Problem with vegas capturing video from DVX

[Miguel Lopez]

Hello people. Please check this image:

www.bachibuzuc.com/vegasproblem.tif

This is one of the many clips that are not very well captured with vegas. The problem as you see is that the red color is unaceptable bad.

I have seen this problem also with interalced video from canon xl1 in ulead video editor and vegas 3. But with dvx100 progressive video, it is even more obvious that the red color is not very good captured.

So what can i do? Do you guys have the same problem?
Any help?

[Don Donatello]

when you transfer from TAPE ( camera) to hard drive over 1394 only DATA is transferred.

IMO there is nothing wrong with the color RED ?? perhaps what you are objecting to is the INTERLACING around it ... i see that your preview windows says preview 720X576x32 ; 25.00i .. also the project has the same spec's ..
it appears you have your project set up as INTERLACE not progressive. try setting it up as progressive ..Vegas 4.0b is set up to handle the DVX 24p ...
i assume you have the PAL version so in V3 or V4 .. to change your current project to progressive FILE /properties/ Video then change the field order to PROGRESSIVE ...

to set up new projects FILE /NEW/Video ..change field order to PROGRESSIVE if you want all NEW projects to be set up as progressive be sure to CHECK the BOX "start all new project with these settings"

sorry for above i assumed that because you shot with DVX you shot progressive ... but appears you shot INTERLACE ...

[Miguel Lopez]

Let see. It is not a problem of the vegas settings.

I am using PAL as you can see.

When you outputs d video via firewire from the camera, the computer software has to recompress it all again. Forget about the loss of quality with iee1394. THere is always a recompresion using the software that you use.

The red is not well handled with standrad dv codecs and things like the picture y posted occur. It is not a problem of setting fields in vegas.

[Don Donatello]

sorry but you are mistaken. when you output from camera over 1394 the computer software does NOT recompress it ... the camera compressed the data when it recorded the imges to tape ... from tape the DATA is transferred to your hard drive .. the only thing your software does is put a "header" on the clip to say if it's a AVI if on a PC and a MOV header if on a mac.

sorry I asumed you shot progressive because this is a DVX 100 my mistake .....


WHAT is wrong with your REDS ??
RED color looks very good to me .. the only thing i see are interlace artifacts around the reds and according to your NLE it see's the clip as interlace ...

[Miguel Lopez]

i bet you 100€ that when you transfer video from the camera to the pc it is actually recompressed.

What are the comparison between same clips captured in differente programs (ie: vegas, avid dv, fcp, ...)

[Jeff Donald]

Don is correct, no recompression of data in just the transfer. Data is data, 1 or 0. The only time the data is altered is if the data is changed (graphics keyed, color correction, resized etc.). If you render then you change the data. Just putting it on your drive or viewing it in your NLE has no effect.

[Miguel Lopez]

Then how do you explain different DV codecs, and different image qualities with the same sources?

Right now i just did another try with avid dv express 3.5 and the artifacts that you see in the reds are minimized.

The truth is that computer recompress all over again when importing from the camera.

That is different when you work in the editing software and render a final video. Then, if the clips were not altered (filters, croping,...) the quality is the same, because there is no recompresion.

If you do not belive me go and try yourself. Find a very saturated red t-shirt, record it with your DV camera, capture the video, and without touching anything just take the video back to the camera. You can do this a couple times to enhance the loss of quality and you will se how the red becomes more soften.

Go to any website where capture images are compared between fcp and avid dv 3.5 and you will see how avid captures better than fcp and any other software. Why? If there is no compression? The reason is that there is actually compresion and avid uses his own "avid DV codec", wich is not microsoft nor quictime DV codec.

Bye ;-D

[Richard Alvarez]

SO the question is actually what are the diffences between various capture codecs?

[Jeff Donald]

Miguel, I will point you, where I've pointed many before you, to Adam Wilt's web site. Read the section on FireWire (IEEE 1394) and Hard Codecs vs. Soft Codecs and it should all become clear. If you have additional questions feel free to post again.

