22nd, 2006, 06:24 PM   #2
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He's right -- rendering with Vegas is all CPU. Not even RAM affects it that much. Video cards don't matter, SCSI arrays wouldn't matter, Decklink doesn't matter . . .

(And it's not a "16% grey" underneath -- it's an RGB value of 16, 16, 16 out of a range of 0-255. 16% grey would be approximately 40, 40, 40, at least as counted up from black.)

A 64-bit processor in and of itself doesn't mean much without a 64-bit operating system or 64-bit software, but the AMD64s all rate as very fast with any software -- especially the dual-core X2s. I run an X2 4400+ myself, and I'd highly recommend it.

But yeah . . . you want to get the fastest processor you can.

You also want to disable everything running in the background while you render -- especially virus protection.

Keep your video on a separate drive from your operating system and software, but for DV, it doesn't really need to be anything more than a 7200 RPM IDE drive. You don't need a RAID.

I don't know why your picture would be off center; I don't think it's a function of the DVD player or the DV codec.

As for the contrast, brightness, etc., that's likely the difference between seeing something on a TV and seeing it on a computer. If you check the Color Corrector presets, you'll find one called "Studio RGB to Computer RGB," which is meant for correcting video for display on a computer monitor. It brigthens the picture a bit, saturates the colors, and crushes the blacks a little (increasing contrast), which is probably exactly what you do with the corrections you've developed yourself.

But be aware -- it optimizes it for viewing on a computer screen, not a TV screen. Always preview out to a TV to see if your color changes look good on one, because they are NOT the same thing, and you can't trust any color correction you do on a computer screen to look good on a TV.

I don't think the DV codec is hurting you at all, but then, I don't know what kind of color space the component-in is bringing in, and maybe uncompressed will preserve color better. (Don't know.) But MPEG-2 isn't as robust a codec as DV, even in terms of color fidelity, so I can't imagine that going uncompressed would be advantageous over DV.

It's certainly not going to help your render time by going uncompressed, and your playback framerate will suffer, too.
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Old March 26th, 2006, 07:03 PM   #3
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Disabling virus protection did help.

Ignoring the speed issues for a second. What about quality? It's pretty expensive to switch to a uncompressed setup - does anyone know if the quality is that big of a difference?

There are other options for quality I might consider. I have a pretty cheap ADS pyro A/v link for analogue to digital conversion.

1-Cannopus makes a number of products (starting with the ADVC300 and going up) which advertise a variety of adjustments to image stabalization and color correction for the incoming signal. Seeing as how these products start at around 500 dollars and go (way) up from there, they must be better quality than my pyro a/v link which I got for less than 50.

2-Also, I don't know if the decklink pro can capture DV video, but if it can, that might be even better, since it would come out of the component outputs of my DVD player and straight into the card, instead of through a converter, into a FW into a card.

3-Do they make DVD players with FW output? Would that be even better than coming out through component?

I honestly don't know, because while I know that DVD's are an optical media holding a digital mpg file, I don't actually know if playing one on a player creates an analogue or digital signal. I'm guessing it's analogue because DVD players traditionally have analogue video outputs, but I don't know.

If anyone who has experience in these different capture methods or who knows something about the clarity of signals, could please let me know which one of these three methods (if any) would be the best, I would really appreciate it.

I am not going to edit mpgs in womble (even if it is the best signal) because fine editing is NOT possible.
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Old March 26th, 2006, 08:45 PM   #4
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You could save yourself a wad of cash and export the MPEGs as AVI and then edit those. Chances are, the quality will be about the same as bringing in the signal analogue, and it'll take less time than brigning them in over analogue in real-time.

Try it and see.
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Old March 26th, 2006, 09:45 PM   #5
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I've tried many different converters and it always brings them in completely out of sync - and not just a matter of pushing it over a few frames - I mean the video and audio are different sizes - and sometimes the audio just won't play.

Have you used a converter that doesn't have these problems? If so, what is it and what video and audio compressions do you use? I think I've had the closest success with video using the panasonic dv codec...but still it came in out of sync with the audio.

Thanks, I'll give this method a try again...if I can get it down pat and with good time then I'll go with it - if I just have to decrypt and convert the vob's to avi - that would be quicker. But if it's something that requires time consuming resyncing and additional reconverting and so on, I'll spend some cash and get a better capture device - time is money.
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Old March 26th, 2006, 11:57 PM   #6
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Your levels problem:
There's two different color spaces when working in Vegas:

Computer RGB, 0-255
Black should be at 0, white at 255.

Studio RGB, 16-235
Black should be at 16 (i.e. 16 16 16 RGB), white at 235.

If you encode a DVD straight out of Vegas, the DVD encoder expects Studio RGB levels.
When decoding DV (i.e. from your firewire device), the levels depend on the DV codec being used. You really have to watch out here. The Sony Vegas DV codec decodes to studio RGB. Most other DV codecs don't do this. I don't know what the Panasonic codec does, it might say in the Vegas manual. In any case, you likely want to use the Sony Vegas DV codec.

Related information + instructions on how to do exactly that:
http://www.sundancemediagroup.com/ar...s_part_one.htm

2- Working with the DVD files digitally would give you the best quality.

I don't work off DVDs so I don't know what the fastest route for you would be.
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Old March 27th, 2006, 06:22 AM   #7
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Quote:
Originally Posted by Eric Stromblad
Have you used a converter that doesn't have these problems? If so, what is it and what video and audio compressions do you use? I think I've had the closest success with video using the panasonic dv codec...but still it came in out of sync with the audio.
I'm talking about pulling the VOBs off the DVD, onto the Vegas timeline, and then exporting AVIs from that.

