Interesting results - DV Camcorders vs VIVO

[kb1985]

Hi,
I often capture some TV series from my VHS to PC. I've recently bought my Sony DCR-H30 digital camcorder with analogue video in. I captured some video using the camcorder as an analogue -> digital converter and compared there results with the same video captured by the cheap VIVO card. The results amazed me. Cheap VIVO card offered better quality than the digital camcorder! As a proof I have following printscreens of the same keframe from both files. I've chosen the one colour frame becauese the difference it's the easiest to notice here.

http://kb.e9.pl/fotosy/sieciowe/dv-vs-vivo/

Am I doing something wrong or are the VIVO cards really better than analogue to digital converters in Sony camcorders?

[adam]

Did you capture to RGB with the VIVO card? If so I think there is less difference then you think.

Tv's use a different colorspace then pc monitors. That dv pic you posted looks very similar to what happens when you display video formatted for tv (luminence range of 16-235) on a pc monitor. This is typical for DV since almost all DV codecs decode the video in this range.

If you captured to RGB with your VIVO, it will have used the full luminence range which is correct for your pc.

Basically, I'd dump the footage for each onto a DVD, VCD, etc.. and try playing it on your tv. Your results may change, but no it wouldn't necessarily suprise me if a relatively cheap capture card outperformed the pass-through function of a DV camcorder.

[kb1985]

The camcorder captures in RGB and the VIVO card captures in YUV2. I use Virtual Dub to capture through VIVO and Mainconcept Mpeg encoder to capture DV. Any ideas how to improve the quality of the footage captured through my DV camera? I don't feel fine with the results. Maybe I have to do something with the color space?

[adam]

DV is YUV. You may be decoding it to RGB at some point (if you encoded with MainConcept I think you had to) but the point is that you may be viewing it on your monitor in its native YUV luminence ranges, which will always look bad. I don't use MainConcept but look to see whether it has luminence levels settings. Maybe they are labeled 0-255 and 16-235? Try changing it to whichever option you didn't use before and of course do all of your final viewing tests on your tv.

The Mainconcept DV codec does decode DV in 16-235, I know because that's what I use and it will look just like that on a pc monitor when previewed. Of course it depends on what you are using to preview it....

[kb1985]

Maybe that's the codec matter? I use Panasonic DV codec. Tried to find sony DV codec but can't find one. Any hints where i could possibly get it?

I googled that Panasonic DV codec works in RGB only. No YUV2 support.

[Richard_G]

I use Virtual Dub to capture through VIVO and Mainconcept Mpeg encoder to capture DV.

Dv transfer using Firewire is just that, a data transfer. If you are using Mainconcept MPEG Encoder you are transferring a file and encoding to MPEG on-the-fly. What you are comparing is a DV file that has already been converted twice, once in the camcorder (from analogue to DV) and again in the computer (from DV avi to Mpeg).

I don't think you will find a Sony DV codec anywhere other than inside a Sony camcorder. You only need a DV codec loaded in order to view the DV footage and most find the Pansonic one to be one of the best.

[edDV]

I get much better results from the camcorder but my goal is DVD display to TV in a home theater environment. The DV camcorder realtime captures to YUV DV format 720x480 direct using CCIR-601 digital levels 16 black 235 white and 4:1:1 color space.

Cheap capture cards capture to 320x240 or 480x240 RGB in single field to avoid expensive motion detection processing for deinterlace. Half the fields are discarded.

To do a real test of video quality, convert the cheap capture to DV format and record back to the DV camcorder for A/B comparison with moving detailed source material on a quality TV monitor.

To test DVD performance, record the same (detailed motion) material both ways and encode to MPeg2 (same encoder - high quality mode) to DVD and see the difference using a DVD player to TV monitor. Don't use a RGB computer monitor for quality judgement.

I get near broadcast VTR performance from even a cheap Digital8 camcorder when analog recording from a high quality source like broadcast Betacam equipment.

[BSR]

Some one gave me a link to the Sony DV codec. I think I might have it at home. I know I have a small exe of it. Or at least that's what it comes up as in GSPOT.

Here is a link at the sony site that someone gave to me, but doesn't work on all computers.
http://ciscdb.sel.sony.com/perl/swu-download.pl?template=EN&upd_id=154&os_id=7&mdl=PCVR549DS
It was intended for Sony computers.
I tried installing it but 3/4 the way through it said not compatible.
Can't remember if it left the Sony DV codec installed or not. Might be worth a try.