[Miguel Lopez]

I am sorry, but no one here has talked about hardware codecs. We are talking about software codec.

The question is very simple. Read this phrase from Bill Angstrom:
"...diffences between various capture codecs?"

CAPTURE CODECS. If it were just simply downloading video files, we wouldn´t use he word capture.

The video cameras companies have been saying since iee1394 was launched that there was no quality loss because it is all digital.

Well that is truth in only a way. It is truth that the firewire cable is digital and digital signals are the same in the begining and the end of the cable. there is no loss of data between conections as it happened with analog I/O.

the thing that they do not say is that recompression occurs when importing in the computer and when importing in the camera.

Again, you go and try the expirement i said and post the results. please

[Jeff Donald]

OK, since you don't want to spend the time to read and learn, I'll quote from it.

When capturing from or or outputting to DV VTRs using a 1394 connection, it doesn't matter what kind of codec you have. A DV-based editor stores the same data on disk that travels across the 1394 wire; no compression or decompression occurs. Thus when you're doing capture or playback across a 1394 connection, all you're doing is a real-time data transfer; the codec isn't even in the loop.

The codec comes into play when you need to:
# Render transitions, titles, and effects.
# Capture from or output to non-DV VTRs
It's here that the differences become apparent.

Rendering transitions, titles, and effects: to add an effect (say, a dissolve or wipe between two clips), the system has to take the two source frames, decompress them, perform the mix, and recompress the resulting frame. The soft codec takes CPU power to run, but the CPU has nothing else to do while waiting for the frames, so it might as well be involved. The hard codec runs in real time, but the CPU, once it has set up the data transfers, has to sit and wait for the output anyway. In early 1998, various vendors claimed a 25% speed advantage of hard codecs over soft codecs, or a 30% advantage of soft codecs over hard codecs, or whatever... Too much depends on other factors, like the speed of the computer's CPU, bus and bus interface chipset, to decisively say that one codec will be faster than the other in effects rendering. However, as CPUs and buses speed up over time, the soft codecs (which, unlike their hard counterparts, aren't limited to running at real-time rates) have taken the lead in speed for rendering operations; Canopus uses software codecs for multiple streams of realtime decompression in the DVRexRT and DVStorm NLEs, only using the hardware codec to recompress the output back to DV.

Capturing from or outputting to non-DV VTRs: hard codec systems come with breakout boxes that include analog (composite, Y/C, and sometimes component YUV) connections as well as 1394 connections. You can connect up any VTR format with analog I/O to the box and capture it in real-time or output to it in real-time. This makes it easy, for example, to bring legacy Hi8 or Betacam footage into the editor to intercut with newer DV material. You don't even need to have a DV VTR or camcorder around to use the system, as it has its own hard codec onboard.

[Miguel Lopez]

;-D yes i have read it. But i think that might be in theory, In the practice, there are differences between dv codecs, and the more you transfer for and from the camera the worst the image becomes.
I will give you some images that you probably have seen.

[Jeff Donald]

Sorry, its a fact. Every camera manufacture and every software company will tell you the same thing. There is no change if all you do is transfer the data back and forth over 1394. The term Capture Codec is a hold over from the early days of Avid when the source material was all analog. Today, with DV, there is no capture codec.

If there was a difference, don't you think Avid would be promoting their capture codec as the best? Avid doesn't do it (or any other company) because their is no capture codec over 1394.

[Miguel Lopez]

Actually avid dv express does include their own dv codec.

Check this comparison:
http://www.24p.com/codecs.htm

[Miguel Lopez]

Well, maybe i am wrong in all that i said, but this thing is the truth:

- when i capture dv video in ulead video editor and then back to the camera, a red car appear soften and not as good as the original one recored. If there was no quality loss in the capturing, where was it? (the video was not touch in any way).

- the same now with vegas and my dvx100

explain me something, please or i will get finally mad.-