Like I said, it probably wouldn't take near as long as playing the DVD out over analogue, and as for the quality, try it and see. I wouldn't think you'd need anything but DV AVIs -- going uncompressed won't get you much.
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Old March 27th, 2006, 11:52 AM   #8
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Quote:
Originally Posted by David Jimerson
I'm talking about pulling the VOBs off the DVD, onto the Vegas timeline, and then exporting AVIs from that.

Like I said, it probably wouldn't take near as long as playing the DVD out over analogue, and as for the quality, try it and see. I wouldn't think you'd need anything but DV AVIs -- going uncompressed won't get you much.
Dragging VOBs onto the timeline and converting them to avi will give me avi's with the same skips as the VOBS. It's like dubbing an old VHS to an HDVD and expecting it to become HD.

I think what Glenn Chan had said about studio vs. computer RGB is correct where my problems were.

Tv's are set to studio RGB and I guess DVD's hold that too right?

My ADS converter must be trying to read computer rgb and thereby making the black less black and the white less white.

I probably need to get a converter that has the option to switch from 0 IRE to 7.5 IRE (the same thing as studio vs. computer RGB from what I read). The cannopus advc500 has that, but maybe I can find something for slightly less. If not, I might get the cannopus.

I am curious: Are DVDs that are sold in north America set to 0 IRE or 7.5 IRE. I know that most players only output to 7.5 IRE but what is actually on the original disc?

Last edited by Eric Stromblad; March 27th, 2006 at 12:39 PM.
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Old March 27th, 2006, 01:53 PM   #9
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Quote:
Originally Posted by Eric Stromblad
Dragging VOBs onto the timeline and converting them to avi will give me avi's with the same skips as the VOBS. It's like dubbing an old VHS to an HDVD and expecting it to become HD.
What "skips"? The difference between editing in MPEG and editing in AVI is interframe vs. intraframe compression. Once you export as AVIs, you'll have intraframe-compressed videos to work with which won't give you the headaches of editing with MPEGs, as you've pointed out.

I never said they would magically be as if they were DV all along (your VHS vs. HD analogy); in fact, I said I didn't know how the quality would compare on the upconvert compared to bringing it in analogue the way you're, and that you should try it and see. The worst you'll lose in trying is a few minutes, and it may save you some steps and a lot of money if you're satisfied with the results.

Quote:
I think what Glenn Chan had said about studio vs. computer RGB is correct where my problems were.

Tv's are set to studio RGB and I guess DVD's hold that too right?
Yes, I referenced that in a post above. The video on a DVD is optimized for the color space of TV (studio), not a computer screen (computer).

Quote:
My ADS converter must be trying to read computer rgb and thereby making the black less black and the white less white.
It's in studio RGB that the blacks are less black and whites are less white.

Quote:
I probably need to get a converter that has the option to switch from 0 IRE to 7.5 IRE (the same thing as studio vs. computer RGB from what I read).
It's not the only difference. Computer RGB has more color saturation and more luma gain.

Quote:
I am curious: Are DVDs that are sold in north America set to 0 IRE or 7.5 IRE. I know that most players only output to 7.5 IRE but what is actually on the original disc?
The DVD player just plays what's on the disk. When it inserts the letterboxing bars, it assumes 7.5 IRE, but it doesn't monkey with the video. If it did, you wouldn't have seen the black banding you were referring to earlier.
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Old March 27th, 2006, 03:13 PM   #10
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Quote:
Tv's are set to studio RGB and I guess DVD's hold that too right?

My ADS converter must be trying to read computer rgb and thereby making the black less black and the white less white.

I probably need to get a converter that has the option to switch from 0 IRE to 7.5 IRE (the same thing as studio vs. computer RGB from what I read). The cannopus advc500 has that, but maybe I can find something for slightly less. If not, I might get the cannopus.

I am curious: Are DVDs that are sold in north America set to 0 IRE or 7.5 IRE. I know that most players only output to 7.5 IRE but what is actually on the original disc?
Hopefully this clarifies some things:
1- TVs usually have analog inputs, whereas studioRGB is relevant to digital formats. Analog and digital are two different things. The problem occurs when converting between digital and analog.

2- There might be two issues at work here:

7.5 IRE setup - this only affects black level. The effect is a little subtle.

studio RGB versus computer RGB- this affects both black and white level. There is too/much little saturation and contrast.

Or it could just be the second issue.

3- I would suggest following David's suggestion. Then you don't even need to worry about 7.5 IRE setup, and you can get the best quality possible.

To figure out studio RGB versus computer RGB, it's kind of easy: In Vegas, the Color Corrector has presets for Studio RGB <--> Computer RGB conversions. Burn a DVD 3 ways (studio to computer, computer to RGB, and no conversion). The one that looks right is the one you should go with (be sure you are using the footage from your DVDs).

4- DVDs store video in digital form. You can get problems in two places:
A- Converting your Vegas footage into DVD form. This is where the computer RGB / studio RGB issue comes into play.
B- The DVD player needs to convert from digital to analog. Here, it may convert digital black level to 0 or 7.5 IRE (IRE is an analog unit). DVD players generally do this correctly, so don't worry about this. Just worry about making the digital levels correct.

5- So you may be wondering... where is 0 / 7.5 IRE setup an issue? It's an issue when you want to monitor footage out from Vegas on an external monitor.
Most DV devices translate digital black level to 0 IRE. Your monitor is expecting black level to be at 7.5 IRE. What I suggest is to set your monitor to expect black level at 0 IRE. The levels article I linked to has instructions.
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