EDIT- Sony DV codec.
Here is a link over at Doom9, see the 6th post on the page.
http://forum.doom9.org/showthread.php?s=e6a6085ea50dad3e264ca3fc762768c8&threadid=5811...0&pagenumber=1

[kb1985]

Dv transfer using Firewire is just that, a data transfer. If you are using Mainconcept MPEG Encoder you are transferring a file and encoding to MPEG on-the-fly. What you are comparing is a DV file that has already been converted twice, once in the camcorder (from analogue to DV) and again in the computer (from DV avi to Mpeg).

But I think that when I select "native device format" then data from the miniDV tape is just transfered to the HDD, without any on-the-fly operations. I think that because of the relatively big file (12,5 GB / hour) and I have to convert the file to TYPE 2 in order to have audio in Virtual Dub. That seems as a DV file, am I right?

[BSR]

kb1985 - I think you are correct on Native Device Format for DV.

Also -
I see DV is showing up wider on your vdub window than the VIVO?
Are these being displayed as 100% and the 4:3 aspect ratio? Just wondering.

[kb1985]

BSR - VIVO footage seems narrower because it is captured in 704x not 720x. It shouldn't affect the video quality.

I've just kicked off the Panasonic DV decoder and installed Sony DV. I hoped that the video will now be visible properly, but it didn't gave me any positive results. Do you have any other ideas? Maybe I should try different capture application instead of Mainconcept MPEG Encoder? Any different ideas?

[adam]

It doesn't matter what DV codec you use. With the exception of the Canapus codec, I think all DV codecs decode DV at its native 16-235 luminence levels. This simply will look incorrect on any standard monitor (non-NTSC monitor).

The solution is to do what EdDV said, don't use your pc monitor to make these judgments. Encode to some format that your tv supports and play it back there. Like I said, if one luminence level setting in your encoder isn't working, then try the other one.

If you really want to know what's going on under the hood, then you need to run some histograms on your sources to see what their luminence levels are. You could, for example, load the DV clip into a NLE like Adobe Premiere and check its levels. If it doesn't go past 16-235 then it will look contrasty and greyish like in your DV sample. Use the levels filter and expand this to 0-255 and it should look more like your captured output. But then you are just going to have to compress it to 16-235 again during encoding.

Basically, there is probably nothing wrong with your method or your DV passthrough quality. You are just judging the quality on a device which runs on a different luminence scale.

Have you tried just playing these clips on your tv?

[kb1985]

I've opend the footage in Virtual Dub and added the Levels filter. I've set the Input levels at 16-235 and output levels at 0-255. The file looked better but also not perfect. I tried to give there some various numbers in the "Input levels". eg. 50-200, 40-210 but it's just guessing the proper value. I don't know what should I set there.

You mean that I should it compress again to 16:235 during encoding to DVD? As i mentioned before I won';t be making a DVD of my files. I don't have the DVD burner and my DVD set can't read DVD-R's. I want to watch these files only on my computer screen. So you suggest that it is everything fine with the file, but the video just looks that way on my monitor because of the different ways of encoding colours? So all i have to do is to find proper values for "Input levels" in my "Levels filter"? Do I have to do something special while capturing the wideo? On the VIVO card I used Virtual'dUb;s histogram function to calibrate sound properly. Should I somehow calibrate the DV Camcorder? As far as I understand the data from camcorder is only copied, not captured. So it seems that there is no calibration of any kind.

[kb1985]

I remember that at the beginning, when I just started to capture video through my cheap VIVO card I found a tutorial in the net where it was said how to calibrate the VIVO using audio and video histograms in Virtual Dub. Problably that's why I get better results on VIVO.

So my question right now is:
1. Do I have to calibrate the camcorder?

2. If no, what should I do to have the proper colors? Shoudl I use the Levels fitler? ?If so, which value shoudl I set as "Input level"? 16:235 is not fine enough - maybe I should change the value that is in the middle (it's 1.000 now)?

3. How to open a histogram of a file that I already have on my HDD?

And one more thing. I have the PAL digital camera, because it's the video standard where I live. Is it still 16:235?

Thanks.